# US 5,703,861 A · Integrated confocal optical pick-up head with a hologram and a polarizer mounted on each side of a transparent heat sink

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- Number: US 5,703,861 A
- Document ID: US5703861A
- Status: Granted
- Kind: A
- Application number: 08/605,842
- Filed: 1996-02-26
- Granted: 1997-12-30
- Earliest claimed: 1995-02-24
- Assignees: Sony Corporation
- Inventors: Osamu Matsuda
- Web page: https://patentgrep.com/patent/US5703861A

## CPC

- G11B 7/1353: Diffractive elements, e.g. holograms or gratings {(diffraction gratings per se G02B5/18; holograms per se G02B5/32; grating systems G02B27/44)}
- G11B 7/123: Integrated head arrangements, e.g. with source and detectors mounted on the same substrate
- G11B 7/133: Shape of individual detector elements
- G11B 11/10543: {using optical beam of radiation}
- G11B 7/0901: {for track following only (G11B7/0925, G11B7/094, G11B7/0941, G11B7/0943, G11B7/0945, G11B7/0946, G11B7/0948 take precedence)}
- G11B 7/0912: {by push-pull method}
- 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

Light is emitted from a light-emitting element toward an irradiated medium, and returning light reflected by the irradiated medium is diffracted by a hologram device. A polarizer polarizes the light diffracted by the hologram device to produce first polarized light that has passed through the polarizer and second polarized light that has been reflected by the polarizer. The first polarized light is detected by a first light-detecting element, and the second polarized light is detected by a second light-detecting element. A magnetooptical signal is generated as the difference between the intensities of the first and second polarized lights which are detected respectively by the first and second light-detecting elements.

## Claims

### Claim 1

An optical head comprising:
a light-emitting element having a top surface disposed on a substrate for emitting light toward an irradiated recording medium;
a transparent heat sink coupled to said light-emitting element and attached on said top surface;
a hologram device mounted on said transparent heat sink for diffracting light returning from the irradiated medium;
a polarizer supported on said transparent heat sink for polarizing the light diffracted by said hologram device to produce first polarized light that has passed through said polarizer and second polarized light that has been reflected by said polarizer;
a reflecting film attached on said transparent heat sink, while film reflects polarized light which travels inside said transparent heat sink;
a plurality of light-detecting elements including a first light-detecting element disposed on said substrate for detecting said first polarized light, and a second light-detecting element disposed on said substrate for detecting said second polarized light; and
means for generating a magneto optical signal as the difference between the intensities of the first and second polarized lights detected respectively by said first and second light-detecting elements.

### Claim 2 (depends on 1)

An optical head according to claim 1, wherein said polarizer comprises a wire grid.

### Claim 3 (depends on 1)

An optical head according to claim 1, wherein said light-emitting element comprises a horizontal resonator laser and a reflecting surface disposed in facing relationship to an end surface of said horizontal resonator laser.

### Claim 4 (depends on 1)

The optical head of claim 1, wherein the heat sink is selected from the group consisting of sapphire, ruby, beryllia, diamond, silicon and silicon dioxide.

### Claim 5 (depends on 4)

The optical head of claim 4, wherein the heat sink is made of sapphire.

### Claim 6 (depends on 1)

The optical head of claim 1, wherein the heat sink has upper and lower parallel surfaces, and the hologram is supported on the upper parallel surface.

### Claim 7 (depends on 1)

The optical head of claim 1, wherein a plurality of polarizers are supported on said heat sink.