JP2009015932A - Optical axis adjusting device, optical axis adjustment method, and hologram device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical axis misalignment adjustment method of two beams of laser light in a hologram device which irradiates sub-laser light different from in the wavelength of main laser light beam for recording and reproducing and performs recording and reproducing position control based on the reflected light thereof. <P>SOLUTION: One of the combined light of the branched and outputted from a means for branching and outputting the combined light of main laser light and sub-laser light is inputted and relating respectively to the main laser light and the sub-laser light, the optical axis positions are detected in a plurality of positions where an optical path difference is given. Based on the result of the detection, the position misalignment of the optical axis positions of the two beams of the laser light is determined in each of the plurality of positions and the relative position relations of the optical axes of the main laser light and the sub-laser light inputted to the means for branching and outputting the combined light and the optical axis angle difference are adjusted. As a result, the adjustment can be so performed as to align the optical axes of the two beams of the laser light and the prevention of the deterioration of the recording and reproducing performance can be achieved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical axis adjusting apparatus and method for adjusting the deviation of the optical axes of a plurality of lights output from different light sources, and a hologram recording in which data is recorded by interference fringes between reference light and signal light. The present invention relates to a hologram apparatus that performs recording or reproduction on a medium.

JP 2007-79438 A

As disclosed in Patent Document 1, a hologram recording / reproducing method is known in which data recording is performed using interference fringes between signal light and reference light. In this hologram recording / reproducing method, at the time of recording, the hologram recording medium is irradiated with signal light that has been subjected to spatial light modulation (for example, light intensity modulation) according to the recording data and reference light that is different from the signal light. Then, data recording is performed by forming these interference fringes on the hologram recording medium.
At the time of reproduction, reference light is irradiated to the hologram recording medium. By irradiating the reference light in this way, diffracted light corresponding to the interference fringes formed on the hologram recording medium as described above can be obtained. That is, a reproduced image (reproduced signal light) corresponding to the recorded data is thereby obtained. The reproduced image obtained in this way is detected by an image sensor such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Oxide Semiconductor) sensor, thereby reproducing the recorded data.

  Here, it is considered that the hologram recording medium is a disc-shaped recording medium such as a so-called optical disk such as a CD (Compact Disc) or a DVD (Digital Versatile Disc). It is assumed that recording / reproducing position control such as tracking servo is performed in the same manner as in the case of an optical disc in accordance with the disc-shaped recording medium.

In a disk drive device that records or reproduces an optical disk, a tracking servo is applied using a recording / reproducing laser beam. That is, recording / reproduction and various servo controls are performed simultaneously by irradiation of one kind of laser beam.
The reason why it is possible to perform recording / reproduction and servo control for an optical disc in this way only by irradiation with one type of laser light is that there is a clear threshold for recording power in the recording layer.

However, the situation of a hologram recording medium is different from that of a conventional optical disk. That is, as a recording material for the hologram recording medium, a photopolymer is currently considered to be promising, but this photopolymer has no clear threshold for recording power. Therefore, even when laser light irradiation with low power is performed as in a conventional optical disk, there is a problem that the monomer is changed to a polymer and the recording characteristics of that portion are deteriorated.
For this reason, when performing position control such as tracking servo as in the conventional optical disc in the hologram recording / reproducing system, a separate laser beam having a wavelength different from that of the recording / reproducing laser beam is used to prevent the reaction of the polymer. It is made to use.

  FIG. 16 shows an example of the structure of a hologram recording medium (referred to as hologram recording medium HM) when recording / reproducing position control is performed by irradiation with laser light having a wavelength different from that of the recording / reproducing laser light. ing. Note that FIG. 16 shows a cross section of the hologram recording medium HM. Further, in this figure, as an example, a structure in the case of a reflective hologram recording medium HM in which the above-described diffracted light (reproduced image) at the time of reproduction is obtained as reflected light from the medium is shown.

  As shown in the figure, the hologram recording medium HM in this case is formed with a cover glass 101, a recording layer 102, and a reflective film 103 in order from the upper layer. As the material of the recording layer 102, for example, the above-described photopolymer is selected, and in this case, recording / reproduction is performed using, for example, a blue-violet laser beam having a wavelength of 405 nm. The reflective film 103 reflects reflected light when a reproduction image corresponding to the data recorded on the recording layer 102 is obtained when the reference light by the blue-violet laser light is irradiated during reproduction. Is provided to guide to the apparatus side. The cover glass 101 is provided for protecting the recording layer 102.

The hologram recording medium HM is provided with a substrate 106 and a reflective film 105 in order to enable recording / reproducing position control. In the substrate 106, for example, guide grooves are formed in a spiral shape from the inner peripheral side to the outer peripheral side of the hologram recording medium HM. With this guide groove, the data recording / reproducing position in the recording layer 102 can be defined. By forming the guide groove in a meandering manner, it is possible to record address information, information for rotation control, etc. according to the meandering period as in the case of a recordable medium such as a CD or DVD. Alternatively, instead of such a guide groove, a pit row can be formed, and various information such as address information can be recorded by this pit row.
A reflective film 105 is formed on the surface (front surface) of the substrate 106 where the guide grooves (or pit rows) are formed, for example, by sputtering or vapor deposition. In this way, the reflective film 105 is formed. The substrate 106 thus bonded is adhered to the lower layer side of the reflective film 103 described above by an adhesive material such as a resin as the intermediate layer 104 shown in the figure, whereby the hologram recording medium HM shown in this figure is formed.

  In the hologram recording medium HM, the reflective film 103 has wavelength selectivity. Here, in the case of a reflection type hologram recording medium, the blue / violet laser beam for recording / reproduction should be reflected by the reflecting film 103 as described above, but it is separately provided for position control. The irradiated laser light reaches the reflection film 105 provided with the uneven cross-sectional shape corresponding to the guide groove (or pit row) and is to be reflected here. For this reason, the reflective film 103 is configured to have wavelength selectivity such that the recording / reproducing laser beam is reflected and the laser beam irradiated for position control is transmitted.

  In this case, as the laser light for position control, for example, red laser light having the same wavelength = 633 nm as that of DVD is used. Since the reflective film 103 is configured to have wavelength selectivity as described above, the laser light for position control in this case passes through the reflective film 103 and reaches the reflective film 105 on the substrate 106. Reflected here. This reflected light is guided to the apparatus side as reflected light for position control.

  By using the hologram recording medium HM having such a structure, the apparatus side irradiates a separate laser beam having a wavelength different from that of the recording / reproducing laser beam, and uses the reflected light for recording such as a tracking servo. / Playback position control can be performed.

  Here, in order to correctly realize the recording / reproducing position control by the method as described above, it is natural that the optical axes of the laser light for position control and the laser light for recording / reproduction coincide with each other. It is necessary to be. Specifically, in the configuration of the hologram recording / reproducing apparatus described in Patent Literature 1, two optical systems are adjusted in advance so that the optical axes of the two laser beams coincide with each other at the time of factory shipment. The optical axes can be matched.

However, the optical axes of the two laser beams may be deviated due to heat or the like during recording / reproduction. Further, there is a possibility that the optical axes of the two laser beams are gradually shifted due to a change with time.
The conventional configuration described in Patent Document 1 does not particularly have a means for correcting the deviation of the optical axis caused by the actual use of such a device. When position control is performed using a technique, there is a possibility that data recording / reproduction cannot be performed with respect to an appropriate position of the recording layer 102. That is, as a result, the recording / reproducing performance may be deteriorated.

Therefore, in the present invention, the optical axis adjusting device is configured as follows.
That is, the first light source that outputs the first light, the second light source that outputs the second light, the first light and the second light are input, and the first light and And a combined branch output means for branching and outputting the combined light of the second light.
In addition, adjustment means for adjusting a relative positional relationship and an optical axis angle difference between the optical axes of the first light and the second light input to the combined branch output means is provided.
Also, one of the combined lights branched and output by the combined branch output means is input, and the optical axis positions of the first light and the second light in the input combined light Is provided with optical axis position detecting means for detecting the optical path length at a plurality of positions where the optical path length difference is given.
Further, based on the detection result by the optical axis position detecting means, a positional deviation amount between the optical axis position of the first light and the optical axis position of the second light is obtained for each of the plurality of positions, and Control means for controlling the adjusting means is provided based on the optical axis position shift amount of the first light and the second light for each position.

As described above, the present invention includes a combined branch output unit that inputs the first light and the second light and branches and outputs the combined light. As a result, one of the combined lights can be guided to a required object, and the other combined light can be guided in a separate direction.
In the present invention, for the combined light guided in a direction separate from the object side in this way, the amount of positional deviation of the optical axis of each light is obtained for each of a plurality of positions where the optical path length difference is given. Based on the optical axis positional deviation amount for each of a plurality of positions, the relative positional relationship and the optical axis angle difference between the optical axes of the respective lights input to the combined branch output means are adjusted.
Here, when the positional deviation amount of each optical axis is obtained for each of a plurality of positions to which the optical path length difference is given as described above, the information on the positional deviation amount is simply the position of each optical axis at the plurality of positions. The information reflects not only the shift amount but also the angle difference between the optical axes. Therefore, as in the present invention, the relative positional relationship and the optical axis angle difference of the optical axes of the respective lights input to the combined branch output means based on the optical axis positional deviation amounts at these plural positions are obtained. If adjusted, the combined branch output means can output combined light in which the optical axes coincide with each other. That is, this makes it possible to irradiate the object with synthetic light having the same optical axis.

As described above, according to the present invention, in the case where a target object is irradiated with the combined light of the first light and the second light, adjustment can be performed so that the optical axes of the respective lights coincide with each other. it can. Thereby, for example, even when a deviation occurs in the optical axis of each light due to actual use of the apparatus, adjustment can be performed so that the optical axes are properly matched.
According to the present invention as described above, when the recording / reproducing position control is performed using the laser beam separate from the recording / reproducing laser beam in the hologram recording / reproducing method, the deterioration of the recording / reproducing performance is prevented. A more stable recording / reproducing operation can be performed.

