Optical write/read head with laser power control

Details Optical write/read head with laser power control Optical write/read head with laser power control

1995-02-14

1996-10-08

Ben, Loha

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

369106, 369110, 369116, G11B 700

Patent

active

055638708

ABSTRACT:
An optical write/read head is provided with apparatus for monitoring the output of a read/write laser so that the laser power may be appropriately adjusted to maintain a desired level. The apparatus features a partially reflective, partially transmissive surface in the optical path between the laser source and the recording medium for reflecting a small percentage (e.g., 4% 6%) of the laser output to a photodetector forming part of an electrooptical feedback loop for controlling the laser power. Preferably, the laser power-controlling photodetector is located adjacent the photodetector used to develop the recording signal, and the partially reflective, partially transmissive surface is tipped a few degrees from normal to the optical axis. Also preferred is that the partially reflective, partially transmissive surface constitutes the rear surface of a quarter-wave plate used to rotate the angle of polarization of the read/write beam to avoid optical feedback to the laser cavity.

REFERENCES:
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patent: 4963003 (1990-10-01), Hiiro
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patent: 5317557 (1994-05-01), Goto
patent: 5444677 (1995-08-01), Hosokawa et al.

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