Disc for recording and reproducing optical information.

摘要

A disc for recording and reproducing optical information has a substrate in the surface of which are formed information signal recording grooves and cue signal recording pits, and a light-absorbing thin film formed on the surface of the substrate, the optical characteristics of the light-absorbing film being changeable thermally through irradiation by a light beam. The pitches of the grooves and pits, as well as the widths of the grooves and pits, are determined to meet specific conditions in relation to the diameter of the leaser beam which is used for recording and reproduction of the signals. The addition, the depths of the grooves and pits are determined suitably in relation to the wavelength of the laser beam. With this arrangement, it is possible to attain a high quality of reproduction of information from the disc.