Hereinafter, the best mode for carrying out the invention (hereinafter referred to as an embodiment) will be described.
<First Embodiment>
[Configuration of hologram device]
FIG. 1 is a block diagram showing an internal configuration of a hologram apparatus that can be configured based on the present invention. In FIG. 1, only the configuration of the optical system of the hologram apparatus is mainly extracted and shown, and other parts are omitted.

First, in this embodiment, a so-called coaxial method is adopted as a hologram recording / reproducing method. That is, the signal light and the reference light are arranged on the same axis, and both are irradiated onto the hologram recording medium HM set at a predetermined position to perform data recording by interference fringes, and at the time of reproduction, the reference light is used as the hologram recording medium. Data recorded by interference fringes is reproduced by irradiating the HM.
Note that the hologram recording medium HM in the figure is disk-shaped (disc-shaped), and its cross-sectional structure is the same as that already described with reference to FIG. 16, and therefore a description thereof is omitted here.

In FIG. 1, a hologram recording medium HM is rotated by a driving means such as a spindle motor (not shown), and recording / reproduction is performed by irradiation with laser light using a main laser 1 shown as a light source.
As the main laser 1, for example, a laser diode with an external resonator is adopted, and the wavelength of the laser light is, for example, 405 nm.

The light emitted from the main laser 1 enters the first shutter 4 after passing through the anamorphic prism 2 → the beam expander 3. The first shutter 4 blocks / transmits incident light based on control from the control unit 36 described later.
Light passing through the first shutter 4 enters the spatial filter 5. In the spatial filter 5, a condenser lens 5a, an aperture 5b, and a collimator lens 5c are provided in this order from the light source side, and the central portion of the laser beam (for example, the light intensity has a peak value (100%) to 80%) due to these configurations. (About 20% range) is extracted and output.
The light emitted from the spatial filter 5 is reflected by the mirror 6, then reflected by the mirror 9 via the half-wave plate 7 → the quarter-wave plate 8, and then SLM (spatial light modulation) as shown in the figure. ).

The SLM 10 performs, for example, spatial light intensity modulation as spatial light modulation for incident light. In this case, the SLM 10 is of a reflective type, and specifically comprises a reflective liquid crystal panel, DMD (Digital Micromirror Device: registered trademark), or the like.
The SLM 10 performs spatial light intensity modulation on incident light, so that only signal light and reference light are generated during recording, and only reference light is generated during reproduction. Specifically, at the time of recording, for example, spatial light intensity modulation corresponding to the recording data is performed within a predetermined range including the central portion of the incident light (that is, the light ON / OFF pattern corresponding to the data pattern of “0” “1”) The signal light is generated, and the reference light is generated by giving a required intensity modulation pattern outside the signal light. Further, only the reference light is generated during reproduction.

  The light subjected to spatial light modulation by the SLM 10 enters the relay lens unit 11 as shown in the figure. The relay lens unit 11 includes a relay lens 11a that condenses incident light from the SLM 10, an aperture 11b that limits the diameter of the light from the relay lens 11a, and light emitted from the aperture 11b as shown in the figure. And a relay lens 11c for converting the light into parallel light.

  Then, the light passing through the relay lens unit 11 passes through the polarization beam splitter 12 and then enters the relay lens unit 13. Similarly to the relay lens unit 11, the relay lens unit 13 condenses incident light, an aperture 13b that limits the diameter of light from the relay lens 13a, and an output from the aperture 13b. And a relay lens 13c for converting incident light into parallel light. The light that has passed through the relay lens unit 13 enters the dichroic prism 14.

  A part of the light incident on the dichroic prism 14 through the relay lens unit 13 is transmitted through the dichroic prism 14 and reflected by a 45 ° mirror through the half-wave plate 15 shown in the figure, as will be described later. After that, the hologram recording medium HM is irradiated through the objective lens 17.

  Here, depending on the spatial light modulation during recording by the SLM 10 described above, signal light and reference light are generated based on laser light using the main laser 1 as a light source. That is, at the time of recording, the laser light is irradiated by the above optical path, so that the hologram recording medium HM is irradiated with the signal light and the reference light. By irradiating the hologram recording medium HM with the signal light and the reference light in this manner, data can be recorded on the recording layer 102 by interference fringes of these lights.

At the time of reproduction, only the reference light is generated by the SLM 10, and this is irradiated onto the hologram recording medium HM through the optical path. In this way, in response to the reference light being applied to the hologram recording medium HM, diffracted light (reproduced light) corresponding to the interference fringes is obtained. The reproduction light thus obtained is returned to the apparatus side as reflected light from the reflection film 103 of the hologram recording medium HM.
The reproduction light is converted into parallel light through the objective lens 17, reflected by a 45 ° mirror, and further transmitted through the half-wave plate 15 → the dichroic prism 14 → the relay lens unit 13, and the polarized beam. The light enters the splitter 12.
The polarization beam splitter 12 reflects the incident reproduction light. The reflected light from the polarization beam splitter 12 is reflected by the mirror 19 through the condenser lens 18 as shown in the figure, and then enters the image sensor 21 through the collimator lens 20.

The image sensor 21 is, for example, a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Oxide Semiconductor) sensor, and receives the reproduction light from the hologram recording medium HM guided as described above, and converts it into an electrical signal. To obtain an image signal. The image signal thus obtained reflects the “0” “1” data pattern (that is, the light ON / OFF pattern) applied to the signal light during recording. That is, the image signal detected by the image sensor 21 in this way corresponds to a read signal for data recorded on the hologram recording medium HM.
In order to finally reproduce the recorded data of “0” and “1”, the read signal from such an image sensor 21 is used for data identification of “0” and “1” in units of data pixels of the SLM 3. A reproduction signal processing unit is provided (not shown). As described above, there are various methods of reproduction signal processing for reproducing the recorded data “0” and “1” from the output of the image sensor 21, and the method is not particularly limited here.

  Further, in the hologram apparatus shown in FIG. 1, the recording / reproducing operation performed using the laser light having the main laser 1 as the light source as described above is separately provided for controlling the recording / reproducing position. An optical system for irradiating laser light is provided. Specifically, a sub laser 22, a photodetector 23, a collimator lens 24, a condenser lens 25, a beam splitter 26, and a mirror 28 are provided.

  The sub laser 22 is configured to irradiate laser light having a wavelength different from that of the main laser 1 for recording / reproducing described above. Specifically, in this case, laser light having a wavelength of, for example, 633 nm is output, which is assumed to have almost no sensitivity to the recording layer 102 of the hologram recording medium HM.

  Laser light emitted from the sub-laser 22 passes through the beam splitter 26 via the collimator lens 24 and is then reflected by the mirror 28 via the optical axis adjustment unit 27 described later. The laser beam reflected by the mirror 28 enters the second shutter 29. The second shutter 29 is configured to block / transmit incident light based on the control of the control unit 36 described later.

As will be described later, a part of the laser light passing through the second shutter 29 is reflected by the dichroic prism 14 and guided to the above-described half-wave plate 15 side.
The laser light using the sub laser 22 guided from the dichroic prism 14 to the half wavelength plate 15 side as the light source is the half wavelength plate as in the case of the laser light using the main laser 1 as the light source. The hologram recording medium HM is irradiated through a 15 → 45 ° mirror 16 → the objective lens 17. As described above with reference to FIG. 16, in the hologram recording medium HM, the laser beam having a wavelength of 633 nm irradiated in this way passes through the reflection film 103 and is reflected by the reflection film 105 below it. That is, the reflected light corresponding to the guide grooves (or pit rows) formed on the substrate 106 is thereby obtained.
The reflected light from the reflective film 105 is also incident on the dichroic prism 14 through the objective lens 17 → 45 ° mirror 16 → half-wave plate 15 as in the case of the light having the main laser 1 as the light source. To do.

  The dichroic prism 14 reflects the reflected light from the hologram recording medium HM with respect to the laser light having the sub laser 22 as a light source, and guides it to the second shutter 29 side as shown in the figure. The laser light thus guided to the second shutter 29 side is reflected by the beam splitter 26 after passing through the second shutter 29 → the mirror 28 → the optical axis adjusting unit 27, and this reflected light passes through the condenser lens 25. To the photo detector 23.

The photodetector 23 controls the recording / reproducing position of the laser beam having the main laser 1 as the light source based on the reflected light from the hologram recording medium HM for the light having the sub laser 22 as the light source obtained as described above. The detection signal is obtained. Based on the detection signal by the photodetector 23, for example, a tracking error signal for performing tracking servo control, a focus error signal for performing focus servo control, and the like are generated.
In FIG. 1, the configuration for recording / reproducing position control performed based on the detection signal of the photodetector 23 is omitted, but tracking performed based on laser light irradiation using the sub laser 22 as a light source. Configurations for performing recording / reproducing position control such as servo control (and other servo control such as focus servo) are, for example, CD (Compact Disc), DVD (Digital Versatile Disc), BD (Blu-ray Disc: registered trademark) The configuration similar to that used in the current optical disc field may be adopted. Such a configuration for recording / reproducing position control is not directly related to the optical axis correction in the present invention, and is not particularly limited here.

