JPH08315399A - Method for adjusting output of optical head and optical output measuring instrument therefor - Google Patents

Abstract

PURPOSE: To provide a method for adjusting the output of an optical head and an optical output measuring instrument, by which the output of the optical head is not changed due to light beam returned from a disk between the time of the output adjustment of the optical head and the time of the disk reproduction. CONSTITUTION: The optical output measuring instrument 16 provided with almost identical reflectivity to the disk for reproducing 8 or the optical output measuring instrument provided with a half mirror is used. Then, when the output of the optical head is measured, the optical output is measured and adjusted by reproducing an identical state to the reproducing time of the disk.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical output adjusting method for an optical head used in an optical information recording / reproducing apparatus and an optical output measuring device for adjusting the optical head output used in this method.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional optical output adjusting method for an optical head. In the figure, 1 is an optical head, and 2 is a semiconductor laser (hereinafter abbreviated as LD) which serves as a light source. A recording / reproducing laser beam (output light) 11 and an LD output monitor laser beam (monitor emission light) 12 are emitted in opposite directions. 3 is a beam splitter, 4 is an objective lens, 5 is a monitor diode, and these L
The optical head 1 is composed of D2, the beam splitter 3, the objective lens 4, and the monitor diode 5. further,
An LD output control circuit 6 is provided for receiving the output signal of the monitor diode 5 and controlling the output of the LD 2 to be constant. Reference numeral 7 is an optical output measuring device used for adjusting the optical output of the optical head 1, and 8 is a recording / reproducing disk. Further, 13 is the reflected light from the disk 8, which is split laterally by the beam splitter 3. Reference numeral 14 denotes reflected light from the surface of the light output measuring device 6.

In adjusting the output power of the conventional optical head 1 having the above-mentioned structure, first, the optical output measuring instrument 7 is set in front of the objective lens 4 as shown in FIG.
Place so that 4 diverges. Next, the output light 11 is emitted from the LD 2, passes through the beam splitter 3 and the objective lens 4, and enters the output light 11 into the optical output measuring instrument 7, and the laser intensity at that time is measured by the optical output measuring instrument 7. To do.
LD2 is adjusted so that this measured value matches the adjusted target value.
The output of is adjusted by the LD output control circuit 6. Since the monitor emission light 12 is emitted from the LD 2 at the same time, the monitor emission light 12 enters the monitor diode 5 and is converted into an electric signal, and the output signal of the monitor diode 5 is LD.
The output control circuit 6 receives and controls the drive current of the LD 2, and controls the output of the LD 2 so that there is no difference between the measured value by the optical output measuring device 7 and the adjustment target value. As a result, the adjustment of the output power of the optical head 1 is completed.

After the output power of the optical head 1 is adjusted, the optical output measuring device 7 is removed, and the disc 8 is placed at a predetermined position to record / reproduce information on / from the disc 8. To briefly describe this, the output light 11 whose output has been adjusted is emitted from the LD 2 and the output light 11
Passes through the beam splitter 3, is focused by the objective lens 4, and is focused on the recording medium of the disk 8,
Information is recorded on the disk 8. On the other hand, at the time of reproducing information from the disk 8, the reflected light 13 from the disk 8 is laterally separated by the beam splitter 3 and guided to a reproducing detector (not shown) for reproduction. Further, during recording / reproducing of the disk 8, the monitor emission light 12 is incident on the monitor diode 5, so that the LD output control circuit 6 outputs the output of the LD 2 so as to maintain the state when the output power of the optical head 1 is adjusted. Is controlled to be constant.

[0005]

However, according to the conventional optical output adjusting method for the optical head, the optical output adjusting state of the optical output of the optical head 1 is measured by the optical output measuring device 7 and the disk 8 thereafter. On the other hand, there was a problem that it varied when recording / reproducing. The cause of this is that the set position of the optical output measuring device 7 is a position where the reflected light 14 becomes a divergent light as shown in FIG. 3, and there is no possibility that the reflected light 14 will enter the monitor diode 5. Recording of disk 8
During reproduction, the reflected light 13 cannot be completely separated by the beam splitter 3, and a part of the reflected light 13 passes through the beam splitter 3,
This is because the light enters the monitor diode 5.
This incident light is generally called "return light". Due to such return light, the output of the monitor diode 5 increases, and it is as if the output of the LD2 increased. Therefore, the LD output control circuit 6 works to decrease the drive current of the LD2, and As a result, the output of the LD 2 is reduced, and there is a problem that a desired optical head output cannot be obtained when the disk 8 is reproduced. Particularly, in the optical head used for recording / reproducing information, since the recording output is calculated and output with reference to the reproducing output of the monitor diode 5, the problem that an accurate recording output cannot be obtained. There was also.

