| 摘要 |
An optical apparatus digitizes a first signal, reproduce or records and reproduce the digital information compressed in a band up to a specified bit rate A1 at a specified rotating speed K or specified linear velocity V, digitizes a second signal, reproduces or records and reproduces the digital information compressed in a band up to a specified bit rate A2 at a rotating speed of about KxA2/A1, or a linear velocity of about VxA2/A1, and thereby reproduce or records and reproduces information of plural signals, or reproduces or records and reproduces information of plural compression rates by using only one apparatus. It also digitizes a first signal, reproduces or records and reproduces the digital information compressed in a band up to a specified bit rate A1 in n optical channels, digitizes a second piece of information, reproduces or records and reproduces the digital information compressed in a band up to a specified bit rate A2 in about nxA2/A1 optical channels, and thereby reproduces or records and reproduces information of plural signals, or reproduces or records and reproduces information of plural compression rates using only one apparatus without notably varying the rotating speed or linear velocity. It further enters the light emitted from a semiconductor laser into a nonlinear optical device (SHG), and reproduces the information on a disk surface or records and reproduces the information on a disk surface using the secondary harmonics delivered from the nonlinear optical device.
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