3-DIMENSIONAL VISUAL STIMULATOR

We describe a newly developed three-dimensional visual stimulator (TVS ) that can change independently the directions, distances, sizes, lumi nance, and varieties of two sets of targets for both eyes. It consists of liquid crystal projectors (LCP's) that generate the flexible image s of targets, Badal otometers that change target distances without cha nging the visual angles, and relay-lens systems that change target dir ections. A special control program is developed for real-time control of six motors and two LCP's in the TVS together with a three-dimension al optometer III that simultaneously measures eye movement, accommodat ion, pupil diameter, and head movement. The TVS measurement ranges are as follows: distance, 0 to -20 D; direction, +/- 16 degrees horizonta lly and +/- 15 degrees vertically; size, 0-2 degrees visual angle; and luminance, 10(-2)-10(2) cd/m(2). The target images are refreshed at 6 0 Hz and speeds with which the target makes a smooth change (ramp stim uli) are as follows: distance, 5 D/s; direction, 30 degrees/s, size, 1 0 degrees/s. A simple application demonstrates the performance.