JPH06101122B2 - Optical axis adjustment method for optical components - Google Patents

Description

TECHNICAL FIELD The present invention relates to a disc-shaped recording medium (hereinafter referred to as a disc).
It is used for an optical disc device such as recording information on a disc or reproducing information recorded on the disc by squeezing a laser beam into a very small amount of light, and in particular, light of an optical component in an optical head part of the optical disc device. It relates to an axis adjusting method.

2. Description of the Related Art In recent years, an optical disk device has been attracting attention from various fields as a conventional information storage device because of its large storage capacity or random access function in a short time. The optical components used in this device are finished with high precision,
Therefore, high precision is required for assembling these optical components, but on the other hand, a simple and accurate assembling adjustment method is desired.

An example of the conventional optical axis adjusting method described above will be described below with reference to the drawings.

FIG. 2 shows an example of an optical system for explaining a conventional optical axis adjusting method for an optical component. In FIG. 2, 1 is a disk, 2 is a laser of a light source, and 3 is a collimating lens. Reference numerals 4a and 4b denote combined cylindrical lenses of irregularities for shaping an elliptical beam with an anisotropic light intensity emitted from the laser 2 into a substantially circular shape. Here, the narrow cross section of the elliptical beam is shown. There is. Reference numeral 5 denotes a polarization beam splitter which reflects a beam from the laser 2 at a right angle on a polarization plane 25 so as to vertically enter the disk 1. 6 is a 1/4 wavelength plate, and the reflected light from the disk 1 is this 1
The polarization direction is changed by the / 4 wavelength plate, and the light passes through the polarization beam splitter polarization plane 6 without being reflected this time. 7
Is an iris lens, which squeezes the laser light into a very small light disk 1
The beam is imaged on the top. On the other hand, the reflected light from the disk 1 passes through the polarization plane 25, changes the optical path at the reflection plane 11, is further narrowed down by the detector lens 8, and is guided to the focus detector 9 and the tracking detector 10. Reference numeral 12 is a mirror that divides the reflected light into the focusing detector 9 and the tracking detector 10 respectively. A conventional optical axis adjusting method in the above-cited optical system will be described. In FIGS. 3 and 4, reference numeral 13 is a reference laser for adjusting the optical axis, 14 is a camera corresponding to this laser light, 15 is a monitor, and the optical axes of the laser 13 and the camera 14 are set in advance. is there. Also, 16 is a camera similarly provided corresponding to the optical axis in the vertical direction with respect to the disk, and 17 is its monitor. Reference numeral 18 is an optical base for housing the optical parts in FIG. 2, and FIG. 3 shows a sectional state from the laser 2 to the polarization beam splitter 5, and the optical base 18 is set on the optical axis of the reference laser 13. To be done. Further, 19 and 26 are holes for passing laser beams in the optical axis direction and the vertical direction, respectively.

The procedure of the optical axis adjusting device configured as described above will be described below. As shown in FIG. 4, the optical parts of the convex cylindrical lens 4b, the concave cylindrical lens 4a and the collimating lens 3 are arranged so that the image forming position of the reference laser 13 on the monitor 15 does not shift with respect to the optical axis of the reference laser 13. The optical axis is adjusted in order, and the laser 2 is also set so that its own light emission pattern comes to the optical axis center position on the monitor 15. By this work, the optical axis adjustment from the laser 2 to the convex cylindrical lens 4b is completed. To do.

Next, adjust the optical axis of the polarization beam splitter 5,
This time, the polarization beam splitter is moved to the third position so that the light reflected by the polarization plane 25 forms an image at the center position of the optical axis of the monitor 17 described above.
The rotation is adjusted in the direction of arrow 21 shown in the figure. Disc 1
The adjustment of the optical axis of the incident optical system with respect to is completed, but the purpose of these optical axis adjustments is to obtain the beam shape narrowed by the diaphragm lens 7 as an ideal shape close to aberration-free. Strict adjustment of the optical axis in the vertical direction is important for the performance of the entire optical disk device.

