# US 5,708,645 A · Semiconductor laser device to detect a divided reflected light beam

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- Number: US 5,708,645 A
- Document ID: US5708645A
- Status: Granted
- Kind: A
- Application number: 08/730,142
- Filed: 1996-10-15
- Granted: 1998-01-13
- Earliest claimed: 1994-03-08
- Assignees: Sony Corporation
- Inventors: Kenji Sahara; Hironobu Narui; Masato Doi; Osamu Matsuda
- Web page: https://patentgrep.com/patent/US5708645A

## CPC

- G11B 7/1365: Separate or integrated refractive elements, e.g. wave plates
- G11B 7/123: Integrated head arrangements, e.g. with source and detectors mounted on the same substrate
- G11B 11/10543: {using optical beam of radiation}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

An optical device for detecting a magneto-optical signal can be simplified and miniaturized in arrangement. An optical device for detecting a magneto-optical signal includes an optical element in which a light-emitting portion and a light receiving portion are closely disposed on a common substrate and in which reflected-back light obtained from a magneto-optical medium after light from the light-emitting portion was reflected on the magneto-optical medium is detected at a position near confocal position by the light receiving portion and another light receiving element. The reflected-back light from the magneto-optical medium is divided. One reflected-back light is detected by the light receiving portion of the optical element and the other reflected-back light is detected by another light receiving element.

## Claims

### Claim 1

A method for detecting a magneto-optical signal comprising the steps of:
generating a light beam with light-emitting portion of a common substrate;
reflecting the light beam off of a magneto-optical medium;
dividing the single beam of reflected-back light from the magneto-optical medium into first and second beams;
detecting the first beam with a light receiving portion of said common substrate, the light receiving portion being located close to the light emitting portion and detecting the second beam with a light receiving element.

### Claim 2 (depends on 1)

The method of detecting a magneto-optical signal of claim 1, further comprising a step of detecting a signal with a differential amplifier.

### Claim 3 (depends on 1)

The method of detecting a magneto-optical signal of claim 1, further comprising a step of transmitting the light beam through a polarizing device.

### Claim 4 (depends on 1)

The method of detecting a magneto-optical signal of claim 1, wherein the light receiving element is a photodiode.