Here, as understood from the above description, in the hologram apparatus shown in this figure, the dichroic prism 14 transmits a part of the laser light having the main laser 1 incident from the relay lens unit 13 as a light source, A part of the laser light having the sub-laser 22 incident from the second shutter 29 side as a light source is reflected so that two different laser lights are combined and guided to the hologram recording medium HM side.
In this embodiment, the dichroic prism 14 combines the two lights and guides them to the hologram recording medium HM side. In the present embodiment, however, the dichroic prism 14 uses a part of each laser beam. It differs from the conventional point in that only the light is transmitted and reflected.
Specifically, the dichroic prism 14 in this case transmits a part of the laser light having the main laser 1 as a light source and reflects a part thereof, and a part of the laser light having the sub laser 22 as a light source. It is configured to reflect and partially transmit. Such a dichroic prism 14 can be realized, for example, by performing thin film processing on the surface so as to obtain the reflection / transmission characteristics as described above. With the configuration of the dichroic prism 14, the combined light of the two laser beams can be output in a direction guided to the hologram recording medium HM side, and can be branched and output in a different direction.
Note that the reflectance of the dichroic prism 14 may be determined so as to satisfy the condition of the light amount necessary for recording / reproducing and servo control.

  In the hologram apparatus of the present embodiment, the combined light branched and output in a direction different from the direction guided to the hologram recording medium HM side by the dichroic prism 14 is input, and the optical axis deviation of the two laser beams is shifted. As a configuration for detection, a condensing lens 30, a half mirror 31, a first detector 32, a second detector 33, a drive unit 34, and a drive unit 35 are provided.

The combined light branched and output by the dichroic prism 14 in a direction different from the direction guided to the hologram recording medium HM side is input to the half mirror 31 via the condenser lens 30.
The half mirror 31 transmits a part of the input combined light and reflects a part thereof. As shown in the drawing, the combined light reflected by the half mirror 31 is applied to the first detector 32, and the transmitted combined light is applied to the second detector 33.

  In the case of the present embodiment, as the first detector 32 and the second detector 33, for example, a quadrant photodetector is used, and laser light using the main laser 1 as a light source and laser light using the sub laser 22 as a light source. Both have sensitivity.

Here, FIG. 2 shows the structure of the first detector 32 and the second detector 33.
As shown in FIG. 2, each of the first detector 32 and the second detector 33 is a quadrant detector, and is composed of a combination of photodetectors A, B, C, and D.
In this case, as shown in the figure, when the horizontal axis direction in the laser beam irradiation surface direction in the detectors 32 and 33 is the x-axis direction and the vertical axis direction is the y-axis direction, a set of photodetectors [A, B], a photodetector [ C, D] are adjacent to each other in the x-axis direction. Further, a set of photodetectors [A, C] and a set of photodetectors [B, D] are adjacent to each other in the y-axis direction.
In this case, the detection signals of the photodetectors A, B, C, and D are expressed as a, b, c, and d, respectively.

  Returning to FIG. 1, the detection signals a, b, c, and d from the photo detectors A, B, C, and D of the first detector 32 and the second detector 33 are input to the control unit 36, respectively. ing.

In FIG. 1, the hologram device of the present embodiment is provided with a drive unit 34 and a drive unit 35 for moving the positions of the first detector 32 and the second detector 33.
Although the detailed illustration is omitted, the first detector 32 is fixed on the surface of the drive unit 34, while the back surface thereof is fixed to the main body side of the hologram device, so that the first detector 32 is connected to the hologram. It is provided so as to be supported from the main body side of the apparatus.
Similarly, the second detector 33 is fixed on the front surface of the driving unit 35 and the back surface is fixed to the main body side of the hologram device, so that the second detector 33 is supported from the main body side of the hologram device. Is provided.

  Here, it should be noted that the first detector 32 and the second detector 33 supported on the main body side through the drive unit 34 and the drive unit 35 in this way have optical path lengths for incident light as shown in the figure. They are arranged so as to give a difference. That is, in this case, when each light source is used as a reference, the optical path length to the first detector 32 and the optical path length to the second detector 33 are made different.

FIG. 3 shows an example of the structure of the drive units 34 and 35.
The drive units 34 and 35 are configured to drive the first detector 32 and the second detector 33 in the x-axis direction and the y-axis direction described above. Specifically, the drive units 34 and 35 in this case are each composed of a combination of two drive elements, ie, first drive elements 34a and 35a and second drive elements 34b and 34b that can be deformed in one predetermined direction.
As shown in the figure, in this case, the deformation direction of the first drive elements 34a and 35a is made to coincide with the x-axis direction, and the deformation direction of the second drive elements 34b and 35b is made to coincide with the y-axis direction. By combining the drive elements, the first detector 32 and the second detector 33 can be driven in the x-axis direction and the y-axis direction.
In addition, as each drive element (34a, 35a, 34b, 35b) which can be deform | transformed in the predetermined axis direction as mentioned above, it is realizable with a piezoelectric element etc., for example.

  In FIG. 1, a control signal supply line from the control unit 36 is connected to the drive units 34 and 35. In other words, this enables drive control to the drive units 34 and 35 by the control unit 36.

  In addition, the hologram apparatus of the present embodiment is provided with an optical axis adjustment unit 27 as a configuration for correcting (adjusting) the optical axis shift of the two laser beams. As understood from the above description, the optical axis adjusting unit 27 is inserted into the optical path between the beam splitter 26 and the mirror 28 in the laser light optical system using the sub laser 22 as a light source. Provided.

FIG. 4 is a diagram schematically showing the internal configuration of the optical axis adjustment unit 27. In this figure, only the optical elements provided in the optical axis adjustment unit 27 are extracted and shown, and other parts are omitted. Further, in this drawing, the state of the laser light input to and output from the optical axis adjustment unit 27 is also shown.
As shown in FIG. 4, in the optical axis adjustment unit 27 in this case, the incident laser light is reflected to the outside after being reflected in the order of mirror 27a → mirror 27b. The optical axis adjustment unit 27 adjusts the optical axis of the incident laser light by adjusting the angles of the two mirrors 27a and 27b.
Although omitted for convenience of illustration, the optical axis adjustment unit 27 is provided with an actuator for supporting the mirrors 27a and 27b from the hologram apparatus main body side and adjusting their angles.
In this case, as the actuator, an actuator for the mirror 27a (referred to as a first actuator) and an actuator for the mirror 27b (second actuator) so that the angles of the respective mirrors 27 can be adjusted independently. 2). The first actuator is configured to be driven by rotating the mirror 27a in two directions with reference to the two axes of the horizontal axis (x-axis in the figure) and the vertical axis (y-axis in the figure) of the mirror 27a. Is done. Similarly, the second actuator is driven to rotate the mirror 27b in two directions with reference to the two axes of the horizontal axis (x-axis in the figure) and the vertical axis (y-axis in the figure) of the mirror 27b. Configured as follows.

In the optical axis adjustment unit 27 as described above, the angle can be changed between the rotation direction with reference to the x-axis and the rotation direction with reference to the y-axis. , And a mirror 27b capable of changing the angle in the rotation direction with respect to the y-axis. The incident light is reflected by the mirror 27a and guided to the mirror 27b, which is reflected by the mirror 27b and output to the outside.
With such a configuration of the optical axis adjustment unit 27, the incident laser beam has an optical axis position in the irradiation plane direction (that is, corresponding to the xy plane direction shown in FIG. 2), and an optical axis angle. Can be adjusted.

  In the present embodiment, it is assumed that the optical axis adjustment unit 27 is inserted only into the optical system of the sub-laser 22 and thereby adjusts the optical axis position and optical axis angle of only the laser beam using the sub-laser 22 as a light source. However, when adjusting the relative optical axis positional relationship and optical axis angle difference with the laser beam using the main laser 1 as the light source, the optical axis adjusting unit 27 is inserted into the optical system of the main laser 1. It is also possible to do. Alternatively, the optical adjustment unit 27 may be inserted into both optical systems.

  Returning to FIG. 1, the optical axis adjustment operation using the two actuators (first actuator and second actuator) in the optical axis adjustment unit 27 is performed based on the control of the control unit 36. Specifically, the control unit 36 instructs the optical axis adjustment unit 27 to adjust the x-axis and y-axis of the first actuator and the adjustment values of the x-axis and y-axis of the second actuator. In the optical axis adjustment unit 27, the first actuator and the second actuator are driven based on the instructed adjustment values, whereby the mirror 27a and the mirror 27b can be adjusted (controlled) to an angle corresponding to the adjustment value. It is said.

  The control unit 36 is configured by a microcomputer including, for example, a ROM (Read Only Memory), a RAM (Randam Access Memory), a CPU (Central Processing Unit), and the like, and an optical axis correction (this embodiment described below) (Adjustment) A control process for realizing the operation is performed.

[Optical axis correction operation]
The optical axis correction (adjustment) operation as the first embodiment performed by the hologram apparatus as the first embodiment having the above-described configuration will be described.
The optical axis correction operation of the first embodiment can be roughly divided into the following three steps.
<1> Position alignment of first and second detectors based on main laser beam <2> Detection of optical axis misalignment amount of main laser beam and sub laser beam using each detector <3> Based on optical axis misalignment amount Optical axis adjustment of sub laser light

<1> Positioning of the first and second detectors with reference to the main laser beam First, when aligning each detector, only the laser beam (main laser beam) using the main laser 1 as a light source is the first. The controller 36 controls the first shutter 4 and the second shutter 29 so as to be incident on the first detector 32 and the second detector 33, respectively. Specifically, control is performed so that the first shutter 4 transmits the incident light and the second shutter 29 blocks the incident light.

And the control part 36 inputs the detection signals a, b, c, and d from the first detector 32 and the second detector 33 when only the main laser beam is irradiated in this way. Then, the detection signals a, b, c, d from the first detector 32 and the detection signals a, b, c, d from the second detector 33 are respectively

(A + c)-(b + d) = x, (a + b)-(c + d) = y

Calculate
Here, it can be seen that the value of x is a value representing the amount of deviation in the x-axis direction shown in FIG. Further, the value of y is a value representing a deviation in the y-axis direction.

