08-08-2012, 04:25 PM
Virtual Retinal Display (VRD)
VIRTUAL RETINAL DISPLAY - Copy.doc (Size: 70.5 KB / Downloads: 43)
Introduction
The Virtual Retinal Display (VRD) is a personal display device under development at the University of Washington's Human Interface Technology Laboratory in Seattle, Washington USA. The VRD scans light directly onto the viewer's retina. The viewer perceives a wide field of view image. Because the VRD scans light directly on the retina, the VRD is not a screen based technology. There are no liquid crystal displays or cathode ray tubes (CRTs) in the system.
The Human Interface Technology Laboratory (HITL) of the Washington Technology Center at the University of Washington is developing a novel display device in which a coherent light source is utilized to scan an image directly on the retina of the viewer's eye. A prototype of this device, the Virtual Retinal Display (VRD), has been developed and is being perfected under a four-year project.
Working of EYE
A brief review of how the eye forms an image will aid in understanding the VRD.
A point source emits waves of light which radiate in ever-expanding circles about the point. The pupil of an eye, looking at the source, will see a small portion of the wavefront. The curvature of the wavefront as it enters the pupil is determined by the distance of the eye from the source. As the source moves farther away, less curvature is exhibited by the wavefronts. It is the wavefront curvature which determines where the eye must focus in order to create a sharp image.
VRD 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 Figure
VRD Features
The following sections detail some of the advantages of using the VRD as a personal display.
Size and weight:
The VRD does not require an intermediate image on a screen as do systems using LCD or CRT technology. The only required components are the photon source (preferably one that is directly modulatable), the scanners, and the optical projection system. Small photon sources such as a laser diode can be used
Resolution:
Limited only by diffraction and optical aberration in the optical components, limits in scanning frequency and modulation b/w of photon source. SLD is a coherent source and offer high modulation b/w to give resolutions well over a million pixels. State of the art scanners can scan over a1000 lines per frame which is comparable to
Power Consumption:
Light sources consume very less power in order of milli watts. Scanning is done with a resonant device (MRS) with high figure of merit. Exit pupil of VRD has very small aperture allowing generated light to enter eyes almost completely. Hence high power efficiency.
Brightness:
Perceived brightness is only limited by power of the light source. SLD sources can provide very good brightness levels even for see through mode in day light.
Field of view:
Inclusive systems provide horizontal field of view b/w 60-100 degrees. See through mode systems have it slightly over 40 degrees. These figures are far better than existing HMD systems.
Stereoscopic display:
Supports stereoscopic display as both eyes can be separately addressed. Thus provides a good approximation to natural vision.
Manufacturing
The same characteristics that make the VRD suitable for medical applications, high luminance and high resolution, make it also very suitable for a manufacturing environment. In similar fashion to a surgery, a factory worker can use a high luminance display, in conjunction with head tracking, to obtain visual information on part or placement locations. Drawings and blueprints could also be more easily brought to a factory floor if done electronically to a Virtual Retinal Display (with the option of see-through mode). Operator interface terminals on factory floors relay information about machines and processes to workers and engineers. Thermocouple temperatures, alarms, and valve positions are just a few examples of the kind of information displayed on operator interface terminals. Eyeglass type see-through Virtual Retinal Displays could replace operator interface terminals. A high luminance eyeglass display would make the factory workers and engineers more mobile on the factory floor as they could be independent of the interface terminal location.
Communications
The compact and light weight nature of the mechanical resonant scanner (MRS) make an MRS based VRD an excellent display for personal communication. A hand held monochrome VRD could serve as a personal video pager or as a video FAX device. The display could potentially couple to a telephone. The combination of telephone services and video capability would constitute a full service personal communication device.
Virtual Reality
The traditional helmet display is an integral part of virtual reality today. The VRD will be adapted for this application. It can then be used for educational and architectural applications in virtual reality as well as long distance virtual conference communications. Indeed it can be utilized in all applications of virtual reality. The theoretical limits of the display, which are essentially the limits of the eye, make it a promising technology for the future in virtual reality HMD's.
Conclusion
VRD provides an unprecedented way to stream photons to the receptors of the eye; affording higher resolution, increased luminance, and potentially a wider field-of view than all previous displays. Virtual retinal display is a breakthrough in imaging technology that will optimally couple human vision to the computer. Cost is currently acting as a blocker of the technology in most industries. If this continues to fall, we will see VRDs fulfill many functions and applications, and may perhaps watch them becoming ubiquitous in near future.