On the other hand, in the reflection optical system from the disk 1, the beam focused by the detector lens 8 must be properly focused on the light receiving portion of the focusing detector 9, and particularly the second beam.
The polarization beam splitter 5 is particularly used when one optical component determines the incident optical axis to the disc and the reflection optical axis from the disc, like the polarizing beam splitter 5 in the figure.
The relative angular accuracy between the polarizing surface 25 and the reflecting surface 11 is an important factor.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described optical axis adjusting method, the above-described confirmation of the reflected optical axis position of the reflective optical system is not performed during the adjustment of the polarization beam splitter 5, and the adjustment step as the optical head unit is performed. That is, it is carried out at the level of the reproduction signal that can be taken out from the disc 1 when adjusting the detector, and if the position accuracy of the reflected optical axis, that is, the one with a low reproduction signal level is found, the focus detector is replaced as a means. It was necessary to replace the polarization beam splitter 5, and the loss in the process was significant.

Further, in the optical system cited in the order of assembling the optical components, the optical axis adjustment is performed by the convex cylindrical lens 4b, the concave cylindrical lens 4a, the collimating lens 3, and the laser 2.
Then, the polarization beam splitter 5 is adjusted at the end. However, a slight optical axis error of each optical component to be assembled is accumulated in this, and the final adjustment of the polarization beam splitter 5 is performed with the correct optical axis. That is, there is a surface lacking in reliability as to whether or not the disk 1 is adjusted in the vertical direction.

In view of the above problems, the present invention enables confirmation of the relative angular accuracy of the polarization beam splitter described above in the initial adjustment step, and at the same time eliminates the accumulated error of the optical axis due to the assembly procedure of the optical components to ensure the accuracy. The present invention intends to provide a method for adjusting the optical axis of an optical component which is efficient and efficient.

Means for Solving the Problems In order to solve the above problems, the optical axis adjusting method of the present invention is
Corresponds to the reference laser, first in the direction perpendicular to the disc
The second camera is arranged at the position of the optical axis reflected from the disc, and a monitor corresponding to each camera is provided.

The present invention has the above-mentioned configuration, thereby eliminating the accumulated error of each optical component in the optical axis setting by adjusting the optical axis of the polarization beam splitter first, and at the same time, the position of the optical axis reflected from the reflecting surface can be adjusted at this stage. It's something to check.

Embodiment An optical axis adjusting method according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an optical axis adjusting device adopting the optical axis adjusting method of the present invention. In FIGS. 1 and 2, reference numeral 31 is a reference laser that serves as a reference of the optical axis, 32 is a first camera which is also arranged at a position vertical to the disk, and 33 is a monitor thereof. Reference numeral 34 is a second camera arranged at the expected optical axis position of the reflected light from the disk, and 35 is its monitor. The predetermined reflected optical axis position described here is an image forming position where the reflected light from the disc is reflected by the reflecting surface 11 of the polarization beam splitter and further focused by the detector lens 8. The corresponding reflection mirror 36 reflects the laser light of the reference laser 31, and the position of the reflected light is confirmed. 37 is an optical stand for accommodating the optical parts shown in FIG.
Is located on the optical axis of. 38 is a housing hole for housing the convex cylindrical lens 4b, the concave cylindrical lens 4a, the collimating lens 3 and the incident optical system parts of the laser 2, 39 is the reflection optics of the detector lens 8, the mirror 12, the focus detector 9 and the tracking detector 10. A storage hole 40 for storing system parts is a hole for passing laser light in the vertical direction of the disk.

With respect to the optical axis adjusting device configured as described above,
The operation will be described with reference to FIGS.

