Optical pick-up head apparatus with optical means having polariz

Details Optical pick-up head apparatus with optical means having polariz Optical pick-up head apparatus with optical means having polariz

1992-10-21

1994-03-22

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

Photocell controls its own optical systems

369 13, G01J 120

Patent

active

052966941

ABSTRACT:
The present invention relates to an optical pick-up head apparatus capable of recording, reproducing, or erasing optical information, and provides an optical pick-up head apparatus which can detect signals in a stable and good condition. A Faraday rotator 20 is disposed on an optical path between a polarized beamsplitter 55 and a polarized beamsplitter 53 so as to rotate polarization directions of a beam 6 emitted from a semiconductor laser source 2 and a beam 6 reflected back at a magneto-optical recording medium 4. A beam passing through the polarized beamsplitter 53 is received by a photodetector unit 83 to detect information signals and a reflected beam from the polarized beamsplitter 53 is received by a photodetector unit 84 to detect focusing- and tracking-error signals. Accordingly, it becomes possible that light quantity supplied to the photodetector unit 83 is adjusted to the optimum amount capable of adequately detecting the information signal and further all the remaining light quantity is supplied to the photodetector unit 84. Therefore, there is no uselessness in the detection of light. That is, both the focusing (or tracking)-error signal and the information signal can be respectively detected with high intensity and excellent S/N ratio. Consequently, it becomes possible to provide an optical pick-up head apparatus assuring very high reliability.

REFERENCES:
patent: 4665310 (1987-05-01), Heemskerk
patent: 4774615 (1988-09-01), Revelli et al.
patent: 4785438 (1988-11-01), Mizunoe
patent: 4812682 (1989-03-01), Holmes
patent: 4929823 (1990-05-01), Kato et al.
patent: 4959821 (1990-09-01), Morimoto et al.
patent: 4995685 (1991-02-01), Armstrong et al.
patent: 5173885 (1992-12-01), Iiyori et al.

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