Calibration services brochure
Transcription
Calibration services brochure
MIKES METROLOGY Calibration Service International competitiveness and reliability Copyright © VTT MIKES 2016 Teknologian tutkimuskeskus VTT Oy PL 1000 (Vuorimiehentie 3, Espoo), 02044 VTT Puh. +358 20 722 111, faksi +358 722 7001 www.vttresearch.com 2 — VTT MIKES METROLOGY Calibration services VTT MIKES - metrology Mass, pressure, flow Calibration of weights.................................................................................... 6 Calibration of pressure measuring devices.................................................. 8 Calibration of force and torque................................................................... 10 Water flow meter calibrations...................................................................... 12 Calibration of gas flows and density of liquids............................................ 14 Acceleration of free fall............................................................................... 16 Temperature, humidity Calibration of hygrometers.......................................................................... 18 Calibration of radiation thermometers........................................................ 20 Fixed point calibration of platinum resistance thermometrs....................... 22 Electricity, acoustics Calibration of direct voltage and current.................................................... 24 Calibration of alternating voltage................................................................ 26 Calibration of capacitance and inductance standards................................ 28 Calibration of resistance............................................................................. 30 Calibration of power and energy at line frequency..................................... 32 RF- and microwave calibrations................................................................. 34 High voltage and high current..................................................................... 36 Acoustic calibrations................................................................................... 38 Time Calibration of time, time interval,and frequency......................................... 40 Optics Optical quantities......................................................................................... 42 Length, geometry Quantitative Microscopy - Atomic force microscope................................... 44 Characterization of nanoparticles............................................................... 46 Calibration of laser interferometers............................................................. 48 Interferometrical calibration of gauge blocks.............................................. 50 Calibration of gauge blocks by mechanical comparison............................ 52 2D- and 3D-measurements of form and surface roughness...................... 54 Optical measurements of surface microstructures..................................... 56 Calibration of tachymeters.......................................................................... 58 Angle and perpendicularity measurements................................................ 60 Measurements of accurate inner and outer dimensions............................ 62 Coordinate measurements......................................................................... 64 Optical coordinate measuring - vision measuring...................................... 66 Calibration of line scales and distance meters........................................... 68 Interferometric measurements of flatness and form................................... 70 Machine tools measurements..................................................................... 72 Measurements of roundness........................................................ ..............74 Calibration of microscopes and calibration standards................................ 76 Length in geodesy....................................................................................... 78 Water quality............................................................................................... 80 VTT MIKES METROLOGY Calibration services 2016 — 3 VTT MIKES - metrology MIKES Tekniikantie 1 02150 ESPOO MIKES-Kajaani Tehdakatu 15, Puristamo 9P19 87100 KAJAANI Tel. +358 020 722 111 (call center) Email: [email protected] www.mikes.fi Finland has a slightly distributed metrology infrastructure. MIKES is the National Metrology Institute and it acts as the National Standards Laboratory for most of the quantities. MIKES designates the other National Standards Laboratories and Contract Laboratories.. MIKES is a specialised research institute for measurement science and technology. As the National Metrology Institute of Finland, MIKES is responsible for the implementation and development of the national measurement standards system and realisation of the SI units in Finland. The MIKES building is situated in the city of Espoo and its branch office in Kajaani is the northernmost National Standards Laboratory in the world. The high-quality laboratories provide the most accurate measurements and calibrations – close to 1600 certificates per year – in Finland. The number of staff is 65 supported by VTT Ltd. administration. MIKES also performs high-level metrological research and develops measuring applications in partnership with industry. The activities of MIKES aim to improve industrial competitiveness, the national innovative environment, and public safety. • We realize SI-system of units in Finland • We do high level research in the field of metrology • We develop measurement methods for industry and society • We offer high level calibration servive, expert service and training 4 — VTT MIKES METROLOGY C alibration services 2016 MIKES is a signatory to CIPM MRA (International Committee for Weights and Measures, Mutual Recognition Arrangement) and a member of EURAMET (European Association of National Metrology Institutes). Through international collaboration, MIKES is linked to the international measurement system and to the European and international metrology research community. MIKES takes actively part in the European Metrology Research Programme (EMRP and EMPIR). The Metre Convention The National Measurement Standards System Electricity, acoustics, time, frequency, temperature, humidity, pressure, mass, force, torque, flow and length Photometry and radiometry Water quality Air quality Ionising radiation Length in geodesy and acceleration of free fall Figure 1. National measurement standards system in Finland. MIKES=VTT MIKES Metrology, Aalto=MIKES Aalto Metrology Insitute, SYKE=Finnish Environment Institute, FMI=Finnish Meterological Institute, STUK=Radiation and Nuclear Safety Authority and FGI=Finnish Geospatial Research Institute. Calibration and MeasurementCapabilities (CMCs)recorded in the BIPM keycomparison database,KCDB Acoustics: 30 Length: 59 Time and frequency: 11 Thermometry: 44 Optics: 53 Mass and related quantities: 28 Electricity: 99 Ionising radiation: 30 Chemistry: 5 Total Finland: 359 / total 24031 entries. Voluntary peer review project MIKES is a coordinator in the EURAMET TC-Q project Peer reviews of Quality Management Systems (QMSs). The other partners in the project are CMI (CZ), GUM (PL) and SMU (SK). The project supports the evaluation and improvement of QMS processes and procedures of the participating institutes. Learning from each other and sharing the best practice for QMS implementation are other goals of the project. The QMSs of the institutes are based on ISO/IEC 17025. A programme with on-site visits by peers is planned on an annual basis and one or twofields in each institute are reviewed every year. In 2012, the QMS of MIKES in the field of length metrology was peer reviewed by an expert from GUM, and vice versa. Also the humidity laboratory of MIKES was peer reviewed by a GUM expert. Source: BIPM, July 1, 2015, kcdb.bipm.org Figure 2. CIPM MRA -logo tells us, that our measurement results are accepted globally. VTT MIKES METROLOGY Calibration services 2016 — 5 Mass, pressure flow Temperature humidity Electricity, time acoustics Length geometry Optics Chemistry Calibration of weights Maija Ojanen-Saloranta, Senior Research Scientist, Tel. +358 50 443 4214 (Espoo) [email protected] Kari Kyllönen, Research Technician Tel +358 50 4434180 (Kajaani), [email protected] MIKES, Tekniikantie 1, 02150 Espoo MIKES-Kajaani, Tehdaskatu 15, 87100 Kajaani, Tel. +358 20 722 111. Traceability Measure methods The weight standards of MIKES mass laboratory are traceable via the Pt-Ir prototype number 23 of kilogram to the international prototype of kilogram kept at the BIPM. The comparability of measurement standards of mass laboratory is maintained by international comparisons (e.g. EURAMET key comparisons). We carry out research and development related to scales and weights and offer expert services on the usage of scales and weights. Our mass laboratories are of high quality and we have scales equipped with automatic weight handlers. Our laboratories are located in Espoo and Kajaani. The measurement range of mass at MIKES is 1 mg ... 2000 kg. The calibrations of weights are performed by using generally accepted weighing methods: the direct comparison method and the subdivision method. In the first method, the weight is directly compared to a standard and in the latter a set of weights is calibrated by using one or several weight standards. 6 — VTT MIKES METROLOGY Calibration services 2016 Calibration of weights Table 1. Measurement uncertainties of weight calibrations. Mass Measurement uncertainty (k=2) 2000 kg *) 3000 mg 1000 kg *) 1500 mg 500 kg *) 750 mg 200 kg *) 300 mg 100 kg *) 200 mg 50 kg *) 30 mg 20 kg 3.0 mg 10 kg 1.5 mg 5 kg 1.0 mg Calibration services 2 kg 0.3 mg 1 kg 0.05 mg 500 g 0.03 mg 200 g 0.02 mg 100 g 0.015 mg 50 g 0.010 mg 20 g 0.008 mg 10 g 0.007 mg 5g 0.005 mg 2g 0.004 mg 1g 0.003 mg 500 mg 0.003 mg 200 mg 0.002 mg 100 mg 0.0015 mg 50 mg 0.0015 mg 20 mg 0.0010 mg 10 mg 0.0008 mg 5 mg 0.0008 mg 2 mg 0.0008 mg 1 mg 0.0008 mg MIKES is capable to calibrate weights of OIML classes E1, E2, and F1, whose nominal masses are at most 20 kg (E1), 50 kg (E2) and 2000 kg (F1). In addition, MIKES offers calibration services for weights of lower OIML classes, whose masses are between 10 kg and 2000 kg. MIKES also calibrates other weights such as weights of pressure balances. In the calibration certificate, the masses are given as conventional masses or as true masses. The smallest achievable measurement uncertainties in mass calibrations are presented in table 1. Weights whose nominal mass is 50 kg or bigger are calibrated at MIKES Kajaani. Calibration of volume of weights When calibrating a weight, a correction due to the air buoyancy has to be made to the weighing result. The magnitude of the correction depends on the volume of the weight and on the density of air. In order to be able to make the correction accurately enough, the volumes of the most accurate weights have to be known. Mass laboratory calibrates volumes and densities of solid artefacts. The density standard is either distilled water or silicon. The measurement methods is hydrostatic weighing. The measuring equipment is suitable for volume calibration of 2-kg weights or lighter. If needed, volumes of bigger weights can be determined by using e.g. dimensional measurements. The measurement uncertainties of volume calibrations of weights are presented in table 2. *) Calibration in MIKES-Kajaani Table 2. Measurement uncertainties of calibrations of weight volumes. Mass 1 g – 2 kg Uncertainty (k=2) Volume 0.1 – 255 cm 3 0.000 3 – 0.008 cm3 VTT MIKES METROLOGY Calibration services 2016 — 7 Mass, pressure flow Temperature humidity Electricity, time acoustics Optics Length geometry Chemistry Calibration of pressure measuring devices Monika Lecklin, Research technician, Tel. +358 50 410 5516 [email protected] Sari Saxholm, Senior Research Scientist, Tel +358 50 410 5499, [email protected] Figure 1. Pressure balance is used for the traceable realization of pressure unit. MIKES has good capabilities to calibrate different measuring devices of pressure. The measuring range for gauge pressure is 0 ... 500 MPa and for absolute pressure 0.0005 Pa ... 1.75 MPa. The best measurement MIKES, Tekniikantie 1, 02150 Espoo Tel +358 20 722 111 www.mikes.fi standards at MIKES are pressure balances, which are used to realise pressure according to its definition p = F / A, i.e. pressure is force divided by area. The force is produced by the mass of the piston of the pressure balance and by the masses of weights loaded over the piston. The local value for the acceleration of free fall must be known. The area A is the effective area of the piston cylinder assembly of the pressure balance. Pressure balances are used for gauge and negative gauge pressure measurements and for absolute pressure measurements. To cover a wide range of pressures, several piston cylinder assemblies of different sizes are needed in order to be able to realise different pressures and to keep the number of weights still easy to handle. In pressure ranges below the range of pressure balances, capacitive sensors and spinning rotor gauges are used as measurement standards. The lowest pressures (absolute pressures 0.0005 Pa ... 2 Pa) are calibrated by using spinning rotor gauges. These measurements are demanding as they require long stabilisation and measurement times. Measurement methods and devices used for pressure depend on the pressure range. Figure 2. Pressure measurements are made in a very broad pressure range, for instance from 10-9 Pascals required in particle accelerators to over 109 Pascals, i.e. 1 GPa, pressures used in powder met-allurgy. Measuring devices and their operational principles are very different in different pressure ranges. The measurement range in MIKES is from 0.5mPa to 500 MPa and is marked with blue bar in the figure. 8 — VTT MIKES METROLOGY Calibration services 2016 Calibration of pressure Absolute pressure Gauge pressure Differential pressure Gauge pressure The reference point is the atmospheric pressure. E.g., the tyre pressure of a car is gauge pressure. Any gauge pressure can be converted to an absolute pressure by adding the momentary atmospheric pressure Atmospheric pressure Absolut pressure P=0 Figure 3. In practice, measurement of pressure is always measuring differential pressure. Depending on the reference point various names are used for pressure and diverse devices used. Absolute pressure The ideal vacuum as reference point (vacuum gauges). Atmospheric pressure Atmospheric pressure is the absolute pressure caused by the atmosphere so the reference is the ideal vacuum (barometers). Absolute pressure gaseous medium Pressure range (Pa) Relative measurement uncertainty k = 2 (%) Negative gauge pressure The reference point is the atmospheric pressure. When converted to absolute pressures, negative gauge pressure is thereby lower than the atmospheric pressure. Thus, negative gauge pressure means that the objects pressure is lower than the pressure in its environment. Differential pressure Pressure is called as differential pressure especially when the reference pressure is other than the vacuum or the atmospheric pressure. The reference pressure is then usually called as a line pressure. Gauge pressure gaseous medium Pressure range (Pa) Relative measurement uncertainty k = 2 (%) 0.0005 9 100 0.03 0.001 6 1000 0.01 0.01 3 10 000 0.004 0,. 3 100 000 (0.1 MPa) 0.003 1 2 1 000 000 (1 MPa) 0.002 10 0.5 10 000 000 (10 MPa) 0.004 100 0.1 16 000 000 (16 MPa) 0.004 1000 0.01 10 000 0.005 100 000 (0,1 MPa) 0.004 1 000 000 (1 MPa) 0.004 1 750 000 (1.75 MPa) 0.003 Negative gauge pressure gaseous medium Pressure range (Pa) Relative measurement uncertainty k = 2 (%) Figure 4. Piston cylinder assemblies of different size for pressure balances. Gauge pressure in oil medium Pressure range (Pa) Relative measurement uncertainty k = 2 (%) -100 0.03 500 000 (0,5 MPa) 0.005 -1000 0.01 1 000 000 (1 MPa) 0.004 -10 000 0.005 10 000 000 (10 MPa) 0.003 -100 000 (-0.1 MPa) 0.004 100 000 000 (100 MPa) 0.003 500 000 000 (500 MPa) 0.01 VTT MIKES METROLOGY Calibration services 2016 — 9 Mass, pressure flow Temperature humidity Electricity, time acoustics Length geometry Optics Chemistry Calibration of force and torque Sauli Kilponen, Research Engineer, Tel. +358 50 443 4178 [email protected] Jani Korhonen, Research Engineer Tel. +35850 443 4206 [email protected] MIKES, Tehdaskatu 15, Puristamo 9P19, 87100 Kajaani, Tel. +358 50 443 4213 www.mikes.fi Traceability and calibration of force VTT MIKES-Kajaani performs force calibrations from 1 N to 1.1 MN. Calibrated measurement devices are usually force transducers, force measurement devices, balances (eg. hook, wheel weight and airplane) and pull force testers. The smallest measurement uncertainty is 2×10-5. The calibration of force is based on the ISO 376 standard. The force calibration from 1 N to 110 kN is carried out in dead weight force standard machines. A dead weight machine is a mechanical structure that generates force by subjecting dead weights to the local gravitational field. Hydraulic force standard can be used in the calibrations from 20 kN to 1.1 MN. The masses that are used in VTT MIKES-Kajaani are traceable to the national standard of mass, which is in turn traceable to the international prototype of the kilogram held in the BIPM. Force traceability is realised from mass calibrations and international comparisons. Figure 1. A 1-MN hydraulic force standard and a 100-kN:n direct load force standard. The total height of the equipment is eight meters, including the load masses below floor level. Table 1. Measurement ranges for force. Load method Measurement range Measurement uncertainty (k=2) Direct load Compression/pulling: 10 nm ... 10 kN 2 . 10-5 Direct load Compression/pulling: 10 kN ... 100 kN 5 . 10-5 Hydraulic load Compression/pulling: 20 kN ... 1 MN 1 . 10-4 Field calibration of force 1 N ... 1 MN 5 10-4 10 — VTT MIKES METROLOGY Calibration services 2016 Calibration of force and torque Traceability and calibration of torque MIKES-Kajaani performs calibrations of torque in the range 0.1 Nm ... 