JP2001209965A - Optical recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly position a pinhole on an optical axis. SOLUTION: An information area 15 on which a cross pattern having positional information on an X axis and a Y axis for positioning the pinhole 11 is marked by etching, printing or the like is provided in a pinhole plate 10, and a reflection type photodetector 16 which emits light and detects return light is provided in the information area 15. The detection of positional information on the X axis and the Y axis from the information area 15 or the like is controlled by a control circuit 17 by driving a semiconductor laser 3, detecting data from a PD 12 and driving/detecting the reflection type photodetector 16. The pinhole plate 10 is movable to the X axis and the Y axis orthogonal to it by an X actuator 13 and a Y axis actuator 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing apparatus, and more particularly to an optical recording / reproducing apparatus having a pinhole portion for controlling light from a plurality of recording layers of a three-dimensional optical recording medium.

[0002]

2. Description of the Related Art In recent years, one of the promising next-generation ultra-high-density optical recording media for recording media such as optical disks is a three-dimensional optical recording medium.

While the conventional optical recording medium records information two-dimensionally on a recording layer, the above-described three-dimensional optical recording medium has a recording film having a film thickness larger than the focal depth of a laser used. In addition to two-dimensional (planar) recording on layers,
Information is also recorded in the depth direction of the layer. For example, if 100 layers are recorded in the depth direction, the current 100
Double recording density can be achieved.

Research reports on such a three-dimensional optical recording medium are not intended for recording / reproducing when the recording medium is in a disk state. Proceedings of the Joint Lectures on Applied Physics 29p-B-11, 29p-B-12.

In an optical pickup device for recording and reproducing information on and from this type of three-dimensional optical recording medium, when reproducing a mark on a desired recording layer among a plurality of recording layers provided in the vertical direction, it is an object. A confocal optical system is configured to reduce crosstalk between marks due to reflected light from a mark recorded three-dimensionally around a mark other than the mark, and a pinhole arranged near the confocal point on the reproduction PD is used. The resolution at the time of reproduction is increased by removing the return light from the mark other than the target mark.

However, in an optical system using such a pinhole, the accuracy of the incident angle from the three-dimensional optical recording medium to the pinhole is strict, and even if it deviates from the standard value by several seconds, the incident light is blocked by the pinhole. However, there is a problem that a sufficiently large reproduced signal amplitude and resolution cannot be obtained.

In order to solve this problem, it is necessary to adjust the center position of the pinhole to the center position of the incident light beam. Changes, the position of the pinhole also moves, causing a problem that the reproduced signal is reduced and the resolution of the reproduced signal is reduced.

For example, in Japanese Patent Application Laid-Open No. Hei 7-141689, a pinhole is formed by two intersecting slits, and a slit plate in which the two slits are formed can be moved independently by an actuator. The position can be adjusted based on information of light transmitted through the pinhole.

[0009]

However, in Japanese Patent Application Laid-Open No. Hei 7-141689, in order to make the spot position of the reproduction light coincide with the pinhole position, at least one slit is moved to sufficiently transmit the transmitted light. If the slit position is largely deviated from the spot position in the initial state, an adjustment operation for moving the slit position to a light transmitting position is required at least. That is, since the alignment cannot be performed unless light is transmitted to the light receiving element by moving the slit plate, initial adjustment is required.

For this reason, when such a component device is arranged in a product such as a drive and the pinhole position is constantly controlled with respect to environmental changes and disturbances, the slit position must be adjusted in advance or There is a problem in that a light-receiving element having a wide-range light-receiving surface is prepared, and a complicated detection device that detects a change in the size of the side lobe with respect to the slit position is required.

Further, the slit plate having the slit formed therein is
To maintain rigidity for movement, it must be a metal or ceramic member with a thickness of at least several hundred microns or more, and pinholes of several microns required to increase the reproduction resolution with high density recording are formed with high precision. There is a problem that you can not.

Furthermore, the above-mentioned prior art does not describe any feasible control method or the like for controlling the position of the pinhole on the optical axis with desired accuracy. There is also a problem that it is difficult to perform positioning control.

The present invention has been made in view of the above circumstances, and has as its object to provide an optical recording / reproducing apparatus capable of accurately positioning a pinhole on an optical axis.

