JPS6119003B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical axis position correction device for detecting the amount of deviation of an optical axis setting position and correcting the optical axis in an optical device or the like.

For example, when the optical axis of an optical device using a laser or a light modulator, such as an optical video disk device, fluctuates due to temperature changes, the focus and tracking accuracy decrease, image quality deteriorates, and the device's original functions cannot be fulfilled. For this reason, until now, optical instruments have been installed in a temperature-controlled temperature-controlled room. However, this method has drawbacks such as limitations on where the optical equipment can be used, and the constant temperature room itself being expensive and requiring equipment costs. Furthermore, it takes time for the temperature of the optical equipment itself and the ambient temperature to become constant, and the equipment cannot be used during that time, resulting in very poor efficiency.

On the other hand, when a fluctuation of the optical axis occurs, one way to correct this is to restore the cause of the fluctuation to its original state. However, for example, if the optical axis changes due to a change in laser temperature,
Moving the laser support and returning it to its original position requires a complicated mechanism and is extremely difficult. Furthermore, if there are many causes of optical axis fluctuation, it is even more difficult to restore each one to its original state.

The present invention detects the position of the optical axis on the optical axis, and when an optical axis fluctuation occurs, the optical axis is always maintained by means of moving the optical axis in parallel and further by changing the angle of the optical axis. This is an attempt to correct it so that it passes through a predetermined point. In other words, even if the optical axis of the light beam generated from a light source such as a laser changes due to various causes, the optical axis of the light beam that has passed through the optical axis position correction device is always kept constant. be.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a laser light source, and 2 is a laser beam emitted from the laser light source 1. In FIG. Reference numeral 3 denotes a reflecting mirror, and 4 indicates a first galvano-type rotating element. The reflecting mirror 3 is fixed to a rotating shaft, and the reflecting mirror 3 is rotated according to an external voltage to change the optical axis angle of the laser beam 2. I can do it. A glass plate 5 having parallel surfaces is fixed to the rotation axis of the second galvano-type rotating element 6, and by rotating the glass plate 5, the optical axis of the laser beam 2 can be moved in parallel. 7 and 8 are beam splitters that separate the laser beam 2 and guide it to a set optical axis 2a and optical position detection elements 9 and 10.

Although not shown, an optical video disc has a lens system placed on the set optical axis 2a, and if the optical axis deviates from the set optical axis 2a, lens aberrations may occur or focus and tracking accuracy may be impaired. It gets worse and the image deteriorates.

The optical position detection elements 9 and 10 are each composed of divided solar cells 9a and 9b and 10a and 10b, and the position of the laser beam 2 is determined by the solar cell 9.
It is expressed by the output difference between a, 9b and 10a, 10b. The optical position detection elements 9 and 10 are provided at positions with different optical path lengths, that is, at different distances from the beam splitter 8, and when the laser beam 2 passes through the set optical axis 2a, the differential output becomes 0. It is located in a certain position. A differential amplifier 11 generates a differential output from each of the solar cells 9a and 9b of the optical position detection element 9. An output amplifier 12 generates an output corresponding to the differential output of the differential amplifier 11, and rotates the second galvano-type rotating element 6 so that the differential output of the optical position detection element 9 becomes zero. A differential amplifier 13 generates a differential output of each solar cell 10a, 10b of the optical position detection element 10.

14 is also a differential amplifier, and the differential amplifiers 11, 1
Generates a difference in output of 3. 15 is the output amplifier,
It generates an output according to the differential output of the differential amplifier 14, and converts the first galvano-type rotating element 4 to the difference between the differential outputs of the optical position detection elements 9 and 10, that is, the output of the differential amplifier 14 becomes 0. Rotate it.

Consider a case where the laser optical axis is shifted in such a configuration. In FIGS. 2 and 3, the optical position detecting elements 9 and 10 are shown as being provided on the setting optical axis 2a in order to clarify the explanation of the operation. In FIG. 2, if the laser beam 2 is shifted as shown in the optical axis 2b, the optical position detecting element 9 is a, and the optical position detecting element 10 is
Then b is shifted. Therefore, an output corresponding to a-b is obtained from the output amplifier 15, the reflecting mirror 3 rotates as shown in FIG. 3, and the laser beam 2 is directed along the optical axis 2c.
, and becomes an optical axis parallel to the set optical axis 2a. At this time, the amount of deviation of the optical axis 2c on the optical position detection element 9 is a'. Therefore, the output of the output amplifier 12 corresponds to a', the glass plate 5 rotates, and the optical axis 2
c moves in parallel and passes through the set optical axis 2a.

As another example, in the configuration shown in FIG. 1, the first galvano-type rotary element 4 is rotated by the differential output of the optical position detecting element 10, so that the laser beam 2 always enters the center of the optical position detecting element 10. Several control methods can be considered. In this way, two optical position detectors are installed at positions with different optical path lengths that are equivalent to the set optical axis, and the optical axis is adjusted so that the laser beam always enters the two optical position detectors even if the optical axis shifts. By controlling the optical axis, the optical axis can be made to coincide with the set optical axis even if the optical axis changes. In this case, a correlation occurs between the control system that performs optical axis angle correction, that is, the control system that rotates the reflecting mirror 3, and the control system that performs optical axis parallel correction, that is, the control system that rotates the glass plate 5. That is, when the reflecting mirror 3 rotates, the position of the laser beam on the optical position detection element 9 changes. Therefore, the glass plate 5 is rotated under control for performing optical axis parallel correction. When the glass plate 5 rotates, the laser beam is not perfectly parallel and the energy density is not constant, so a signal is generated in the differential amplifier 14, and the reflection mirror 3 is controlled by the optical axis angle correction control. Rotate. In this way, since there is a correlation between the two controls,
Mutual hunting may occur and the control system may become unstable.

