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Contents

•Abstract•Introduction•VRD (Virtual Retinal Display) Basics •Basic diagram of VRD•Key features of VRD•VRD System Overview•Applications•VRD versus Pixel Based Displays•Future Scope•Conclusion

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Abstract

•The Virtual Retinal Display (VRD) is a personal display device.

•The VRD scans light directly onto the viewer's retina.

•The special consequences of its mechanism of action and potential medical applications of the VRD.

•Surgical displays and displays for people with low vision.

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Introduction

•Invented at the University of Washington in the Human Interface Technology Lab (HIT) in 1991. by Dr. Thomas.•The development began in November 1993.•New technology for creating visual images. •Creates images by scanning light directly on to retina of eye.•Because scans light directly on the retina, the VRD is not a screen based technology.•Full colour, high resolution, high brightness, wide field of view virtual display without flickering.•Potential applications for military, aerospace, engineering, medical fields.

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VRD (Virtual Retinal Display) Basics

•Uses scanned light beams.•Small spot is focused onto the retina.•Swept over it in a raster pattern.•LED triads of R,G&B emits light. Mixing in proportions can produce any colour.•As light scans the retina, it is intensity modulated by the video signal.•The VRD uses very low power and yet can be very bright.

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Basic diagram of VRD

VRD consists of a light source, a modulator, vertical and horizontal scanners, and imaging optics. On a basic level, as shown in the following figure1:

The resultant imaged formed on the retina is perceived as a wide field of view image originating from some viewing distance in space.

Figure1:Basic block diagram of VRD

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Basic diagram of VRD(cont.)

The following figure illustrates the light raster on the retina and retina converts the light into signals that percolate into your brain via the optic nerve and the resultant image perceived in space.

Figure2: The viewer perceives a wide field of view image as if from a screen placed some distance away.

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Key features of VRD

•Size and Weight: Small size as no intermediate screen is present. •Power consumption: Light sources consume very less power in order of milli watts.•Resolution: Give high resolutions well over a million pixels.•Brightness: Provide very good brightness levels even for see through mode in day light.

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Key features of VRD(cont.)

•Field of view: Inclusive systems provide horizontal field of view 60-100 degrees.

•Stereoscopic display: Supports stereoscopic display as both eyes can be separately addressed.Thus provides a good approximation to natural vision.

•Inclusive & See through: See through works very well even at very high illumination conditions.

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VRD System Overview

•Laser sources are introduced into a fiber optic strand which brings light to the Mechanical Resonance Scanner (MRS).•The MRS is the heart of the system.•As the MRS mirror moves, the light is scanned in the horizontal direction for both the forward and reverse direction of the oscillation.•The scanned light is then passed to a mirror galvanometer or second MRS which then scans the light in the vertical direction.

Figure 3. Block Diagram of VRD systems

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Applications

VRDs can reduce the read-time and can act as always present guides for many tasks.

The various fields of application of VRD technology are listed.

•Radiology•Surgery•Therapeutics•Production•Communication•Augmented \ Virtual reality•Aerospace•Military

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VRD versus Pixel Based Displays

The differences between the pixel based display and the VRD:

Pixel Based Display VRD•Illumination constant over whole pixel Light scanned across retina•persistent light emission Short transient light emission•non coherent light Coherent light•broadband color Narrow band color•pixels separated by mask Spot can overlap retinels in scans

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Future Scope

•When cost of production falls further, we will see VRDs fulfilling many functions and applications.

•Future systems will be even more compact with the advent of MEMS(Micro Electro Mechanical System) scanners, miniature laser diodes and application specific IC technology.

•Another key development to come is the advent of Augmented Reality display systems to assist people in their various tasks.

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Conclusion

•The VRD is a safe new display technology.

•The combination of high brightness and contrast and high resolution make the VRD an ideal candidate for use in a surgical display.

•If cost continues to fall, we will see VRDs fulfill many functions and applications.

•VRD to be a display technology for patients with low vision.

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Thanks To All