JPH0846294A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To realize the reduction of the mumber of part items and the cost of optical pick-up of three beam method using the diffraction grating by providing the semiconductor system having high general purpose applicability. CONSTITUTION:Within an upper and lower case containing a semiconductor laser device, an upper case 16 provided with a diffraction grating on a window part and an upper case 18 provided with a transparent glass 17 are quick disconnectably constituted. In such a constitution, the cylindrical inside of the upper case is internally threaded while the cylindrical outside of the lower case is externally threaded.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor laser. Particularly, it relates to a semiconductor laser for an optical pickup.

[0002]

2. Description of the Related Art In recent years, optical video discs and digital audio discs have been put into practical use, and semiconductor lasers are used for optical pickups in their players.

Various types of optical pickups using semiconductor lasers have been invented and put into practical use, but the most prevalent one is the 3B (three-beam) method.

FIG. 1 shows an optical system of the 3B method. The method of arranging the optical components is not unique, and two examples (a) and (b) are given as examples. The same numbers in (a) and (b) indicate the same parts. Let us explain about (a). The light emitted from the semiconductor laser 1 becomes three beams by the diffraction grating 2. Only the P wave passes through the polarization beam splitter 3 and is converted into parallel rays by the collimator lens 4. The parallel light rays pass through a quarter-wave plate to become circularly polarized light, and a spot is formed on the disk 7 by the objective lens 6.

The light reflected by the disk 7 again passes through the quarter-wave plate and enters the polarization beam splitter 3. At this time, since the light is an S wave, it is reflected, passes through the cylindrical lens 8, and reaches the light receiving element 9. The arrangement of (b) is different from that of (a) in that the collimator lens 4 is adjacent to the semiconductor laser 1, but in principle, it is exactly the same.

[0006]

The number of parts in the 3B method is
There are eight types as described above. At present, for example, in a digital audio disc player, the pickup is large even if the device is relatively compact, and it is difficult to incorporate the pickup into the device. Moreover, the price is considerably higher than that of the conventional record player. One of these causes is the large size of the pickup and its high cost.

Therefore, an object of the present invention is to provide a semiconductor laser for an optical pickup which is small in size and low in cost.

[0008]

[Means for Solving the Problems]

(1) The semiconductor laser of the present invention is characterized in that a diffraction grating is provided in a window portion of a case of the semiconductor laser through which light of the semiconductor laser is emitted.

(2) Further, in (1), a male screw is cut outside the cylindrical portion of the lower case on which the semiconductor laser chip is mounted, and the diffraction grating or transparent glass is provided in the window portion. It is characterized in that a female screw is cut inside the tubular portion of the upper case.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a specific example of the present invention.
Reference numeral 10 is a semiconductor laser chip, 11 is a case, and 12 is a diffraction grating. Conventionally, the portion 12 is a transparent glass window, but since the 3B method of the optical pickup always uses the diffraction grating, the transparent glass is replaced with the diffraction grating. By doing so, the number of parts is reduced by one.

FIG. 3 shows another embodiment of the present invention. Reference numeral 13 is a semiconductor laser chip, and 14 is a lower case. As shown in the drawing, a male thread is cut in the cylindrical portion. 15 is a diffraction grating 16
Is the upper case. The inside of the upper case 16 is the lower case 14
The female thread is cut to fit the screw of. Reference numeral 17 is a transparent glass, and 18 is a lower case. In this specific example, an upper case with transparent glass or an upper case with a diffraction grating can be used depending on the application.
It is more versatile than the invention of FIG.

According to the present invention, in the optical pickup of the 3B method, the number of parts is reduced by one, and when the polarization beam splitter is replaced with a half prism in FIG. Reduce by 2 points. This optical system is used to slightly return to the semiconductor laser and suppress noise.

According to the present invention, in the 3B method optical pickup, the number of parts can be reduced by 1 to 2 points, and the size, weight and cost can be reduced. As a result, it is possible to reduce the size, weight and cost of the digital audio disc player and the optical video disc player.

[0014]

As described above, if the semiconductor laser having the diffraction grating on the window of the case is used for the 3B method pickup, the size and weight of the optical pickup can be reduced and the cost can be reduced. The player was smaller and lighter,
Cost reduction is also possible.

[Brief description of drawings]

1A and 1B are views showing an optical system of a 3B method optical pickup.

FIG. 2 is a diagram showing a specific example of the present invention.

FIG. 3 is a diagram showing another specific example of the present invention.

[Explanation of symbols]

 1: Semiconductor Laser 2: Diffraction Grating 3: Polarization Beam Splitter 4: Collimator Lens 5: Wavelength of 4 Minutes 6: Objective Lens 7: Disc 8: Silicon-Dryal Lens 9: Light-Receiving Element 10: Semiconductor Laser Chip 11 : Case 12: Diffraction Grating 13: Semiconductor Laser Chip 14: Lower Case 15: Diffraction Grating 16: Upper Case 17: Transparent Glass 18: Upper Case

[Procedure amendment]

[Submission date] October 6, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

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[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

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[0008]

Means for Solving the Problems The semiconductor laser of the present invention
Is a case having a window on the emitting surface of the laser beam, and the case
Semiconductor laser chip built in the
It is electrically connected to the case and pulled out of the case.
A semiconductor laser having a lead wire
It is characterized in that a diffraction grating is provided in the window of the source.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Delete

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

[0014]

As described above, the semiconductor according to the present invention
The laser has a diffraction grating on the laser light emitting surface of the case.
Since the area of the diffraction grating can be reduced,
In addition, the optical axis adjustment when incorporating it into the pickup optical system is reduced.
it can. Also, a diffraction grating is held in the optical pickup optical system.
No holding member is required, and the number of parts and assembly steps
Can be reduced and the productivity of optical pickup optical system
Improvement, downsizing of pickup optical system, and cost reduction
It becomes Noh.

Claims (2)

[Claims] 1. A semiconductor laser having a diffraction grating in a window portion of a case of the semiconductor laser through which light of the semiconductor laser is emitted. 2. A male screw is formed on the outside of the cylindrical portion of the lower case on which the semiconductor laser chip is mounted,
2. The semiconductor laser according to claim 1, wherein a female screw is formed inside a cylindrical portion of an upper case having the diffraction grating or transparent glass in the window portion.