20 kNm, the smallest uncertainty being 5×10–4. The calibration of torque is carried out using reference standards for torque or standards based on reference sensors. The need for torque calibrations can be classified in three groups of different types of devices. The most stringent accuracy requirement (< 0.05 % ... 0.5 %) is for calibration of torque sensors that are used e.g. in measurement of torque in research of rotating machines such as pumps and motors. The second group is devices used for calibration of torque-controlled assembly tools. In calibration of these devices, the uncertainty of the torque standard should not exceed 0.5 %. The third group is calibration of torque-controlled assembly tools for industries that do not have their own calibration devices. The calibration uncertainty for torque-controlled assembly tools is typically from 1 % to 10 %. There exist only a few standards for torque calibrations. For torque-controlled assembly tools is the standard ISO 6789, which however mainly describes test methods but also defines a cali-bration procedure. There is no standard for devices used for calibration of torquecontrolled assembly tools. For torque sensors there exists the recommendation Euramet/cg-14. Torque is a derived quantity that consists of known masses and a known length of a lever arm. Even though traceability for masses and length can be achieved separately, verifying the consistency of torque in entity is mainly verifying the consistency of torque in entity is mainly based on interlaboratory comparisons Figure 2. A 2-kNm torque standard used for comparison measurements in the range 100 Nm – 2 kNm and for calibration of torque sensors. Figure 3. A 20-kNm torque standard based on a reference sensor. Table 2. Measurement ranges for torque. Torque standard Measurement range Measurement uncertainty (k=2) Lever – mass 0.1 ... 10 Nm right/left 5 . 10-4 Lever – mass 10 ... 2000 Nm right/left 5 . 10-4 2 ... 20 kNm right/left 5 . 10-4 Reference standard VTT MIKES METROLOGY Calibration services 2016 — 11 Mass, pressure flow Temperature humidity Electricity, time acoustics Optics Length geometry Chemistry Water flow meter calibrations Mika Huovinen, Researcher, Timo Nissilä, Research Engineer, Tel. +358 50 443 4175 Tel. +358 50 415 5974 [email protected] [email protected] MIKES, Tehdaskatu 15, Puristamo 9P19, 87100 Kajaani, Tel. +358 50 443 4213 Calibration provides reliability Accurate liquid flow measurements are needed in many areas of industry, such as process, mining and energy industry. To maintain global competitiveness and high quality of the end products, accurate liquid flow measurements make it possible to optimise different industrial processes and in this way reduce raw material consumption and emissions to environment. Regular calibration and stability tracking of liquid flow meters are essential part of measurement reliability, regardless of the application. 12 — VTT MIKES METROLOGY Calibration services 2016 Figure 1. Graphical user interface of the D200 liquid flow calibration rig. Water flow meter calibrations Traceability The most important activities of MIKES Kajaani are to implement the traceability of the flow measurements in Finland, maintain liquid flow measurement standards, and provide calibration and expert services. These are achieved by participating in international and domestic research and intercomparisons projects. The MIKES’s liquid flow calibration laboratory’s quality management system is based on the ISO/IEC 17025 standard. Calibration services MIKES Kajaani has three different calibration rigs for liquid flow calibrations. One of the rigs is the national measurement standard of flow. In this rig, the measuring principle is gravimetric and the measurements carried out are traceable to the national standards of mass, temperature and time. ter is first continuously pumped up to a constant head tank located 20 m above ground level. The water level is held constant in the tank by sufficient overflow and by adjusting the water flow in a measuring pipe section, where the flow meters under test are placed. The calibration is done by comparing the results of the balance and the meter under test reading. In the closed loop type calibration rigs, the referencemeters are usually magnetic or coriolis mass flow meters. In these rigs, the source of traceaility up to DN200 is based on the national flow standard. For pipe sizes DN200 > , the source of traceability is a foreign NMI, typically PTB from Germany. The measuring principles, ranges, and reachable measurement uncertainties are shown in Table 1. The gravimetric reference standard of water flow is based on weighing the water. In the measurements, waTable 1. Measuring ranges of the liquid flow calibration rigs and the measurement uncertainty. Equipment Measuring principle Pipe sizes Volume flow Pressure Measurement uncertainty(k=2) D100 reference meter DN 15 DN 50 0.3…20 L/s <0.7 MPa 0.3 % D500 reference meter DN 150 DN 500 7… 750 L/s <0.5 MPa 0.3 % D200 gravimetric DN 10 DN 50 DN 100 DN 200 0.1 l/s… 200 L/s 0.2 MPa 0.03 % For pulp and paper industry, MIKES Kajaani has a mass circulating rig applied with a cooling system. Consistency area 0 – 12 % and flow speed 0.5 – 3 m/s. Figure 2. Part of the D500 liquid flow calibration rig. VTT MIKES METROLOGY Calibration services 2016 — 13 Mass, pressure flow Temperature humidity Electricity, time acoustics Optics Length geometry Chemistry Calibration of gas flows and density of liquids Richard Högström, Senior Research Scientist, Tel +358 50 303 9341 [email protected] Heikki Kajastie, Researcher, Martti Heinonen, Principal Metrologist, Tel. +358 400 686 Tel +358 50 410 5511 553, [email protected] [email protected] Calibration gives reliability Nowadays, measurement of small gas flows is needed in various applications. For instance, in health care and medical industry is very impor-tant to assure the safety of customers. In order to maintain international competiveness and to guarantee the high quality of products, the accuracy of gas flow measurements in process industry has to be reliably verified. No matter what the application is, the regular calibration and stability monitoring of gas flowmeters is an essential part of quality control. MIKES cali-brates gas flowmeters in the flow range 5 ml/min...110 l/min and offers research and expert services in the field of gas flow meas-urements and their reliability MIKES, Tekniikantie 1, 02150 Espoo Puh. 020 722 111 www.mikes.fi Traceability MIKES provides circumstances for traceable gas flow measurements in Finland by developing and maintaining standards for gas flows and offers calibration and expert services. The traceabiltity of gas flows at MIKES is based on a dynamic weighing system, DWS developed at the flow laboratory of MIKES. The measurements performed using this system are traceable to the national standards of mass and time. The DWS equipment is used to calibrate measurement standards based on laminar flow elements (LFE) and customers’ devices whose relative accuracy level is better than 1 %. The high level of our gas flow measurement activities is maintained by actively participating in international research projects and compari-sons and by carrying out own research projects in this field. 14 — VTT MIKES METROLOGY Calibration services 2016 Calibration of gas flow and density of liquids Calibration services If the relative accuracy level of a gas flowmeter is better than 1 %, the DWS equipment will be used in the calibration. Typical examples of such flowmeters are high-quality laminar flow elements and some piston-cylinder volume flowmeters. Most of our customers’ flowmeters are calibrated at MIKES using the LFE calibration equipment. It is much more convenient to use than the DWS equipment and it does not have such a strict tolerances for environmental conditions. Performing of calibrations are thus more flexible and faster. The equipment has proven to be well suited for calibration of gas flowmeters having relative accuracy above 1 %. Such meters include thermal mass flowmeters and controllers. Furthermore, MIKES performs liquid density measurements. We calibrate for instance areometers and density meters based on vibra-tions and determine densities of customers own liquid samples in the density range 600 kg/m3 ... 2000 kg/m3. Table 1. Measurement ranges and best achievable calibration uncertainties at MIKES. Quantity Measurement range Measurement uncertainty (k=2) Mass flow (DWS) 0.1 mg/s...625 mg/s 0.3 %...0.8 % Mass flow (LFE) 0.1 mg/s...625 mg/s 0.4 %...0.9 % 5 ml/min...30 l/min 0.4 %...0.9 % Density of liquid (LDCS) 600 kg/m3...2000 kg/m3 15 ppm Calibration of areometers (HCS) 600 kg/m3...2000 kg/m3 0.05 % Volume flow (LFE) DWS = Dynamic weighing system LFE = Laminar flow element LDCS = Liquid density calibration system HCS = Hydrometer calibration system VTT MIKES METROLOGY Calibration services 2016 — 15 Mass, pressure flow Temperature humidity Electricity, time acoustics Optics Length geometry Chemistry Acceleration of free fall Markku Poutanen, Prof., Tel. +358 29 531 4867, [email protected] Mirjam Bilker-Koivula, Senior research scientist Tel. +358 29 531 4696 [email protected] Hannu Ruotsalainen, Senior research scientist, Tel. +358 29 531 4876 [email protected] Finnish Geospatial Research Institute, FGI Geodeetinrinne 2, 02430 Masala, Tel. +358 29 530 1100, www.fgi.fi Finnish Geospatial Research Institute, FGI The Finnish Geospatial Research Institute, FGI, of the National Land Survey of Finland maintains measurement standards for geodetic and photogrammetric measurements and is the National Standards Laboratory of acceleration of free fall and length. The FGI takes care of the fundamental measurements in Finnish cartography and of geographical information metrology and carries out scientific research in geodesy, geographic information sciences, positioning, navigation, photogrammetry and remote sensing. Methods and traceability The national measurement standard is the absolute gravimeter FG5-221. Its results are directly traceable to length and time standards. We have participated in all international comparisons since the year 1989. At a customer’s site the measurements are usually performed with a relative gravimeter, measuring the gravity difference with respect to a point with known gravity. Acceleration of free fall and gravity The acceleration of free fall depends on location and time. The time dependence originates from tidal forces (variation in Finland 3 μm s–2) and from mass variations of groundwater and atmosphere (at least an order of magnitude smaller). When the most important time variations are removed from the acceleration of free fall by using agreed methods, the result is the acceleration due to gravity, which can be treated as a time independent quantity.. 16 — VTT MIKES METROLOGY Calibration services 2016 Figure 1. Acceleration of free fall in Finland, unit m s-2. Acceleration of free fall Calibration services and uncertainty Research, development and reporting We measure gravity at requested sites and report the value for the acceleration of free fall. The time variation is included in the uncertainty of 4 μm s–2 (k=2). If needed, we supply an accurate value for gravity (the smallest uncertainty is 0.008 μm s–2) and methods to predict the time variation (the smallest uncertainty 0.10 μm s–2). We maintain an open calibration line where customers can verify their gravimeters. We carry out research and develop national infrastructure for measurements of gravity and acceleration of free fall for all applications (e.g geodesy, geophysics and geology). With the help of the 30 000 points in the national gravity grid, the acceleration of free fall can be estimated with an accuracy of 0.1 mm s–2 without any new measurements. We have performed measurements using absolute gravimeters in 20 countries. Figure 2. A measurement using a relative gravimeter. Figure 3. The absolute gravimeter FG5X-221 is based on a free fall experiment. Figure 4. Superconducting gravimeter (Metsähovi, Kirkkonummi) registers even 0.1 nm s–2 variations in the acceleration of free fall. VTT MIKES METROLOGY Calibration services 2016 — 17 Mass, pressure flow Temperatue, humidity Electricity, time, acoustic Optics Length, geometry Chemistry Calibration of hygrometers Martti Heinonen, Pricipal Metrolo- Heikki Kajastie, Researcher, gist, +358 400 686 553, Tel +358 50 410 5511 [email protected] [email protected] Hannu Räsänen, Senior Research Technician, Tel +358 50 410 5497, [email protected] MIKES, Tekniikantie 1, 02150 Espoo, Tel +358 20 722 111 www.mikes.fi Reliability from calibration Traceability to humidity measurements Reliability of humidity measurements is impor- tant, e.g. in storage of wood, paper, food, etc. in aviation and environmental monitoring as well as in diverse fields of industry and research. Cali-bration of hygrometers at regular intervals and monitoring their stability is an essential part of verification of measurements. MIKES creates conditions for traceable humidity measurements in Finland by developing and maintaining measurement standards for humidity and by offering calibration and expert services. MIKES provides high-quality calibration services for instruments measuring humidity of gases and expert services on research and development related to humidity measurements and their reliability.. 18 — VTT MIKES METROLOGY Calibration services 2016 The high quality of the humidity laboratory is maintained by taking part in international research and comparison projects and by carrying out own research projects. Calibration of hygrometers Traceability Traceability of humidity measurements is based on a dew-point temperature scale. The scale is realised by using a humidity generator, which is the national measurement standard in Finland. The core of a dew-point generator is a saturator in which total saturation of air with respect to water or ice is reached. The dewpoint temperature of the air coming out of the generator is calculated from the saturator temperature and from the pressure difference between the saturator and the device under calibration. When saturated air is led into the measurement chamber of the generator, the equipment is also suitable for calibration of relative humidity sensors.. The dew-point meter under calibration is directly connected to the dew-point generator. In calibration of a relative humidity sensor, the sensor is placed in the measurement chamber system. The reading of the sensor is compared to the value of relative humidity that is calculated from the dew-point temperature and the air temperature inside the chamber. Calibration services Most dew-point meters are calibrated using a dewpoint generator. The measurement standards of humidity laboratory at MIKES cover the dew-point temperature range -80 °C to +84 °C. Dew-point calibrations are also carried out as comparison calibrations in calibrators, for instance for capacitive dew-point meters. Most relative humidity sensors are calibrated in a climatic chamber. The dew-point temperature and the air temperature in the chamber are measured by using a chilled mirror hygrometer and a digital thermometer, respectively. The relative humidity is calculated from measured temperature and dew-point temperature. If the achievable uncertainty is not sufficient or the temperature range extends to below +10 °C, the calibration is performed using a humidity generator. Relative humidity sensors are calibrated in the range 10 %rh to 95 %rh at temperatures between -20 °C and +85 °C. In cases of other humidity quantities, calibrations are performed with the same equipment the relative humidity calibration systems. The values of these quantities are calculated from measured dew point temperature, temperature, and pressure. Figure 1. Calibration of chilled mirror hygrometers. Table 1. Measurement ranges and best achievable calibration uncertainties at Quantity Measurement range Measurement uncertainty (k=2) Dew-point temperature -80 °C ... -60 °C -60 °C ... +84 °C 0.2 °C ... 0.1 °C 0.05 °C ... 0.06 °C Relative humidity 10 %rh ... 95 %rh (-20 °C ... +85 °C) 0.1 %rh ... 1.0 %rh (generator) Relative humidity 10 %rh ... 95 %rh (+10 °C ... +85 °C) 0.4 %rh ... 2.0 %rh (climatic chamber) VTT MIKES METROLOGY Calibration services 2016 — 19 Mass, pressure flow Temperatue, humidity Electricity, time, acoustic Optics Length, geometry Chemistry Calibration of radiation thermometers Hannu Räsänen, Senior Research Technician, Tel +358 50 410 5497, [email protected] Martti Heinonen, Principal Metrologist, Tel +358 400 686 553 [email protected] MIKES, Tekniikantie 1, 02150 Espoo Tel. +358 20 722 111 www.mikes.fi Measurement methods Blackbody radiatiors are used in calibration of radiation thermometers. The operation range of MIKES radiators is -40 °C ... 