When the values of x and y are calculated for each detector in this manner, the position of each detector is adjusted so that x = y = 0. That is, by controlling the drive units 34 and 35, the first detector 32 and the second detector 33 are moved to positions where x = y = 0.
According to the description of FIG. 3 above, in the drive units 34 and 35, the adjustment in the x-axis direction is performed by the first drive elements 34a and 35a, and the adjustment in the y-axis direction is performed by the second drive elements 34b and 35b. Yes. Therefore, the control unit 36 controls the first drive elements 34a and 35a in each drive unit so that x = 0, and controls the second drive elements 34b and 35b in each drive unit so that y = 0. .

Here, various specific methods for adjusting the position of each detector so that x = y = 0 as described above can be considered. For example, the values of x and y are monitored and the first drive elements 34a and 35a and the second drive elements 34b and 35b are driven and controlled so that the values are zero, and finally the values of x and y are zero. There is a method of finishing the adjustment according to the situation.
Alternatively, a function representing the relationship between the driving amount of the first driving elements 34a and 35a and the second driving elements 34b and 35b and the amount of change in the values of x and y is calculated in advance, and the calculated x, It is also possible to calculate the driving amount of each driving element for setting the value of y to 0 and drive the first driving elements 34a and 35a and the second driving elements 34b and 35b by the driving amount.
Here, as an example, it is assumed that the former method of monitoring the values of x and y is employed.

<2> Detection of optical axis position shift amount of main laser beam and sub laser beam using each detector By performing the position adjustment operation as described above, each detector has the optical axis position of the main laser beam and the center position of each detector. It is adjusted so that it matches.
After adjusting the position of each detector in such a state, subsequently, each of these detectors is irradiated only with laser light (sub laser light) using the sub laser 22 as a light source, and the optical axis position of the sub laser light is detected by each detector. Is detected.
Specifically, the control unit 36 cancels the incident light blocking state of the second shutter 29 (that is, makes it incident), and performs control so that the first shutter 4 blocks the incident light, so that only the sub-laser light is the first. The first detector 32 and the second detector 33 are irradiated. Then, for the detection signals a, b, c, and d obtained from the first detector 32 and the second detector 33, the above-described calculation is performed to calculate the values of x and y.

Here, as described above, the position of each detector is adjusted to a position where the values of x and y calculated in accordance with the irradiation of the main laser beam are both zero. Therefore, for each detector adjusted to such a position, the values of x and y calculated according to the irradiation of the sub laser light as described above are values representing the optical axis position shift amount of the sub laser light with respect to the main laser light. It becomes. Specifically, the values of x and y calculated from the detection signal of the first detector 32 in this case represent the optical axis position shift amount between the main laser beam and the sub laser beam at the position of the first detector 32, and The values of x and y calculated from the detection signal of the two detectors 33 represent the optical axis position shift amount between the main laser beam and the sub laser beam at the position of the second detector 33.
That is, as a result, the optical axis position shift amount between the main laser beam and the sub laser beam at a plurality of positions is obtained.

At this time, it should be noted that there is a difference between the optical path length to the first detector 32 and the optical path length to the second detector 33 as described above with reference to FIG.
In the present embodiment, the optical axis position deviation amounts of the two laser beams are detected at the two locations where the optical path length difference is given in this way. In consideration of the fact that there is an angular shift as well as a positional shift at (that is, a shift in the x- and y-axis directions). In other words, if only one detector is used, even if the optical axis positions of the two laser beams coincide with each other in the detector, it means that two laser beams with different irradiation angles coincide with each other by chance. There may be no case. In consideration of this, in the present embodiment, the optical axis position shift amount of each laser beam is detected at two places having different optical path lengths.

<3> Optical axis adjustment of sub laser light based on optical axis position shift amount According to the above description, the values of x and y calculated for each detector in accordance with the irradiation of the sub laser light are simply two at each position. In addition to representing the amount of optical axis position deviation in the laser beam irradiation surface direction, the amount of deviation of the optical axis angles of the two laser lights is also represented.
Therefore, if the relative positional relationship between the optical axes of the two laser beams and the optical axis angle difference are adjusted based on the x and y values obtained for each detector in this way, the optical axes of the two laser beams are adjusted. Can be matched.

Here, the optical axis adjustment in this case is performed by the optical axis adjustment unit 27 inserted in the optical system for the sub laser light. According to the above description, the optical axis adjustment in the optical axis adjustment unit 27 is performed by adjusting the x-axis and y-axis adjustment values of the first actuator that drives the mirror 27a, and the x-axis and y of the second actuator that drives the mirror 27b. It is executed by giving an adjustment value of the axis.
In this case, the control unit 36 uses the adjustment value table as shown in FIG. 5 to obtain an adjustment value corresponding to the x and y values calculated for each detector.

As shown in FIG. 5, the adjustment value table includes x and y values calculated from the detection signal of the first detector 32, and x and y values calculated from the detection signal of the second detector 33. And the adjustment values of the x- and y-axes of the first actuator and the x-axis and y of the second actuator to be set to make their values 0 (that is, to match the two laser optical axes) The information is associated with the combination with the adjustment value of the axis.
In addition, what is necessary is just to calculate | require the correspondence of each value in such an adjustment value table, for example from the result of having experimented beforehand at the time of manufacture etc.
Although not shown in FIG. 1, it is assumed that such an adjustment value table is stored in, for example, a ROM in the control unit 36.

The control unit 36 calculates the x and y values for each detector in accordance with the irradiation of the sub-laser light as described above, and associates them with the calculated combinations of the x and y values in the adjustment value table. The adjustment values of the x-axis and y-axis of the first actuator and the x-axis and y-axis of the second actuator are acquired. In addition, the obtained adjustment values are instructed to the optical axis adjustment unit 27 to execute angle adjustment of the mirror 27a and the mirror 27b.
Thereby, adjustment can be performed so that the optical axes of the main laser beam and the sub laser beam coincide.

As described above, in the first embodiment, first, the positions of the first detector 32 and the second detector 33 are moved so that the optical axis of the main laser beam coincides with the center position thereof, and in this state. Each detector detects the irradiation position of the sub laser beam. That is, by this, the optical axis position shift amount between the main laser beam and the sub laser beam is detected for each detector. Then, based on the optical axis position shift amount calculated for each detector as described above, the optical axis adjustment unit 27 adjusts the relative optical axis positional relationship between the two laser beams and the optical axis angle difference. .
Thereby, adjustment can be performed so that the optical axes of the two laser beams coincide with each other.

  If the optical axis deviation of the two laser beams is actually detected in this way and correction can be made so that the optical axes coincide with each other based on the result, the deviation of the optical axes of the two laser beams with the use of the apparatus. This can also be corrected when it occurs. That is, this makes it possible to perform correction so that the optical axes of the recording / reproducing laser beam as the main laser beam and the recording / reproducing position control laser beam as the sub-laser beam coincide with each other. Therefore, it is possible to effectively prevent the deterioration of the recording / reproducing performance, which has been a problem in the prior art.

  Further, as can be understood from the above description, in the present embodiment, adjustment of the main laser beam is not performed in correcting the relative positional relationship between the two laser beam axes and the optical axis angle difference. In addition, adjustment is performed only for the sub laser beam. Here, since the main laser beam is a laser beam for recording / reproducing, if the optical axis is adjusted, the recording / reproducing performance may be deteriorated. From this point, according to the present embodiment in which only the optical axis on the sub laser beam side is adjusted, it is possible to prevent the recording / reproducing performance from being deteriorated.

[Processing behavior]
FIG. 6 is a flowchart showing the processing operation to be executed to realize the optical axis correction (adjustment) operation as the first embodiment described above.
The processing operation shown in FIG. 6 is executed by the control unit 36 based on, for example, a program stored in a built-in ROM.

  In FIG. 6, first, in step S101, a process for blocking only the sub laser beam is executed. That is, the first shutter 4 is controlled to transmit incident light, and the second shutter 29 is controlled to block incident light.

  In the subsequent step S102, (a + c)-(b + d) = x and (a + b)-(c + d) = y are calculated for each detector. In response to the execution of the process of step S101, only the main laser light is irradiated to the first detector 32 and the second detector 33. In step S102, the values of x and y are calculated based on the detection signals a, b, c and d obtained from the detectors 32 and 33 in accordance with the irradiation of the main laser light in this way.

  In the next step S103, processing for adjusting the position of each detector is executed so that x = y = 0 in both cases. That is, as described above, the values of x and y are monitored, and the first drive elements 34a and 35a and the second drive elements 34b and 35b are driven and controlled so that the values become zero. The adjustment ends when the values of x and y become 0.

  In a succeeding step S104, a process for releasing the blocking of the sub laser light is executed. That is, the second shutter 29 is controlled to transmit incident light. In the next step S105, as a process for blocking the main laser beam, the first shutter 4 is controlled to block the incident light.

  In the subsequent step S106, the values of x and y are calculated for each detector. As described above, the values of x and y calculated for each detector in accordance with the irradiation of the sub laser light in this way are simply the optical axes in the in-plane directions of the two laser lights at the respective positions. This not only represents the amount of positional deviation, but also represents the amount of deviation of the optical axis angles of the two laser beams.

  In the subsequent step S107, an adjustment value is acquired from the adjustment value table based on the x and y values of each detector. That is, as described above, for example, from the adjustment value table stored in the built-in ROM, the x-axis of the first actuator associated with the combination of the x and y values calculated in step S106. , Y-axis adjustment values and second actuator x-axis and y-axis adjustment values are acquired.

Further, in the next step S108, the optical axis adjustment unit 27 is controlled based on the acquired adjustment value. That is, the angle adjustment of the mirror 27a and the mirror 27b is executed by instructing the optical axis adjustment unit 27 of each adjustment value acquired in step S107.
When the process of step S108 is executed, the optical axis correction process shown in FIG.