[0014]

According to the present invention, there is provided an optical recording / reproducing apparatus for recording / reproducing or erasing information on / from an optical recording / reproducing medium having a plurality of recording layers for recording information. A recording / reproducing light source that emits a recording / reproducing beam for irradiating the recording layer, a pinhole plate having a pinhole for transmitting only desired return light from the recording layer by the recording / reproducing beam, Recording / reproduction return light detecting means for detecting the return light of the beam, an information pattern having position information of the pinhole provided on the pinhole plate, a pattern detection means for detecting the information pattern, The pinhole plate is returned so that the optical axis center position of the return light and the pinhole position match based on the detection result of the pattern detection means. Constituted by and a plate movement control means for moving two-dimensionally in a plane perpendicular to the optical axis of the light.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 8 relate to a first embodiment of the present invention. FIG. 1 is a configuration diagram showing a configuration of an optical system of an optical recording / reproducing apparatus. FIG. 2 is an information area of a pinhole plate in FIG. FIG. 3 is a block diagram showing a configuration of a main part of the control circuit of FIG. 2, FIG. 4 is a diagram showing a signal sequence when reading a pattern in the X direction of FIG. 2, and FIG. FIG. 6 is a diagram showing a signal sequence when reading the pattern in the Y direction in FIG. 2;
FIG. 7 is a diagram showing a modification of the pattern of FIG. 2, FIG. 7 is a configuration diagram showing a configuration of a first modification of the optical system of FIG. 1, and FIG. 8 is a configuration of a second modification of the optical system of FIG. FIG.

In the optical recording / reproducing apparatus 1 of the present embodiment, as shown in FIG.
The light is emitted from the semiconductor laser 3. The laser light emitted from the semiconductor laser 3 is incident on the polarization beam splitter 4 as P-polarized light, and the laser light transmitted through the polarization beam splitter 4 is converted into a parallel light by a collimator lens 5 to be 1/4.
After passing through the wave plate 6, the light is focused on an information track of a desired recording layer 9 of the three-dimensional information recording medium 8 by the objective lens 7.
The objective lens 7 is configured to be driven in a focus direction and a tracking direction with respect to the three-dimensional information recording medium 8 by a biaxial actuator (not shown).

The information-reading laser beam 2 reflected by the three-dimensional information recording medium 8 follows a path reverse to the outward path and passes through the objective lens 7 and the quarter-wave plate 6 to the polarization beam splitter 4. Make it incident. Here, the reflected light from the three-dimensional information recording medium 8 entering the polarization beam splitter 4 passes through the quarter-wave plate 6 on the outward path and the return path, so that S
It becomes polarized light and is reflected by the polarization beam splitter 4. The laser beam reflected by the polarization beam splitter 4 is received by a photodiode (hereinafter, referred to as PD) 12 via a pinhole 11 provided in a pinhole plate 10 and three-dimensional information recording is performed based on the output. The information recorded on the desired recording layer 9 of the medium 8 is reproduced.

Here, the pinhole plate 10 can be moved by the X-axis actuator 13 and the Y-axis actuator 14 to the x-axis and the Y-axis orthogonal thereto.

In the pinhole plate 10, an information area in which an intersection pattern having X-axis and Y-axis position information as shown in FIG. 2 for positioning the pinhole 11 is engraved by etching or printing. And a reflection type photodetector 16 for irradiating the information area 15 with light and detecting return light.
Is adjusted and arranged at a position mechanically determined in advance with respect to the optical axis of the laser beam incident on the PD 12. That is, although not shown, the base holding the reflection-type photodetector 16 and the base holding the polarization beam splitter 4 are set at mechanically known dimensional intervals.

Driving and detection of the reflection type photodetector 16 are performed by a control circuit 17, which drives the semiconductor laser 3, detects data from the PD 12, and drives the reflection type photodetector 16. Control such as detection of the X-axis and Y-axis position information from the information area 15 by the detection is performed.

More specifically, in the control circuit 17, as shown in FIG.
The IV conversion circuit 23 converts the photoelectric conversion signal, which is the X-axis and Y-axis position information from the information area 15 from the PD 24 in the reflection-type photodetector 16, into a voltage signal. Then, the voltage signal from the IV conversion circuit 23 is
The binarization is performed by the binarization circuit 25, and position information is detected and encoded by the position detection encoding circuit 26 from the binarized signal. The position detection encoding circuit 26 outputs the encoded position information to the spot position control circuit 27 so that the spot position control circuit 2
7 controls an actuator control circuit 28. The actuator control circuit 28 controls the pinhole actuator 2 including the X-axis actuator 13 and the Y-axis actuator 14.
9 is driven and controlled.