1500 °C. The temperature of a blackbody radiator can be measured using e.g. a temperature sensor that is embedded in the radiator wall. When calculating the radiation temperature from the measured temperature, the emissivity of the wall and bottom materials of the radiating cavity and the geometry of the blackbody radiator as well as the temperature gradients are taken 20 — VTT MIKES METROLOGY Calibration services 2016 into account. The radiation temperature measured by a radiation thermometer is often lower than the surface temperature of the measured object, since the surface emissivity is usually lower than the emissivity of an ideal blackbody (the emissivity of a blackbody is 1 but the emissivity of a glossy copper surface is 0.1). In MIKES radiation thermometers are calibrated by using either a calibrated reference pyrometer or reference radiators. Calibration of radiation thermometers Traceability Size-of-source-effect The international temperature scale ITS-90 is realised above the temperature of 962 °C with a reference pyrometer and fixed-point radiators (962 °C, 1064 °C and 1085 °C). Of these fixed-points MIKES has the first and the last one which are the freezing points of silver (figure 1) and copper. Below the temperature of 962 °C, ITS-90 is realised by using resistance thermometers instead of a pyrometer. The reference equipment for radiation temperatures between –40 °C … 962 °C at MIKES are based on resistance thermometers calibrated according to the ITS-90.. The size of the radiation source (size-ofsourceeffect, SSE) affects the calibration results of a radiation thermometer. A radiation thermometer detects thermal radiation also outside the blackbody radiator or the object to be measured. The significance of this additional thermal radiation depends on the construction of the optics (figure 2). On demand, the size-of-source-effect is measured at MIKES. Outer cover graphite Figure 1. A silver cell that is used in the calibration of a reference pyrometer. Inner cover graphite Silver Figure 2. SSE: In this example, a pyrometer detects lower temperatures when the aperture of the radiator is less than 15 mm and the temperature of the radiator is higher than ambient temperature. Vocabulatory • reference meter: measurement standard • pyrometer: radiation thermometer (infrared thermometer) • a blackbody radiator does not reflect at all radiation coming from the outside. The temperature of an object depends only from the heat energy brought to the object and hence its radiation intensity is proportional to the temperature of the object. VTT MIKES METROLOGY Calibration services 2016 — 21 Mass, pressure flow Temperatue, humidity Electricity, time, acoustic Optics Length, geometry Chemistry Fixed point calibration of platinum resistance thermometers Ossi Hahtela, Senior Reseach Scientist, Tel +358 50 303 9340, [email protected] Hannu Räsänen, Senior Research Technician, Tel +358 50 410 5497 [email protected] MIKES, Tekniikantie 1, 02150 Espoo Tel +358 20 722 111 www.mikes.fi Calibration objects and methods Standard platinum resistance thermometers (SPRT) of good quality (i.e. stable) are calibrated at the fixed points of the ITS-90 temperature scale. A fixed point cell (Figure 1) usually contains pure metal, e.g. tin, zinc, aluminium or silver (Table 1) sealed in a crucible f purified graphite. The purity of the metal is typically ca. 99.99995 %. The graphite crucible is enclosed in a fused quartz tube. The fixed point cell is placed in a vertical tube furnace and the temperature is slowly raised until the melting is complete. At this stage the furnace temperature is reduced to a value slightly below the melt temperature in order to start solidification. When the metal is in a su-percooled state, the thermometer to be calibrated is carefully inserted into the cell. The thermometer is coupled to a resistance bridge using four wire coupling. The solidification state can be maintained up to 10 hours (Figure 2) and the temperature of the fixed point cell stays within ±0.5 mK. The resistance bridge is used to measure the electrical resistance of the thermometer during the solidification state. The thermometers are usually calibrated using three or five different fixed points. Figure 1. Pt25-sensor (SPRT) in a fixed point cell. 22 — VTT MIKES METROLOGY Calibration services 2016 Fixed point calibration of platinum resistance thermometers Calculation of calibration coefficients The temperature T90 is determined according to the ITS-90 temperature scale. First a resistance ratio W(T90) = R(T90) / R(T0.01°C) is calculated by dividing the sensor resistance at a given fixed point by the resistance value at the water triple point. A deviation function of the resistance ratio and calibration constants (a, b, …) are de-termined for each sensor under calibration. The deviation function can be e.g. W(T90) - Wr(T90) = a[W(T90) - 1] + b[W(T90)-1]2 where Wr(T90) is a reference function given in the ITS-90 scale. The deviation function to be used and the number of calibration constants depend on the temperature range and the used fixed points. The deviation function can also be used to determine any temperature between the fixed points when the constants a and b are known. In this case, W(T90) is first determined at the unknown temperature and the resulting Wr is used to calculate T90. Uncertainties in fixed point calibration The uncertainties of the fixed points at MIKES are between 0.0002 ... 0.010 °C. The lower limit is reached at the triple point of water and the upper limit at the fixed points of aluminium and silver. The uncertainty of the resistance thermometer calibrations is larger since it includes also un-certainties of the calibration equipment (resis-tance bridge, reference resistor) and the stability of the thermometer during the calibration. Traceability The MIKES fixed points are part of the realisation of the international ITS-90 temperature scale. The stability of the fixed point cells are monitored and the temperatures they provide are compared to the temperatures from similar cells at our own and foreign laboratories. Table 1. MIKES fixed points for resistance thermometers Substance Temperature (°C) State * Argon (Ar) -189.3442 t Elohopea (Hg) -38.8344 t Vesi (H2O) 0.01 t Gallium (Ga) 29.7646 m Indium (In) 156.5985 f Tina (Sn) 231.928 f Sinkki (Zn) 419.527 f Alumiini (Al) 660.323 f Hopea (Ag) 961.78 f * t = triple point, m = melting point, f = freezing point Abbreviations: Pt25 = 25-ohm platinum resistance thermometer HTPRT = high temperature platinum resistance thermometer Other fixed point calibrations Noble metal thermocouples of B-, R- and Stype are also calibrated at fixed points. The highest fixed point temperature is the freezing point of copper at 1084.62 °C. Figure 2. Freezing curve of zinc. VTT MIKES METROLOGY Calibration services 2016 — 23 Mass, pressure flow Temperature humidity Electricity time acoustics Optics Length, geometry Chemistry Calibration of direct voltage and current Pekka Immonen, Researcher, Risto Rajala, Researcher, Ilkka Iisakka, Researcher, Tel +358 50 721 8397, Tel +358 50 410 5519, Tel +358 50 410 5520 [email protected] [email protected] [email protected] MIKES, Tekniikantie 1, 02150 Espoo, Tel +358 20 722 111 www.mikes.fi Accuracy of almost all electrical measuringinstruments is based on traceability of direct voltage and resistance. MIKES maintains thenational standard of direct voltage and direct current in Finland. The unit of direct voltage, volt, is determined very accurately (repeatability even 10–10) by using Josephson voltage standard. The volt is transferred from the Josephson standard to Zener working standards and further to calibrators and multimeters. The measurement range is extended above 10 V by using resisive voltage dividers. In practice traceability of direct current comes from voltage and resistance using Ohm’s law. Traceability of currents smaller than 100 pA can be realized also by charging a capacitor by a linearly increasing voltage. One research topic is the development of a quantum standard for direct current based on singleelectron phenomena in nanostructures. The methods and measuring instruments developed at MIKES are of high international level. One demonstration of this is the excellent success in international comparison measurements with other national metrology institutes. Moreover, MIKES research on direct current metrology is in the international front line. Most important research topics are development of voltage standards based on microelectrome-chanical systems (MEMS) and closing the so-called quantum metrological triangle to prove by Ohm’s law that there is a mutual agreement between the quantum standards of electric current, voltage, and resistance.. Figure 1. The traceability of direct current is based on a Josephson standard cooled in liquid helium. 24 — VTT MIKES METROLOGY Calibration services 2016 Calibration of direct voltage and current Calibration services In addition to accredited calibration laboratories, MIKES provides services to all customers requiring low measurement uncertainty. The most important calibration subjects in the field of direct current are solid state voltage standards, dc- and multifunction calibrators as well as precision multimeters. Zener standards are calibrated usually by comparison to MIKES working standards. A relay scanner connects the voltage difference of the standards to a nanovoltmeter and the results are recorded at regular intervals for a couple of weeks. Routine calibrations of direct voltage and current ranges of calibrators and multimeters are carried out using a reference multimeter and a multifunction calibrator. The measuring ranges and uncertainties of calibrations for voltages up to 1 kV are presented in table 1. ficate. Stability or temperature dependence measurements can be carried out on customer’s request. MIKES follows the longterm stability of customers’ voltage standards and can attach follow-up results to the calibration certificate if needed. In addition to the calibration, we carry out special assignments related to voltage and current measurements and actively participate in research and development projects in these fields. Direct current calibrations are usually performed for currents between 0.1 mA and 1 A with relative uncertainty of 10 μA/A and for 100 fA – 100 μA with uncertainties varying from 600 μA/A to 20 μA/A. When lower uncertainties are needed, calibrations can be performed by using directly the MIKES Josephson standard. On special order, calibrations of multimeters and calibrators can also be carried out using directly the Josephson and Zener standards and a resistive voltage divider. Direct current calibrations requiring lower than 10 μA/A uncertainties and measurements above 1 A current levels can be performed by measuring the voltage across a resistance standard. The lowest achievable uncertainties of these measurements can be found in table 2. Resistive voltage dividers are calibrated by comparison to the MIKES reference divider or with the Josephson standard. The value of voltage or current together with its uncertainty is given in the calibration certi- Figure 2. A Zener direct voltage standard. Table 1. The smallest measurement uncertainties for the most common direct voltage calibrations. By using special techniques even much lower calibration uncertainties can be achieved. Device Zener-standard Calibrator or multimeter Voltage (V) 1 1.018 10 0 ... 10 10 ... 100 100 ... 1000 Uncertainty (μV) 0.2 0.2 2 0.3 ... 20 70 ... 610 1000 ... 10000 Table 2. The smallest uncertainties of direct current calibrations for currents less than 20 A. Current < 0.1 pA (0.1 ... 100) pA (1 ... 100) nA (0.1 ... 100) μA (0.1 ... 100) mA (0.1 ... 20) A Uncertainty 0.1 fA (1 ... 0.6) mA/A (0.1...2) pA 20 μA/A 5 μA/A (5 ... 20) μA/A VTT MIKES METROLOGY Calibration services 2016 — 25 Mass, pressure flow Temperature humidity Electricity time acoustics Optics Length, geometry Chemistry Calibration of alternating voltage and current Tapio Mansten, Senior Research Scientist, Tel +358 400 767 427, [email protected] Risto Rajala, Researcher, Tel +358 50 721 8397, [email protected] MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi In society, many important functions such as the measurement of electrical energy, which is supplied by electrical power networks to consumers, are based on the accurate measurement of alternating voltage and current. MIKES is responsible for the traceability of alternating voltage and current in Finland. The traceability of the most accurate measurements of AC voltage is based on thermal converters and range resistors acting as secondary standards. The traceability of AC voltage and AC current ranges of multifunctional calibrators and precision multimeters comes from AC voltage standards calibrated at MIKES or at other national metrology institutes and from their calibrated range and shunt resistors. The reliability of results is verified by taking part in international comparisons. MIKES performs also high level research on AC voltage metrology. Especially, MIKES is at the top of international metrology research in development work of two different types of AC voltage standards in domestic collaboration with VTT: a primary standard for AC voltage based on Josephson effect and an AC voltage working standard based on micromechanical sensors (MEMS). Figure 1. Equipment of the national metrology laboratory for alternating voltage and current. 26 — VTT MIKES METROLOGY Calibration services 2016 Calibration of altrnating voltage Calibration services MIKES has accurate AC voltage meters and calibrators as working standards. We calibrate voltages from 1 mV to 1000 V in a frequency range from 10 Hz to 1 MHz and currents from 100 μA to 20 A in a frequency range from 50 Hz to 10 kHz (up to 8000 A in the frequency range 45 Hz …. 65 Hz). Typical devices that we calibrate include: thermal converters, precision multimeters and calibrators and current sources and sensors. Also, other devices can be calibrated in agreement with a customer. Usually customer’s AC voltage and current devices are calibrated by comparing their AC/DC difference to the AC/DC difference of a Fluke 5790A working standard and Fluke A40 AC/DC current shunts or by comparing the rms values directly to the rms value of a MIKES device. The measuring ranges and smallest achievable uncertainties for these calibrations are shown in the tables below. Figure 2. AC-DC-relay and two thermal convertes. Table 1. Measurement ranges and smallest relative uncertainties in parts per millions from measurement results (μV/V) for the alternating voltage range of a multifunctional calibrator. 10 Hz 20 Hz 40 Hz 53 Hz 400 Hz 1 kHz 10 kHz 20 kHz 50 kHz 100 kHz 500 kHz 1 MHz 1 mV 1200 1200 1200 - 1200 1200 1200 1200 1200 1400 3300 5000 2 mV 590 590 590 - 590 590 590 590 590 680 1600 4600 20 mV 130 120 120 - 120 120 120 120 120 140 350 580 100 mV 50 50 30 - 30 30 30 30 35 60 220 450 1V 40 40 20 - 15 15 15 15 30 50 110 440 10 V 40 40 20 - 20 20 20 20 30 45 140 400 100 V 40 40 30 - 20 20 20 20 35 40 - - 1000 V - - 50 50 50 - - - - - - - Table 2. Measurement ranges and smallest relative uncertainties in arts per million of measurement result (μA/A) for the alternating current range of a multifunctional calibrator. na mittaustuloksesta (µA/A). Frequency Current (rms value) Voltage (rms value) Frequency 40 Hz 400 Hz 1 kHz 5 kHz 10 kHz 100 µA 80 80 80 90 110 1 mA 35 35 35 35 40 10 mA 35 35 35 35 50 100 mA 35 35 35 35 60 1A 35 35 35 50 110 10 A 110 110 110 150 210 20 A 110 110 110 180 260 VTT MIKES METROLOGY Calibration services 2016 — 27 Mass, pressure flow Temperature humidity Electricity time acoustics Optics Length, geometry Chemistry Calibration of capacitance and inductance standards Tapio Mansten, Senior Research Scientist, Tel +358 400 767 427, [email protected] Risto Rajala, Researcher, Tel +358 50 721 8397, [email protected] Capacitors and inductors are essential components in electronics. Moreover, capacitive sensors are used in many high-precision measurements: e.g. in measurements of position, distance and level. For calibration of precision LCR meters, inductance and capacitance standards are needed. Therefore, traceable measurements of capacitance and inductance are of utmost importance. In Finland, MIKES is responsible for the traceability of capacitance and inductance. MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi cy — quantities which are maintained at MIKES. The reliability of the results is verified by international comparisons and by taking advantage of capacitance measurement services at the BIPM. The capacitance values between calibration points are interpolated by using measuring bridges based on inductive dividers. Inductance standards in the range 100 μH – 100 mH are traceable to the MIKES capacitance and resistance standards. In MIKES, ac coaxial bridges are used to provide traceability of the decade capacitance standards in the range 10 pF – 1 μF to resistance and frequen- Calibration services MIKES calibrates capacitance standards in the range 0 pF up to 1 μF by using a very stable capacitance bridge and reference capacitance standards. The measurements are usually carried out at 1 kHz but other measurement frequencies are also possible. The calibration is performed using either two-terminal or three-terminal method by connecting the calibrated capacitance standard through a 16-channel coaxial relay to the capacitance bridge and by measuring automatically for about two or three days. The device under calibration is placed together with a Pt-100 sensor into a volume having a constant temperature. The temperature is varied during the measurement by about one or two degrees in order to measure the temperature coefficient of the device under calibration. The results are corrected to the temperature of 23 °C. Figure 1. Traceability to capacitance from resistance and frequency in MIKES impedance laboratory. 