Optical recording and reproducing disc

摘要

An optical recording and reproducing disc for recording and/or reproducing information by the application of laser beams having a wavelength lambda in the range of 0.7 to 1.0 mu m, the disc being constituted by a disc-shaped base having at least one spiral guide track thereon with top surfaces parallel to the surface of the base at a height above the base different from the top surfaces of the portions of the base between the spires of the track, which height is in the range of lambda /12 to lambda /6, the guide track having a width approximately equal to the effective diameter of the laser beams; and a uniform thickness coating of a light recording material on the top surface of the guide track and the portions of the base between the spires of the guide track, the light recording material being a material the transmittance and/or the reflectance of which is varied by irradiation by the laser beams.