VIRTUAL RETINAL DISPLAY: Your Eye Is The Screen

By Nelson Johny - 16 June, 2004

The commercial launch of a device named Nomad by Bothell-based Microvision Inc has turned fiction into reality. Nomad is a device based on the Virtual Retinal Display (VRD), a new display technology that projects modulated low energy laser light directly onto the viewer´s retina, producing a rasterized image.

The viewer gets to see the source image as if he/she is standing two feet away in front of a normal CRT monitor. In reality, the image is on the retina of its eye and not on a screen. The quality of the image is excellent with stereo view, full color, wide field of view and no flickering characteristics.

Microvision has the exclusive license to develop and market the retinal-scanning technology, which was first patented by researchers at the University of Washington’s Human Interface Technology Lab (HIT) in 1991. Retinal scanning was the brainchild of Tom Furness, Founder of the HIT. The development began in November 1993. The aim was to produce a full color, wide field-of-view, high resolution, high brightness, low cost virtual display.

A laser light that shoots directly on to the retina sounds dangerous. But, Microvision says the technology is a lot safer because of the very low strength of the laser used. The power of the light is about a thousandth of a watt.

Besides, the laser light does not stay fixed on one location of the retina and continuously sweeps across the retina at a very high rate both horizontally and vertically, making it much more safer. Some experts say that staring at a fluorescent bulb would be much more dangerous than the laser light in Nomad which produces light levels much lower than nationally accepted standards.

HOW IT WORKS
VRD works very much like a CRT monitor. But, in a VRD, the source image is projected directly onto the retina instead of the back of the screen. In a conventional display, a real image is produced, which is either viewed directly or projected through an optical system and the resulting virtual image is viewed.

With the VRD, no real image is ever produced. Instead, an image is formed directly on the retina of the user’s eye. Unlike CRT monitors, the VRD has no phosphorus persistence but, depends on the light-gathering properties of the photo-receptors and the temporal integration properties of the visual system.

The device which looks more like a virtual reality gaming headset consists of five components, namely: drive electronics, light sources, scanner assembly, pupil expander and viewer optics. The electronics acquire and process signals from data or an image source, say a graphic card or a video camera.

The signals contain vital information about the intensity and mix of the colors which can be reproduced by the light source. The scanner then applies the image to the retina. It is made up of a tiny mirror that sweeps the light beam until a full image appears to the user. The scanned beam is focused onto an optical element called an exit pupil expander.

VRD APPLICATIONS
The industry is in need of cost effective and portable devices that will consume very lower energy and bandwidth and yet be powerful in all respects. The Nomad Expert Technician System from Microvision is the first such device currently being marketed commercially for the auto industry technician.

"It is a powerful, wearable information delivery tool that will help your business achieve new levels of service productivity and customer satisfaction," says a dealer who sells this device for $3995 on the Internet.

With this device, technicians can read the detailed service information and follow complex instructions directly at their point of task, head-up and hands-free. "No guessing, no shortcuts, no waiting for printouts  just cars back in service faster, fixed right the first time. The Nomad Expert Technician System is easy to set up and incredibly simple to use," he adds. Honda is probably the first automobile company which has brought this device in to use among its dealers. The monocle is worn in front of the eye and reflects scanned laser light to the eye allowing mechanics to view car diagnostics and instructions superimposed on their field of vision.

According to Honda, it has found that technicians are saving about 40% in terms of the time spent working on engines, saving the company an estimated $2,000 per month, per technician.

Surgeons have also tested a version of the system which gives them vital patient data, such as heart rate and blood pressure, as they operate. According to some reports on the Internet, around 100 of the see-through laser-based displays have been shipped to Iraq for use by the US Army’s Stryker Brigade.

APPLICATIONS IN THE OFFING
VRD technology has many potential applications, from head-mounted displays for military, aerospace, automobile applications to medical use. If you want data right in front of you, while on the move, this is the technology.

It could provide three dimensional realistic images in gaming applications. Within few years, such systems may find a place in mobile phones, hand-held computers and digital cameras.

The present VRD devices are a little bulkier in size. The ultimate aim is to get this technology in form of lightweight eyewear. The device is for professionals from any industry who need data quickly and easily and are willing to pay the current high cost.

But over the year, the device is expected to be more affordable just like the home computers. One day it could even replace the regular CRT or LCD monitors attached to our personal computers.

NELSON JOHNY

CHARACTERISTICS OF VRD

  • Very small and lightweight, glasses mountable
  • Large field of view, greater than 120 degrees
  • High resolution, approaching that of human vision
  • Full color with better color resolution than standard displays
  • Brightness sufficient for outdoor use
  • Very low power consumption
  • True stereo display with depth modulation
  • Capable of fully inclusive or see through display modes
  • Does not block the user’s vision

Source: Human Interface Technology Lab

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abhishek Thu Jun 20 at 04:44 PM

Adstuck is working on VRD to launch its Augmented reality glasses called "EYE"

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