Stereoscopic visual displays: Principles,viewing devices,alignment procedures

The principle of binocular (stereoscopic) depth perception is that the visual system interprets the slight differences between the views seen by the two eyes as depth cues. In computer-generated displays, two slightly different images are produced on the left and right halves of the display surface and viewed by a prism, mirror, or binoculars system that delivers the appropriate image to each eye. The prism system is the simplest, the mirror system gives the best optical quality, and the binoculars system is useful for producing large apparent images from small display surfaces. All three systems can be adapted for group viewing and all require careful alignment (null adjustment of accommodative distance and vergence distance). Objective and subjective methods of alignment are described.