JP2002335033A - Apparatus and method of adjusting laser diode unit and optical unit manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, in the conventional collimation adjustment with parallel light, the collimator lens is shifted back and forth on the optical axis to find a collimation point, taking much time for the collimation, and if the beam diameter is less than the pixel size of a CCD, the size cannot be measured resulting in reduction of the collimation precision of the light. SOLUTION: The apparatus is composed of an image forming lens 3 which takes an incident light emitted from a collimator lens 2, a multilayer reflection mirror 10 which takes an incident light emitted from the lens 3 and a CCD camera 5 which takes a light reflected from the mirror 10. The emission light of the collimator lens 2 is collimated, based on the intersection of two reflected lights tangent to the beam envelope from the mirror 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information storage medium of an optical disk system, for example, a DVD (Digital Vers).
The present invention relates to an apparatus and a method for adjusting a laser diode unit including a semiconductor laser and a light-receiving unit, and a method for manufacturing an optical unit in an optical pickup for reading and writing information from and to an optical disk.

[0002]

2. Description of the Related Art Conventionally, in assembling an optical pickup, a semiconductor laser, a mirror, a lens, and a light receiving unit are incorporated in one optical base, and an optical axis measurement and a radiation distribution measurement are performed.
The adjustment of the laser, the mirror, and the lens, and the adjustment of the light-receiving section were performed while reproducing the signal.

However, in the above-described method, the adjuster must be switched for each adjustment step, which increases the tact time and easily causes an error due to the mounting of the base to the adjuster.

In order to shorten the tact time for assembling and adjusting the optical pickup and improve the accuracy of the adjustment, it has been proposed to make the semiconductor laser and the light receiving unit as one unit and to perform optical adjustment in advance.

In this optical adjustment, the emitted light from the semiconductor laser is collimated, and the radiation distribution azimuth measurement, the laser light emitting point position measurement, and the light receiving portion position measurement are performed. In order to perform this, it is necessary to accurately convert the emitted light from the semiconductor laser into parallel light in a short time.

Referring to FIG. 4, a conventional method for adjusting an optical unit will be described. 1 is a semiconductor laser, 2 is a collimator lens, 3 is an imaging lens, 4 is a CCD camera, which is arranged at the focal position of the collimator lens 3. 5 is monitor T
V.

In order to make the light emitted from the semiconductor laser 1 parallel by the collimator 2, the light emitted from the collimator 2 is condensed by the imaging lens 3. The beam shape is imaged by the CCD 4 and displayed on the monitor TV 5. When the light emitted from the collimator lens 2 is not parallel light, the beam shape at the CCD 4 is 8
When the light emitted from the collimator lens 2 is parallel, the beam shape becomes an image as shown by 7, and
The beam diameter is minimized. Therefore, by moving the collimator lens 2 in the optical axis direction and searching for the position of the collimator lens 2 where the beam diameter on the monitor TV 5 is minimized, the light emitted from the collimator lens 2 can be made into parallel light.

[0008]

However, in this method, when the light emitted from the collimator lens is not parallel light, it is not possible to determine in which direction the collimator lens can be moved. Therefore, it was necessary to search for a position where the light became parallel light, and it took a long time for adjustment. In addition, when the beam diameter is smaller than the pixel of the CCD, the size cannot be measured, so that there is a problem that the adjustment accuracy of the parallel light is reduced.

[0009]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention condenses a light to be measured, divides the converged light to be measured, and changes the focal position in the same direction. Aim the light, observe each light, measure the position of the intersection of the two tangents in contact with the outer shape of the light, determine the amount of displacement of the optical components that make up the laser diode unit from this intersection, and The position of the optical component is moved according to the amount.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIG.

1 is a semiconductor laser, 2 is a collimator lens for collimating the light emitted from the semiconductor laser 1, 3 is an imaging lens for condensing the light emitted from the collimator lens 2, and 10 has a plurality of reflecting portions inside. Each of the reflecting portions is a multilayer reflecting mirror which is parallel to each other and arranged at equal intervals. Multilayer reflection mirror 1
0 is disposed at approximately 45 ° with respect to a straight line passing through the centers of the collimator lens 2 and the imaging lens 3. Here, a description will be given as three reflection surfaces, namely, a front surface, a center, and a back surface. Reference numeral 4 denotes a CCD camera that uses light emitted from the multilayer reflection mirror 10 as incident light, and reference numeral 5 denotes a monitor TV.

The light emitted from the semiconductor laser 1 passes through the collimator lens 2 and enters the imaging lens 3. Imaging lens 3
Is reflected by each reflection surface of the multilayer reflection mirror 10,
The light enters the CCD 4. Numeral 11 denotes the surface reflected light of the multilayer reflecting mirror 10, 12 denotes the reflected light at the center, and 13 denotes the back surface reflected light.

Light beams 11, 12, and 13 are projected onto CCD 4
The centers of the light beams enter the CCD 4 at equal intervals in the order of 11, 12, and 13 from the left side of FIG.

