| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk which lessens the influence to be exerted by land prepits on information signals, makes it possible to obtain land prepits signals with sufficient amplitude and may be manufactured by the conventional process. SOLUTION: The optical disk has grooves 12 formed to a concentric circle form or spiral form, the land prepits 16 disposed to connect the adjacent grooves to each other and pit regions formed with pits 17 of the physical depth approximately equal to the physical depth of the land prepits. When the wavelength of the laser beam to be used for recording and reproducing is defined as λ, the numerical aperture of an objective lens as NA, the phase depth of the grooves is set within a range of λ/6.5 to λ/11 and the length of the land prepits is <=0.45 λ/NA. There is the following relation between the length (LPP length) of the land prepits and the width of the groove: 0.8×D< groove width ×NA/λ<1.2×D, where D=0.31-0.33×LPP length × NA/λ. |