<Modification of the first embodiment>
Here, in the hologram apparatus shown in FIG. 1, the half mirror 31 is provided to guide the laser light to the first detector 32 and the second detector 33. Instead of this, for example, the following FIG. It can also be set as the structure which provided the mirror 37 as shown by these.
FIG. 7 shows a configuration of a hologram apparatus as a modification of the first embodiment. In this figure, portions already described in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.
In the configuration of the modification shown in FIG. 7, the half mirror 31 provided in the case of FIG. 1 is omitted, and the laser light obtained through the dichroic prism 14 → the condensing lens 30 is directly applied to the first detector. 32 ref is irradiated.

In this case, the first detector 32ref is a four-divided detector composed of only a photodetector having sensitivity to both the main laser beam and the sub laser beam, like the first detector 32 shown in FIG. Although it is common, it is different in that it is a reflective photodetector that reflects a part of incident light.
The laser beam reflected by the first detector 32 ref of the reflection type is reflected by a mirror 37 provided so as to face the first detector 32 ref as shown in the figure, and is reflected by the second detector 33. Irradiated.

Even with such a configuration, the laser light via the dichroic prism 14 → the condenser lens 30 can be guided to the two detectors. At the same time, a difference can be given between the optical path length to the first detector 32ref and the optical path length to the second detector 33.

<Second Embodiment>

Next, a second embodiment will be described.
In the second embodiment, an optical axis correction operation can be performed in real time.
FIG. 8 shows an example of the configuration of a hologram apparatus as the second embodiment. In this figure as well, parts already described in FIG.
In the hologram apparatus shown in FIG. 8, instead of the first detector 32 and the second detector 33, which are provided in the hologram apparatus of FIG. A first detector 41 and a second detector 42 are provided which are a combination of a photodetector having sensitivity only to the main laser beam and a photodetector having sensitivity only to the sub laser beam.
Furthermore, instead of the control unit 36, a control unit 40 that performs optical axis correction control in real time based on detection signals from the first detector 41 and the second detector 42 is provided. The control unit 40 is also composed of, for example, a microcomputer including a ROM, a RAM, and a CPU.

FIG. 9 schematically shows the structure of the first detector 41 and the second detector 42 shown in FIG.
As shown in the figure, the first detector 41 and the second detector 42 in this case include a total of 8 photo detectors A, B, C, D, E, F, G, and H that are radially divided with reference to the center thereof. It consists of a combination of two photodetectors.
In this case, the photodetectors A, B, C, and D are configured to have sensitivity only to the main laser beam. Further, the photodetectors E, F, G, and H shown by coloring are configured so as to be sensitive only to the sub laser light. The photodetectors A, B, C, D, E, F, G, and H having wavelength selectivity as described above can be realized by attaching a wavelength filter to the detection surface.

In the first detector 41 and the second detector 42, as shown in the figure, a photodetector having sensitivity only to the main laser beam and a photodetector having sensitivity only to the sub laser beam are alternately arranged. Specifically, in this case, the photo detectors are arranged in the order of photo detectors A → F → B → H → D → G → C → E.
Here, as shown in the figure, the direction in which the pair of photodetectors A and F and the pair of photodetectors G and D are adjacent to each other is defined as an x-axis direction. The direction in which the pair of photodetectors B and H and the pair of photodetectors E and C are adjacent to each other is taken as a y-axis direction.

Further, in this case, the inward angle of each photo detector is set in each of a set of photo detectors A, B, C, and D sensitive to main laser light and a set of photo detectors E, F, G, and H sensitive to sub laser light. To be equal. That is, when the inward angles of the photodetectors A, B, C, and D are LA, LB, LC, and LD and the inward angles of the photodetectors E, F, G, and H are LE, LF, LG, and LH as shown in the figure,

LA = LB = LC = LD, LE = LF = LG = LH

It is supposed to be.

In FIG. 9, the detection signals from the photodetectors A, B, C, and D are a, b, c, and d, respectively, as shown in the figure. Similarly, detection signals by the photodetectors E, F, G, and H are e, f, g, and h.
These detection signals a, b, c, d, e, f, g, and h are supplied from the first detector 41 and the second detector 42 to the control unit 40 shown in FIG.

Here, in the hologram apparatus of the second embodiment, as described above, the first detector 41 and the second detector, which are a combination of the photodetector having sensitivity only to the main laser beam and the photodetector having sensitivity only to the sub-laser beam. 42, the main laser beam and the sub laser beam are not blocked as in the case of the first embodiment, and the optical axis positions of the respective laser beams are detected even when they are simultaneously irradiated. can do. In other words, it is possible to perform the optical axis correction operation without interrupting each laser beam even during recording / reproduction. In the second embodiment, this point is utilized to perform the optical axis correction operation in real time like servo control.
Hereinafter, an optical axis correcting operation as the second embodiment will be described.

First, also in the optical axis correction operation in this case, as in the case of the first embodiment, first, the position of each detector is adjusted based on the main laser beam. Specifically, the control unit 40 inputs only the detection signals a, b, c, d from the first detector 41 and the second detector 42 (that is, the detection signals from the photodetector having sensitivity to the main laser beam),
(A + c)-(b + d) = x1
(A + b)-(c + d) = y1
Calculate That is, by this, the optical axis position shift amount of the main laser light with respect to the center position of the detector at each position of the first detector 41 and the second detector 42 is calculated. From the previous FIG. 9, the value of x1 represents the amount of displacement in the x-axis direction, and the value of y1 represents the amount of displacement in the y-axis direction.
After that, the position of each detector is adjusted so that x1 = y1 = 0 in both detectors (41, 42). In this case as well, the position adjustment of each detector may be performed in the same manner as in the first embodiment.

  In the second embodiment, for the purpose of determining the reference position of each detector, the position of each detector is adjusted based on such main laser light. That is, by performing such adjustment, when the optical axis of the laser beam is at the center position in one detector, it is guaranteed that the optical axis of the laser beam is also at the center position in the other detector. become.

After determining the reference position of each detector as described above, the relative optical axis position shift amount between the main laser beam and the sub laser beam in each detector is sequentially calculated, and the optical axis adjustment unit is based on the result. 27 is repeatedly performed. As a result, a real-time optical axis correction operation is realized.
Specifically, after the reference position of each detector is determined, the control unit 40 performs the following operation in accordance with, for example, the start of a recording / reproducing operation with respect to the hologram medium HM.
First, detection signals a, b, c, d, e, f, g, and h from the detectors 41 and 42 are input, and (a + c) − (b + d) = x1 for each detector.
(A + b)-(c + d) = y1
(E + g)-(f + h) = x2
(E + f)-(g + h) = y2
Calculate
Then, using these values of x1, x2, y1, and y2, the amount of relative positional deviation between the main laser beam and the sub laser beam is calculated for each detector. In particular,
x1-x2 = x
y1-y2 = y
Calculate

Here, the value of x calculated in the first embodiment is a value representing the amount of optical axis positional deviation in the x-axis direction for the main laser beam and the sub laser beam. Similarly, the value of y is a value representing the relative optical axis position shift amount of the main laser beam and the sub laser beam in the y-axis direction.
Based on this point, the value of x1 calculated by (a + c) − (b + d) as described above represents the optical axis position in the x-axis direction of the main laser beam in each detector (41, 42). Value. Further, the value of x2 calculated by (e + g) − (f + h) is a value representing the optical axis position in the x-axis direction of the sub-laser light in each detector. Accordingly, the value of x calculated by the above x1-x2 is the same as the value of x calculated in the first embodiment, but the optical axis position shift amount in the x-axis direction between the main laser beam and the sub laser beam. Is a value representing.
Similarly, the value of y1 calculated by the above (a + b)-(c + d) is a value representing the optical axis position of the main laser light in each detector in the y-axis direction, and also by (e + f)-(g + h) The calculated value of y2 is a value representing the optical axis position in the y-axis direction of the sub-laser light in each detector. Therefore, also as the value of y calculated by y1−y2, the optical axis position shift in the y-axis direction between the main laser light and the sub laser light is the same as the value of y calculated in the first embodiment. A value representing the quantity.
Thus, the x and y values calculated in the second embodiment can be treated as equivalent to the x and y values calculated in the first embodiment.

If the values of x and y equivalent to those in the first embodiment are obtained as described above, the optical axes of the two laser beams using the same adjustment value table as in the first embodiment. The optical axes can be adjusted so as to match.
In this case, for example, an adjustment value table similar to that described with reference to FIG. 5 is stored in the built-in ROM. The control unit 40 calculates the x and y values for each detector as described above, and in the adjustment value table, the control unit 40 associates with the combination of the x and y values for each detector. The actuator x-axis and y-axis adjustment values and the second actuator x-axis and y-axis adjustment values are acquired, and these adjustment values are instructed to the optical axis adjustment unit 27 to adjust the angles of the mirrors 27a and 27b. Is executed.
As a result, adjustment can be performed so that the optical axes of the main laser beam and the sub laser beam coincide.

  In this case, the control unit 40 repeatedly performs the operations from the calculation of x1, x2, y1, and y2 described above to the adjustment value instruction to the optical axis adjustment unit 27 until, for example, the recording / reproducing operation is stopped. Has been. Thereby, optical axis correction can be performed in real time during recording / reproduction.

  As can be understood from the above description, according to the hologram apparatus of the second embodiment, the main laser beam and the sub-laser beam are used for optical axis correction as in the first embodiment. There is no need to shut off. Therefore, from the viewpoint of optical axis correction alone, the first shutter 4 and the second shutter 29 shown in FIG. 8 can be omitted. If the first shutter 4 and the second shutter 29 can be omitted, the apparatus configuration can be simplified and miniaturized and the apparatus manufacturing cost can be reduced accordingly.