A condensing lens (not shown) is provided on the emission side of the LED 22 of the reflection type photodetector 16.
Light emitted from the ED 22 is focused on the information area 15 to form a light spot.

The control circuit 17 adjusts the optical axis of the laser beam incident on the PD 12 based on the turning on of the power supply or receives the pinhole reset signal, and adjusts the optical axis of the laser beam. LED2 of photodetector 16
2 irradiates the information area 15 with light, and at the same time, for example, drives the X-axis actuator 13 to move the pinhole plate 10
Bobbling about 1 mm in the axial direction, the reflection type photodetector 1
6, the detection of the X-axis position information of the information area 15 is detected as a signal sequence as shown in FIG. 4 to detect the current X-axis position, and then the Y-axis actuator 14 is driven to move the pinhole plate 10 After bobbing about 1 mm in the Y-axis direction, the detection of the Y-axis position information of the information area 15 is detected by the PD 24 of the reflection-type photodetector 16 as a signal train as shown in FIG. 5 to detect the current Y-axis position. .

Then, the IV conversion circuit 23 converts the photoelectric conversion signal, which is the X-axis and Y-axis position information from the information area 15 from the PD 24 in the reflection type photodetector 16, into a voltage signal. Circuit 25 converts the voltage signal from
Then, the position detection encoding circuit 26 locks the binary signal of the X-axis position information composed of data bits sandwiched between clock bits as shown in FIG. (PLL), by performing encoding processing at regular intervals, information on where the position of the reflection type photodetector 16 is located with respect to the pinhole 11 is obtained. Note that the Y-axis position information is obtained in a similar manner.

Then, the position detection encoding circuit 26 outputs the encoded position information to the spot position control circuit 27, so that the spot position control circuit 27 controls the actuator control circuit 28, and the actuator control circuit 28 By driving and controlling a pinhole actuator 29 composed of the actuator 13 and the Y-axis actuator 14, the position of the pinhole 11 is aligned with the optical axis (reproducing spot) of the laser beam incident on the PD 12.

Here, the process of determining the position of the pinhole 11 from the X-axis and Y-axis position information of the information area 15 stamped on the pinhole plate 10 will be described in detail.

The size of the pinhole diameter and the diameter of the light spot formed on the pinhole plate differ depending on the specifications of the drive and the dimensional configuration of the optical system. A case where the position control is performed will be described as an example.

Although the base holding the reflection type photodetector 16 and the base holding the polarization beam splitter 4 are set at mechanically known dimensional intervals, the mechanical alignment accuracy is set to 0. 0.2 mm. Also, a data area necessary for detecting the X-axis and Y-axis position information of the pattern engraved in the information area 15 on the pinhole plate 10 (the minimum amount of movement for bobbling and moving the pinhole plate 10 at the time of detection) ) Is several hundred microns. Further, the accuracy of adjusting the imaging position of the light spot with respect to the position of the polarization beam splitter 4 is set to about 0.2 mm.

Assuming the above, the reflection type photodetector 1
The positioning accuracy of the imaging position of the light spot with respect to the position of the polarizing beam splitter 4 with respect to the arrangement position of the pinhole 11 with respect to the position of the pinhole 11 is about 0.5 mm.

On the premise of the above positioning accuracy, the pinhole plate 10 is moved by the pinhole actuator 29 composed of the X-axis actuator 13 and the Y-axis actuator 14, and the pinhole 11 is moved to a light spot or a position 1 mm or less near the light spot. Moving. Next, the pinhole actuator 29 is bubbling about 1 mm in the X and Y directions in order, and the change in the light amount of the photodiode 12 immediately below the pinhole 11 and the light amount fluctuation signal of the PD 24 of the reflection type photodetector 16 are compared. .

The data area required to detect the X-axis and Y-axis position information of the pattern engraved in the information area 15 is several hundred microns as described above, and the data pitch is 1 micron in this data area. The degree data pattern is imprinted in the X-axis and Y-axis directions, respectively. Also, a clock pattern having a width several times the data pitch of the data pattern is engraved on both ends of the data area. Then, the data pattern is detected based on the timing of the clock locked by the clock pattern.

