| 摘要 |
A coordinate input device having two beams of pulsed laser light passing through a photochromic glass plate. The successive intersection points of pulses from the two beams scan the plate along a raster to successively mark each coordinate position on the plate. A light pen directs ultraviolet light onto the surface of the plate to generate a scattering center at any chosen coordinate on the plate. Laser light is scattered by such centers and is detected by the light pen. The greater amount of light scattered at an intersection point is used to generate an indication of the chosen coordinate. Another embodiment uses roughened glass, rather than photochromic glass, to cause scattering. |