FIG. 2 shows an image on the monitor TV. When the light emitted from the collimator lens 2 is parallel light, the beam 11,
The position of the CCD camera 4 is adjusted in advance so that the beam 13 has substantially the same diameter and the beam 3 has the minimum diameter. Two straight lines in contact with the outer shapes of the beams 11, 12, and 13 are drawn, and the position of the intersection is defined as the origin. When the light emitted from the collimator lens 2 becomes divergent light, the diameters of the beams 11 and 12 increase, and the diameter of the beam 13 decreases. Beam 11,
When two straight lines in contact with the outer shapes of 12 and 13 are drawn and their intersection is found, the position is shifted from the origin. In convergent light,
The intersection is shifted in the opposite direction to the case of the divergent light. This shift amount is
It is almost proportional to the amount of movement of the collimator lens 2. Therefore, by adjusting the position of the collimator lens 2 in the direction of the optical axis so that this intersection point is aligned with the origin, the light emitted from the collimator lens 2 can be made parallel.

Using a semiconductor laser as a reference and a collimator lens, the relationship between the intersection point of two straight lines contacting the outer shapes of the beams 11, 12, and 13 and the amount of deviation from the focal position of the collimator lens is determined in advance. By measuring, the amount of movement and the direction of movement of the collimator lens can be accurately obtained, and the parallel light adjustment of the collimator lens can be performed with one adjustment.

In this embodiment, the multi-layer reflecting mirror is a three-surface reflecting surface, center, and back surface, but may have four or more reflecting surfaces. Further, a multilayer reflective layer may be formed inside without using front and rear surface reflection.

The reflecting surfaces may not be at equal intervals but may be at known intervals.

Further, when there are three or more beams by the multi-layer mirror, by drawing a straight line such that the sum of the distances from the outer shapes of the respective beams becomes the smallest, the influence of errors due to beam intensity variation and dust can be reduced. It can be hard to receive.

FIG. 3 is a schematic diagram of an optical disk drive. Reference numeral 21 denotes a laser unit adjusted by the laser diode unit adjusting device according to the present invention, reference numeral 22 denotes an optical unit incorporating the laser diode, an objective lens, a rising mirror, and the like, and reference numeral 23 denotes an optical disk. Reference numeral 24 denotes an optical disk drive that reads signals from the optical disk 23 with the optical unit 22. The optical disk drive is a CD-ROM, CD-RW, or D-ROM.
Any of a VD-ROM and a DVD-RAM may be used.

By using a laser diode unit in which laser light is adjusted in parallel by the laser diode adjusting apparatus of the present invention, highly accurate parallel light can be obtained. The distortion is reduced, and the signal reading accuracy from the optical disk can be improved. Further, since the offset at the time of the focus adjustment of the objective lens is reduced, the drive current for the focus adjustment coil can be reduced, and power saving can be achieved.

[0021]

As described above, according to the present invention, the light to be measured is condensed, the collected light to be measured is branched, and the light is directed in the same direction with different focal positions. Observing each light, measuring the position of the intersection of two tangents tangent to the outer shape of the light, obtaining the amount of displacement of the optical components constituting the laser diode unit from the position of the intersection, and according to this amount of displacement, By moving the position of the optical component, the direction and amount of moving the collimator lens can be determined,
The adjustment of the parallel light can be performed by one movement of the collimator lens, and the adjustment time can be reduced. Furthermore, since the focal position is determined at the intersection of two tangents tangent to the beam outline,
Since it is hard to be limited by the pixel size of the CCD, highly accurate parallel light adjustment can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic view showing adjustment of a laser diode unit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a beam shape at the time of defocus;

FIG. 3 is a schematic diagram of an optical disk drive.

FIG. 4 is a schematic view showing adjustment of a conventional laser diode unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor laser 2 Collimator lens 3 Imaging lens 4 CCD camera 10 Multilayer reflection mirror

Claims (5)

[Claims] An imaging lens that uses light to be measured as incident light;
A multi-layer reflecting mirror arranged so that the light emitted from the imaging lens is incident light and inclined with respect to the optical axis of the emitted light, a CCD camera that uses the reflected light of the multi-layer reflecting mirror as incident light, An apparatus for adjusting a laser diode unit, comprising: means for obtaining a shift amount of an optical component of the measured light from light; and means for adjusting the optical component of the measured light according to the shift amount. 2. The adjustment device for a laser diode unit according to claim 1, wherein the multilayer reflection mirror has reflection surfaces arranged at equal intervals. 3. A step of condensing the light to be measured, a step of branching the condensed light to be measured, and directing the light in the same direction with different focal positions, and observing each light. Measuring the position of the intersection of two tangents that are in contact with the outer shape of the light, determining the amount of displacement of the optical components constituting the laser diode unit from the position of the intersection, and determining the position of the optical component according to the amount of displacement. Moving the position of the laser diode unit. 4. The method for adjusting a laser diode unit according to claim 3, wherein, in the step of changing the focal position, the focal positions are set at equal intervals. 5. A method for manufacturing an optical unit, comprising: adjusting a laser diode unit by the method according to claim 3; and incorporating the laser diode unit into an optical unit. .