To prevent this, by making the response speeds of both control systems different, the optical axis angle deviation component and the optical axis parallel deviation component can be easily adjusted independently, and the influence of the correlation between the two control systems is reduced, resulting in stable control. I can do it. As the optical axis angle variable means and the optical axis parallel movement means, in addition to the method of attaching a plane mirror and a glass plate to a galvano-type rotating element as shown in FIG. 1, the methods shown in FIGS. 4 and 5 can be considered as examples. , will be explained according to the drawings. In FIG. 4, reference numeral 16 denotes a laser beam, and 17 denotes a reflecting mirror, which is fixed to the rotating shaft of a galvano-type rotating element 18, and changes the angle of the laser beam 16. 1
9 is a moving table on which a galvano-type rotating element 18 is mounted;
It moves in parallel in the direction of the arrow regulated by the guide rail 20. The moving table 19 is fitted with a male screw 21 and is driven by a motor 22 connected to the male screw 21. With this configuration, when the optical axis of the laser beam 16 deviates, angle correction can be made by rotating the galvano-type rotating element 18 by a certain angle, and parallel correction can be made by moving the movable table 19 a certain distance by the motor 22.

Further, in FIGS. 5 and 6, 23 is a laser beam, and 24 and 25 are reflecting mirrors. Reference numeral 26 denotes a galvano-type rotating element, on which a reflecting mirror 25 is fixed to a rotating shaft, and can be rotated in the direction of arrow A. Reference numeral 27 denotes a reflecting mirror rotary table to which the reflecting mirror 24 and the galvano-type rotating element 26 are fixed, and can be rotated in the direction of arrow B about the rotating shaft 28 as a fulcrum. Note that a motor or a galvano-type rotating element may be considered as a driving source for rotation, but these are omitted in the figure. In such a configuration, the laser beam 23
Let us consider a case where the optical axis of is shifted as shown in 23a. The above-mentioned optical position detection means detects the optical axis angular deviation and optical axis parallel deviation. The detected optical axis angle deviation output drives the galvano type rotating element 26 and the reflecting mirror 25
to the position 25a and the laser beam 23a to the 23
Correct it to be parallel to the set optical axis. Next, based on the detected optical axis parallel deviation output, the reflector rotating table 27
Rotate. According to optical theory, if the angle of intersection of the mirrors is constant, the reflected light will become parallel light and exit as parallel light.
7, the reflecting mirror 24 becomes 24a, and the reflecting mirror 2
5a moves to the position 25b, and the reflected light of the laser beam 23a moves in parallel from 23b to 23c to coincide with the set optical axis.

The above explanation has been about the optical axis position correction device when the optical axis has both angular and parallel deviations, but if the optical axis has only parallel deviation, only the optical axis parallel movement means can be used. Bye. In this case, it is sufficient to have either one of the optical position detecting elements 9 and 10 as the optical position detecting means.

As described above, according to the present invention, the first detection means and the second detection means are provided at positions with different optical path lengths and are equivalent to the set optical axis, and the signal of the first detection means and the second detection means are provided at positions equivalent to the set optical axis. The optical axis angle deviation component is detected by taking the difference between the signal from the detection means, and the optical axis angle variable means is rotated based on the signal to correct the optical axis angle, and the signal from one of the detection means is detects the optical axis parallel misalignment component, and uses the signal to move the optical axis parallel means to correct the optical axis parallelism. Therefore, optical axis misalignment caused by temperature changes, etc. can be automatically and easily corrected. Stable operation of the equipment can be expected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
2 and 3 are enlarged views of the main parts of FIG. 1, respectively, and FIG. 4 is a side view of the main parts of another embodiment of the present invention.
5 and 6 are side views of yet another embodiment of the present invention in different operating states. 1...Laser light, 3...Reflection mirror, 4,6
... Galvano type rotating element, 5 ... Glass plate, 7,
8... Beam splitter, 9, 10... Optical position detection element, 11, 13, 14... Differential amplifier.

Claims (1)

[Claims] 1. Optical axis angle variable means for varying the optical axis angle of incident light in accordance with a control signal, parallel movement means for translating the optical axis of incident light in accordance with a control signal, and The first detects the amount of deviation from a predetermined position and generates an electrical signal according to the amount of deviation.
and a second detection means, the first detection means and the second detection means are arranged at different positions on the optical axis of the light that has passed through the optical axis angle variable means and the parallel movement means. a first control loop for applying an electrical signal from the first or second detecting means as a control signal to the parallel moving means; and an electrical signal from the first and second detecting means. An optical axis position correcting device comprising a second control loop that applies a difference signal between the two as a control signal to the optical axis angle variable means.