The pinhole 11 is moved to a position where the light quantity of the photodiode 12 becomes maximum by the coarse adjustment of the actuator in the data area and the fine adjustment in the data pitch. The maximum light amount position of the photodiode 12 is a position where the pinhole 11 and the light spot coincide with each other, and the actuator positioning accuracy at that time is 1 micron, which is sufficient for a pinhole diameter of 10 to 10 microns. .

When the position of the light spot is likely to deviate from the position of the pinhole 11 due to disturbance (mechanical vibration, deformation due to temperature, etc.) after the initial adjustment, the above operation is repeated to correct the position and periodically. Perform position correction.

The signal at the time of actuator adjustment uses a repetition pulse of every several hundred microns reproduced from the clock pattern at the time of coarse adjustment, and a repetition pulse of 1 micron level reproduced from the data pattern within the data area at the time of fine adjustment. Use

The pinhole actuator 29 is
The moving area of the pinhole plate 10 is required to have a stroke of several mm and a positioning accuracy of 1 micron. In addition, pulse driving is desirable because a bobbling operation is performed in units of 0.1 mm or 1 mm. As a specific mechanism, an actuator having a structure in which a two-axis fine movement stage of a piezoelectric element is mounted on a two-axis coarse movement stage of a pulse motor or an electromagnetic linear drive system, or an ultrasonic drive stage as a whole is desirable.

As described above, in this embodiment, the information area 15 in which the X-axis and Y-axis position information is engraved as a pattern is provided on the pinhole plate 10, and the X-axis and Y-axis position information is detected. Then, the pinhole actuator 29 is driven to control the movement of the pinhole plate 10 in the X-axis and Y-axis directions, so that the pinhole is accurately positioned on the optical axis (reproducing spot position) of the laser beam incident on the PD 12. Can be positioned.

The pattern provided in the information area 15 is the intersection pattern shown in FIG. 2, but is not limited to this. A concentric pattern in which a plurality of marks are engraved as shown in FIG. 6 may be used. The mark pitch becomes coarser toward the outer diameter, so that the pinhole actuator 29 is controlled in a direction in which both X and Y signal distances are increased by bobbing in the X and Y directions.

As a first modification of the present embodiment, FIG.
As shown in FIG. 3, a hologram 51 is provided on the exit surface side of the polarizing beam splitter 4 that enters the PD 12, the diffracted light of the laser beam is irradiated on the information area 15, and the return light from the information area 15 is detected by the PD 52. You may comprise. First
In the embodiment, the position information of the information area 15 is detected by LE.
Although the method of detecting the change of the reflected light using the reflection type photodetector 16 composed of D and PD was used, when the light source was an LED, the shape and size of the spot condensed on the pinhole plate 10 were highly accurate. For example, it was difficult to make the size of the laser beam several tens of microns, and it was difficult to perform high-precision positioning with the reproduction spot. However, in the first modification, the reproduction spot from the semiconductor laser 3 was separated by the hologram 51 and the In order to form a light spot for detection, a small spot of several tens of microns can be formed.

In the above embodiment and the first modification, the pinhole plate 10 is formed of a reflection plate. However, as a second modification of the present embodiment, as shown in FIG. The plate 10 may be composed of a translucent plate, and the information reading laser beam 2 may be transmitted through the pinhole plate 10 and detected by the PD 12. In this case, the signal transmitted through the information area 15 is low. Since the signal from the recording layer 9 is a high frequency signal, the signal transmitted through the information area 15 is extracted by the LPF 61, and the signal from the recording layer 9 is extracted by the HPF 62. Various operational effects can be obtained. Further, a pattern of the information area 15 on the pinhole plate is formed by a film having a different reflectance depending on the wavelength, and the two wavelengths L
The position signal may be detected by wavelength separation using a D light source.

In this case, the signal transmitted through the information area 15 is detected by the PD 12 and the reflection type photodetector 16 is not used. Therefore, the polarization beam splitter 4 of the light spot with respect to the position where the reflection type photodetector 16 is disposed. Influence of the positioning accuracy of the imaging position on the center of the pinhole 11 with respect to the position can be eliminated.

