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Virtual Retinal Display Options
Daemon
Posted: Friday, October 20, 2017 12:00:00 AM
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Virtual Retinal Display

Newly developed virtual retinal display (VRD) technology allows devices to project a graphical display directly onto a user's retina, creating the impression that the display is hovering in space in front of him. In the past, similar systems, which often came in the form of large sunglasses, simply projected images onto a small "screen" in front of the user's eye. Only recently have a number of developments made a true VRD system practical. What applications could VRDs have? More...
raghd muhi al-deen
Posted: Friday, October 20, 2017 2:45:25 AM

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Virtual retinal display
Also found in: Acronyms.
Virtual retinal display
A diagram showing the workings of the virtual retinal display

A virtual retinal display (VRD), also known as a retinal scan display (RSD) or retinal projector (RP), is a display technology that draws a raster display (like a television) directly onto the retina of the eye. The user sees what appears to be a conventional display floating in space in front of them. (However, the portion of the visual area where imagery appears must still intersect with optical elements of the display system. It is not possible to display an image over a solid angle from a point source unless the projection system can bypass the lenses within the eye.)[1]
The basic system

In a conventional display a real image is produced. The real image is either viewed directly or, as in the case with most head-mounted displays, projected through an optical system and the resulting virtual image is viewed. The projection moves the virtual image to a distance that allows the eye to focus comfortably. No real image is ever produced with the VRD. Rather, an image is formed directly on the retina of the user's eye. A block diagram of the VRD is shown in the Figure above.

To create an image with the VRD a photon source (or three sources in the case of a color display) is used to generate a coherent beam of light. The use of a coherent source (such as a laser diode) allows the system to draw a diffraction limited spot on the retina. The light beam is intensity modulated to match the intensity of the image being rendered. The modulation can be accomplished after the beam is generated. If the source has enough modulation bandwidth, as in the case of a laser diode, the source can be modulated directly.

The resulting modulated beam is then scanned to place each image point, or pixel, at the proper position on the retina. A variety of scan patterns are possible. The scanner could be used in a calligraphic (vector) mode, in which the lines that form the image are drawn directly, or in a raster mode, much like standard computer monitors or television. Use of the raster method of image scanning allows the VRD to be driven by standard video sources. To draw the raster, a horizontal scanner moves the beam to draw a row of pixels. The vertical scanner then moves the beam to the next line where another row of pixels is drawn.

After scanning, the optical beam must be properly projected into the eye. The goal is for the exit pupil of the VRD to be coplanar with the entrance pupil of the eye. The lens and cornea of the eye will then focus the beam on the retina, forming a spot. The position on the retina where the eye focuses the spot is determined by the angle at which light enters the eye. This angle is determined by the scanners and is continually varying in a raster pattern. The brightness of the focused spot is

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KSPavan
Posted: Friday, October 20, 2017 3:20:21 AM

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Article of the Day
Virtual Retinal Display
Newly developed virtual retinal display (VRD) technology allows devices to project a graphical display directly onto a user's retina, creating the impression that the display is hovering in space in front of him. In the past, similar systems, which often came in the form of large sunglasses, simply projected images onto a small "screen" in front of the user's eye. Only recently have a number of developments made a true VRD system practical.
KSPavan
Posted: Friday, October 20, 2017 3:21:24 AM

Rank: Advanced Member

Joined: 1/28/2015
Posts: 2,005
Neurons: 1,975,780
Location: Kolkata, Bengal, India
Article of the Day
Virtual Retinal Display
Newly developed virtual retinal display (VRD) technology allows devices to project a graphical display directly onto a user's retina, creating the impression that the display is hovering in space in front of him. In the past, similar systems, which often came in the form of large sunglasses, simply projected images onto a small "screen" in front of the user's eye. Only recently have a number of developments made a true VRD system practical.
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