Patent ID: 6487163
Filing Date: 2002-11-26
Classification: G11B,H04N

Abstract:
An optical disk comprising: a substrate in which information to be picked up by a light beam radiated thereto through an objective lens are recorded as pit arrays formed at a predetermined track pitch; and a reflective layer formed on the substrate,wherein the track pitch is set within a range of (0.72 to 0.8)&agr;Ã—(&lgr;/NA)/1.14 &mgr;m, when a wavelength of the light beam is &lgr;&mgr;m and a numerical aperture of the objective lens is NA,the &agr; is represented by: &agr;=3.617Ã—10âˆ’14Ã—(&thgr;A ds/&lgr;)3+1.248Ã—10âˆ’9Ã—(&thgr;A ds/&lgr;)2+0.865 when a thickness of the optical disk is ds &mgr;m, and an allowable tilt angle of the optical disk is &thgr;A mrad, andthe allowable tilt angle &thgr;A is not more than 7 mrad.