virtual retinal dispaly

8/6/2019 Virtual Retinal Dispaly

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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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virtual retinal dispaly

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