FIGS. 9 to 11 relate to a second embodiment of the present invention. FIG. 9 is a structural view showing an optical system of an optical recording / reproducing apparatus, and FIG. 10 is a structural view of the semiconductor substrate of FIG. FIG. 1 and FIG. 11 are second views showing the configuration of the semiconductor substrate of FIG.

Since the second embodiment is almost the same as the first embodiment, only different points will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, the information reading laser beam 2 is emitted from the semiconductor laser 3 as shown in FIG. The laser light emitted from the semiconductor laser 3 is incident on the polarization beam splitter 4 as P-polarized light, and the laser light transmitted through the polarization beam splitter 4 is converted into parallel light by a collimator lens 5 and the quarter-wave plate 6 is formed. Then, the light is condensed on an information track of a desired recording layer 9 of the three-dimensional information recording medium 8 by the objective lens 7. The objective lens 7 is configured to be driven in a focus direction and a tracking direction with respect to the three-dimensional information recording medium 8 by a biaxial actuator (not shown).

The information-reading laser beam 2 reflected by the three-dimensional information recording medium 8 follows a path reverse to the outward path and passes through the objective lens 7 and the quarter-wave plate 6 to the polarization beam splitter 4. Make it incident. Here, the reflected light from the three-dimensional information recording medium 8 entering the polarization beam splitter 4 passes through the quarter-wave plate 6 on the outward path and the return path, so that S
It becomes polarized light and is reflected by the polarization beam splitter 4. The laser light reflected by the polarization beam splitter 4 is received by a pin photodiode 74 via a pinhole 73 formed in a pinhole plate 72 in a semiconductor substrate 71 as shown in FIG. Thus, information recorded on a desired recording layer 9 of the three-dimensional information recording medium 8 is reproduced.

The semiconductor laser 3 is fixed to a base 76 provided on a base 75. The semiconductor substrate 71 is fixed on a base 75, and the polarization beam splitter 4 is fixed to a portion having the pinhole 73 and the pin photodiode 74 on the semiconductor substrate 75 by bonding or the like.

The pin photodiode 74 forms ap ⁺ region on the surface side of an n ⁻ semiconductor substrate 71 such as silicon, and forms a p-side electrode made of Al or the like by bonding to the p ⁺ region. Made of Al or the like via an n ⁺ layer
It is configured by forming side electrodes.

As shown in FIGS. 10 and 11, the semiconductor substrate 71 comprises a box-shaped first Si substrate base 81 and a mouth-shaped second Si substrate base 82. A pin photodiode 74 is formed in the center of the inner bottom surface, and four coils 83a to 83d are arranged around the pin photodiode 74. Further, two coils 85a and 85b are arranged on the upper surfaces of the coils 83a to 83d via an insulating sheet 84. ing.

In the second Si substrate base 82, the magnet sheet 8 magnetized in the thickness direction (see FIG. 11)
Pinhole plate 7 made of a translucent member with 6 fixed
2 are supported and arranged by a support member 88 composed of two right and left members. The pinhole plate 72 has a pinhole 73 formed in the center, and a circular information area 15 is provided around the pinhole 73. The center of the magnet sheet 86 is a circular information area 1.
A hole 92 corresponding to No. 5 is formed.

In this embodiment, the information reading laser beam 2 is transmitted through the pinhole plate 72 and detected by the pin photodiode 74. In this case, since the signal transmitted through the information area 15 has a low frequency and the signal from the recording layer 9 has a high frequency, the signal transmitted through the information area 15 is extracted by the LPF, and the signal is transmitted from the recording layer 9 by the HPF. Take out the signal of

Then, based on the position information from the information area 15, the coils 83a to 83d or the coils 85a,
The pinhole plate 72 made of a translucent member to which the magnet sheet 86 is fixed by passing a current through the
Alternatively, it is moved in the Y direction to match the position of the reproduction spot with the position of the pinhole 73. Specifically, as shown in FIG. 10, the pinhole plate 72 is moved in the −Y direction by energizing the coils 85 a and 85 b in the direction i1, and the Y85 is energized in the direction −i1 by the coils 85 a and 85 b. The pinhole plate 72 is moved in the direction. Similarly, the pinhole plate 72 is moved in the -X direction by energizing the coils 83a to 83d in the direction i2, and the pinhole plate 72 is moved in the X direction by energizing the coils 83a to 83d in the direction -i2.

