HOLOGRAM GRAPHIC DATA TABLET

摘要

A holographic tablet device comprises a recording plate on which an array of holograms is arranged. Each hologram has coded positional information therein corresponding to its location on the plate. The recording plate is illuminated with a collimated monochromatic or substantially monochromatic beam by an indicating device. Diffracted beams are thereby produced corresponding to which of the holograms have been illuminated. The diffracted beams are detected and corresponding binary signals are produced. Also disclosed is an arrangement for maintaining a desired constant angle between the illuminating device and the recording plate.