[Processing behavior]
FIGS. 10 and 11 are flowcharts showing processing operations to be executed to realize the optical axis correction operation as the second embodiment described above. The processing operations shown in FIGS. 10 and 11 are executed by the control unit 40 based on a program stored in a built-in ROM or the like, for example.

First, FIG. 10 shows processing operations to be executed for determining the reference position of each detector described above.
In FIG. 10, in step S201, (a + c)-(b + d) = x1 and (a + b)-(c + d) = y1 are calculated for each detector. That is, only the detection signals a, b, c, and d from the first detector 41 and the second detector 42 are input, and the above x1 and y1 are calculated.
In subsequent step S202, the position of each detector is adjusted so that x1 = y1 = 0 for both detectors.

  It should be noted that the reference position of each detector may be determined at least once, for example, at the timing when the hologram apparatus is used for the first time. Therefore, the processing operation shown in FIG. 10 may be performed at least once, for example, at the timing when the hologram apparatus is used for the first time.

FIG. 11 shows processing operations to be performed for actual optical axis correction, which are performed after the reference positions of the respective detectors are determined.
In FIG. 11, in step S301, the start of adjustment is waited. For example, it waits for establishment of a predetermined condition for starting the optical axis adjustment operation such as the start of the recording / reproducing operation described above.

  If the condition for starting the adjustment is satisfied, in step S302, for each detector, (a + c) − (b + d) = x1, (a + b) − (c + d) = y1, (e + g) − (f + h) = Calculate x2, (e + f)-(g + h) = y2. That is, the detection signals a, b, c, d, e, f, g, and h from the detectors 41 and 42 are input, and the above x1, y1, x2, and y2 are calculated for each detector.

  In the subsequent step S303, x1-x2 = x and y1-y2 = y are calculated for each detector. Further, in the next step S304, an adjustment value is acquired from the adjustment value table based on the x and y values of each detector. That is, as described above, for example, from the adjustment value table stored in the built-in ROM, the first actuator associated with the combination of the x and y values for each detector calculated in step S303. The x-axis and y-axis adjustment values and the x-axis and y-axis adjustment values of the second actuator are acquired.

  In the subsequent step S305, the optical axis adjustment unit 27 is controlled based on the adjustment value. That is, the angle adjustment of the mirror 27a and the mirror 27b is executed by instructing the optical axis adjustment unit 27 of each adjustment value acquired in step S304. Thereby, adjustment is performed so that the optical axes of the main laser beam and the sub laser beam coincide with each other.

In the next step S306, the process waits for the generation of a stop trigger. That is, it waits for establishment of a predetermined condition for stopping the adjustment operation, for example, stop of the recording / reproducing operation. If a negative result is obtained that the condition for stopping the adjustment operation is not satisfied, the process returns to the previous step S302 as shown in the figure, and the adjustment operation is repeated until the stop condition is satisfied. It will be. That is, as a result, real-time adjustment control such as servo control is realized.
Further, when a positive result is obtained because the stop condition is satisfied, RETURN is set as shown.

Here, the case where the optical axis adjustment operation is always executed during recording / reproduction has been described, but instead of this, for example, it is executed once every predetermined time, or for each detector. It is also possible to monitor the relative positional deviation amount and execute it only when the positional deviation amount exceeds a predetermined value. In other words, the optical axis correction operation as the second embodiment should not be limited to being always performed during recording / reproduction, and may be performed at least at an appropriate timing.
In any case, in the second embodiment, since it is possible to detect the optical axis position shift amount of each laser beam without blocking the laser beam, the optical axis adjustment operation is performed so as not to disturb the recording / reproduction. There is no change in what can be done. In other words, the optical axis adjustment operation can be performed even during recording / reproduction.

Further, in FIG. 8, the case where each laser beam is configured to be guided to the first detector 41 and the second detector 42 using the half mirror 31 as in the case of FIG. Instead of this, a configuration in which the half mirror 31 is omitted as in the modification shown in FIG. Specifically, for example, the first detector 41 is a reflective first detector 41ref, and incident light from the condenser lens 30 is guided to the second detector 42 via the first detector 41ref → mirror 37. It is.
Even in such a configuration, the processing operation to be executed by the control unit 40 may be the same as that shown in FIGS. That is, this can provide the same effect as the configuration shown in FIG.

<Modification of Second Embodiment>
Then, each modification (Modification 1-Modification 3) of 2nd Embodiment is demonstrated.
As in the configuration shown in FIG. 8, the modified example of the second embodiment is configured so that the optical axis positions of the main laser beam and the sub laser beam can be detected simultaneously as shown in FIG. Rather than combining a photodetector that is sensitive to the main laser beam and a photodetector that is sensitive to the sub-laser beam in one detector, the main detector that combines only the photodetector that is sensitive to the main laser beam, and the sub-laser beam A sub detector in which only a photo detector having sensitivity is combined is provided separately.

FIG. 12 shows a configuration of a hologram device as a first modification of the second embodiment.
In this figure, parts that are the same as those already described so far are assigned the same reference numerals, and descriptions thereof are omitted.
As shown in the figure, in the hologram apparatus in this case, a sub detector 52, a sub detector 54, a main detector 55, and a main detector 57 are provided separately. In this case, the sub detectors 52 and 54 are, for example, quadrant detectors having sensitivity only to the sub laser light. The main detectors 55 and 57 are, for example, quadrant detectors having sensitivity only to the main laser beam.
In other words, in terms of correspondence, the four photodetectors in the sub detector 52 and the four photodetectors in the sub detector 54 are respectively the photodetectors E, F, G, and H in the first detector 41 in FIG. This corresponds to the photodetectors E, F, G, and H in the second detector 42. Similarly, the four photodetectors in the main detector 55 and the four photodetectors in the main detector 57 are the photodetectors A, B, C, and D in the first detector 41, and the photodetectors A and B in the second detector 42, respectively. It corresponds to B, C, D.
From this, the detection signals obtained from the detectors in the sub detectors 52 and 54 correspond to the detection signals e, f, g, and h, respectively. The detection signals from the detectors in the main detectors 55 and 57 correspond to the detection signals a, b, c and d, respectively.

12, in the hologram apparatus in this case, a dichroic prism 51 is provided in place of the half mirror 31 shown in FIG. The dichroic prism 51 is configured to reflect the sub laser light and transmit the main laser light.
The sub laser beam reflected by the dichroic prism 51 is reflected by the sub detector 52 which is a reflection type, and is then reflected again by the mirror 53 provided on the side facing the sub detector 52 to be sub. The detector 54 is irradiated.
The main laser beam that has passed through the dichroic prism 51 is reflected by the main detector 55, which is also a reflection type, and then reflected again by the mirror 56 provided on the side facing the main detector 55. The main detector 57 is irradiated.

According to the description of the second embodiment, in the configuration shown in FIG. 8, the photodetector having sensitivity to the main laser beam and the photodetector having sensitivity to the sub-laser beam are integrated as one split detector. Therefore, the photodetector having sensitivity to the main laser beam and the photodetector having sensitivity to the sub laser beam have the same optical path length.
Therefore, in order to cope with this, also in the hologram apparatus shown in FIG. 12, the optical path length to the sub detector 52 and the optical path length to the main detector 55 are made equal, and the optical path to the sub detector 54 is set. The length and the optical path length to the main detector 57 are made equal.

  As described above, the synthesized light is separated into main laser light and sub laser light by the dichroic prism 51, the separated sub laser light is separated into the sub detectors 52 and 54, and the main laser light is transformed into the main detector 55, By guiding to 57, the optical axis position of each laser beam can be detected without blocking the main laser beam and the sub laser beam.

However, it should be noted here that the detectors (55, 57) having sensitivity to the main laser beam and the detectors (52, 54) having sensitivity to the sub laser beam are provided at different positions. The point is that the reference position of each detector cannot be automatically determined on the apparatus side as in the configuration shown in FIG.
That is, in this case, it is a premise that the reference position of each detector is manually set in advance at the time of manufacture. Specifically, for example, after adjusting the optical system so that the optical axes of the main laser beam and the sub laser beam coincide with each other, the optical axis position of the laser beam in each detector (52, 54, 55, 57) in that state. It is assumed that the positions of the detectors are adjusted so that each coincides with the center position.

  Since it is assumed that the reference position of each detector is previously determined at the time of manufacture or the like as described above, the hologram apparatus in this case is provided with a drive unit for each detector as shown in FIG. It has never been.

From this point, the control unit 50 in this case does not execute the processing operation for determining the reference position as shown in FIG. 10, but performs the actual adjustment operation as shown in FIG. Only the processing operation is performed.
Here, as understood from the above description, in this case, the detection signal of each detector in the sub detector 52 is, for example, the detection signal e from the photodetectors E, F, G, and H in the first detector 41. , F, g, h. Similarly, the detection signals of the detectors in the sub detector 52 can be handled as detection signals e, f, g, and h from the photodetectors E, F, G, and H in the second detector 42. The detection signals of the detectors in the main detector 55 can be handled as detection signals a, b, c, d from the photo detectors A, B, C, D in the first detector 41, for example. The detection signal of each detector in 57 can be handled as detection signals a, b, c, d from the photodetectors A, B, C, D in the second detector 42.
Therefore, also in this case, the control unit 50 determines the detection signals e, f, g, h from the sub detectors 52, 54 and the detection signals a, b, c, d from the main laser detectors 55, 57. By executing the same processing operation as that shown in FIG. 11, the same effect as that of the configuration shown in FIG. 8 can be obtained.

Next, the configurations of Modification 2 and Modification 3 of the second embodiment will be described with reference to FIG. In FIG. 13, only the configuration of the optical system from the dichroic prism 14 to each detector (52, 54, 55, 57) is extracted from the configuration of the hologram apparatus as the second and third modifications. ing. In this figure, the parts denoted by the same reference numerals and the other parts not shown in this figure are the same as those in FIG.
FIG. 13A shows the configuration of the second modification, and FIG. 13B shows the configuration of the third modification.