28 — VTT MIKES METROLOGY Calibration services 2016 Traceability of inductance standards at MIKES is based on the link to the capacitance (100 pF) standards which are calibrated at BIPM and the resistance standards, calibrated from the Quantum Hall Resistance in MIKES. The 100 mH inductance is linked to capacitance standards at 1 kHz and 1.59 kHz with the use of series resonance method, where 253 nF and 100 nF capacitors are used as references. Calibration of capacitance and inductance standards Sampling method, which is based on the use of 2 DVM is used to define the values of inductance standards in the range 100 μH – 10 mH. Impedance of the calibrated inductors is compared with the impedance of the reference resistor, by measurements of the voltage ratios at frequencies below 1 kHz. In addition to the calibration of capacitance and inductance standards, we carry out special assignments related to impedance measurements and actively participate Figure 2. AH2500A measuring bridge and a 1-nF capacitance standard under calibration. Table 1. Measuring ranges and smallest calibration uncertainties at MIKES for calibration of capacitive standards at 1 kHz frequency. The expanded relative uncertainty (k = 2) is expressed as parts per million of measured capacitance. Capacitance value 10 pF Relative uncertain- 5 ty (µF/F) 100 pF 1 nF 10 nF 100 nF 5 10 30 100 Table 2. Measuring ranges and smallest calibration uncertainties at MIKES for calibration of capacitive standards that have capacitance values smaller than 10 pF or larger than 100 nF or whose value is not even decade. The expanded relative uncertainty (k = 2) is expressed as parts per million of measured capacitance. For capacitances lower than 10 pF a base apacitance of 5 aF is added to the uncertainty. Capacitance value 0 pF - 10 pF 10 pF - 1 nF 1 nF - 10 nF 10 nF - 100 nF 100 nF - 1 μF Relative uncertainty (µF/F) 10 (+ 5 aF) 10 30 200 400 Table 3. Measurement methods, inductance values, and reference standards used in calibration of inductance standards at 1 kHz. Method Inductance Impedance 1 kHz Reference Uncertainty 2s Relative uncertain- 5 ty (µF/F) 5 10 30 2 DVM 1W 1W 50 0.1 mH 2 DVM 1 mH 10 W 10 W 50 2 DVM / SR 10 mH 100 W 100 W 20 SR / 2 DVM 100 mH 1 kW 253 nF / 100 W 20 VTT MIKES METROLOGY Calibration services 2016 — 29 Mass, pressure flow Temperature humidity Electricity time acoustics Optics Length, geometry Chemistry Calibration of resistance Ilkka Iisakka, Researcher, Tel +358 50 410 5519, [email protected] Risto Rajala, Researcher, Tel +358 50 721 8397, [email protected] Resistance is the most important quantity of electrical measurements together with direct voltage. In addition to resistance calibrations, resistance standards are needed for providing traceability to other electrical quantities. MIKES is the national standards laboratory of resistance. The traceability of resistance standards at MIKES is based on its own quantum Hall standard, which connects the unit of resistance to the values of physical constants with a relative uncertainty of 10–8. The dissemination to secondary and working standards, which are stored in oil or air baths, is performed by using a cryogenic current comparator or a direct current comparator resistance bridge. The 30 — VTT MIKES METROLOGY Calibration services 2016 MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi traceability of resistance standards with value above 1 GΩ is realized by using a modified Wheatstone bridge. The accuracy of MIKES’s resistance standard calibrations is at high international level, confirmed by good results in international resistance comparisons. MIKES has also participated in coordination of international key comparisons, in which the accurate resistance transfer standards developed at MIKES have been used. Calibration of resistance Calibration services In addition to accredited calibration laboratories, MIKES provides services to all customers requiring very low measurement uncertainty. In resistance calibration the resistance of the device under calibration is measured and the uncertainty of the measurement result is calculated. On demand, temperature, power, or voltage dependence of resistance standards can be determined, too. MIKES follows the long-term stability of customer’s resistance standards and when requested attaches the results to the calibration certificates. In addition to resistance standards, other calibration services for calibration of precision multimeters and multifunction calibrators are offered. In the range 0.0001 Ω ... 100 MΩ, the resistance standards are calibrated by comparing them to the prima- ry and working standards of MIKES by using a MI 6242B resistance bridge. When special accuracy is needed, the measurements can be carried out by using a cryogenic current comparator. In the range 1 MΩ ... 100 TΩ, a modified Wheatstone bridge is used. During the calibration, the resistance standards are placed in a thermal bath. Either two point or four point measurements are used and when needed a guarded measurement is carried out. The resistance ranges of multimeters are calibrated by using MIKES multimeters. In addition to calibrations, we provide special assignments related to resistance measurements and actively participate in research and development projects in this field. Figure 1. Measurement ranges and measurement uncertainties for resistance standards. VTT MIKES METROLOGY Calibration services 2016 — 31 Mass, pressure flow Temperature humidity Electricity time acoustics Optics Length, geometry Chemistry Calibration of power and energy at line frequency Esa-Pekka Suomalainen,Senior Research Scientist, Tel +358 50 382 2463, [email protected] Pekka Immonen, Researcher, Tel +358 50 410 5520, [email protected] The measurement of electric energy consumption has a huge economic importance. Through the development of electric energy market, the importance of measurement accuracy and traceability is further emphasised. Accurate electric power standards are required in the calibration of energy meters. At MIKES, measurements of electric power at 50 Hz are traceable to SI units through a sampling power standard. Calibrations are performed using either single-phase or three-phase measurements. Typical devices that we calibrate are electric power meters and converters. At MIKES power laboratory, the traceability of electric power at 50 Hz is based on direct voltage from a Josephson standard and resistance realised by a quantum Hall equipment. The sampling power standard consists of two 8½ digit voltmeters, which are accurately synchronised. Currents smaller than 20 A are converted to voltages using specially constructed shunt resistors, whose resistance values are traceable to the quantum Hall resistance standard. As a result of the construction of the shunts, their frequency dependence is very small. Measurement results of voltage meters are based on fast sampling and traceable to the Josephson voltage standard. The same measurement equipment together with a current sensor based on a Rogowski coil is used to measure currents and current ratios up to 8000 A. The measurement uncertainty of the MIKES power reference equipment is 0.005 % at its best. Figure 1. In power and energy measurements traceability for large currents is also needed. Parts of 8000 A measuring setup based on a Rogowski coil. 32 — VTT MIKES METROLOGY Calibration services 2016 MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi The methods and equipment of MIKES power laboratory represent international top quality. The high quality of measurements is verified by taking part in international comparison measurements together with national metrology laboratories from other countries. MIKES is also an active member in different expert working groups at international level and takes part in national as well as international joint research projects. Several projects are in the European Metrology Research Programmes EMRP and EMPIR.. Calibration of power and energy at line frequency Calibration services MIKES calibrates especially reference standards of customers who need the best available measuring accuracy. Typical instruments are power comparators and converters. The calibrations are performed by connecting the same current and voltage to the customer’s device and the reference meter of MIKES. If necessary, effect of the power source used in the calibrations is minimized by accurately synchronising the meters. The reference meter used in the calibrations is either a single-phase sampling power standard or a three-phase power comparator. In addition to power standards, we calibrate current and voltage transformers and transducers up to 200 kV voltage and 8 kA current. We carry out special assignments related to the measurement of electric power and energy and take part in research and development cooperation projects in this field. Moreover, we organise educational opportunities in this field and custom tailored training. Figure 2. A coaxial shunt resistor of the sampling power standard. Table 1. Measuring ranges and calibration uncertainties at MIKES for calibrations of power and energy at line frequency. Expanded relative uncertainty (k = 2) Measured quantity Single phase, 30 V – 500 V, 5 mA – 10 A Active power 50 μW/VA Reactive power 100 μvar/VA 3-vaihe, 50 V – 350 V, 5 mA – 12 A Active power 120 μW/VA Reactive power 250 μvar/VA Active energy 120 μWh/VAh Reactive energy 250 μvarh/VAh VTT MIKES METROLOGY Calibration services 2016 — 33 Mass, pressure flow Temperature humidity Electricity time acoustics Optics Length, geometry Chemistry RF- and microwave calibrations Kari Ojasalo, Researcher, Tel +358 50 410 5557 [email protected] The importance of measurement reliability is emphasized along with the continuously increasing amount of applications in RF- and microwave ranges. MIKES is the national metrology institute in this field and offers traceability with low uncertainty to internationally accepted measurement standards in RF and microwave power measurements and measurements of S parameter (reflection and attenuation). We calibrate power sensors and attenuators for instance. MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi of results are mainly automated. The measurements are carried out in a controlled 23 °C temperature in an electromagnetically shielded room. The high standard of the measurements is verified by actively taking part in international comparisons together with other national metrology institutes. The traceability is based on power and attenuation calibrations at NPL (National Physical Laboratory) in U.K. and on the primary standards at MIKES. Our calibration equipment is equipped with precision type N connectors, thus our measu-rement range extends to 18 GHz. The measurements and the analysis Figure 1. Measurement of power sensors. 34 — VTT MIKES METROLOGY Calibration services 2016 RF- and microwave calibrations Calibration services Power The calibration coefficients of sensors are determined with measurement equipment based on a power divider. Measurement of reflection coefficient by using a vector network analyzer is included in the sensor calibration. Typically, calibration takes five workdays. The calibration of the absolute power of a power reference in a power meter is performed for thermocouple and diode power sensors. The reflection coefficient of the power source is determined at the same time. Figure 1. Measurement set-up for power sensors. Attenuation Attenuation calibrations are carried out by traceable vector network analyzer measurements. Determination of reflection coefficient by is included in the calibration. We calibrate fixed value attenuators as well as step attenuators. The step attenuators can be controlled by using a GPIB bus, RS-232 connection or directly using the step attenuator controller Agilent 11713A.. Reflection coefficient Traceable measurements of reflection coefficient are performed using a vector network analyzer. The impedance of the impedance standards used in the measurements is determined at MIKES with accurate dimensional measurements. Dimensional measurement services for N-type airlines are offered for customers, also. Figure 2. Measurement of reference step attenuator. Table 1. Measurement ranges and uncertainties Quantity Measurement range Measurement frequency range Uncertainty Calibration coefficients of power sensors 1 mW 10 MHz – 18 GHz(1) 0.4 % – 1.1 % (k=2)(2) Absolute power 1 mW 10 MHz – 18 GHz(1) 4 mW/W – 11 mW/W (k=2) Attenuation 0 dB – 80 dB 300 kHz – 6 GHz 0.02 dB – 0.17 dB (k=2) Attenuation 0 dB – 60 dB 6 GHz – 18 GHz 0.05 dB – 0.18 dB (k=2) Reflection coefficient (real and imaginary parts) -1 ja 1 välillä 10 MHz – 18 GHz 0.013 – 0.024 (k=2,45)(3) 1) Tehon kalibrointitaajuudet ovat: 10, 30, 50, 100, 300, 500 MHz, 1 GHz, 1.5 GHz, 2 GHz – 18 GHz 1 GHz askelin. 2) Heijastuskertoimen itseisarvo ≤ 0.08 3) Kompleksimuuttujan kompleksiselle epävarmuudelle 95 % kattavuus saadaan, kun k=2.45. VTT MIKES METROLOGY Calibration services 2016 — 35 Mass, pressure flow Temperature humidity Electricity time acoustics Optics Length, geometry Chemistry High voltage and high current Esa-Pekka Suomalainen, Senior Research Scientist, Tel +358 50 382 2463 [email protected] Jussi Havunen, Research Scientist, Tel +358 50 590 6536 [email protected] MIKES, Tekniikantie 1,02150 Espoo Puh. 020 722 111 www.mikes.fi High voltage quantities Traceability The importance of high voltage measurements has been emphasized with the opening of electricity markets. The quality of electricity, transmission losses and the sale of electricity for industry and for private households have become more important measuring and monitoring subjects. In addition to electricity, electronics and information industries, high voltage users can be found, in almost every industrial sector. High voltage metrology at MIKES is internationally respected and provides services on traceability also at customers premises in Finland and globally. The high voltage measurements at MIKES are traceable to capacitance, resistance and voltage, which in turn are based on quantum primary standards: quantum Hall resistance standard and Josephson voltage standard. We have performed well and also acted as a coordinator in international comparisons in high voltage metrology. As an example of this is the coordination of broad European and worldwide comparisons of lightning impulse voltage measuring systems. 36 — VTT MIKES METROLOGY Calibration services 2016 High voltage and high current Calibration services Calibration subjects MIKES offers calibration services for almost all high voltage quantities and measuring systems up to 200 kV voltage. The range of alternating current calibrations extends to 6 kA. The measuring range for pulse quantities covers a voltage range from millivolts up to megavolts and currents up to tens of kiloamperes. Our expert services cover different aspects of calibration of measuring systems. If wanted, we evaluate customer’s measuring systems and modify them to be more accurate and stable if needed. In future, our area of qualification will be extended to calibrations related to measurements on the quality of electricity. Devices that we calibrate include: • voltage dividers • voltage and current transformers • measuring probes, voltage and current sensors and current shunts • high voltage inductors and capacitors • transient recorders, peak voltage meters • surge-, EFT- ja ESD- test devices • voltage testers • pulse calibrators • partial discharge calibrators The best calibration uncertain y is achieved when calibrations are performed in a laboratory at MIKES but calibrations can be carried out at customer’s premises, also. Measuring systems can be calibrated on-site when the voltage level, the size of the system, grounding conditions or proximity effects necessitate it. Table 1. Calibration services of high voltage Quantity Measurement range Uncertainty (k=2) Direct voltage 1 kV - 1000 kV 0.0005 - 0.01 % Alternating voltage, voltage ratio 1 kV - 200 kV 0.002 - 0.01 % – angle error 0 - 100 mrad 0.02 mrad Alternating current, current ratio 1 A - 6 kA 0.025 - 0.02 % – angle error 0 - 100 mrad 0.2 - 0.4 mrad Capacitance 1 - 100 kV / 10 pF - 200 µF 0.002 - 0.05 % -– loss coefficient tan δ 1.10-5 - 2 1 % (1.10-5 abs) Inductance / losses 1 µH - 10 H 0.03 % / 0.2 mrad Lightning impulse 50 mV - 400 kV 0.1 - 0.5 % Switching impulse 1 V - 200 kV 0.1 - 0.2 % Other voltage impulses (e.g. surge) 1 V - 400 kV 0.1 - 0.5 % Current impulses 1 A - 10 kA 3% ESD-pulssi 1 A - 50 A 5% Time parameters of pulses 0.7 ns - 100 ms 0.5 - 5 % Apparent charge of a pulse (partial discharge) 1 pC - 1 nC 2 % (0.2 pC abs) VTT MIKES METROLOGY Calibration services 2016 — 37 Mass, pressure flow Temperature humidity Electricity time acoustics Optics Length, geometry Chemistry Acoustic calibrations Kari Ojasalo, Researcher, Tel +358 50 410 5557 [email protected] Jussi Hämäläinen, Researcher, Tel +358 50 410 5518 [email protected] The need of accurate acoustic measurements is growing for instance due to regulations and legislations concerning noise emissions and exposure to vibrations. A good measurement accuracy requires, in addition to high-quality measurement devices, regular and traceable calibrations. In Finland, MIKES is responsible for the traceability of the acoustic quantities: sound pressure and acceleration. Sound pressure is transformed into an electrical signal by using accurate condenser microphones, whose primary calibration equipment is in use at MIKES. Sound level calibrators are calibrated using these condenser microphones. The traceability chain of sound pressure level starts from the calibration of laboratory grade microphones by using a so-called reciprocity calibration system. This calibration gives Figure 1. A reciprocity calibration of microphones is starting in the soundproof laboratory at MIKES. 38 — VTT MIKES METROLOGY Calibration services 2016 MIKES, Tekniikantie 1, 02150 Espoo Tel +358 20 722 111 www.mikes.fi the voltage-pressure sensitivities of the microphones. The method is described in the standard IEC 610942 (1992-03) and it is in use in severalother national metrology institutes. A vibration transducer produces a signal, typically a voltage or a charge, which is proportional to the acceleration of mechanical motion. Therefore, in the calibration of a vibration transducer, the sensitivity (typically mV/(m/s2) or pC/(m/s2) of the sensor is determined as a function of frequency. MIKES calibrates vibration transducers by comparing their readings to a known vibration produced with a vibration exciter. The real amplitude of acceleration and frequency is simultaneously measured by using a reference sensor. The method is described in the standard ISO 1606321:2003. Acoustic calibrations Vibration transducers and loggers Calibration services Microphones We calibrate ½ (LS2P) and 1 (LS1P) inch condenser microphones described in the standard IEC 61094-1 (Table 1). The calibration method depends on the accuracy required by the customer. The smallest calibration uncertainties can be achieved by using the reciprocity method. In many cases, a comparison with a reference microphone by a sound level calibrator is adequate. We calibrate vibration transducers, loggers and vibration measurement devices in the frequency range 1 Hz – 10 kHz. Typical nominal acceleration is 10 m/s2. The calibration gives the magnitude and the phase of the sensitivity of the vibration transducer. The uncertainty of the calibration depends on the transducer under calibration. Typical uncertainties for the magnitude are 1–3 % and for the phase 1–2° depending on the frequency (Figure 2). Table 1. Uncertainties of calibration for measurement microphones. Type of microphone LS 1 LS 2 Taajuus [kHz] Uncertainty [dB] 0.0315 0.06 0.063 ... 2 0.04 4 0.05 5 0.06 8 0.08 10 0.10 0.0315 0.08 0.063 0.06 0.125 ... 