Optical disk and optical disk apparatus.

摘要

An optical disk comprises a substrate (101, 102), and a recording layer (103, 104) which is formed on the substrate and on which information is recorded at specific pitches in the form of pit trains, wherein the information is reproduced by projecting a light beam via an object lens, and when the wavelength of the light beam is lambda mu m and the numerical aperture of the object lens is NA, the track pitch is set in the range of (0.72 to 0.8) x lambda /NA/1.14 mu m, and each of the pits (10) has a trapezoid cross section whose upper width is in the range of (0.3 to 0.5) x lambda /NA/1.14 mu m and whose lower width is in the range of (0.2 to 0.32) x lambda /NA/1.14 mu m or whose inner wall has an angle of 30 DEG to 70 DEG .