In these modified examples 2 and 3, the main laser beam and the sub-laser beam are separated and output using an element different from the dichroic prism 51 used in the modified example 1 above.
Specifically, in Modification 2 of FIG. 13A, the main laser beam and the sub laser beam are separated and output by using the dispersion prism 60 instead of the dichroic prism 51. In Modification 3 of FIG. 13B, the main laser light and the sub laser light are separated and output by a HOE (Hologram Optical Element).

In addition, for the sake of confirmation, in the second and third modifications, the reference positions of the detectors (52, 54, 55, 57) are manually set in advance at the time of manufacture. Is the premise. Also in this case, the control unit 50 executes the same processing operation as that shown in FIG. 11 based on the detection signals input from the detectors, so that the configuration shown in FIG. An effect can be obtained.

<Common modification>

FIG. 14 is a diagram for explaining a modification common to the embodiments, and shows a configuration example when the modification is applied to the hologram apparatus shown in FIG. In this figure as well, parts already described so far are denoted by the same reference numerals and description thereof is omitted.
As shown in FIG. 14, as a common modification, the means for adjusting the optical axis is configured differently from the conventional one.
Specifically, the optical axis adjustment is performed by directly adjusting the position and angle of the sub-laser 22 instead of the optical axis adjustment unit 27 inserted into the optical path of the sub-laser light to adjust the optical axis. The optical axis adjustment part 70 which performs is provided.

  As shown in the figure, the optical axis adjusting unit 70 has the one surface thereof fixed to the back surface of the sub laser 22 (the surface opposite to the laser emission surface), and the surface opposite to this is fixed to the apparatus main body side. Thus, the sub laser 22 is supported from the main body side.

FIG. 15A shows an example of the structure of the optical axis adjustment unit 70 shown in FIG. In this figure, the sub-laser 22 is also shown.
As shown in the figure, the optical axis adjusting unit 70 in this case is formed by laminating a driving element 70a, a driving element 70b, a driving element 70c, and a driving element 70d in order from the sub laser 22 side. First, the drive element 70c and the drive element 70d are deformed in one predetermined direction in the same manner as the first drive elements 34a and 35a and the second drive elements 34b and 35b in the drive units 34 and 35 shown in FIG. Possible piezo elements, for example. Also in this case, these elements are combined so as to be deformed in orthogonal directions in the in-plane direction of the sub laser light. In this figure, the drive elements 70c are combined so as to be deformed in the x-axis direction and the drive elements 70d are deformed in the y-axis direction. The drive element 70c and the drive element 70d can adjust the optical axis position of the sub laser light.
The drive element 70a and the drive element 70b are provided for adjusting the optical axis angle of the sub laser light. As shown in the drawing, the drive element 70a is configured to have a movable portion that can be rotated in a direction in which the optical axis angle of the sub laser beam can be changed in the x-axis direction as the θ1 direction in the drawing. Further, the drive element 70b includes a movable portion that can be rotated in a direction in which the optical axis angle of the sub laser light can be changed in the y-axis direction as the θ2 direction in the drawing. By such a combination of the drive element 70a and the drive element 70b, the optical axis of the sub laser light can be adjusted in the x-axis direction and the y-axis direction.

As shown in FIG. 14, an adjustment value supply line from the control unit 71 is connected to the optical axis adjustment unit 70. In this case, the control unit 71 supplies an adjustment value for each drive element (70a, 70b, 70c, 70d) in the optical axis adjustment unit 70 to the optical axis adjustment unit 70. Although not shown in FIG. 15, a drive circuit for driving each drive element according to the adjustment value is provided in the optical axis adjustment unit 70, and the drive circuit performs each drive according to each adjustment value. The element is driven and controlled.
With such a configuration, the control unit 71 controls the optical axis position in the x-axis direction, the optical axis position in the y-axis direction, the optical axis angle in the x-axis direction, and the y-axis direction for the sub laser light. The optical axis angle can be controlled.

In this case, the adjustment value is different from the adjustment value for the optical axis adjustment unit 27 described above. Therefore, in the case of the modification, the adjustment value table includes each drive element (70a, 70b, 70) for setting the x and y values to 0 for the combination of the x and y values calculated for each detector. 70c, 70d) may be associated with a combination of adjustment values.
The control unit 71 uses the adjustment value table to perform the same adjustment control as in the first embodiment, and in this case also, adjustment is performed so that the optical axes of the respective laser beams coincide with each other. be able to. Even when the modification is applied to the second embodiment, adjustment can be performed so that the optical axes of the respective laser beams coincide with each other by using a similar adjustment value table.

FIG. 15B shows another structural example of the optical axis adjustment unit 70.
The structural example of the optical axis adjusting unit 70 shown in FIG. 15B is a structural example corresponding to a case where a surface orthogonal to the laser emission surface is fixed instead of the back surface of the laser emission surface of the sub laser 22.
In the optical axis adjusting unit 70 shown in FIG. 15B, a driving element 70e, a driving element 70f, a driving element 70g, and a driving element 70h are sequentially stacked from the sub laser 22 side. As shown in the drawing, a surface orthogonal to the laser emission surface of the sub laser 22 is fixed to the drive element 70e on the surface opposite to the surface fixed to the drive element 70f.
In the optical axis adjusting unit 70 in this case, the driving elements 70g and 70h are, for example, piezoelectric elements that can be deformed in one predetermined direction like the driving elements 70c and 70d described above. These elements are combined so as to be deformed in directions perpendicular to each other in the in-plane direction of the sub laser light. As shown in the figure, for example, the drive elements 70g are combined so as to be deformed in the x-axis direction and the drive elements 70h are deformed in the y-axis direction.
The drive element 70f has a movable part similar to the drive elements 70a and 70b described above, and the movable part can change the optical axis of the sub laser light in the y-axis direction. It is incorporated in the optical axis adjustment unit 70 so as to rotate in the direction (θ2 direction in the figure). Furthermore, the drive element 70e is configured to be deformable in a direction in which the optical axis angle of the sub laser light is changed in the x-axis direction as the θ1 direction in the drawing.
Also by such a structure of the optical axis adjustment unit 70, the optical axis position of the sub laser light in the x-axis direction and the y-axis direction and the optical axis angle in the x-axis direction and the y-axis direction can be adjusted.

[Other variations]
As mentioned above, although each embodiment of this invention was described, as this invention, it should not be limited to the example demonstrated so far.
For example, the calculation formulas for x and y illustrated in the first embodiment are merely examples, and other formulas can be used as long as the formula can calculate the deviation amounts in the x-axis direction and the y-axis direction shown in FIG. It can also be adopted.
Similarly, the calculation formulas of x1 and x2 and the calculation formulas of y1 and y2 exemplified in the second embodiment are merely examples, and the deviation amounts in the x-axis direction and the y-axis direction shown in FIG. 9 are calculated. Other formulas can be used if possible.

  In addition, in detecting the optical axis position of each laser beam at each position where the optical path length difference is given, a four-divided photodetector is used. As a detector for detecting such an optical axis position, A detector with four or more divisions can also be used.

In the above description, the case where the dichroic prism 14 is used as the means for synthesizing the laser beams and branching out the combined light has been exemplified. However, there are other means for branching out the combined light as described above. It can also be realized with the configuration.
For example, instead of the dichroic prism 14, a dichroic prism that transmits the main laser beam and reflects the sub laser beam (that is, the same as the dichroic prism 51 shown in FIG. 12) is provided. The 45 ° mirror 16 is a half mirror after being guided only in one direction. That is, this half mirror is configured to branch and output the combined light.
In this case, the dichroic prism (51) and the 45 ° mirror as the half mirror form the combined branch output means referred to in the present invention.

  In the above description, the case where the present invention is applied to a recording / reproducing apparatus capable of both recording and reproduction has been exemplified. However, as the present invention, only a recording-only apparatus capable of recording or only reproduction is possible. The present invention can also be suitably applied to other reproduction-only devices.

  In the above description, the case where the present invention is applied to a hologram apparatus has been exemplified. However, the present invention can be preferably applied to a case where a composite light of two lights is irradiated onto an object. In this case, adjustment can be performed so that the optical axes of the two lights coincide with each other.

  Further, the present invention can be suitably applied not only when adjusting the optical axes of only two lights, but also when adjusting the optical axes of three or more lights. That is, in that case, for example, after adjusting the optical axis according to the present invention for two of the three or more lights and matching them, one of the remaining lights and the already adjusted light Any one of them may be made to coincide with the method of the present invention. Thereby, it is possible to finally adjust so that the optical axes of all the lights coincide.

