JPS61122945A - Optical information reading device - Google Patents

Abstract

PURPOSE:To make a device small, to make a wiring simple and to make adjustment easy by installing a laser and light detecting element for reading information at the close position and installing the detecting element and the light detecting element for stabilizing an output of the laser on the same substrate. CONSTITUTION:Coming-out light from a front side of a laser 1 is outwardly reflected by a surface 10 of an optical member 9, arrives at a collimator lens 7, made into a parallel beam by the collimator lens 7, converged to n objective lens 6 and falls on a disk 5. A signal light reflected by the disk 5 goes in the opposite direction to a common light path 8 of the same light path as incident light, arrives at the optical member 9, passes through the surface 10, reflected by a surface 11, the reflecting light detecting element 3. Thus, an incident light path to the light detecting element 3 is dislocated and is close and in parallel to the coming-out path from the laser 1. A detecting element 2 for stabilizing a laser output and the light detecting element 3 which are installed in the backward direction of the laser, are installed adjoining to the same substrate 4. By such a constitution, the device can be made small, the wiring can be made simple and the adjustment can be made easy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical information reading device, that is, an optical information reading device in which laser light is incident on an information medium and the reflected light is received by a photodetecting element.

[Prior art]

Most conventional optical information reading devices use optical elements such as half prisms or half mirrors in the common optical path of incident light and reflected light to separate the reflected optical path from the incident optical path in a direction perpendicular to the incident optical path, thus making it difficult to read information. The photodetector element is located at a distance in a direction perpendicular to the laser, which increases the size of the device, complicates the wiring, and makes adjustments troublesome. On the other hand, by using a polarizing beam splitter as a 4-terminal network, the output optical path from the laser and the input optical path to the photodetecting element can be brought close together, and the laser and the photodetecting element can be placed in close positions. An optical information reading device that realizes miniaturization of the device and simplification of adjustment is disclosed in Japanese Patent Publication No. 1971-71537 and No. 57.
This method has been proposed in Publication No. 71538. However, even in such a reading device, the light emitted from the back side of a semiconductor laser that emits laser light from both end faces is received by a photodetector element for stabilizing the laser light output, and the output of the photodetector element is used to detect the light emitted from the back side of the semiconductor laser. When using a laser device designed to stabilize the laser beam, adjustment is troublesome because it requires a lot of wiring or multiple koji.

[Purpose of the invention]

The present invention has been made in order to provide an optical information reading device that solves the above-mentioned problems, and the laser and the photodetecting element for reading information are provided in close positions, so that the device can be miniaturized. To provide an optical information reading device that uses a laser device that is equipped with a photodetection element for stabilizing laser light output and can obtain stable laser light, and that has simplified wiring and can be easily adjusted.

[Structure of the invention]

The present invention will be explained below using illustrated examples.

1 and 2 are schematic side views each showing an example of the reading device of the present invention.

In the figure, 1 is a semiconductor laser (hereinafter simply referred to as a laser) that emits laser light from both end faces, 2 is a photodetector element for stabilizing laser light output that receives laser light that is emitted from the back side of the laser l, Reference numeral 3 denotes a photodetection element for reading information, and the photodetection elements 2 and 3 are integrally provided on the base 4 side by side. Therefore, wiring is simplified and adjustment is also facilitated.

5 is an information carrier disk, 6 is an objective lens, 7 is a collimator lens, and 9 is two parallel or nearly parallel surfaces 10 inclined to a common optical path 8 of the incident light to the disk 5 and the reflected light from the disk 5, that is, the signal light. The optical member 9 has an angle of 11 degrees and shifts the signal optical path from the incident optical path between the two surfaces. The incident optical path and the incident optical path of the signal light to the photodetector element 3 are arranged close to each other and parallel to each other.

That is, in the reading device shown in FIG. 1, the light emitted from the front side of the laser 1 is externally reflected by the surface 10 of the optical member 9, reaches the collimator lens 7, is made into parallel light beams by the collimator lens 7, and is passed through the objective lens 6. The signal light that is focused on the disk 5 and reflected by the disk 5 travels backwards along the common optical path 8 that is the same optical path as the incident light, reaches the optical member 9, passes through its surface 10, and is reflected by the surface 11. The reflected light passes through the surface 10 again and enters the photodetecting element 3, so that the optical path of incidence on the photodetecting element 3 is shifted to be closely parallel to the optical path of the laser 1. In addition, in the reading device shown in FIG. 2, the light emitted from the front side of the laser 1 passes through the optical member 9, enters the disc 5 through the collimator lens 7 and the objective lens 6, and is reflected by the disc 5. The signal light travels backward along the same common optical path 8 as the incident light, reaches the optical member 9, passes through its surface 10, is reflected by the surface 11, and the two-way emitted light is further reflected by the surface 10. The light that has been reflected twice passes through the surface 11 and enters the photodetector element 3.
The incident optical path of the laser 1 is shifted so that it is closely parallel to the output optical path of the laser 1.