8 0.05 10 0.06 12.5 0.08 16 0.10 20 0.14 Sound level calibrators The most common devices calibrated at MIKES acoustics laboratory are sound level calibrators and pistonphones. We calibrate the sound pressure levels at fixed frequency points. At the same time, the distortion and frequency of the sound source is measured (Table 2). Figure 2: The measurement ranges and uncertainties of calibration of vibration transducers. Table 2. Calibration ranges and uncertainties for sound level calibrators. The type of the measurement Frequency (Hz) Sound level [dB re 20 μPa] Uncertainty [dB] Single-frequency 125 – 1000 70 – 130 0.08 31,5 94 – 114 0.15 Multi-frequency 63 – 4000 94 – 114 0.10 8000 - 12500 94 - 114 0.15 Type of calibrator VTT MIKES METROLOGY Calibration services 2016 — 39 Mass, pressure flow Temperature humidity Electricity time acoustics Optics Length, geometry Chemistry Calibration of time, time interval,and frequency Ilkka Iisakka, Researcher, Tel 358+50 410 5519, [email protected] Mikko Merimaa, Principal Metrologist, Tel 358+ 50 410 5517 [email protected] Measurements of frequency and time interval are needed in various direct and indirect measurements, e.g., in telecommunication; therefore, precise and traceable frequency and time interval measurements are important nationally. The importance of absolute time is increasing, too (e.g. time stamps). MIKES, Tekniikantie 1,02150 Espoo Tel 358+ 20 722 111 www.mikes.fi MIKES is responsible for the traceability of time, time interval, and frequency in Finland. MIKES time laboratory maintains the official time in Finland with an uncertainty of 10 ns in relation to the coordinated universal time (UTC) and national frequency with a 1•10-13 relative uncertainty. The reference standards for time and frequency are one caesium atomic clock, four hydrogen masers and several GPS receivers. Finland participates in maintaining of the UTC with its five reference standards through GPS based time comparison. Figure 1. The traceability of time and frequency is based on hydrogen masers (in the figure above) and on caesium atomic clocks, which are located in enclosures having with a special climate control. 40 — VTT MIKES METROLOGY Calibration services 2016 Calibration of time, time interval, and frequency Calibration services We calibrate e.g. GPS receivers (frequency), oscillators, time interval counters, stopwatches, stroboscopes, and optical tachometers. The frequency range is 1 mHz to 5 GHz. We make time interval measurements according to customer’s need, with a lower limit of approximately one nanosecond. Furthermore, MIKES has a transmitter for time code and precise 25 MHz frequency for those near the Helsinki metropolitan area who need precise time and frequency. In addition to calibration, we carry out special assignments related to time and frequency measurements and participate in research and development collaboration projects in this field. NTP - network time service Computer clocks can be synchronised with the national time in Finland maintained by MIKES by using Network Time Protocol, NTP. The achievable uncertainty depends on network connections but it is around one millisecond at its best. MIKES maintains NTP servers subject to charge for institutions and companies. We have four servers of the highest level (stratum-1): two of them are synchronised directly to MIKES atomic clocks and two to GPS receivers. Moreover, we control two public NTP servers that are locked to MIKES servers. These servers are available free of charge for public use. Figure 3. Stabilities of various frequency standards as a function of integration time. VTT MIKES METROLOGY Calibration services 2016 — 41 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Optical quantities Farshid Manoocheri, TkT, Tel +358 9 470 22337, [email protected] Petri Kärhä, TkT, Tel +358 9 470 22289, [email protected] MIKES-Aalto Metrology Research Institute Metrology Research Institute (MIKES-Aalto Mittaustekniikka) is a joint laboratory of Aalto University and MIKES. It is the national standards laboratory of optical quantities in Finland. The laboratory is a research and education unit belonging to the Department of Signal Processing and Acoustics at the Aalto University. The laboratory carries out basic research on LED measurements, temperature measurements, optical properties of materials, measurement electronics and on various measurement methods of photometry and radiometry. In addition to calibration services, the laboratory offers expert services and educates Diploma Engineers (M. Sc.) and Doctors of Technology for demanding professional tasks in academy and industry. Figure 1. Integrating sphere is used as a light source in calibration of luminance and radiance. The sphere has a uniform spatial distribution of the outcoming light intensity. 42 — VTT MIKES METROLOGY Calibration services 2016 MIKES Aalto Mittaustekniikka, Otakaari 5A, 02150 Espoo http://metrology.tkk.fi Research activities Research activities and assignments of a national standards laboratory require continuous international cooperation. International comparisons have an essential role in creating traceability chains and verifying measurement uncertainties. The laboratory has an active role in, e.g. EURAMET, CCPR, and CIE organisations and takes actively part in the EU research programs. Optical quantities Calibration services Metrology Research Institute offers calibration services to the optical quantities listed in the following table. All measurements are traceable to national and international measurement standards. Measurement uncertainties are verified by international comparison measurements. We are pleased to give further information, e.g. on the contents of calibration services and on the measurement uncertainty in different measurement and wavelength ranges. Calibration objects lInstruments that we calibrate include among others: Figure 2. The spectral irradiance of a lamp is measured by positioning the lamp at an accurately determined distance from a radiometer, whose spectral responsivity and surface area are known. • illuminance meters • standard lamps • radiance and luminace meters • laser power meters • optical filters • reflectance references • UV-meters • fluorescent samples Quantity Figure 3. Part of the calibrations can be carried out as field calibrations at customer’s laboratory premises. A filter radiometer developed in our laboratory for calibration of spectral irradiance or illuminance of standard lamps is shown in the figure. Measurement range Wavelength range Uncertainty (k=2) Luminous intensity 1 – 10 000 cd - 0.5 % Illuminance Illuminance responsivity 0.1 – 5 000 lx - 0.5 % - 0.7 % Luminance Luminance responsivity 1 – 40 000 cd/m2 - 0.8 % - 1.0 % Luminous flux 10 – 10 000 lm - 1.0 % Spectral irradiance 100 μW m nm – 500 W m-2 nm-1 290 – 900 nm 0.8 % - 2.9 % Spectral radiance 100 μW m-2 sr -1 nm-1 – 1 W m-2 sr -1 nm-1 360 – 830 nm 1.4 % - 4.2 % Color coordinates (x, y) 0.1 – 0.9 - 0.0005 Color temperature 2800 – 3250 K - 5K Optical power 0.1 – 0.5 mW 325 – 920 nm 0.05 % - 1.0 % Spectral responsitivity 0.01 – 20 μW 0.05 – 5.0 mW 380 – 1700 nm 250 – 380 nm 0.5 % - 4.0 % 2.0 % - 5.0 % Transmittance 0.0001 – 1 250 – 1700 nm 0.2 % - 5.0 % Absorbance 0–4 250 – 1700 nm 0.0009 – 0.022 Regular reflectance (5° – 85°) 0.01 – 1 250 – 1000 nm 1.0 % - 5.0 % Diffuse reflectance factor 0.1 – 1 360 – 830 nm 0.4 % - 1.0 % Fiber optic power (in collaboration with MIKES) 1 nW – 200 mW 1310 – 1550 nm 1.2 % - 2.0 % -2 -1 VTT MIKES METROLOGY Calibration services 2016 — 43 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Quantitave Microscopy Atomic Force Microscope Virpi Korpelainen, Senior Research Scientist, Tel. +358 050 410 5504 [email protected] MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi Development and research in nanotechnology has increased the need for accurate measurements in research institutes and industry. Different kinds of Scanning Probe Microscope (SPM) measurements are commonly used in many institutes and companies. In order to guarantee accurate and reliable dimensional measurements at nanometre range, MIKES has a traceably calibrated Atomic Force Microscope (AFM). Thus, MIKES can provide customers with traceable measurements also at nanometre range. MIKES provides accurate AFM measurement services to match the needs of customers. In addition we calibrate SPM transfer standards. Figure 1. Alignment of laser beams for interferometric calibration of y axis of the AFM. 44 — VTT MIKES METROLOGY Calibration services 2016 Quantitave Microscopy - Atomic Force Microscope MIKES has a PSIA XE-100 AFM, which is calibrated interferometrically and with grating calibrated by laser diffraction at MIKES. The AFM is traceable to the definition of the metre. The xy-movements of the AFM are mechanically separated from the z-movements. This increases the linearity of the movements, decreases out of plane movements and eliminates cross-talk. The structure of the device allows rather large samples to be measured, also measurements can be done using the most usual measurement modes: contact, non-contact, tapping and lateral force. The measurement results can be analysed using SPIP software 1. Scale errors of uncalibrated SPMs typically range from 2 % to 20 %. In addition measurement errors may cause distortions in the measured figure, which might be difficult to detect from the figure. Therefore, the device has to be calibrated. New, more advanced SPMs have increased measurement precision, but the development does not remove need for calibration. Especially in all quantitative form measurements, the measurements should be traceable to the definition of the metre. Usually SPMs are calibrated by using calibrated transfer standards. 1 The Scanning Probe http://www.imagemet.com Image Processor Property Data Sample size <100 mm × 100 mm Sample thickness <20 mm Sample mass <500 g Measurement range (xy) 100 µm × 100 µm Measurement range (z) 12 µm Resolution (xy) 0.15 nm 0.02 nm (low voltage mode*) Resolution (z) 0.05 nm 0.01 nm (low voltage mode*) Uncertainty (k=2), x and y directions Q [3; 2 L/µm] nm Uncertainty (k=2), z direction Q [3; 2 L/µm] nm Q [x; y] = (x2 + y2)1/2 SPIPTM Figure 2. 2-D grid standard. Figure 3. AFM image of Seeman tile type DNA nano-origami structures. VTT MIKES METROLOGY Calibration services 2016 — 45 Mass pressure flow Temperature humidity Electricity time acoustics Length geometry Optics Chemistry Characterization of nanoparticles MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi Virpi Korpelainen, Senior Research Scientist, Tel. +358 050 410 5504 [email protected] Nanoparticles are widely used in many applications. Accurate characterization of the nanoparticles is important in research, production and applications in several fields including industry, health, safety and related regulation. At VTT MIKES metrology the particles can be characterized using two different methods: Dynamic Light Scattering (DLS) and atomic force microscopy (AFM). The measurements are traceable to the definition of the metre via MIKES interferometrically traceable metrological atomic force microscope (IT-MAFM). Both methods have advantages and limitations. DLS is fast method and the results are statistically representative. In DSL measurements even a small number of large particles can prevent detection of small particles. AFM can be used to measure both size and shape of single particles. The disadvantage of AFM measurements is that only limited number of particles can be measured which leads to poor statistics. Tip sample interaction is important especially when measuring small particles. Also sample preparation might be challenging. Figure 2. DLS measurements Table 1. VTT MIKES metrology has two instruments suitable for nanoparticle measurements. Figure 1. AFM image of 100 nm nanoparticles 46 — VTT MIKES METROLOGY Calibration services 2016 Instrument Zetasizer Nano PSiA XE-100 Measurement method DLS AFM Measurands Size distribution, Zeta potential Size, Shape Measurement range 0,3 nm - 10 µm 5 nm – 5 µm Measurement uncertainty 2% from 1 nm Characterization of nanoparticles Zetasizer Nano Atomic force microscopy (AFM) Dynamic Light Scattering is used to measure particle and molecule sizes. This technique measures the diffusion of particles moving under Brownian motion, and converts this to size and a size distribution using the Stokes-Einstein relationship. An AFM uses a cantilever with a very sharp tip to scan over a sample surface. As the tip approaches the surface, the close-range, attractive force between the surface and the tip cause the cantilever to deflect towards the surface. However, as the cantilever is brought even closer to the surface, such that the tip makes contact with it, increasingly repulsive force takes over and causes the cantilever to deflect away from the surface. Laser Doppler Micro-electrophoresis is used to measure zeta potential. An electric field is applied to a solution of molecules or a dispersion of particles, which then move with a velocity related to their zeta potential. The services for nanoparticle characterization at MIKES In AFM images the topography of a sample surface by scanning the cantilever over a region of interest. The raised and lowered features on the sample surface influence the deflection of the cantilever, which is monitored by a position-sensitive photo diode (PSPD). By using a feedback loop to control the height of the tip above the surface the AFM can generate an accurate topographic map of the surface features. • Nanoparticle size and shape measurements using AFM • Nanoparticle size distribution in solution using DLS • Nanoparticle surface charge (Zeta-potential) measurements in solution Figure 3. DLS results of ~100 nm nanoparticles VTT MIKES METROLOGY Calibration services 2016 — 47 Mass pressure flow Temperature humidity Electricity time acoustics Length geometry Optics Calibration of laser interferometers Jeremias Seppä, Senior Research Scientist, Tel +358 50 410 5503 [email protected] Veli-Pekka Esala, Senior Research Scientist, Tel +358 40 866 7636 [email protected] Laser interferometers together with gauge blocks are the most important measurement standards in modern length metrology. At 1980s a common understanding was that laser interferometers are accurate and hence do not need any calibration. However, ever increasing demand for accuracy and long experience on usage of laser interferometers have shown that it is necessary to calibrate laser interferometers, also. At MIKES, we have traceable procedures to calibrate laser interferometers. The calibration of laser interferometers improves their reliability and accuracy essentially. MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi Figure 1. Functional testing of a laser interferometer Figure 2. An iodine-stabile HeNe-laser used for the practical realisation of the metre. 48 — VTT MIKES METROLOGY Calibration services 2016 Chemistry Calibration of laser interferometers Calibration and functional testing of environmental sensors Calibration procedure Calibration of laser frequency The vacuum wavelength of lasers used in laser interferometers is calibrated using iodine-stabilised lasers. Traceability to the definition of the metre is guaranteed as frequencies (vacuum wavelength) of the iodine-stabilised lasers are determined by an optical frequency comb refer-enced to an atomic clock. MIKES maintains the following lasers that are locked to iodine absorption lines according to international recommendations: He-Ne lasers at wavelengths: 633 nm (Figure 2) and 543.5 nm and a Nd:YAG-laser at 532 nm. These laser have a relative frequency uncertainty better than 10-10 (expanded uncertainty, k=2). The frequency of the laser under calibration is compared to the frequency of an iodinestabilized laser. The calibration includes a long term frequency (vacuum wavelength) calibration and repeatability measurements. Moreover, the frequency difference of the horizontally and vertically polarised lights is determined and the separation of the polarisation planes inspected. Together these measurements provide good indication of the frequency stability of the laser under calibration. Lasers that operate at wavelengths not reachable by iodine-stabilized lasers can be calibrated using a frequency comb. In addition to laser vacuum wavelength calibration the environmental sensors are calibrated and their operation tested. These measurements are necessary to achieve the naturally good measurement accuracy of a laser interferometer. Especially, by calibrating the environmental sensors order of magnitude better measurement accuracy can be achieved for a laser interferometer. The calibration of environmental sensors includes the calibration of air temperature sensors, atmospheric pressure sensors and material temperature sensors. The functional testing is performed in a temperature stabilised laboratory room by measuring the locations of a moving carriage equipped with a retroreflector with the laser interferometer under calibration and with a reference laser interferometer (Figure 1). In these measurements, both laser beams travel through the same optical components and data is collected with and without the environmental sensors operating. Also, the angle-scale is tested using a reference laser. If necessary, the quality of the optical components is tested with a flatness interferometer. If the readings of the environmental sensors deviate remarkably from readings of the reference instruments they should be adjusted. By adjusting them, the accuracy of the laser interferometer can easily be improved (Figure 3), e.g. the adjustment is relatively easy to perform in Agilent laser interferometers. Traceability Figure 3. Errors in environmental sensors can have remarkable effects on the readings of a laser interferometer.. Quantity Measuring range Uncertainty(k=2) Wavelength 633 nm; 543,5 nm; 532 nm ~10-9 (suhteellinen) Air pressure 970…1050 hPa (730…790 mmHg) 40 Pa Air temperature 17…25 °C 0.10 °C Material temperature 15…25 °C 0.050 °C The frequencies of the iodine-stabilised lasers which are national measurement standards of length are determined using an optical frequency comb referenced to MIKES atomic clocks. The instruments used in the calibration of environmental sensors are calibrated in the corresponding national standards laboratories. Thus, the measurements are traceable to the corresponding definitions of the units. Table 1. Uncertainty of