It is a block diagram which shows the internal structure of the hologram apparatus as the 1st Embodiment of this invention. It is the figure which showed typically the structure of the detector used in 1st Embodiment. It is the figure which showed the structural example of the drive part for moving a detector. It is the figure which showed typically the internal structure of the optical axis adjustment part. It is the figure which showed the data structure of the adjustment value table used by the optical axis correction operation | movement of embodiment. It is the flowchart which showed the processing operation which should be performed in order to implement | achieve the optical axis correction operation | movement as 1st Embodiment. It is a block diagram which shows the internal structure of the hologram apparatus as a modification of 1st Embodiment. It is a block diagram which shows the internal structure of the hologram apparatus as 2nd Embodiment. It is the figure which showed typically the structure of the detector used in 2nd Embodiment. It is the flowchart which showed the processing operation for performing the reference position of each detector as processing operation which should be performed in order to implement | achieve the optical axis correction operation | movement as 2nd Embodiment. It is the flowchart which showed the processing operation which should be performed corresponding to the time of actual adjustment operation | movement as a processing operation which should be performed in order to implement | achieve the optical axis correction operation | movement as 2nd Embodiment. It is a block diagram which shows the internal structure of the hologram apparatus as the modification 1 of 2nd Embodiment. It is a figure for demonstrating the modification 2 and the modification 3 of 2nd Embodiment. It is a figure for demonstrating the common modification of embodiment. It is the figure which showed the structural example of the optical axis adjustment part as a modification. It is a cross-sectional structure diagram of a hologram recording medium.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Main laser, 4 1st shutter, 14,51 Dichroic prism, 16 45 degree mirror, 17 Objective lens, 22 Sub laser, 27,70 Optical axis adjustment part, 27a, 27b Mirror, 29 2nd shutter, 30 Condensing lens, 31 Half mirror, 32, 41 1st detector, 32ref (reflection type) 1st detector, 33, 42 2nd detector, 34, 35 drive part, 34a, 35a 1st drive element, 34b, 35b 2nd drive element, 36 , 40, 50, 71 Control unit, 37, 53, 56 Mirror, 52, 54 Sub detector, 55, 57 Main detector, 60 Dispersing prism, 61 HOE (hologram element), 70a-70h Drive element, HM hologram recording Medium

Claims (18)

A first light source that outputs first light;
A second light source that outputs a second light;
A combined branch output means for inputting the first light and the second light and branching out the combined light of the first light and the second light;
Adjusting means for adjusting a relative positional relationship and an optical axis angle difference between the optical axes of the first light and the second light input to the combined branch output means;
While inputting one of the combined lights branched and output by the combined branch output means, the optical axis positions of the first light and the second light in the input combined light, Optical axis position detection means for detecting at a plurality of positions given optical path length differences;
Based on the detection result by the optical axis position detection means, a positional deviation amount between the optical axis position of the first light and the optical axis position of the second light is obtained for each of the plurality of positions, and for each of the plurality of positions. Control means for controlling the adjusting means on the basis of the optical axis position shift amount of the first light and the second light,
An optical axis adjusting device comprising: The first light source and the second light source are configured to output light having different wavelengths as the first light and the second light, respectively.
2. The optical axis adjusting apparatus according to claim 1, wherein the combined branch output means is constituted by a dichroic prism. A first transmission / blocking unit that is inserted into an optical path from the first light source to the combined branch output unit and transmits / blocks the first light; and the combined branch from the second light source. Second transmission / blocking means inserted into the optical path to the output means and transmitting / blocking the second light,
The optical axis position detecting means is
The split light output from the combined branch output means is provided with two split detectors composed of photodetectors that are split into four or more equal parts that are sensitive to both the first light and the second light. The combined light is guided to each of the divided detectors so as to give the optical path length difference,
The control means includes
The first transmission / cutoff means and the second transmission / cutoff means are arranged so that either one of the first light and the second light is sequentially irradiated to both of the divided detectors. Controlling and obtaining the optical axis position deviation amount for each of the plurality of positions based on the detection result of the optical axis position for the first light and the second light obtained by each of the divided detectors. Controlling the adjusting means based on the amount of optical axis displacement for each position;
The optical axis adjusting device according to claim 1. With detector drive means for moving the position of each of the divided detectors in the optical axis position detection means,
The control means includes
By controlling the first transmission / blocking means and the second transmission / blocking means to irradiate both the divided detectors with the first light, the optical axis of the first light is divided by each divided detector. And detecting the position based on the result of the detection, controlling the detector driving means so that the optical axis position of the first light in both split detectors coincides with the center position of each split detector, and The light of the second light detected by each of the divided detectors when both the divided detectors are irradiated with the second light by controlling one transmitting / blocking means and the second transmitting / blocking means. An axial position is acquired as an optical axis positional deviation amount for each of the plurality of positions.
The optical axis adjusting device according to claim 3. The optical axis position detecting means is
A half mirror that branches the combined light input from the combined branch output unit in two directions and outputs the first combined light and the second combined light is provided, and one of the split detectors is branched by the half mirror The first synthesized light is incident and the other is provided so as to be incident on the second synthesized light branched by the half mirror.
The optical axis adjusting device according to claim 3. The optical axis position detecting means is
One of the two split detectors is a reflective split detector configured to reflect a part of incident light, and the split split detector is irradiated with the composite light from the composite branch output means. And the reflected light from the reflective split detector is guided to the other split detector.
The optical axis adjusting device according to claim 3. The first light source and the second light source are configured to output light having different wavelengths as the first light and the second light, respectively.
The optical axis position detecting means is
Two wavelength-divided detectors comprising a combination of a photodetector that is sensitive to the first light divided into four or more equal parts and a photodetector that is sensitive to the second light and divided into four or more equal parts And is configured to guide one of the combined lights branched and output from the combined branch output means to each of the wavelength division detectors so as to give the optical path length difference,
The control means includes
From the detection results of the optical axis positions for the first light and the second light respectively obtained by the two wavelength-specific division detectors in the optical axis position detection means, the optical axis position deviation amount for each of the plurality of positions. By calculating, and controlling the adjustment means based on the calculated optical axis position deviation amount for each of the plurality of positions,
The optical axis adjusting device according to claim 1. A detector driving means for moving the position of each of the wavelength division detectors in the optical axis position detecting means;
The control means includes
Based on the detection result of the optical axis position of the first light detected by each of the wavelength-specific division detectors, the optical axis position of the first light in both wavelength-specific division detectors matches the detector center position. To control the detector driving means,
The optical axis adjusting apparatus according to claim 7. The optical axis position detecting means is
A half mirror that branches the combined light input from the combining branch output means in two directions and outputs the first combined light and the second combined light is provided. One of the wavelength-division detectors is branched by the half mirror. The first synthesized light is incident on the other side, and the other is provided so as to be incident on the second synthesized light branched by the half mirror.
The optical axis adjusting apparatus according to claim 7. The optical axis position detecting means is
One of the two wavelength-specific division detectors is a reflection-type division detector configured to reflect a part of incident light, and the reflection-type division detector emits the synthetic light from the synthetic branch output means. The reflected light from the reflective split detector is guided to the other wavelength-specific split detector.
The optical axis adjusting apparatus according to claim 7. The first light source and the second light source are configured to output light having different wavelengths as the first light and the second light, respectively.
The optical axis position detecting means is
The four combined detectors composed of photodetectors that are divided into four or more equal parts that are sensitive to both the first light and the second light, and the one of the composites that is branched and output from the composite branch output means A separation element that separates and outputs the light into the first light and the second light, and outputs the first light separated by the separation element from two of the four divided detectors. The other two light beams are configured so as to be guided so as to give the optical path length difference to each other, and the second light beams separated by the separation element are also given the same optical path length difference. Is configured to guide the split detector,
The control means includes
The detection result of the optical axis position for the first light respectively obtained by the two split detectors to which the first light is guided, and the two obtained by the two split detectors to which the second light is guided, respectively. From the detection result of the optical axis position for the second light, the optical axis position deviation amount for each of the plurality of positions is obtained by calculation, and the adjustment means is controlled based on the calculated optical axis position deviation amount for each of the plurality of positions. To
The optical axis adjusting device according to claim 1.   12. The optical axis adjusting device according to claim 11, wherein the separation element in the optical axis position detecting means is constituted by a dichroic prism.   12. The optical axis adjusting device according to claim 11, wherein the separation element in the optical axis position detecting means is constituted by a dispersion prism.   12. The optical axis adjusting device according to claim 11, wherein the separating element in the optical axis position detecting means is constituted by a hologram element. The adjusting means is
Comprising two mirrors inserted in the optical path between the first light source and / or the second light source and the combined branch output means, and an actuator for driving the mirror,
The optical axis adjusting device according to claim 1. The adjusting means is
The actuator is configured to move the first light source and / or the second light source.
The optical axis adjusting device according to claim 1. A combined branch that inputs the first light output from the first light source and the second light output from the second light source, and branches and outputs the combined light of the first light and the second light. An optical axis adjustment method in an optical axis adjustment apparatus having at least an output means,
While inputting one of the combined lights branched and output by the combined branch output means, the optical axis positions of the first light and the second light in the input combined light, An optical axis position detection procedure for detecting at a plurality of positions given optical path length differences;
Based on the detection result of the optical axis position detection procedure, the amount of positional deviation between the optical axis position of the first light and the optical axis position of the second light is obtained for each of the plurality of positions, and for each of the plurality of positions. Relative to the optical axes of the first light and the second light input to the combined branch output means based on the optical axis positional deviation amounts of the first light and the second light. Adjustment procedure to adjust the positional relationship and optical axis angle difference,
An optical axis adjustment method comprising: Recording or recording on a hologram recording medium provided with a data recording layer in which data is recorded by interference fringes of reference light and signal light, and a position control information recording layer in which guide grooves for recording or reproducing position control are formed A hologram device for performing reproduction,
A first light source that outputs a first light for generating the reference light and / or the signal light;
A second light source that outputs a second light for performing the recording or reproduction position control;
A first direction which is a direction in which the first light and the second light are input, and a combined light of the first light and the second light is guided to the hologram recording medium side; Combined branch output means for branching and outputting in a second direction different from the direction of 1;
Adjusting means for adjusting a relative positional relationship and an optical axis angle difference between the optical axes of the first light and the second light input to the combined branch output means;
The combined light output in the second direction by the combined branch output means is input, and the optical axis positions of the first light and the second light in the input combined light are optical paths. Optical axis position detecting means for detecting at a plurality of positions given a length difference;
Based on the detection result by the optical axis position detection means, a positional deviation amount between the optical axis position of the first light and the optical axis position of the second light is obtained for each of the plurality of positions, and for each of the plurality of positions. Control means for controlling the adjusting means on the basis of the optical axis position shift amount of the first light and the second light,
A hologram apparatus comprising:

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