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:
                                                  
                                            Figure1:Basic block diagram of VRD
     The resultant imaged formed on the retina is perceived as a 
     wide field of view image originating from some viewing 
     distance in space.
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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.
     10:45:20 PM                                                         6