As described above, also in the second embodiment,
Similarly to the first embodiment, the position information of the X axis and the Y axis is detected and the coils 83a to 83d or the coils 85a to 83d are detected.
a, 85b are driven to control the movement of the pinhole plate 72 in the X-axis and Y-axis directions, so that the pinhole 73 is accurately positioned on the optical axis of the laser beam incident on the pin photodiode 74 (reproducing spot position). Can be positioned.

[0053]

As described above, according to the present invention, there is an effect that the pinhole can be accurately positioned on the optical axis.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of an optical system of an optical recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a view showing a pattern imprinted on an information area of the pinhole plate of FIG. 1;

FIG. 3 is a block diagram showing a configuration of a main part of the control circuit of FIG. 2;

FIG. 4 is a diagram showing a signal sequence when reading a pattern in the X direction in FIG. 2;

FIG. 5 is a diagram showing a signal sequence when reading a pattern in the Y direction in FIG. 2;

FIG. 6 is a diagram showing a modification of the pattern of FIG. 2;

FIG. 7 is a configuration diagram showing a configuration of a first modification of the optical system of FIG. 1;

FIG. 8 is a configuration diagram showing a configuration of a second modification of the optical system of FIG. 1;

FIG. 9 is a configuration diagram showing a configuration of an optical system of an optical recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 10 is a first view showing a configuration of the semiconductor substrate of FIG. 9;

FIG. 11 is a second diagram showing the configuration of the semiconductor substrate of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical recording / reproducing apparatus 2 ... Information reading laser beam 3 ... Semiconductor laser 4 ... Polarization beam splitter 5 ... Collimator lens 6 ... 1/4 wavelength plate 7 ... Objective lens 8 ... 3D information recording medium 9 ... Recording layer 10 ... Pinhole plate 11 Pinhole 12 Photodiode (PD) 13 X-axis actuator 14 Y-axis actuator 15 Information area 16 Reflection-type photodetector 17 Control circuit

[Procedure amendment]

[Submission date] January 27, 2000 (2000.1.2
7)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 11

Claims (6)

[Claims] 1. An optical recording / reproducing apparatus for recording / reproducing or erasing information on / from an optical recording / reproducing medium having a plurality of recording layers for recording information, wherein the recording layer emits a recording / reproducing beam applied to the recording layer. A light source for reproduction, a pinhole plate having a pinhole for transmitting only return light from the recording layer desired by the recording and reproduction beam, and a return light for recording and reproduction for detecting the return light of the recording and reproduction beam Detecting means; an information pattern having position information of the pinhole provided on the pinhole plate; a pattern detecting means for detecting the information pattern; and light of the return light based on a detection result of the pattern detecting means. The pinhole plate is two-dimensionally moved on a plane perpendicular to the optical axis of the return light so that the center position of the axis and the position of the pinhole coincide with each other. An optical recording / reproducing apparatus, comprising: 2. The information processing apparatus according to claim 1, wherein the pinhole plate is formed of a reflective film, and the pattern detection unit irradiates the information pattern with a light spot, and information for detecting return light of the light spot from the information pattern. 2. The optical recording / reproducing apparatus according to claim 1, further comprising a return light detecting means for a pattern. 3. The pinhole plate is formed of a reflection film, and has a hologram for diffracting / separating the recording / reproducing beam, and the pattern detecting means is configured to provide the information pattern of diffracted light diffracted / separated by the hologram. 2. The optical recording / reproducing apparatus according to claim 1, further comprising an information pattern return light detecting means for detecting return light from the optical disc. 4. The pinhole plate is formed of a translucent film, the pattern detecting means is constituted by the recording / reproducing return light detecting means, and irradiating the information pattern with the return light of the recording / reproducing beam; The optical recording / reproducing apparatus according to claim 1, wherein transmitted light of the information pattern is detected. 5. A first extracting means for extracting a detection signal based on the information pattern from the recording / reproducing return light detecting means, and a detection based on a desired recording layer from the recording / reproducing return light detecting means. The optical recording / reproducing apparatus according to claim 4, further comprising a second extracting unit that extracts a signal. 6. The optical recording / reproducing apparatus according to claim 4, wherein said recording / reproducing return light detecting means, said pinhole plate and plate movement control means are formed in a single semiconductor substrate.