VIRTUAL RETINAL DISPLAY: Your Eye Is The Screen

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

Source: Human Interface Technology Lab