In order to avoid the influence of the above-mentioned return light, for example, Japanese Patent Laid-Open No. 64-37736 discloses an example in which a monitor diode is arranged behind a disk and a side of a beam splitter (a detector for reproduction). Although an example in which a monitor diode is arranged on the opposite side) is shown, the publication does not disclose an initial optical head output adjusting method. In the former example, the light transmitted through the disc in the reproducing state is detected by the monitor diode to control the output of the LD. Since the optical head and the monitor diode are separately configured, In order to follow the movement of the optical head, it is necessary to make the area of the monitor diode large, and there are problems in terms of accuracy and cost due to movement of the light detection point. In the latter example, the optical head is large. There are problems such as becoming

The present invention has been made in order to solve the above-mentioned problems, and by reproducing the same state as when reproducing a disk at the time of measuring the optical output of the optical head, the light which is not affected by the returning light is reproduced. An object of the present invention is to provide a head output adjusting method and an optical output measuring device for adjusting the optical head output.

[0008]

An optical head output adjusting method according to the present invention measures an optical output of an optical head by an optical output measuring means, and a light source of the optical head so that the measured value matches a target value. In the optical head output adjusting method for adjusting the output, the optical output of the optical head is measured by using an optical output measuring instrument having a reflectance almost the same as that of the reproducing disk.

Further, according to the present invention, an optical output measuring instrument having a half mirror for reflecting and transmitting the output light of the optical head is used, and the light transmitted through the half mirror is measured by the optical output measuring instrument. is there.

Then, the half mirror has substantially the same reflectance as that of the reproducing disk. In addition, the half mirror is arranged so as to substantially coincide with the focal position of the optical head and measurement is performed. The half mirror is arranged at the same position as the disk, and the objective lens of the optical head is moved so that the focal position is adjusted to the half mirror. The focus position is adjusted to the half mirror by controlling the position of the objective lens.

Further, the optical output measuring device according to the present invention has substantially the same reflectance as a reproducing disk.
Further, it has a half mirror that reflects and transmits the output light of the optical head, and the half mirror has substantially the same reflectance as the reproducing disk.

[0012]

In the optical head output adjusting method of the present invention constructed as described above, an optical output measuring instrument having a reflectance substantially the same as that of the reproducing disk, or a half mirror of the optical output measuring instrument, is used for the optical head. Since the light output is measured by arranging it near the focal point of the objective lens, a part of the reflected light from the light output measuring device or the half mirror passes through the beam splitter and LD and returns to the monitor diode when measuring the light output. . Therefore, this return light and L
Since the monitor emission light from D is incident at the same time, the light output can be adjusted under the same conditions as when reproducing the disc.

Further, since the reflectance of the half mirror is almost the same as the reflectance of the reproducing disk, an adjustment error is unlikely to occur.

Furthermore, since the focus position of the objective lens is controlled so as to be always focused on the half mirror, adjustment can be performed under the same conditions at all times, an adjustment error is less likely to occur, and stable measurement is possible.

[0015]

【Example】

Example 1. First Embodiment FIG. 1 shows a light output adjusting method according to a first embodiment of the present invention. In this embodiment, an optical output measuring device 16 having substantially the same reflectance as the reproducing disk 8 is used. A film 17 is partially coated on the surface of the light output measuring device 16 in order to make the reflectances equal. When adjusting the optical output of the optical head 1, this optical output measuring device 16
Are arranged under the same conditions as when reproducing the disk 8 (that is, the measurement surface of the optical output measuring device 16 is set to the objective lens 4).
The light output is measured. At the time of this measurement, the same state as at the time of reproducing the disk 8 is reproduced, so that as shown in FIG. 1, the monitor emission light 12 from the LD 2 and the reflected light from the optical output measuring device 16 are reflected by the monitor diode 5. The return light 15, which is a part, is incident at the same time. Therefore, the LD output control circuit 6 receives the output signal of the monitor diode 5 and controls the output of the LD 2 in a state where the monitor emission light 12 and the return light 15 are applied to the monitor diode 5.
The optical output of can be adjusted under the same conditions as when reproducing the disk 8.