VIRTUAL RETINAL DISPLAY - Copy.doc (Size: 70.5 KB / Downloads: 43)
Introduction
The Virtual Retinal Display (VRD) is a personal display device under development at the University of Washington's Human Interface Technology Laboratory in Seattle, Washington USA. The VRD scans light directly onto the viewer's retina. The viewer perceives a wide field of view image. Because the VRD scans light directly on the retina, the VRD is not a screen based technology. There are no liquid crystal displays or cathode ray tubes (CRTs) in the system.
The Human Interface Technology Laboratory (HITL) of the Washington Technology Center at the University of Washington is developing a novel display device in which a coherent light source is utilized to scan an image directly on the retina of the viewer's eye. A prototype of this device, the Virtual Retinal Display (VRD), has been developed and is being perfected under a four-year project.
Working of EYE
A brief review of how the eye forms an image will aid in understanding the VRD.
A point source emits waves of light which radiate in ever-expanding circles about the point. The pupil of an eye, looking at the source, will see a small portion of the wavefront. The curvature of the wavefront as it enters the pupil is determined by the distance of the eye from the source. As the source moves farther away, less curvature is exhibited by the wavefronts. It is the wavefront curvature which determines where the eye must focus in order to create a sharp image.
VRD 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 Figure
VRD Features
The following sections detail some of the advantages of using the VRD as a personal display.
Size and weight:
The VRD does not require an intermediate image on a screen as do systems using LCD or CRT technology. The only required components are the photon source (preferably one that is directly modulatable), the scanners, and the optical projection system. Small photon sources such as a laser diode can be used
Resolution:
Limited only by diffraction and optical aberration in the optical components, limits in scanning frequency and modulation b/w of photon source. SLD is a coherent source and offer high modulation b/w to give resolutions well over a million pixels. State of the art scanners can scan over a1000 lines per frame which is comparable to
Power Consumption:
Light sources consume very less power in order of milli watts. Scanning is done with a resonant device (MRS) with high figure of merit. Exit pupil of VRD has very small aperture allowing generated light to enter eyes almost completely. Hence high power efficiency.
Brightness:
Perceived brightness is only limited by power of the light source. SLD sources can provide very good brightness levels even for see through mode in day light.
Field of view:
Inclusive systems provide horizontal field of view b/w 60-100 degrees. See through mode systems have it slightly over 40 degrees. These figures are far better than existing HMD systems.
Stereoscopic display:
Supports stereoscopic display as both eyes can be separately addressed. Thus provides a good approximation to natural vision.
Manufacturing
The same characteristics that make the VRD suitable for medical applications, high luminance and high resolution, make it also very suitable for a manufacturing environment. In similar fashion to a surgery, a factory worker can use a high luminance display, in conjunction with head tracking, to obtain visual information on part or placement locations. Drawings and blueprints could also be more easily brought to a factory floor if done electronically to a Virtual Retinal Display (with the option of see-through mode). Operator interface terminals on factory floors relay information about machines and processes to workers and engineers. Thermocouple temperatures, alarms, and valve positions are just a few examples of the kind of information displayed on operator interface terminals. Eyeglass type see-through Virtual Retinal Displays could replace operator interface terminals. A high luminance eyeglass display would make the factory workers and engineers more mobile on the factory floor as they could be independent of the interface terminal location.
Communications
The compact and light weight nature of the mechanical resonant scanner (MRS) make an MRS based VRD an excellent display for personal communication. A hand held monochrome VRD could serve as a personal video pager or as a video FAX device. The display could potentially couple to a telephone. The combination of telephone services and video capability would constitute a full service personal communication device.
Virtual Reality
The traditional helmet display is an integral part of virtual reality today. The VRD will be adapted for this application. It can then be used for educational and architectural applications in virtual reality as well as long distance virtual conference communications. Indeed it can be utilized in all applications of virtual reality. The theoretical limits of the display, which are essentially the limits of the eye, make it a promising technology for the future in virtual reality HMD's.
Conclusion
VRD provides an unprecedented way to stream photons to the receptors of the eye; affording higher resolution, increased luminance, and potentially a wider field-of view than all previous displays. Virtual retinal display is a breakthrough in imaging technology that will optimally couple human vision to the computer. Cost is currently acting as a blocker of the technology in most industries. If this continues to fall, we will see VRDs fulfill many functions and applications, and may perhaps watch them becoming ubiquitous in near future.