n - Triumf

"Light: from simple optics to
amazing applications"
Andrzej Kotlicki, Alex Rosemann
and Helge Seetzen
The Structure Surface Physics
Laboratory
Faculty: Dr. Lorne Whitehead (In charge of the lab
and the inventor)
Dr. Andrzej Kotlicki
RA: Dr. Michele Mossmann
Post Doctoral Fellows: Dr. Alexander Rosemann and
Dr. Yasser Abdelaziez.
PhD student Helge Seetzen (also Chief Technology
Officer of Brightside Technologies)
Graduate Students and Undergraduate researchers
Outline
• Geometrical optics reminders: reflection, refraction, Snell’s
Law, Total Internal Reflection (TIR)
• Applications of TIR: fiber optics, retro-reflectors, guiding
film
• Frustrated TIR – applications to “real” black and white
reflective display. Electronic paper?
• New Developments in Solar Lighting Systems
based on Prism Light Guides will be presented by Alex
Rosemann
• New concept of electronic display – High Dynamic Range
Display from our Spin-off company Brightside
Technologies - will be presented by Helge Seetzen
• Ray model of light.
• When we can use it?
• Wavelength of light 0.4 - 0.6µm
Snell’s Law:
When light passes from the medium with
refraction index n1 into another with
refraction index n2:
n1sin(θ1) = n2sin(θ2)
n2
1
1
1
1.6
1.6
1.6
n1
0º
Slide by Lorne Whitehead
n2
1
1
1
1.6
1.6
1.6
n1
10º
Slide by Lorne Whitehead
n2
1
1
1
1.6
1.6
1.6
n1
20º
Slide by Lorne Whitehead
n2
θt
1
1
1
1.6
Snell’s Law
1.6
1.6
n1
θr = θi
⎛ ⎛ n1 ⎞
⎞
θt = sin ⎜ ⎜ ⎟ sin(θi )⎟
⎝ ⎝ n2 ⎠
⎠
−1
θi θr
20º
Slide by Lorne Whitehead
n2
1
θr = θi
1
1
1.6
Snell’s Law
1.6
1.6
n1
⎛ ⎛ n1 ⎞
⎞
θt = sin ⎜ ⎜ ⎟ sin(θi )⎟
⎝ ⎝ n2 ⎠
⎠
−1
20º
Slide by Lorne Whitehead
n2
1
θr = θi
1
1
⎛ ⎛ n1 ⎞
⎞
θt = sin ⎜ ⎜ ⎟ sin(θi )⎟
⎝ ⎝ n2 ⎠
⎠
−1
1.6
1.6
1.6
n1
30º
Slide by Lorne Whitehead
n2
1
θr = θi
1
1
⎛ ⎛ n1 ⎞
⎞
θt = sin ⎜ ⎜ ⎟ sin(θi )⎟
⎝ ⎝ n2 ⎠
⎠
−1
1.6
1.6
1.6
n1
38.682º
Slide by Lorne Whitehead
n2
1
θ r = θi
1
θ t = no answer!
1
1.6
1.6
1.6
n1
38.683º
Slide by Lorne Whitehead
n2
1
θ r = θi
1
θ t = no answer!
1
1.6
1.6
1.6
n1
50º
Slide by Lorne Whitehead
n2
1
θ r = θi
1
θ t = no answer!
1
1.6
1.6
1.6
n1
60º
Slide by Lorne Whitehead
n2
1
θ r = θi
1
θ t = no answer!
1
1.6
1.6
1.6
n1
70º
Slide by Lorne Whitehead
Critical angle
•
•
•
•
•
n1sin(θ1) = n2sin(θ2)
θ2 = 90º
θ1 = sin-1(n2 / n1 )
For water θ1 = 49º
For glass θ1 = 42º
Fiber Optics
• Fiber optics for communication
Fiber Optics
Endoscopes
Guiding film
3M Optical Lighting Film (OLF)
Micro-replicated light guiding film uses
linear 90 degree prisms
Samples
Rainbow
Reflective side
Transparent side
Image deformations
air n1 = 1
Prismatic Film n2 =1.6
air n1 = 1
The critical angle for total internal reflection is
αc = sin -1(n1/n2) = 38.7°.
The angle of incidence, 45°, is larger than critical, therefore
a total internal reflection occurs and the light is reflected at
the angle 45°. The same happens on the second face, so the
light is send back and leaves the film at 180° to the original
direction.
air n1 = 1
Prismatic Film n2 =1.6
air n1 = 1
The light comes from the medium with a smaller
so there is no total internal reflection. The
refracted angle is
αr = sin -1(sin(45°)n1/n2) = 26.2°.
