OPTICAL DISK AND OPTICAL DISK DEVICE

摘要

PURPOSE:To obtain an optical disk capable of making a crosstalk between adjacent tracks small to a degree that a practical problem is not present even when a track pitch and a pit pitch are set to be smaller than the diameter of the beam spot of a reproducing optical beam and dramatically making high density and a large capacity. CONSTITUTION:When the wavelength of the reproducing optical beam is defined as lambdanm and the numerical aperture of an objective lens is defined as NA, the track pitch is made to be (0.72 to 0.8)Xlambda/NA/1.14mum. The width Wm of the upper part of a pit 10 is made to be Wm=(0.3 to 0.45Xl/NA/1/14mum, the width Wi of the lower part of the pit 10 is made to be Wi=(0.2 to 0.25)Xlambda/NA/1.14mum.