High density optical disc and optical disc player
AssigneeSanyo Electric Co., Ltd.
InventorsYoichi Tsuchiya, Hitoshi Terasaki, Shuichi Ichiura, Toshio Ito, Yasuyuki Kano, Yoshimoto Yamaguchi, Seizo Kato, Osamu Ota
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Abstract
A high density optical disc having a track pitch of 0.85 .mu.m, a shortest pit length of 0.49 .mu.m, a pit depth of 100 nm, and a pit width of 0.35 .mu.m is rotated at a linear velocity of 2.4-2.8 m/s such that the same is optically reproduced by a laser beam having a wavelength of 635 nm which is converged to a spot size of 0.9 .mu.m by an objective lens having a numerical aperture of 0.6. Accordingly, data is read from the optical disc at a transfer rate of 5.6 Mbps.
Claims10
An optical disc having a track pitch of 0.7-0.85 .mu.m, a pit width of 0.20-0.35 .mu.m, and a shortest pit length of 0.42-0.49 .mu.m.
An optical disc player for reproducing information signals from an optical disc having a track pitch of 0.7-0.85 .mu.m, a pit width of 0.20-0.35 .mu.m, and a shortest pit length of 0.42-0.49 .mu.m, comprising:
- a semiconductor laser having a wavelength of 590-670 nm;
- irradiating means for irradiating a beam from said semiconductor laser onto said optical disc with a spot size of 0.85-0.95 .mu.m;
- and
- a photo-receiving means for receiving a reflected beam from said optical disc and outputting a reproduced signal.
Dependencies are inferred from the claim text.