Engineers at the University of Washington have for the first time used manufacturing techniques at microscopic scales to combine a flexible, biologically safe contact lens with an imprinted electronic circuit and lights. Previously the Virtual Retina display (VRD) was invented at the University of Washington in the Human Interface Technology Lab in 1991.
Advances in printable electronics will make these systems very powerful and affordable in the future. Carbon nanotubes placed onto plastic are at 300 Mhz or the speed of a Intel Pentium 2.
"Looking through a completed lens, you would see what the display is generating superimposed on the world outside," said Babak Parviz, a UW assistant professor of electrical engineering. "This is a very small step toward that goal, but I think it's extremely promising."
Contact lens with electronics being worn by a rabbit in tests
A contact lens with electronics that are mostly outside the transparent field of view part of the eye
Applications for the contact lens displays:
Drivers or pilots could see a vehicle's speed projected onto the windshield. Video-game companies could use the contact lenses to completely immerse players in a virtual world without restricting their range of motion. And for communications, people on the go could surf the Internet on a midair virtual display screen that only they would be able to see.
A full-fledged display won't be available for a while, but a version that has a basic display with just a few pixels could be operational "fairly quickly," according to Parviz.
Future improvements will add wireless communication to and from the lens. The researchers hope to power the whole system using a combination of radio-frequency power and solar cells placed on the lens.
Previously head mounted displays were considered leading edge
Both head mounted displays and contact lens displays enable augmented reality.
A virtual retinal display (VRD), also known as a retinal scan display (RSD), is a new 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.
Virtual retina display overview from the US navy
Virtual retina display graphic from Microvision
This is a see through system. The see through systems for glasses have been commercialized (admittedly limited to military and some car applications) and would have similar issues of focus and comfort.
This 14page pdf discusses various aspects of these systems.
For heads up displays:
Refocusing the eyes can cause fatigue, so an aircraft’s heads up display is “focused at infinity” allowing the pilot to read the display without shifting focus. When used in automobiles, the display is focused closer, somewhere near the end of the hood. Motorcycle helmets also have a relative focal point for maximum comfort.
For virtual retina displays:
VRD has been commercialized in specialized sectors of the display market such as automobile repair and some parts of the military.
Microvision describes their see through display glasses, helmet mounted systems and other wearable displays.
See through display glasses
A 2 page brief on how see through displays on glasses work.
The claimed viewing experiences for see through displays (using glasses with built in displays. The image is perceived and designed to be sharp at a certain preceived distance:
Some references discussing how the virtual image perception works.
NASA discusses some of the virtual miage perception of see through systems
A University of Washington Master's thesis from 1995 discusses the perception of the virtual image for see through systems.
A lot of head mounted displays of various types are on the market