Here is a complete overview of the Virtual Retinal Display (VRD).

This technology describes how the source image is projected directly onto the retina. The VRD technology eliminates any screen outside of the eye and addresses the retina with a single stream of pixels.
The retina has no persistence like phosphorus. Moreover, there is no flickering and the produced image is very bright with very high resolution. The time each pixel is projected onto the retina is very small (30-40ns). Furthermore, these devices consume very little amount of energy. They also provide a wider field of view.

The VRD was invented at the University of Washington in the Human Interface Technology Lab (HIT) in 1991. The development began in November 1993. Using the VRD technology it is possible to build a display with the following characteristics:

* 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

A very sophisticated representation of how the beam is projected through the pupil can be found in the HIT Lab of Washington University (VRD animations).