In the reading device shown in FIG. 1, the laser 1 on the surface 10
In order to appropriately distribute the amount of reflected light from the laser 1 to the disk 5 and the amount of incident signal light from the disk 5 to the effective reflecting surface portion that externally reflects the emitted light and enters the collimator lens 7. -7 mirror coat 12 is provided on the surface 11 where the signal light is internally reflected, an increasing and opposite coating 13 is provided in order to increase the reflectance, and the area where the internally reflected light passes through the surface 10. is provided with an anti-reflection coating 14 in order to reduce loss of signal light. This allows more signal light to enter the photodetector element 3. Furthermore, an anti-reflection coating 14' is provided at a portion where the emitted light from the laser 1 passes through the surface 10 and reaches the surface 11 to prevent internal reflection. This removes unnecessary light that causes noise. In the reading device shown in FIG. 2, a half-mirror coat 12 and an anti-reflection coating 14 are provided on the surface 11 where the signal light is internally reflected and where it passes, respectively, and the signal light on the surface 10 is internally reflected on the surface where the signal light passes through. An anti-reflection coating 14 and an anti-reflection coating 13 are provided on each portion to allow more signal light to enter the photodetector element 3.

The present invention is not limited to the illustrated example, and may be applied to an optical system such as that shown in Japanese Patent Laid-Open No. 57-71537, etc., which brings the output optical path from the laser and the input optical path of the signal light to the photodetector element close to each other. good. However, compared to an optical system using optical members as shown in the figure, the incident optical path to the disk and the signal optical path from the disk are perpendicular to each other in the middle, which tends to increase the size of the device and also requires a large number of optical components. If there are many cases, the cost will be high.

Even when using an optical member like the illustrated example, coating the surface of the optical member can of course be omitted, and instead of using a plate-like optical member, two right-angled triangular prisms with their slopes They may be provided so as to face each other with a gap therebetween, and the signal optical path may be shifted from the incident optical path by the gap. Additionally, although not directly related to the present invention,
For example, in the reading device shown in FIG.
If the shape of the effective reflecting surface portion is made into a paraboloid that serves as the emission point of the laser 1, the externally reflected light becomes a parallel ray, and the collimator lens can be omitted.

Further, in the above-described embodiment, the photodetecting element 3 is used as a signal light reading element, in other words, as a detecting element for reading information recorded on a disk, but the present invention is not limited to this. The detection element 3 can also be used as a photodetection element for focusing or tracking. In this case, signal detection may be performed by the same photodetector element 3, or the self-coupling effect of the laser 1 itself may be used. When the photodetection element 3 is used as a detection element for focusing, the shape of the inner reflection portion of the surface 11 is made such that the inner reflection light becomes astigmatic light, so that there is no need to provide a separate cylindrical lens or the like. It is also possible to perform focus error detection using a normal astigmatism method.

〔Effect of the invention〕

In the optical information reading device of the present invention, a laser and a photodetecting element for information reading are provided in close proximity to each other, so that the device can be miniaturized, and the laser is equipped with a photodetecting element for output stabilization, so that the laser can be stabilized. Even if a laser device that generates light is used, the photodetection element and the photodetection element for reading information are integrated and lined up on the same base, so wiring is significantly simplified and adjustment is easy. Qin has excellent effects that can be achieved.

[Brief explanation of drawings]

1 and 2 are schematic side views each showing an example of the reading device of the present invention. DESCRIPTION OF SYMBOLS 1...Semiconductor laser, 2...Photodetection element for laser light output stabilization, 3...Photodetection element for information reading, 4...Base, 5...Disk, 6...
...Objective lens, 7...Collimator lens,
8... Common optical path, 9... Optical member, 10.
11... Surface, 12... Bar 7mi 2-coat, 13... Increased reflection coat, 14... Anti-reflection coat.

Claims (1)

[Claims] In an optical information reading device in which laser light is incident on an information carrier and the reflected light is received by a photodetection element, an optical system in which the output optical path from the laser and the input optical path to the photodetection element are close to each other. and a photodetection unit in which the photodetection element and a photodetection element for stabilizing the laser light output provided behind the laser are integrally provided side by side on the same base. Information reading device.