High density optical disk with V-shaped grooves

Abstract

Properties of diffracted light back from an optical disk, which has grooves with a V-shaped cross-sectional configuration, are studied by employing scalar diffraction theory. The V-shaped grooves are spaced bottom to bottom by a presently used track pitch, and all walls of the grooves are capable of storing information. If the optical depth of the V-shaped groove is one-fourth of the wavelength of the laser, the 2nd or (−2)nd diffracted light beam contains only the information on a single wall. This property is utilized to double the information density of the optical disk.