calibration.. VTT MIKES METROLOGY Calibration services 2016 — 49 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Interferometrical calibration of gauge blocks Pasi Laukkanen, Research Engineer, Tel +358 50 382 9674, [email protected] Antti Lassila, Pricipal Metrologist, Tel +358 40 767 8584 [email protected] MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi Calibration of gaugeblocks Gauge blocks are the most important measurement standards of length in industry. Interferometric measurement of gauge blocks provides an absolute calibration method. By using interferometers, the practical realisation of the metre is transferred to a gauge block via the calibrated wavelength of the frequency-stabilised laser used in the interferometer. Gauge blocks calibrated by comparison must be traceable to gauge blocks calibrated by interferometry. The length of a gauge block is defined in an ISO standard as the distance from the centre of the gauge face to an auxiliary reference plane wrung to the other end of the gauge block at 20 °C temperature and at 1013.25 hPa barometric pressure. Gauge block sets calibrated by interferometry give a lower uncertainty for mechanical calibrations for instance in accredited calibration laboratories. Figure 1. Tesa-NPL gauge block interferometer. Interferometers at MIKES MIKES have gauge block interferometers for short (0…300 mm) and for long (100…1000 mm) gauge blocks and end standards. The interferometers are located in a laboratory room having well stabilised environmental conditions and they are equipped with temperature, humidity and pressure sensors. Low uncertainties for refractive index of air and for thermal expansion compensation can be achieved with a precise control and monitoring of the environmental conditions. Difference in surface roughness between the gauge block face and the reference plane is measured and corrected for in results. The parallelism and flatness of the surfaces can be measured, also. The MIKES PSIGB interferometer for short gauge blocks (Fig. 1) uses stabilised He-Ne lasers at 633 nm and 543.5 nm. The interferometer is equipped 50 — VTT MIKES METROLOGY Calibration services 2016 with a large wringing bed which enables fast and automated calibration of even 14 gauge blocks in sequence. In the Tesa interferometer, the gauge blocks are positioned vertically. The long gauge blockinterferometer (Fig. 2) utilises white light and 633-nm laser light interference patterns. By using white light, beforehand knowledge of the length of the end standard is not required. The end standards and gauge blocks are positioned horizontally and supported at the Bessel points in such a way that the weight of the reference plane is compensated for. Interferometrical calibration of gauge blocks Traceability The regular calibration of length standards and length measuring equipment is a necessary part of measurement quality control. Traceable calibreations and knowledge on the measurement uncertainty are basic demands for good and constant quality. The traceability to gauge block calibrations is achieved by calibrating the wavelengths of lasers used in the interferometers against national measurement standards of length, iodine-stabilised He-Ne lasers. Measuring devices for temperature, humidity and pressure used in the interferometers are calibrated in corresponding MIKES laboratories. The reliability of calibrations are verified by taking regularly part in international comparisons. Calibration services Gauge block interferometers can be used to measure even other artefacts whose surfaces are flat and smooth enough; for instance to determine the thermal expansion coefficient of ceramic sealings and to measure the air gap between two parallel glass plates. Interferometric calibration sets also demands for gauge blocks: their end surfaces must be parallel, flat and without scratches. MIKES calibrates gauge blocks of grades K (00) and O and end standards, e.g. quartz metres, according to the following table. Figure 2. MIKES length bar interferometer for calibration of long gauge blocks. Table 1. Calibration subjects and measurement uncertainties Device Measurement range Uncertainty (k=2) Gauge blocks, small 0.5 mm ... 300 mm Q[20; 0,3L] nm Gauge blocks, long 100 mm ... 1000 mm Q[30; 0,11L] nm Quartz meters 1000 mm 72 nm 2 2 1/2 L is measured in millimetres Q[x; y] = (x + y ) VTT MIKES METROLOGY Calibration services 2016 — 51 Mass pressure flow Temperature humidity Electricity time acoustics Length geometry Optics Chemistry Calibration of gauge blocks by mechanical comparison Ilkka Raeluoto, Senior Research Technician, Tel +358 050 410 5562, [email protected] Veli-Pekka Esala, Senior Research Scientist, Tel +358 40 866 7636 [email protected] MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi Mechanical comparison measurement is the most common way to determine the length of a gauge block. In this method, the length of the gauge block under calibration is compared to the length of a calibrated gauge block with same nominal length by using a specific comparator, Figure 1. Gauge block measurement Comparison measurements of gauge blocks that have the same nominal length and that are of the same material are simple, reliable, fast and inexpensive. The method is also applicable to gauge blocks whose surfaces have been wornout in use. MIKES calibrates steel, hard-metal, and ceramic gauge blocks in lengths 0.1....1000 mm (Table 1). In calibration we check the flatness of the surfaces and remove splatters that could prevent reliable use of the gauge blocks. A regular inspection of gauge blocks prevents a possible damage to affect the whole set. The use of uncalibrated gauge blocks in production quality control and in calibration of measurement equipment causes extra risks and costs. Figure 1. The sensor of the gauge block comparator identifies the location of the surface by using 0.6 Nm measurement force. Table 1. Calibration of gauge blocks by mechanical comparison.. Measurement device Measurement range Uncertainty (k=2) Tesa gauge block comparator 0,1 mm …100 mm Q[0,050; 0,00087L] µm MIKES comparator for long gauge blocks 100 mm …1000 mm Q[0,20; 0,00087L] µm L is the nominal length in millimeters 52 — VTT MIKES METROLOGY Calibration services 2016 Calibration of gauge blocks by mechanical comparison Traceability The reference gauge blocks used in mechanical comparison measurements are regularly calibrated using MIKES gauge block interfereometers. The wavelengths of lasers used in these interferometers are calibrated by national measurement standard of length, iodine-stabilised He-Ne lasers. Table 2. Accuracy grades of ISO 3650:1998 standard:. Nominal length range mm Calibration grade K μm Grade 0 μm Grade 1 μm Grade 2 μm Alaraja Yläraja ±te tv ±te tv ±te tv ±te tv 0.5 10 0.20 0.05 0.12 0.10 0.20 0.16 0.45 0.30 10 25 0.30 0.05 0.14 0.10 0.30 0.16 0.60 0.30 25 50 0.40 0.06 0.20 0.10 0.40 0.18 0.80 0.30 50 75 0.50 0.06 0.25 0.12 0.50 0.18 1.00 0.35 75 100 0.60 0.07 0.30 0.12 0.60 0.20 1.20 0.35 100 150 0.80 0.08 0.40 0.14 0.80 0.20 1.60 0.40 150 200 1.00 0.09 0.50 0.16 1.00 0.25 2.00 0.40 200 250 1.20 0.10 0.60 0.16 1.20 0.25 2.40 0.45 250 300 1.40 0.10 0.70 0.18 1.40 0.25 2.80 0.50 300 400 1.80 0.12 0.90 0.20 1.80 0.30 3.60 0.50 400 500 2.20 0.14 1.10 0.25 2.20 0.35 4.40 0.60 500 600 2.60 0.16 1.30 0.25 2.60 0.40 5.00 0.70 600 700 3.00 0.18 1.50 0.30 3.00 0.45 6.00 0.70 700 800 3.40 0.20 1.70 0.30 3.40 0.50 6.50 0.80 800 900 3.80 0.20 1.90 0.35 3.80 0.50 7.50 0.90 900 1000 4.20 0.25 2.00 0.40 4.20 0.60 8.00 1.00 Note: The calibration ISO grades 0, 1, and 2 correspond to accuracy classes A, B, and C in OIML standard nr. 30, respectively. Abbreviations in the table 2:: te = deviation of length from nominal length tv = variation in length VTT MIKES METROLOGY Calibration services 2016 — 53 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry 2D- and 3D- measurement of form and surface roughness Björn Hemming, Senior Research Scientist, Tel +358 50 773 5744 [email protected] Maksim Sphak, Researcher, Tel. +358 504155976 [email protected]” MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi The manufacturing tolerances of modern products and the aim to high quality require the ability to measure different form measurands of small artefacts having complicated shapes. Examples of such form measurands are straightness, parallelism, radius of curvature and surface roughness. MIKES measurement and calibration services using a computer controlled form and surface texture instrument provides one solution to these measurement problems. Form measurements The form measurement instrument can detect form deviations even as small as 0.6 nm. Examples of typical form measurements are accurate measurements of straightness, inner and outer determinations of radiation of curvatures and diverse dimensional measurements of small artefacts (Figure 1). These include determinations of grooves lengths and depths and inner and outer angle measurements. The most important technical specifications of the Taylor Hobson Form Talysurf instrument are gathered in table 1.. Figure 1. Straightness measurement on a cylindrical surface. 54 — VTT MIKES METROLOGY Calibration services 2016 2D- and 3D- measurement of form and surface roughness Surface roughness measurements In addition to calibration of surface roughness normals, the surface texture instrument at MIKES is used for tasks related to quality control and product development. The surface roughness measurements at MIKES are based on the following standards: ISO 5436-1 and ISO 4287. Traceability Traceability to the form measurement instrument comes from interferometrically calibrated gauge blocks, a line scale, an optical flat and a sphere. Measurement subjects • traceable calibration of surface roughness standards • divers measurements in development of prosthesis in health care industry • measurement of tribological samples • profile measurements of blades of excavation machinery • geometrical measurements in product development and quality control of electronic components • product development and quality control measurements of metal packings and components in hydraulics and pneumatics. Figure 2. Measurement of sideline. Taulukko 1. The most important technical specifications of the Taylor Hobson Form Talysurf instrument. Ominaisuus Tiedot Instrument and operational principle Taylor Hobson Form Taly-surf Ser. 2, Type 112/2815-02, inductive Measurement tips Tdiamond tip, radius 0.002 mm; spherical sapphire tip, radius 0.397 mm Measurement forces 1.0 mN (using diamond tip), 15-20 mN (sapphire tip) Surface texture parameters R3y, R3z, Ra, Rc, Rda, Rdc, Rdq, RHSC, Rku, Rln, RLo, Rlq, Rmr, Rmr(c), Rp, RPc, Rq, RS, Rsk, RSm, Rt , Rv, RVo, Rz, Rz(JIS). In addition, a series of waviness parameters. Longest measurement length 120 mm Maximum height of artefact 700 mm, maximum width in 2D measurements is 50 mm Largest allowed from deviation 28 mm (120 mm arm) Measurement speed 1 mm/s Resolution 0.0006 µm Lowest uncertainty Q[10; 70P] nm where P is the deviation from flatness in micrometers VTT MIKES METROLOGY Calibration services 2016 — 55 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Optical measurement of surface microstructures Ville Heikkinen, Researcher, Puh. +358 50 415 5980 [email protected] Björn Hemming, Senior Research Scientist, Tel +358 50 773 5744 [email protected] MIKES, Tekniikantie 1, 02150 Espoo Puh. +358 20 722 111 www.mikes.fi Micro to millimeter range structures can be measured at MIKES using scanning white light interference microscope (SWLI). The SWLI has sub-nm vertical and µm level horizontal resolution. It can measure square mm areas in a single scan. Benefit of SWLI compared to other instruments with similar vertical resolution include large measurement area ability to measure high steps and ability to measure overlapping surfaces inside of transparent structures. See table 1 for more properties of the instrument. Real life measurement uncertainty is case dependent and depends on measurement environment, properties of instrument and properties of measured sample. At MIKES we take care that the sample is clean, sample temperature is known, sample is well attached and properly aligned. Measurements are done traceably under consistent conditions and results are well documented. Figure 1. Bruker ContourGT-K Scanning white light interferometer We do different measurements using the SWLI Examples of potential measured objects • Bearings, contact surfaces, surface topography and wear • Semiconductors and MEMS • Medical instruments and implants • Optical components • Precision machined components 56 — VTT MIKES METROLOGY Calibration services 2016 • different type of objects o surface shape measurements o x,y,z dimensions of details on surface o film thickness measurement, layer separation o surface roughness (2D and 3D ISO roughness parameters), flatness, deviation from a shape • calibration of different instruments • calibration of reference artefacts o step heights, air gap artefacts, film thickness artefacts • calibration of reference artefacts o step heights, air gap artefacts, film thickness artefacts Optical measurements of surface microstructures Figure 2. Measurement of machined aluminium surface. Figure 3. Measurement of a groove on a glass surface. Optimal measurement condition Traceability SWLI is in underground measurement room with 20 ± 0,1 °C temperature. Most heat sources in the room have been eliminated by venting warm air out. SWLI is traceable to SI-metre through MIKES’s own transfer standards such as step height standards, gauge blocks and laser-interferometry. Table 1. Properties of SWLI Property Information Optical x-y resolution Pixel size Vertical resolution Step height measurement: • repeatability • accuracy Sample reflectivity: Maximum surface tilt (smooth samples): 3.8 – 0.7 µm 7.2 – 0.2 µm < 0.1 nm < 0.1 % < 0.75 % 0.05 % - 100 % 3 ° (2.5× objective), 18.9 ° (20× objective) Magnifications 2.5× and 20× objectives, 0.55×, 1× ja 2× zoom lenses 3 Measurement area (X × Y × Z mm ): smallest magnification 3.5 × 4.6 × 3.5 largest magnification 0.4 × 0.6 × 3.5 Measurement area in pixels 640 × 480 Programs Vision64 Analysis Software, MountainsMap, MatLab Maximum size of measured object 10 cm high × 20 cm wide, one dimension can be long Ability to measure overlapping surfaces 2 surfaces in single measurement Maximum depth is dependent on refractive index, geometry and magnification, e.g. it is possible to measure through 0.3 mm thick glass 7 mm maximum depth limited by working distance VTT MIKES METROLOGY Calibration services 2016 — 57 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Calibration of tachymeters Jarkko Unkuri, Research Scientist, Tel +358 50 410 5506 [email protected] Antti Lassila, Pricipal Metrologist, Tel +358 40 767 8584 [email protected] MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi MIKES calibrates angle and distance measurements functions of tacheometers. Calibration of a distance meter in a 30-metre measuring rail Readings from a distance meter of a tachymeter is compared to readings from a laser interferometer of the 30 meter measuring rail. The measurement axis of the tachymeter and the laser interferometer are aligned to be parallel. The reading of the interferometer is set to zero at the beginning of the measuring rail. The observed reading of the distance meter at the zero point of the interferometer is subtracted from Figure 1. MIKES 30-m measuring rail. 58 — VTT MIKES METROLOGY Calibration services 2016 the readings of the distance meter. In the calibration certificate, the deviations from the references distances and the expanded measurement uncertainty are given for each target point. The target point can be a prism, a reflector tape or a target plate. The measurement uncertainty depends on the scatter of the measurement results and is typically between 0.05 – 0.25 mm for accurate distance meters.. Calibration of tachymeters Calibration of angle measurements by using a rotary table and collimation tubes The vertical and horizontal scales of a tachymeter are calibrated by using a Eimeldingen rotary table as a reference. The rotary table is calibrated using polygons and collimation tubes. In the calibration of the horizontal scale, the tachymeter is placed to the rotary table in such a way that the vertical axis is aligned to the rotational axis of the table (Figure 2). The table is rotated 360° in 30° steps and at each step the reading of the tachymeter that has been targeted to the collimation tube are recorded. The vertical scale of the tachymeter is calibrated in the same way but now the rotary table is turned to vertical position by using optomechanics that have been designed especially for this purpose. Contents of tacheometer calibration Figure 2. Calibration of the horizontal plane of a tachymeter in an Eimeldingen rotary table with a collimation tube as a target point. Typical measurement uncertainty calibration of length scale deviation from reference precision target 0.15 mm spherical target 0.15 mm reflector tape 0.20 mm without target calibration of angle scale scale error of the vertical circle 2-3” scale error of the horizontal circle 1-2“ tilting axis error 1-2“ index error of the vertical circle 0.5 - 1.5 “ line-of-sight error 0.5 - 1.5 “ crosshair alignment and perpendicularity influence of focussing checking the readings of the environmental sensors divergence test of automatic targeting VTT MIKES METROLOGY Calibration services 2016 — 59 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Angle and perpendicularity measurements Asko Rantanen, Senior Research Technician, Tel +358 400 925 594 [email protected] Björn Hemming, Senior Research Scientist, Tel +358 50 773 5744 [email protected] Angle measurements are important in all me-chanical engineering and construction industry. The significance of angle measurements is increased also in dimensional measurements when dimensions increase. Perpendicularity that is related to right angles and square blocks is an important special case of angle mesurement. MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi • As a result the width t of tolerance zone is given • One side is defined as the reference side and only against this side the perpendicularity is determined. The SI-unit for angle is radian (rad) but depending on the branch of industry and the measurement subject other unist of angle are commonly used. In mechanical engineering angles are normally expressed in degrees [°], minutes [’] and seconds [”], in geodesy the most commonly used unit is gon (also referred to as grade) [gon]. In earth-moving work and for small angles the unit [mm/m] is generally used. The diverse group of units for angle include also the following ways to express the angle: percent [%] and length ratios. Perrpendicularity according to the ISO1101 standard: Figure 1. Polygon attached to a rotary table. Errors from the rotary table and the polyhedron can be separated by performing a measurement series using a Moller Wedel HPR autocollimator. 