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PRESENTED BY:ASHISH KUMAR CHAURASIA
EC 3rd yr.
0800131024
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OUTLINE :-
Introduction
How we perceive image
VRD Technology Overview
Safety Analysis
Advantages
Potential Applications
Conclusion
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INTRODUCTION :- Virtual Retinal Display is a display
technology which scans modulated laser light
on the retina of viewers eye to
create an image.
The viewers perception & Virtual.
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THE EYE:
Retina
Photoreceptors
y Rods: 125 x 10^6
y Cones: 6 x 10^6
Macula Fovea
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HOW WE PERCEIVE IMAGES :-
angular resolution =1.22lambda/D
where:
lambda = wavelength of light
D = diameter of the pupil
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Virtual Retinal Display: Technology
Overview
System Description
Video Source
Control and DriveElectronicsLight Source(photon generator)
Modulators
ScannerAssembly
Optical projection
VRD withEyeTracking
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SYSTEM DESCRIPTION (LIGHT
SOURCE)
Type Wavelength[nm]
Optical Power[
mW]
Red lightsource Diode laser 650 3.0
Green
light
source
Helium-Neon 543.5 1.5
Blue light
source
Argon laser 488 14.5
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System Description
Control and DriveElectronics:
Processing of input video signal.
Generation ofcontrol Signals for theacousto-optical modulators.
Synchronization of the vertical and
horizontal scanner.
Overall system timing
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SYSTEM DESCRIPTION
:SCANNER ASSEMBLY Horizontal Scanner Mechanical Resonant Scanner(MRS) :
Operating frequency = 15.75 KHz ~18.9KHz
Contain neither moving magnet nor moving coil.
Torsional spring and mirrorconfiguration with mirror(3mm X 6mm).
MEMS(Micro Electromechanical System)
6mm).
Vertical Scanner Galvanometer with a second mirror(60 Hz).
Constraints:Resolution, field of view or image
size.
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SYSTEM DESCRIPTION:
SCANNER ASSEMBLY
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Virtual Retinal Display: Technology
Overview(working)
Red Diode Laser
BlueArgon Laser
Green Helium Laser
Modulate Light
Signals accordingto pixel
Intensity
A-O
Modulators
A-O
Modulators
Control and Drive
Electronics
VGA Video Sourc Eye
Viewing Optics
Scanner
Assembly
Multiplexing
Circuit
Optical
Fiber
Synchro
nization
Signals
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THE VRD WITH EYE TRACKING
A map of landmarks of retina is
generated.
Unmodulated light from the retina is
monitored.
Changing content of reflected light is
sampled at the sampling rate.
Scanner position at the time ofeach sample
is used to correlate the position of sample.
Sample position and thecontent represent a
map.
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Relative position of landmarks is used to
track the viewing direction ofeye.
relative position of generated map or
pattern will vary according to the viewing
direction.
By identifying the pattern and correlating
relative orientation of pattern to referenced
pattern orientation, viewing direction isdetermined at thecurrent instant.
THE VRD WITH EYE TRACKING
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SAFETY ANALYSISSOURCE USED MPE in Watts
MPE for pulsed Lasers 0.13 Watt
MPE forcontinuous sources 0.16 Watt
MPE forextended sources 1.5 x 10-3 Watt
MPE for different sources
Wavelength (nm) MPE (microwatts)
400-500
600
640
670
700
0.385
2.17
8.62
24.29
68.47
MPE values as a function of Wavelengths in case of scanner failure
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ADVANTAGES :-
Color range:High saturated purecolors.
Luminance and Viewing Modes (60nW ~
300nW)
Contrast Ratio
PowerConsumption
Low Cost
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APPLICATIONS: HEAD MOUNTED
DISPLAYS Commercial Purposes
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APPLICATIONS: HEAD MOUNTED
DISPLAYS DefensePurpose
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APPLICATIONS : LOW VISION
AID
Get Input FromCamera
Apply machineVision Lagos to
detect Obstacles
Input to VRDwith Enhanced
Information
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APPLICATIONS: LO ISION
AID
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APPLICATIONS: INTERACTIVE VRD
Pilots Dilemma :Spent about 50% timewhile looking
down on the navigational scales to
identify their locations.
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CONCLUSION :-
Sufficient amount of work still left
Color displays
Size
Resolution limitations
Stereo displays.
Detailed safety analysis
Current research issueMEMS based one scanner for both
horizontal and vertical scanning.
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Any Query
???
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