The incidence angle on the bottom surface is
45 - 26.2 = 18.8
which is less than critical angle so there in no
total internal reflection and we have an other
refraction:
αr2 = sin -1(sin(18.8°)n2/n1) = 31°.
Retro-Reflection
Light undergoing 1- 3 reflections from a corner
cube with the inner reflecting surfaces returns at
180 degree to the incident light - “retro-reflection”.
TM
Grade
3M Diamond
Reflective Sheeting
An array of corner cubes forms
retro-reflective sheet material
The prism light guide
McDonald’s Roof Beam Light Guide System
Vertical Light Guides 3M Bldg. 275 St. Paul, MN
Light Guide Illumination of Boston’s Callahan Tunnel
Highly directional
down lighting from
new Light Guides and
Sulfur Lamps in
Smithsonian Air and Space
Museum
Solar Lighting Systems
based on Prism Light Guides
• Long History
• New Developments will be presented by
Alex
Frustrated TIR – applications to
“real” black and white reflective
display.
Electronic paper?
TIR...
air gap
glass
glass
TIR...
glass
glass
Frustrated TIR
glass
glass
Principle of a TIR-based Reflective Display
light ray is
reflected
light ray is
absorbed
micro-prisms
(n1)
gap (n2)
absorptive
material
“White State”
“Black State”
Electrophoresis
• Controlled motion of charged particles in a
medium in response to an applied electric
field
d
+
-
-
-
+
+
-
+
-
-
+
-
+
+
+
electrophoretic mobility: µ
-
V
Slide by Michele Mossman
d
+
-
-
-
+
+
+
+
-
+
+
+
-
Particle velocity:
ν=
µV
d
-
V
Slide by Michele Mossman
d
+
-
-
-
+
+
-
+
-
+
+
+
-
+
V
Slide by Michele Mossman
d
+
-
-
-
+
+
+
-
-
+
+
+
-
+
V
Slide by Michele Mossman
d
-
-
-
+
-
-
-
+
+
+
+
-
+
-
+
+
V
Slide by Michele Mossman
Electrophoretic TIR Display
ON STATE
OFF STATE
High Index
Retro-reflective Surface
V
Electrophoretic
Suspension
Slide by Michele Mossman
CLEAR Electronic Paper
Conventional LCD
Display
NonNon-switching
Demonstration
Of
TIRTIR-based reflective display
The TIR-based reflective display has an image quality
very similar to printed white paper.
Slide by Michele Mossman
Hemispherical Microstructures
reflected light
rays
bright annulus
dark center
Slide by Michele Mossman
Hemispherical Microstructures
Microstructured
surface
high density
pigment suspension
Slide by Michele Mossman
New concept of electronic display
– High Dynamic Range Display
from our Spin-off company
Brightside Technologies - Helge
Light: from simple optics to
amazing applications
The Solar Lighting Project at UBC
Alexander Rosemann
February 18, 2006
Solar Lighting Project – Project Partners
• Korea Institute of Energy
Research, Taejon, Korea
• Natural Resources
Canada, Ottawa, ON
• University of British Columbia
Vancouver, BC
Motivation for daylight utilisation
In Vancouver,
daylight is
available during
94 % of the
working hours
Project Aim
• Daylight Utilisation in Deeper Building zones
• Use of materials that are potentially low-cost
in mass production
• Demonstration of the system in a portable
test environment
• Demonstration of the system in a real
building
• …
Basic Idea
Solar Canopies
Example building cross section with solar canopies on
south-facing wall feeding prism light guides
UBC Solar Lighting Project
Control Unit
Sun
Adaptive
Butterfly
Array
Heliobox
Solar Canopy
Light
Guide
TFL +
el.
ballasts
Hybrid Prism Light Guide
Portable Testroom
Heliostat design
Sun positions in Vancouver
Adaptive Butterfly Array
Adaptive Butterfly Array – April 21st
9 pm
10
11
1
noon
2
am
am
Canopy System
mirror array
mirror array
Fresnel lens
Mi
rro
Mi
rro
r2
M
r2
o
r
ir
Fresnel lens
rr
i
M
r1
3m
Light
pipe
or 1
1m
Prism Light Guide
Fluorescent Lamps
Extractor
Highly reflective film
Microprismatic film
Portable testroom
South Wall
Redirecting the direct sunlight with
the Adaptive Butterfly Array
Measurement Overview
•
•
Artificial Lighting
Daylighting
•
•
Daylight entering through the South window
Daylight entering through the solar canopy
system
What did we measure?
