Method of making a digital recording medium

Abstract

Abstract A digital recording medium formed of a thermoplastic substrate having a regular array of microscopic optically-alterable mirrors each supported by a mesa projecting from one surface of the substrate. The parallel rows of the mirrors are the same distance apart as the mirrors in each row. The medium can be formed from a single transparent thermoplastic substrate with an array of indentations in a first surface. The bottom of each indentation is coated with a reflective material. When viewed from the opposite surface of the substrate, the indentations become mesas. The reflective coating is sputtered onto the first surface thereby coating the first surface and the bottoms of the mesas. The reflective coating is then removed by abrasion from the first surface. Recording is by exposure through a second surface of the substrate to a laser beam that reduces the reflectivity of selected mirrors. After exposure to the recording laser beam, the mirrors retain enough reflectivity to be distinguishable from the intervening valleys. The mirrors serve as timing and tracking markers prior to and during recording, and during read-out. The area and location of each information bit is determined prior to recording: not as a result of the recording process.

Inventors

• 👤 Arthur M. Gerber

Bibliographic Details