Optical information reproducing apparatus and recording medium

Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium

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369 4423, 3692753, G11B 700

Patent

active

056108940

ABSTRACT:
Light emitted from a semiconductor laser is collimated by a collimator lens into a parallel beam. The parallel beam enters a phase plate which provides a phase difference of .pi. to a half of the beam. The beam, which has passed through the phase plate, enters an objective lens and is converged onto an optical disc. The optical disc has a number of mark sets along the track, each mark set comprising optically detectable two marks. The beam from the optical disc is collected into the objective lens and is reflected by a polarized beam splitter into a light detector. The output from a light-element of the light detector is delivered to a differential amplifier and a summing amplifier. The outputs from the differential amplifier and summing amplifier are input to a divider. The output from the divider is delivered to an information reproducing unit. The information reproducing unit reproduces information recorded on the optical disc on the basis of the input, and outputs the reproduced information.

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"Isolation of Axi-Symmetrical Optical-Resonator Modes"; Applied Physics Letters, vol. 2, No. 3, Feb. 1, 1963.

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