60 — VTT MIKES METROLOGY Calibration services 2016 Angle and perpendicularity measurements Instruments for measuring angle Measurement uncertainty The most typical objects of calibration in mechanical workshops are rotary tables of machine tools and measuring machines, universal bevel proctractors, angle blocks, and different kinds of spirit (bubble) levels. Typical angle measurement instruments used in machine installation and in construction engineering are e.g. electronic levels, theodolites, levelling instruments, tacheometers, laser interferometers, autocollimators and polygons. Figure 2. Calibration of the horizontal scale of a tacheometer using an Eimeldingen rotary table and an autocollimator as a target point. All measurements are performed in a well-controlled laboratory room at temperature +20 °C ± 0.1°C. The achievable measurement uncertainty depends critically on the artefact under calibration and its properties (e.g. its form errors and surface roughness). Figure 3. Calibration of a granite square using a measuring machine developed at MIKES. Table 1. Examples of lowest uncertainties for angle measurement instruments. Instrument Measuring range Measurement uncertainty (k=2) Limitations Optical polygons 0 ° - 360 ° 0.2 ” Rotary indexing table 0 ° - 360 ° 0.5 ” Rotary table 0 ° - 360 ° 0.2 ” Autocollimator 0°-1° 0.02 ” Electronic level 0 ° - 360 ° 0.2 ” Theodolite 0 ° - 360 ° 0.2 ” Angle block 0 ° - 360 ° 0.2 ” Steel or granite squares 90 ° 0.5 ” max. length 1 m Cylinder square 90 ° 0.5 ” max. length 1 m Optical right angle 90 ° 0.5 ” indexing angle n x 15° instrument limits the vertical angle VTT MIKES METROLOGY Calibration services 2016 — 61 Mass pressure flow Temperature humidity Electricity time acoustics Length geometry Optics Measurements of accurate inner and outer dimensions Ilkka Raeluoto, Senior Research Technician, Tel +358 50 410 5562, [email protected] Veli-Pekka Esala, Senior Research Scientist, Tel +358 40 866 7636 [email protected] Measurements using SIP length measuring machine Precise measurements of inner and outer diameters are performed using SIP length measuring machine either by using its own scale or by referencing to a standard of equal length (Figure 2). In the measurement a contact is made using a ceramic spherical measuring probe, a flat tip or in inner measurements a lever probe. If the measurement depth in inner measurements is over 15 mm, special hook-shaped jaws are used. The measuring force can be tuned between 0.3…11 N. By measuring with several different forces, the deformations due to the measuring forces can be eliminated from calculations and the result can be given at so-called zero-force. This is essential when the reference and the artefact under calibration are made of different materials or have MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi shapes. The accuracy of the length scale in SIP length measuring machine can be improved by using a laser interferometer (5528A) and a separate readout program. Measurements are performed in a well-controlled laboratory room at temperature + 20 °C ± 0.1 °C. Different types of heat sources are eliminated by using vent pipes, heat shields, and when necessary with a separate laminar flow. In addition to the measurement length, the measurement uncertainty depends on the measured artefact (shape and surface texture), on measuring instrument, measurement conditions, and on the method used. In addition to diameter measurements, the SIP length measuring machine is used for thread measurements and tolerance comparisons. The inner threads are measured using spherical probes and in outer thread measurements three wire method is used. Figure 1. Measurement using SIP length measuring machine. 62 — VTT MIKES METROLOGY Calibration services 2016 Chemistry Measurements of accurate inner and outer dimensions Measurements supplementing diameter measurements In order to get a precise picture of the features of an axially symmetrical artefact that is under measurement, one should also measure its roundness, surface roughness and straightness of sides using appropriate instruments. Traceability Measurements made using the SIP length measuring machine are traceable to corre-sponding transfer standards that are calibrated at MIKES. The linear scale is calibrated using a laser interferometer, the reference gauge blocks are calibrated interferometrically, and the temperature sensors are calibrated in temperature baths against reference Pt25 thermocouples. Figure 2. Mounting side by side the artefact under calibration and the reference in a comparison measurement. Table 1. Measurement uncertainties achievable in diameter measurements. Measurement artefact Measurement uncertainty (k=2) Thread plug 0 mm - 550 mm Q[0,2; 0,87L] µm Ring gauge 1 mm - 500 mm Q[0,2; 0,87L] µm Sphere 0.2 mm …200 mm Q[0,15; 0,7L] µm L in metres Figure 3. SIP 550M length measuring machine. VTT MIKES METROLOGY Calibration services 2016 — 63 Mass pressure flow Temperature humidity Electricity time acoustics Length geometry Optics Coordinate measurement Pasi Laukkanen, Research Engineer, Tel +358 50 382 9674, [email protected] Veli-Pekka Esala, Senior Research Scientist, Tel +358 40 866 7636 [email protected] The coordinate measuring services at MIKES include measurements with an optical coordinate measuring machine and with a high-accuracy industrial size contact probe coordinate measuring machine. Contacting coordinate measurement The basic properties of MIKES coordinate measuring machine are accuracy, flexibility, speed, and automatic calculation of results. The MIKES 3D coordinate measuring machine is a Mitutoyo Legex 9106 with portal structure (Figure 1). Further information on this machine can be found in Table 1. The true measurement uncertainty is always case-specific and depends on the environmental conditions, on the machine, and on the properties of the work piece. We pay special attention in our working on surface cleanliness, temperature, mounting (Figure 2), alignment, measuring system, and on the documentation of results. Figure 1. Mitutoyo Legex coordinate measuring machine. 64 — VTT MIKES METROLOGY Calibration services 2016 MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi Chemistry Coordinate measurement The coordinate measuring machine is used for: • pcustom measurements of 3D workpieces (Figure 3) and difficult shapes - scanning - digitizing of point clouds • various calibration of measurement devices - rulers, surface plates, gauges, cones, squares • calibration of transfer standards for coordinate machines - step gauges, ball cubes, Optimal measurement conditions underground The coordinate measuring machine is located in a large volume underground laboratory room held at + 20 °C ± 0.2 °C constant temperature. Most of the heat sources in the laboratory are eliminated using vent pipes. Moreover, the room is equipped with a 1000-kg load lifter on rails and a lift with 4000 kg maximum load capacity can be used to haul the goods into the laboratory.tauksena (substitution method) . Jäljitettävyys In commissioning, various laser and gauge block measurement were carried out on the coordinate measuring machine. Furthermore, the machine is regularly calibrated using our own measurement standards: step gauges, ball plates, and a laser interferometer. The measurement uncertainty and traceability are verified in each case separately using so-called substitute method, i.e. results are corrected using the results of a calibrated standard. Figure 3. A typical artefact that can be measured using a coordinate measuring machine. Figure 2. The proper mounting of work pieces is important. Table 1. The main properties of the coordinate measuring machine. Property Performance checked according to ISO 10360-2: • maximum error in lengtmeasurements • maximum 3D contact deviation • maximum error in scanningmeasurement Data MPEe = (0.35 + L /1000) µm, L = mm MPEP = 0.35 µm MPEthp = 1.4 µm Scales Mitutoyo Zerodur scales with floating mounting, reolution 0.01 μm. Travelling length X-910 mm, Y-1010 mm ja Z-610 mm Contact probe Renishaw indexing head PH10MQ, Renishaw SP25M contact and scanning probe. Software Mitotoyo COSMOS-software pakage • Geopak-Win geometry program • Statpak-Win geostatistical analysis for quality control • Scanpak-Win form measurement program 3Dtol-Win/MCAD300 comparison with CAD models and importing CAD data for programmingi Measuring force 0.03 N…0.09 N Maximum work piece mass 800 kg Diameters of probes 0.5 mm…30 mm VTT MIKES METROLOGY Calibration services 2016 — 65 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Optical coordinate measuring – vision measuring Ville Byman, Research Scientist, Tel +358 50 386 9327, [email protected] Björn Hemming, Senior Research Scientist, Tel +358 50 773 5744 [email protected] MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi The manufacturing tolerances of modern products and the aim for high quality require ability to make precise measurement of dimensional measurands on small artefacts of complicated shapes. The use of vision measuring machines and machine vision is wellestablished in non-contact high-precision measurement. MIKES have a Mitutoyo Quickvision Hyper QV-350 vision measuring machine (optical CMM or video measuring machine) that is equipped with a CCD-camera as well as with a contact probe. In non-contact optical measurements, the machine takes advantage of the measurement point location detected by the CCDcamera and location information from the precise scales attached to mechanical guides.sta. 66 — VTT MIKES METROLOGY Calibration services 2016 Figure 1. The artefact under study can be illuminated with ring, coaxial or stage light. Optical coordinate measuring – vision measuring The machine is computer-controlled and measurements are fully automated. The machine is capable to measure length, diameter, angle, straightness, flatness, parallelism, and roundness. The machine is especially suitable for measurements of circuit boards, thin-walled fragile plastic and metallic artefacts, and other artefacts that are inconvenient or impossible to measure with techniques using contact probes. The artefact under study can be illuminated with ring, coaxial or stage light. There are four controllable segments in the ring light and its height can be adjusted. MIKES provides precise optical and contact dimensional measurements tailored according to customers’ needs. Depending on the work order a calibration certificate or a field log is provided. Table 1. Properties of the vision measuring machine. Property Data Measuring volume 350 mm x 350 mm x 150 mm Size of the bench 490 mm x 550 mm Maximum work piece mass 15 kg Lowest measurement uncertainty (k=2) , optical mode U1XY = (0.8 + 2 L/1000) µm * U2XY = (1.4 + 3 L/1000) µm * U1Z = (3 + 2 L/1000) µm * Lowest measurement uncertainty (k=2) , contact probe U1XY = (1.8 + 2 L/1000) µm * Maximum speed (rapid travel) 100 mm/s MMaximum acceleration 490 mm/s2 * L is length in mm. U1 is uncertainty along to one axel and U2 along two axels. Figure 2. A contact probe complements the vision measuring machine. VTT MIKES METROLOGY Calibration services 2016 — 67 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Calibration of line scales and distance meters Jarkko Unkuri, Researcher, Tel +358 50 410 5506 [email protected] Antti Lassila, Pricipal Metrologist, Tel +358 40 767 8584 [email protected] Calibration services at interferometric measuring rails Line scale interferometer MIKES calibration equipment for precision line scales allows calibration of up to 1.12-m long line scales with best possible accuracy. The measuring instrument is located in an air-conditioned laboratory room in which the tem-perature is held at + 20 ± 0.05 °C and the relative humidity at 45±5 %. The instrument performs computer-controlled measurements of distances between the graduation lines using a micro-scope equipped with a CCD camera for line detection and a Michelson interferometer for position measurement of the microscope. The line scales are supported at Airy points which minimizes bendings. The refractive index of air is calculated from the measured air temperature, pressure and humidity data by using updated Edlen’s equation. Thermal expansion is corrected to 20 °C using material temperature measured with four Pt100 sensors attached to the line scale. The graduation line distances can be between 10 μm ... 1.12 m. The line scale interferometer is suitable for calibrations of me-tallic or glass graduated line scales. MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi carriage. A microscope, a CCD camera and a monitor used in line scale measurements are mounted on the carriage, The position of the microscope is measured using a laser interfereometer. The temperature stability of the measurement room and precise gauges and sensors allow precise thermal expansion and refractive index of air compensation. The rail is suitable for calibration of various length standards. The calibrated devices can be physical artefacts like tapes and machinist scales or e.g. optical distance meters. Tapes and other flexible length standards are tensioned using a standardized force, a force given by the manufacturer or a force separately agreed with customer. Most commonly a 50-Nm force of is used for tapes. For thermal expansion compensation, a measured temperature and a coefficient given by the manufacturer or by the customer are used. Calibration of line scales and distance meters 30-m measuring rail MIKES 30-m measuring rail (Figure 2) offers good possibilities for calibration of precise length measuring devices. The temperature of the measurement room is kept at a + 20 °C ± 0.5 °C and the relative humidity at 45±5 %. The 30-m rail is realised using a highquality linear motion guide and a movable measurement 68 — VTT MIKES METROLOGY Calibration services 2016 Kuva 1. Piirtomittainterferometri. Calibration of line scales and distance meters Traceability The wavelengths of the lasers used in the line scale interferometer and in the 30-m measuring rail are calibrated using national measurement standard of length, iodine-stabilized He-Ne laser. The temperature, pressure, and humidity sensors used in the measuring rail are calibrated at MIKES. Table 1. Line scales, measuring ranges and measurement uncertainties.. Device Measuring range Uncertainty (k=2) Precision line 10 µm ... 1 m scales, microscope scales Q[6,2; 82L] nm** Tapes, wires Q[35; 2L] µm 0.001 m ... 30, (60, 90 ...) m Machinist scales 0.001 m... 5 m Q[4; 1L] mm** Circometer 0.1 m ... 9,55 m (diameter) Q[7; 2D] mm** Plumb tapes 1 m ... 30, (60, 90) m Q[250; 5L] mm** Other devices 0 m ... 30 m (case dependent) L, D = measured length or corresponding diameter in meters *The uncertainty of calibration is usually larger than the aforementioned uncertainties due to the uncertainty resulting from the device to be calibrated. **Calculation of uncertainty Q[x; y]=(x2+y2)½ Figure 2. 30-m measuring rail.. VTT MIKES METROLOGY Calibration services 2016 — 69 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Interferometric measurement of flatness and form Björn Hemming, Senior Research Scientist, Tel +358 50 773 5744 [email protected] Ville Byman, Research Scientist, Tel +358 50 386 9327, [email protected] Tasomaisuus The surface structure and especially the flatness of the surface are important features of various components used in different areas of technology and physics. Examples of these include silicon wafers in semiconductor industry, sealing faces, bearing areas, contact surfaces in contact measurement methods, and surfaces of optical flats and lenses used for reflecting and refracting light. An optical flat is an easy to use transfer standard for flatness. In industry, optical flats are used, e.g. for Figure 1. Calibration of an optical flat. 70 — VTT MIKES METROLOGY Calibration services 2016 MIKES, Tekniikantie 1,02150 Espoo +358 20 722 111 www.mikes.fi flatness measurements of gau ge blocks and contact surfaces of micrometer gauges. In these cases, the quality of the surfaces of optical flats is of essential importance for successful measurements of subject sur-faces. Moreover, optical flats are used to transfer flatness to interferometers measuring flatness and to other devices inspecting flatness in industry. MIKES provides a measurement place for aforementioned measurements and metrological traceability with its equipment for flatness and form measurements (Figure 1). Interferometric measurement of flatness and form Measurement method The measurement device for flatness at MIKES is a Fizeau interferometer that uses a He-Ne laser at wavelength 633nm as a light source. Interference fringes are obtained by adjusting a small angle between the reference plane and the plane to be measured. The shapes of the inter-ference fringes are analysed by using a so-called phase stepping method. As a result, one receives deviations of the plane under inspec-tion from the reference plane (Figure 2). The advantages of the method are speed, precision, and the fact that the entire measurement area is measured at once. Figure 2. Examples of measured surface profiles of optical flats. Traceability The reference plane of the optical flat used in the interferometer is of high-quality: deviations from a perfect plane are less than 20 nm. The reference plane is calculated either by using an absolute three-point method or by comparing it to a liquid plane. Optical flats having different reflection coefficients are available which allows inspections of mirror surfaces as well as glass surfaces. Measurement services The MIKES equipment (Zygo GPi) can be used for surface profile measurements of objects that have diameters below 150 mm, best available measurement precision being 45 nm. A prerequi-site for such measurements is that the height variations of the artefact are less than 12 μm and slowly varying. As the method is based on interference of light and thus it is a non-contacting method it is also applicable for fragile materials. Moreover, it is applicable for very demanding measurement tasks due to its precision. VTT MIKES METROLOGY Calibration services 2016 — 71 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Machine tool measurements Asko Rantanen, Senior Research Technician, Tel +358 400 925 594 [email protected] Veli-Pekka Esala, Senior Research Scientist, Tel +358 40 866 7636 [email protected] MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi Machine tool measurements Demands of production and quality systems require knowledge on the precision of machine tools. Different measurement are performed on machine tools during acceptance inspection, in connection with transfers, and when striving for preventive maintenance. MIKES provides its wide experience on dimensional and geometrical measurements, positioning and repeatability accuracy measurements, and measurements on machine tooled test work pieces. The competent and experienced personnel of MIKES, modern equipment and continuous development of new measurement methods guarantee customers precise measurements performed according standards. Figure 2. Setup for machine tool measurements. 