Illuminance (Luminous Flux / Area), measured in lx
Measuring height: 0.8 m
What are the target values?
Recommendation in office buildings: 500 lx on the task area and
300 lx in surrounding areas
Artificial lighting
dimming characteristics
Illuminance distribution for a
dimming voltage of 10 V
The relative illuminacne
distribution does not change
with dimming.
r i ght
centr e
l ef t
2
3
4
0-500
5
500-1000
6
7
8
1000-1500
Dimming Characteristics
Mean Illuminance in lx
1
The mean illuminance varies
with the dimming voltage as
shown in the figure.
This data is useful for the
control algorithm
1400
1200
1000
800
600
400
200
0
0
2.5
5
Dimming Voltage in V
7.5
10
Daylighting measurements 1
Setup: SOUTH WALL uncovered
Hybrid light guide blocked
E = 527 lx
right
centre
Illuminance in lx
2000
1500
1000
500
0
left
1
2
3
4
0-500
500-1000
5
1000-1500
6
1500-2000
Illuminance distribution
7
8
0
2
4
6
8
measurement point #
Illuminance along the centre line
The illuminance is very non-uniform. Although the mean
illuminance is above 500 lx, the values drop below 500 lx in
the second half of the room. For this scenario artificial lighting
is required all the time.
Daylighting measurements 2
Setup: SOUTH WALL covered
Hybrid light guide open
11:08 am TLT
E = 550 lx
right
centre
Illuminance in lx
1000
800
600
400
200
0
left
1
2
3
0-200
4
200-400
5
400-600
6
600-800
7
800-1000
Illuminance distribution
8
0
2
4
6
8
measurement point #
Illuminance along the centre line
The mean illuminance is above 500 lx, the values are well
above 500 lx in the centre line, even in the second half of the
room. For this scenario artificial lighting is not required.
Combined Daylighting Results
Setup: SOUTH WALL open
Hybrid light guide open
Simulated results
E = 1094 lx
right
centre
Illuminance in lx
2500
2000
1500
1000
500
0
left
1
2
3
0-500
4
500-1000
5
6
1000-1500
1500-2000
7
2000-2500
Illuminance distribution
8
0
2
4
6
measurement point #
combined
8
window only
Illuminance along the centre line
The mean illuminance is above 500 lx, the values are well
above 500 lx in the centre line, even in the second half of the
room. For this scenario artificial lighting is not required.
Illumination in deeper building zones
Thank you for your attention
The Solar lighting project at UBC
Luminous Transmittance of the
optical lighting film
High Dynamic Range Imaging Pipeline
Helge Seetzen
February, 2006
Imaging Pipeline – 8-bit rules!
2/18/2006
©2005 Brightside Technologies Inc.
2
Image Quality – What are we missing?
Human Overall Luminance Vision Range
(14 orders of magnitude, scale in log cd/m2)
-6
-4
-2
0
2
4
6
8
starlight moonlight indoor lighting sunlight
Human Simultaneous
Luminance Vision Range
Today’s Devices
BrightSide Technologies
2/18/2006
5 orders
of magnitude
2-3
orders
5 orders
of magnitude
©2005 Brightside Technologies Inc.
3
Overcoming the 8-bit Barrier
Requirements:
1. High Dynamic Range
2. Compatibility
ƒ New devices need to function in 8-bit environment and still
deliver significant benefit
ƒ New devices need to be usable in stand-alone mode
3. Cost
ƒ Ideally no extra cost compared to 8-bit devices
ƒ If extra cost is necessary then in line with benefit
2/18/2006
©2005 Brightside Technologies Inc.
4
The Scene
(cd/m2)
Stanford Memorial Church
Courtesy Paul Debevec
2/18/2006
©2005 Brightside Technologies Inc.
5
Image Capture – Multiple Exposures
2/18/2006
©2005 Brightside Technologies Inc.
6
Image Capture – 8-bit to 16-bit CCDs
Compatibility
• existing CCD
• can output 8-bit image
(ignore second exposure)
Shutter is closed
Shutter opens and
light hits the CCD.