Example 2. FIG. 2 shows a light output adjusting method according to a second embodiment of the present invention. This embodiment uses an optical output measuring device 19 having a half mirror 18 that reflects and transmits the output light 11 of the optical head 1. 20 in the figure
Is a spacer. The half mirror 18 has almost the same reflectance (for example, 80%) as the reproducing disk 8. Therefore, 80% of the output light 11 of the optical head 1 is the half mirror 1.
It is reflected by 8, and the remaining 20% passes through the half mirror 18 and is measured by the optical output measuring device 19. Also in this embodiment, the half mirror 18 is set to the focus position 1 of the optical head 1.
The measurement is performed by arranging so as to almost match with 0. According to the present embodiment, since the half mirror 18 can more accurately match the reproduction condition of the disk 8, the adjustment accuracy of the optical output of the optical head 1 can be improved.

Embodiment 3. FIG. 3 shows a light output adjusting method according to a third embodiment of the present invention. This embodiment is the second embodiment.
The measurement is performed by using the same optical output measuring device 19 used in 1. but the objective lens 4 is moved by an objective lens driving means (not shown) so that the focal position 10 of the optical head 1 is aligned with the half mirror 18. It was done. In addition,
In the second embodiment, the half mirror 18 is moved so as to match the focal position 10 of the optical head 1. Therefore, the half mirror 18 and the reproducing disk 8 are exactly the same in positional relationship, so that the adjustment accuracy of the optical output is further improved.

Example 4. In the present embodiment, although illustration is omitted, the half mirror 1 is always operated by performing feedback control on the driving means of the objective lens 4 in the third embodiment.
The focus position 10 of the optical head 1 is made to coincide with the position 8 above. This enables stable light output adjustment.

[0019]

Since the present invention is constructed as described above, it has the following effects.

Since the optical head output is measured using an optical output measuring instrument having a reflectance almost the same as that of the reproducing disk or an optical output measuring instrument having a half mirror, the optical output is measured under the same conditions as when reproducing the disc. Can be adjusted,
The optical head output can be adjusted without being affected by the returning light.

Since the optical output measuring device or the half mirror provided in this measuring device has almost the same reflectance as that of the reproducing disk, the adjustment error can be reduced.

By arranging the half mirror near the focal point of the optical head, the returning light from the reproducing disk can be made constant.

By fixing the half mirror and moving the objective lens of the optical head, adjustment is possible even in an optical disk device or the like.

By performing feedback control of the objective lens so that the optical head is focused on the half mirror, it is possible to stably create the same state as during disk reproduction, and more stable adjustment is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing Embodiment 3 of the present invention.

FIG. 4 is a diagram showing a conventional optical head output adjusting method.

[Explanation of symbols]

1 optical head, 2 optical output measuring device, 3 LD, 4 objective lens, 5 monitor diode, 6 LD output control circuit, 8 disk, 10 focus position, 11 output light, 1
2 monitor emission light, 13 reflected light, 15 return light, 1
6 Optical output measuring device, 17 films, 18 half mirrors, 1
9 light output measuring device, 20 spacers.

Claims (8)

[Claims] 1. An optical head output adjusting method for measuring an optical output of an optical head by an optical output measuring means and adjusting an output of a light source of the optical head so that the measured value coincides with a target value. An optical head output adjusting method, characterized in that the optical output of the optical head is measured by using an optical output measuring instrument having a reflectance substantially the same as that of a disk. 2. An optical head output adjusting method for measuring an optical output of an optical head by an optical output measuring means and adjusting an output of a light source of the optical head so that the measured value coincides with a target value. An optical head output adjusting method comprising: using an optical output measuring instrument having a half mirror that reflects and transmits the output light of 1., and measuring the light transmitted through the half mirror by the optical output measuring instrument. 3. The optical head output adjusting method according to claim 2, wherein the half mirror has substantially the same reflectance as a reproducing disk. 4. The optical head output adjusting method according to claim 2, wherein the half mirror is arranged so as to substantially coincide with a focal position of the optical head and measurement is performed. 5. The half mirror is arranged at the same position as the disk, and the objective lens of the optical head is moved to adjust the focal position of the half mirror to the half mirror. The optical head output adjusting method according to claim 4. 6. The optical head output adjusting method according to claim 5, wherein the focal position of the objective lens is adjusted to the half mirror by controlling the position of the objective lens. 7. An optical output measuring device for adjusting the output of an optical head, which has substantially the same reflectance as a reproducing disk. 8. An optical output measuring instrument for adjusting the output of an optical head, which has a half mirror that reflects and transmits the output light of the optical head, and the half mirror has substantially the same reflectance as a reproducing disk.