72 — VTT MIKES METROLOGY Calibration services 2016 Figure 1. Scale measurement for a machine tool.. Machine tool measurements Geometrical measurements Geometrical measurements are used for finding out the form defects in the most important organs of a machine tool and the mutual locations and positions of the organs. MIKES performs geometrical measurements according to ISO and DIN standards. The most important measurements subjects are: measurement of spindle runout, the parallelism between the spindle and the machine, perpendicularity measurements, and straightness and perpendicularity measurements of machine movements. Positioning and repeatability accuracy measurements Spindle positioning and repeatability measurements reveal errors at different points of the spindle. Errors in spindle movement can be compensated for by giving the compensation values to the control unit memory of the machine tool. The positioning measurement performed using MIKES laser interferometer is a fast and precise way to adjust the spindle movements of a machine (Figure 3). By using this method, the measurement precision is at its best below 0.001 mm/m. Table 1. Devices used in machine tool measurements Geometrical and positioning and repeatability accuracy measurements:: Measurements of test work pieces: - laser interferometers - surface structure, form, roundness and length measuring machines - autocollimators - iinductive sensors - electronic spirit level - common workshop measurement devices - inductive sensors - coordinate measuring machine - plumb - other devices Traceability All measurement standards used in machine tool measureentsare calibrated using similar but more accurateMIKES transfer standards. Measurements on test work pieces Machine-tooling tests are used to find out the precision of the machine in true machining circumstances. MIKES geometrical measurements and measurements on work pieces made in machine-tooling tests complement each other. The work pieces are measured in a temperature-controlled laboratory room using versatile and modern measurement devices and methods. MIKES have a variety of the most common workshop measurement equipment and a selection of special tools (see Table 1). Figure 3. X-axis errors of a broaching machine before laser measurement and adjustment and after. VTT MIKES METROLOGY Calibration services 2016 — 73 Mass pressure flow Temperature humidity Electricity time acoustics Length geometry Optics Chemistry Measurement of roundness Björn Hemming, Senior Research Scientist, Tel +358 50 773 5744 [email protected] Veli-Pekka Esala, Senior Research scientist, Tel +358 40 866 7636 [email protected] MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi Roundness in mechanical engineering industry Approximately 80 % of machined work pieces have elements with surfaces of revolution. Roundness has an important role for guaran-teeing faultless operation of machines and devices. This is even emphasized when reli-ability, longevity, low operating costs, and friendliness to the environmental are required. At MIKES we perform measurements of roundness on ring gauges, screw-plug gauges, slide bearings, metallic packings and hydraulic and pneumatic components. We also measure runout eccentricity, coaxiality, parallelism and straightness (Figure 1). Figure 1. Roundness measurement is an essential part of workshop manufacturing. 74 — VTT MIKES METROLOGY Calibration services 2016 Measurement of roundness Measurement potential Roundness is measured either by using a rotating spindle or using a roundness measurement instrument equipped with a rotating table. Measurements can be performed using several different filters according to the ISO 1101 standard’s definition (MZ) or other computing methods (MC, MI, and LS). The use of two alternative machines guarantees the customer that the artefacts can be measured properly and cost effectively. More information on the machines can be found in table 1. Cylindricity is measured using a machine equipped with a rotating table (Figure 2), with almost the same settings also the following measurement can be performed: coaxiality, runout eccentricity, parallelism and straightness. Cylindricity measurements are a part of the calibration of ring gauges and screw-plug gauges. Traceability Traceability to the sensors in both machines comes from magnification standards that are calibrated using MIKES form measurement instrument which in turn gets it traceability from gauge blocks calibrated Figure 2. Measurement instrument Talyrond 262 for roundness using an interferometer. The guide bars and shafts in and cylindricity. the machines are calibrated using error separation. Table 1. MIKES roundness and cylindricity measurement instruments Model Rotating part Maximum height of the artefact / mm Maximum inner/ outer diameter of the artefact / mm Maximum mass of the artefact / kg Other Expanded uncertainty (k=2) Talyrond 73 HR roundness spindle 400 175 / 300 100 surface can be discontinuous or asymmetrical Q[0,01; 0,01R ] µm Talyrond 262 cylindricity table 500 - 50 surface can be discontinuous Q[0,1; 0,5L] µm / 350 R is the deviation from roundness in micrometers; L is the height of the cylinder in meters Q[x; y]=√(x2+y2) VTT MIKES METROLOGY Calibration services 2016 — 75 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Calibration of microscpes and calibration standards Virpi Korpelainen, Senior Research Scientist, Tel. +358 50 410 5504 [email protected] Reliable measurement results in research, manufacture and quality control require knowledge of accuracy of measurement intruments. Calibration is the best way to check the accuracy and stability of the instrument. The calibration can be done with calibrated transfer standards. Official calibration certificate guarantees traceability to the definition of the metre. MIKES, Tekniikantie 1,02150 Espoo Tel +358 20 722 111 www.mikes.fi 2], which can be calibrated at MIKES. 1-D and 2-D gratings are calibrated either by laser diffraction or by metrology atomic force microscope (MAFM). Pitch and orthogonality of the grid can be measured. Step height standards or z scale of 1-D or 2-D gratings can be calibrated. For optical microscopes MIKES provides calibration of high quality line scales. Scanning probe microscopes (SPMs) can be calibrated using several kinds of transfer standards [1, [1] Guideline VDI/VDE 2656 Part 1 (Draft): Determination of geometric quantities by Scanning Probe Microscopes - Calibration of Measurement Systems [2] V. Korpelainen and A. Lassila, Calibration of a commercial AFM: traceability for a coordinate system, Meas. Sci. Technol. 18 (2007) 395–403 Figure 1. MIKES interferometrically traceable metrology AFM (MIKES IT-MAFM). 76 — VTT MIKES METROLOGY Calibration services 2016 Calibration of microscopes and calibration standards measured using a flatness standard. In the most accurate calibrations also some other error types has to be measured and corrected; e.g. orthogonality of z axis, rotational and other guiding errors. There are also other error sources which should be taken into account, e.g. tip-sample interactions, vibrations, noise and thermal drift. Calibration period depends on the stability of the device, e.g. microscopes with open loop scanner need calibration before and after each measurement. Calibration itself gives information about the accuracy of the instrument. Accuracy of the measurement can be increased by corrections of the errors detected in the calibration either directly in the measurement software or after the measurement with separate software. The first step in the calibration is measurement of x and y scale errors by 1-D or 2-D gratings and z scale errors by step height standards. The calibration of the x and y scales gives also information about the linearity of the scales. The linearity of the z scale needs to be checked by several different step height standards. Orthogonality errors can be detected by 2-D grids. Out-of-plane errors can be Figure 3. Some error types of SPMs. Table 1. Calibration services for SPM standards. Uncertainty Range 1-D grid (diffraction measurement) Pitch 300 nm - 10 µm 50 - 100 pm 300 nm - 10 µm 50 - 100 pm 100 nm - 10 µm Q [3.4; 0.2 p/µm] nm 2-D grid (diffraction measurement) Pitch Orthogonality 1-D grid (AFM measurement) Pitch, p Orthogonality 14 mrad Step height, h 10 nm - 2 µm Q [2; 0.2 h/µm] nm Flatness 100 µm × 100 µm 5 nm Step height standard 10 nm - 2 µm Q [2; 0.2 h/µm] nm Flatness standard 100 µm × 100 µm 5 nm VTT MIKES METROLOGY Calibration services 2016 — 77 Mass pressure flow Temperature humidity Electricity time acoustics Optics Length geometry Chemistry Length in geodesy Markku Poutanen, Prof., Tel. +358 29 531 4867, [email protected] Paavo Rouhiainen, Senior research scientist, Tel +358 29 531 4875 [email protected] Jorma Jokela, Research manager, Tel +358 29 531 4743 [email protected] Finnish Geospatial Research Institute, FGI, Geodeetinrinne 2, 02430 Masala, Tel. +358 29 530 1100, www.fgi.fi Finnish Geospatial Research Institute, FGI The Finnish Geospatial Research Institute, FGI, of the National Land Survey of Finland maintains measurement standards for geodetic and photogrammetric measurements and is the National Standards Laboratory of acceleration of free fall and length. The FGI takes care of the fundamental measurements in Finnish cartography and of geographical information metrology and carries out scientific research in geodesy, geographic information sciences, positioning, navigation, photogrammetry and remote sensing. Calibration services The FGI calibrates high precision electronic distance measurement (EDM) instruments, geodetic baselines and photogrammetric test fields. Moreover, we calibrate precise levelling rods, digital and traditional, and system calibration of digital level instruments. The calibrations are performed in addition to the Masala laboratories at Nummela Standard Baseline and at Metsähovi Fundamental station. Most of our work is carried out in field conditions or conditions analogous to operating situations. 78 — VTT MIKES METROLOGY Calibration services 2016 Figure 1 and 2. The Nummela standard baseline measured by using the Väisälä comparator has been one of the most accurate and stable lengths over the past half decade. Length in geodesy Traceability and uncertainty Research and development National measurement standards for length at the FGI are a Väisälä interference comparator with a quartz meter system and a levelling rod comparator system with a laser interferometer. All the measurements are traceable with a known uncertainty. Baselines (864 m and 432 m) measured with the Väisälä interference comparator have typically a measurement uncertainty ranging from 0.1 ppm to 0.2 ppm (k=2) and the measurement uncertainty for other baselines (1 m - 10 km) is at its best 0.2 ppm. The measurement uncertainty for calibration of levelling rods is 1 ppm and 5 ppm for calibration of levelling systems. The FGI carries out research and development on methods and equipment for the measurements for geodesy and geospatial information science. In addition to length measurements, we perform other precision measurement in surveying, e.g. measurements of angle, azimuths, determination of coordinates and satellite positioning. We also participate in GNSS metrology related projects. International cooperation is a central part of our work and we have measured baselines in about 20 countries. Figure 3. Calibration of the most accurate distance meters of the world can be done at the Nummela Standard Baseline. Nummela scale has been transferred also to several foreign baselines. Figure 4. Calibration of a digital precise level instrument and system calibration of a barcode rod. Figure 5. Research on the accuracy of GNSS antennas can be made at the test field of the Metsähovi observatory. VTT MIKES METROLOGY Calibration services 2016 — 79 Massa, paine ja virtaus Lämpötila, kosteus Sähkö, aika ja akustiikka Optiikka Pituus, geometria Kemia Water quality Teemu Näykki, PhD, Associate Professor, Senior research scientist Tel. +358 29 525 1471, [email protected] Timo Sara-Aho, Researcher, Tel. +358 29 525 1618 [email protected] ENVICAL SYKE is focusing on the research and development of metrology in chemistry. Our activities include development of accurate and traceable calibration methods, testing the reliability of new measurement techniques and validation of methods of analysis and quality assurance. Traceable calibrations The SYKE accredited calibration laboratory (K054: EN ISO/IEC 17025) produces calibration results with high accuracy and traceability and is responsible for developing methods based on primary techniques. In general, Isotope Dilution Mass Spectrometry (IDMS) can be regarded as one of the main referen- Finnish Environment Institute Hakuninmaantie 6, 00430 Helsinki, Tel. +358 29 525 1000, www.syke.fi/envical/en ce methods for elemental analysis, and appropriately applied it offers the highest accuracy and smallest measurement uncertainty. This method is used to measure the elemental content (usually mass fraction) of an unknown test sample, which has natural isotopic composition. This sample is mixed with another sample (spike) containing a known amount of the same element under investifgation. Isotopic composition of the spike sample is known and it is different from the isotopic composition of the test sample; usually such a way that the rarer isotopes of the element are enriched. When the test sample and the spike are completely mixed, the resulting mixture (blend) has a new (isotope diluted) isotopic composition, where the isotope ratios are between the test sample and the spike Photo Timo Vänni 80 — VTT MIKES METROLOGIA Kalibrointipalvelut 2016 Water quality sample added. The isotope ratios of the mixture are measured and the result is directly proportional to the mass fraction or concentration of the element in the sample. At present, the scope of SYKE’s calibration laboratory accreditation includes measurement of lead (Pb) in natural water and mercury (Hg) in natural and waste water. The methods are based on the isotope dilution inductively coupled plasma mass spectrometric (ICP-MS) technique. The range of measurements is being complemented with tests for dissolved oxygen and also nickel and cadmium, listed as priority substances in the Water Framework Directive. The isotope dilution mass spectrometric technique is widely utilized by SYKE also for measurement of organic chemical contaminants. Our customer base consists of public and private parties requiring accurate and reliable measurement results for their environmental samples. For instance, we have produced traceable reference values for proficiency tests (PTs). Research Activities The comparability of the measurement results is internationally very important. Reliability and comparability of the measurement results can be improved with the realistic measurement uncertainty estimation, validation of the measurement methods, and ensuring the traceability of the measurement results. ENVICAL SYKE is an experienced in research and development of the instrument’s reliability and procedures for measurement uncertainty estimation. We have constructed new tools for both laboratory measurements as well as for portable and continuous field water quality measuring devices to indicate and improve the reliability of the measurement results. Examples of these tools are MUkit- and AutoMUkitmeasurement uncertainty calculation software. We also actively participate in organizing proficiency tests for water quality sensor measurements. In addition to maintenance of measurement standards’ international traceability, our activities include national and international communication, publication, and training in the field of metrology. Upon request, we arrange customized training in the estimation of measurement uncertainties in chemical measurements or validation of analytical methods. Table 1. CMC data.. Quantity / method / object Measurement range CMC, Expressed as Expanded Uncertainty (k=2) ) Chemical analyses; amount of substance Mass fraction of soluble total mercury (Hg) in synthetic water, fresh natural water (not sea water) and waste water Photo Timo Vänni Mass fraction of soluble total lead (Pb) in synthetic water and fresh natural water (not sea water) 30 - 125 ng/kg >125 - 5 000 ng/kg 6% 3% 0,200 – 1,00 μg/kg >1,00 - 100 μg/kg 0,030 μg/kg 3% VTT MIKES METROLOGY Calibration services 2016 — 81 MIKES Tekniikantie 1 02150 ESPOO MIKES-Kajaani Tehdakatu 15, Puristamo 9P19 87100 KAJAANI Tel +358 20 722 111 email: [email protected] www.mikes.fi