System Coding Parameters, Mechanics and Electromechanics of the Reflective Videodisc Player

The choice of a coding system for an optical videodisc system is determined by the recording process, the optical stylus, the associated servo systems, and the disc properties. The videodisc system described employs a master disc that is prepared by modulating a laser beam with video and audio information to expose a photosensitive surface on the disc; after processing, minute pits of varying length are produced in a spiral pattern on the disc — rather like the continuous pattern of an ordinary phonograph record but without grooves. Pressing copies from the master also follows the phonograph record analogy. The pit side of a disc is covered with a highly reflective metallic coating and an additional protective coating; the video and audio information is read by a focused laser beam from the other side of the disc, through the transparent material of the disc. The control mechanisms necessary for operation are discussed, and it is shown that a 30-min high-quality television program with two separate sound channels can be compressed to a 30-cm-diameter disc format while allowing adequate tolerances for all aspects of the signal processing.

Print ISSN

0036-1682

Published

1977-02

Content type

Original Research

DOI

10.5594/J13239