| 摘要 |
PURPOSE:To eliminate disturbance in the waveform of a detection signal by specifying the pitch and width of the rugged grooves and pits of a disk for recording and reproducing optical information with respect to the diameter of a laser spot for recording and reproduction and specifying the depth of the rugged grooves and pits with respect to the wavelength of the laser. CONSTITUTION:A light absorptive thin film 1 which changes thermally the state when irradiated with light is formed by using a lower oxide of Te or the like, with the groove forming part of a UV curing resin, on a substrate 3 formed with rugged grooves or rugged pits 2 on a resin plate of polycarbonate or polymethacrylate then a tight protective layer 4 is provided over the entire surface thereby forming a disk. The pitch of the grooves 6 and rugged pits of such disk is made <=2 times the diameter of a laser spot 10 for recording and reproduction and the width thereof is made 60-80% the diameter of the spot 10 as shown in the magnified view. The depth of the grooves 6 and pits is made within + or -10% the optical path length of lambda/8 with respect to the wavelength lambda of the laser. The disturbance in the waveform of the detection pit signal is thus eliminated, the signal detection is made possible at high S/N and the tracking stability and the access speed to a track address are improved. |