Cost
• firmware change only
• zero incremental cost
CCD shifts
charges under
shadow-mask
More light hits the
CCD (causing a
second pattern)
Shutter closes
(transfer to register
and readout)
2/18/2006
©2005 Brightside Technologies Inc.
7
Imaging Pipeline – Our Progress
2/18/2006
©2005 Brightside Technologies Inc.
8
Data Storage – Size is a Problem!
2/18/2006
ƒ RAW Image Data ->
ƒ Radiance XYZE ->
4.5Mb
1.3Mb
(100%)
( 29%)
ƒ 8-bit BMP
ƒ 8-bit JPEG
->
->
1.2Mb
65kb
( 27%)
( 1.4%)
ƒ JPEG HDRTM
->
70kb
( 1.5%)
©2005 Brightside Technologies Inc.
9
Data Storage – JPEG / MPEG HDR
HDR Image
Encoder
L(HDR(x,y))
L(TM(x,y))
Standard JPEG
or MPEG
Compression
Sub-band
Ratio Image
Sub-band Encoding
of HDR Images
Tone Map
Standard or
BrightSide
RGB8 Tone
Mapped
Image
Sub-band
Ratio Image
Tone
Mapped
Image
2/18/2006
Decoder
L(TM(x,y))*RI
Compressed
RGB8 JPEG or
MPEG with
Sub-band
Decompress
with Sub-band
Yes
HDR
Image
©2005 Brightside Technologies Inc.
HDR
Device?
No
Normal
Decompress
Tone
Mapped
Image
10
Data Storage – Image Quality
Compatibility
• indistinguishable from
RGB8 JPEG
• tone mapped image can
be customized
• compatible with most formats
Cost
• very low (~5% extra size)
• real time decoding possible
Tone-Mapped RGB8
Visual Difference Predictor
Subband Image
2/18/2006
©2005 Brightside Technologies Inc.
11
Imaging Pipeline – Our Progress
2/18/2006
©2005 Brightside Technologies Inc.
12
Image Processing
ƒ Floating point GPUs are becoming standard
ƒ Most CG and Games done in HDR today
ƒ TV remains low dynamic range and is unlikely to change soon
ƒ Reverse Tone Mapping and Saturation Extension provide
quality gain even for legacy content
2/18/2006
©2005 Brightside Technologies Inc.
13
Image Processing - Extension
650 56
Gradiant
Colour Space
Size
569 24
16-bit Value
487 92
406 60
325 28
243 96
162 64
81 32
0
3 50
370
3 90
4 10
43 0
4 50
P ix el N u m b e r
2/18/2006
©2005 Brightside Technologies Inc.
14
Image Processing - Extension
Compatibility
• only needed for legacy
content
• calculation supported in
8-bit processor
Cost
• very fast (1-2 operations
per pixel)
2/18/2006
©2005 Brightside Technologies Inc.
15
Imaging Pipeline – Our Progress
2/18/2006
©2005 Brightside Technologies Inc.
16
Display Technology – Concept
High resolution
colour LCD
2/18/2006
High Dynamic
Range Display
Low resolution
Individually Modulated
LED array
©2005 Brightside Technologies Inc.
17
Display Technology – Image Processing
HDR Image
2/18/2006
LED array
LCD with correction
©2005 Brightside Technologies Inc.
Output image
18
Display Technology – Review
ƒ Compatibility
Š Legacy support through Reverse Tone Mapping and Saturation
Extension
Š Small number of LEDs allows encoding of LED data in
conventional video signal
ƒ Cost
Š LED cost money (less every day)
Š Significant power reduction (~25% of comparable constant
backlight LCD on average)
2/18/2006
©2005 Brightside Technologies Inc.
19
Display Technology – Results
(cd/m2)
Stanford Memorial Church
Courtesy Paul Debevec
2/18/2006
©2005 Brightside Technologies Inc.
20
Imaging Pipeline – Completing the Equation
2/18/2006
©2005 Brightside Technologies Inc.
21
DR37-P
“When these displays become
more affordable in the next year
or two, I don't know how we'll
ever go back to the old way.”
David Kirk, NVIDIA
“The item with the biggest
“WOW” factor at SIGGRAPH”
Game Developers Magazine
“The Future of Gaming”
Hollywood Reporter Magazine
“This product really is so different that
your brain has trouble remembering that
it actually is an LCD display”
Bit Tech Magazine
2/18/2006
“… creating the unnerving
sensation that you are somehow
seeing beyond the display
screen”
VFXWorld Magazine
©2005 Brightside Technologies Inc.
22