Optical disk which reduces cross erasure of data recorded on lands and

Abstract

An optical disk is formed with grooves and lands for optically tracking an optical signal along a disk substrate. The lands and grooves are tracking guides on the surface of the disk substrate are coated with a recording film. The recording film varies in thickness over different portions of the tracking guides on the surface of the disk. A number of relationships and critical values may be determined by defining film thickness over the top of a land defined by (a), film thickness over a groove by (b), film thickness along a sidewall of a land by (c), groove depth from the top of a land to the bottom of a groove by (d1), and vertical film depth from the top of the film over a land to the top of the film over a groove by (d2). A difference in level (d2) of the recording film is preferably between 100-800 nm and a ratio (b/a) is preferably between 0.6-1.1. Also, a ratio (c/a) is preferably between 0-0.8. The relationships and critical values increase resistance to cross-erasure and allow track pitch to be decreased to enhance high density recording.