| 摘要 |
PURPOSE:To enable the writing of a large number of bit lines even if the diameter of a disc is small, by projecting laser beam to a rotary disc and scanning said rotary disc in the radial direction thereof. CONSTITUTION:Laser beam emitted from the laser of an optical pick-up part 14 is allowed to irradiate the bits 13 of a rotary disc 12 from an objective lens part 15 through an optical lens system. The lens part 15 scans the rotary disc 12 over the range shown by the arrow (a) in the radial direction thereof on the basis of a fulcrum by a voice coil actuator. The laser beam allowed to irradiate the bits 13 is reflected or diffracted to be brought to an optical signal of 1 or 0. The bits 13, for example, 12-bits are written to the entire periphery of the rotary disc in the radial direction by a binary code of 1 or 0.
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