The optical axis adjusting method of the present invention is characterized in that the optical component that makes the beam finally enter the disc in the vertical direction is adjusted first, and in the optical system in FIG. 2, it is handled from the polarization beam splitter 5. It will be. As a procedure, the polarization beam splitter 5 is rotated in the arrow direction 41 to determine the optical axis center position by the first monitor 32, and then the reflection position of the laser beam of the reference laser 31 is determined by the second monitor 35 by the mirror 36. As you can see, if there is reflected light at the center of the monitor 35 at this time, it can be determined that the relative angular accuracy of the polarization beam splitter 5 has been set correctly, but if the reflected light is significantly deviated on the monitor 35, An error is recognized in the relative angle between the polarization plane 25 and the reflection plane 11, and at this point the suspicious polarization beam splitter can be removed. After the adjustment of the polarization beam splitter 5, the convex cylindrical lens 4b, the concave cylindrical lens 4a, the collimating lens 3 and the laser 2 are arranged in this order along the optical axis of the reference laser 31 in the order of the optical axis on the monitor 32 as in the conventional case. Just set it to the position.

As described above, according to the present embodiment, since each camera and monitor corresponding to the incident optical axis with respect to the disc or the reflection axis position reflected by the disc are provided, both are simultaneously adjusted when the polarization beam splitter is adjusted. It can be confirmed, and by adjusting the polarization beam splitter first, the setting of the optical axis in the vertical direction with respect to the disk becomes reliable without including the optical axis error of the incident optical system optical component.

FIG. 5 shows a second example of the optical system, in which 41 is a polarization beam splitter, 42 is a mirror for converting the reflected light path,
Others are the same as the configuration of FIG. In this example, compared with the example shown in FIG. 2, the position of the optical axis reflected from the disk is intended to be freely adjusted by rotating the mirror 42 in the arrow direction 43, but in this case also, the polarization beam splitter 41 is used. When the optical axis adjustment is started from, the optical axis in the vertical direction with respect to the disk can be surely set without including the optical axis error of each optical component of the incident optical system.

EFFECTS OF THE INVENTION As described above, according to the present invention, in setting the optical axis of the optical component, the reference laser, the first camera and the monitor arranged in the vertical direction with respect to the disc, and the position of the reflected light from the disc are arranged. By providing a second camera and monitor, it is possible to easily adjust the incident angle to the disc by the polarization beam splitter and confirm the positional accuracy of the reflected optical axis thereof, and finally determine the incident optical axis to the disc. By starting the optical axis adjustment from the polarization beam splitter, which is an optical component, the optical axis error of each of the other incident optical system components is eliminated and the incident optical axis is set reliably.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an optical axis adjusting device adopting the optical axis adjusting method of the present invention, FIG. 2 is a configuration diagram showing an example of an optical system, and FIG. 3 is an optical axis adopting a conventional optical axis adjusting method. Conceptual diagram of the adjusting device,
FIG. 4 is a diagram showing a state in the middle of adjustment of FIG. 3, and FIG. 5 is a configuration diagram showing a second example of the optical system. 1 ... Disk, 31 ... Reference laser, 32 ... First camera, 33 ... First monitor, 34 ... Second camera, 35 ...
… Second monitor, 5 …… Polarizing beam splitter, 37…
… Optical bench.

Claims (2)

[Claims] 1. An optical component for directing light emitted from a reference laser serving as an optical axis reference to a disk-shaped recording medium and directing light reflected by the recording medium toward a detector.
Corresponding to the reference laser, a first camera and a monitor are arranged in a vertical direction with respect to the recording medium, and a second camera and a monitor are arranged at a reflection optical axis position from the recording medium. The position adjustment of the optical component that determines the incident optical axis vertical to the recording medium based on the positional relationship between the reference position and the incident light to the camera and the positional accuracy confirmation of the reflected optical axis from the recording medium are performed at the same time. A method for adjusting an optical axis of an optical component, characterized by: 2. The optical axis adjusting method for an optical component according to claim 1, wherein the optical axis adjustment is performed with an optical component for determining an incident optical axis vertical to the recording medium as a head.