JP2576504B2 - Optical information processing device - Google Patents

Description

The present invention relates to an optical information processing apparatus, and in particular, records optical information on an optical recording medium by scanning a light spot across a running direction of the recording medium, Alternatively, it is suitable for application to one that can be reproduced.

B. Summary of the Invention The present invention is directed to obtaining a multi-beam for light intensity detection by a polarizing beam splitter after diffracting a deflected incident beam by a deflecting element into a zero-order light beam and a first-order light beam. APC (automated power management) of multiple light source elements with a simpler configuration and higher light energy utilization efficiency
atic power control) control.

C Prior Art As shown in FIG. 4, a conventional optical information processing apparatus is formed on a tape-shaped optical recording medium 1 by a laser beam in a scanning direction b across a running direction a. An optical information writing / reading device for a recording track TR by scanning a writing or reading optical spot 2 has been proposed.

Here, the diameter of the optical spot 2 can be converged to, for example, about 1 [μm] (for example, a wavelength of 780 [nm]).
When using the laser light of the above). Therefore a large number of recording tracks
If, for example, the TR is formed so as to sandwich the guard band GB and the optically recorded information can be reproduced from each recording track TR, the optical information can be recorded and reproduced at a higher density.

In particular, when recording or reproducing optical information on the recording track TR on the optical recording medium 1, as shown in FIG.
If the two optical spots 2A to 2D can be scanned in the scanning direction b so as to keep a predetermined interval, the optical recording medium 1
The optical information processing speed at the time of recording or reproducing data to or from the optical disk can be further increased.

D Problems to be Solved by the Invention By the way, as shown in FIG. 6, the main laser beam LA1 emitted forward from the laser diode 3 is actually acousto-optically configured to obtain the scanning light spot 2 shown in FIG. A light source 4 that can be deflected by a deflection element (AOD) (not shown) is used.

However, the laser diode 3 has temperature characteristics, emission characteristics,
There is a variation in input current characteristics, etc., and so-called automatic output control (APC control) is performed so that the light intensity of the main laser beam LA1 becomes a predetermined value by compensating for this. The sub laser beam LA2 to be
An automatic output control circuit (APC circuit) 7 irradiates the monitor photodiode 6 provided above and emits the light intensity detection signal S1.
The driving voltage S2 applied to the laser diode 3 is controlled to a predetermined voltage.

6, the light intensity of the main laser light LA1 is detected by the photodiode 6 via the sub-laser LA2, and the APC circuit 7 detects the light intensity of the laser diode 3 by the light intensity detection signal S1. By changing and controlling the drive voltage S2, the light intensity of the main laser beam LA1 can always be controlled to a predetermined reference value.

On the other hand, as described above with reference to FIG. 5, as shown in FIG. 7, the light spots 2A, 2B, 2C, and 2D are used as the light source 4A for simultaneously scanning the plurality of light spots 2A to 2D.
The main laser beams LA1A, LA1B, LA1C, LA1D for obtaining the laser beam are emitted from the corresponding laser diodes 3A, 3B, 3C, 3D.

Here, the laser diodes 3A, 3B, 3C, and 3D are arranged at predetermined intervals so as to overlap each other, and the sub-laser light LA
2A, LA2B, LA2C, LA2D on the substrate 5A with laser diode 3
Irradiate the photodiodes 6A, 6B, 6C, 6D provided to face A, 3B, 3C, 3D.

The light source 4A having such a configuration is used, and the laser diodes 3A, 3B, 3C, and 3D correspond to the corresponding photodiodes 6A, 6B, and 6D.
Light intensity detection signals S1A, S1B, S1C, S1D obtained from C and 6D
If the APC circuit (not shown) is provided so as to independently control the APC based on the laser beam, the main laser beams LA1A, LA1B, LA1
The light intensity of C and LAID can be controlled to a predetermined value by compensating so as to be applied to the variation in characteristics.

However, if a configuration as shown in FIG. 7 is used to obtain a plurality of light spots, the sub-laser light beams emitted from adjacent laser diodes enter the photodiodes 6A, 6B, 6C and 6D while overlapping so as to overlap each other. Thus, it is unavoidable that the light intensity information of the sub-laser light emitted from the adjacent laser diode cross-talks with the light intensity detection signals of the photodiodes 6A, 6B, 6C, 6D.

Incidentally, the sub-laser beams LA2A, LA2B, LA2C, LA2D emitted from the laser diodes 3A, 3B, 3C, 3D actually have a considerably large divergence angle, and accordingly, the sub-laser beams emitted from the adjacent laser diodes. Cannot be avoided to such an extent that the irradiation range of the above-mentioned area irradiates the adjacent photodiode at the position of the substrate 5A.

The present invention has been made in view of the above points, and proposes an optical information processing apparatus capable of obtaining a light intensity detection signal with a simple configuration while effectively avoiding the possibility of occurrence of crosstalk. What you want to do.

E Means for Solving the Problems In order to solve such problems, in the present invention, based on a plurality of light source elements 13A to 13D and a plurality of light beams LA11 emitted from the plurality of light source elements 13A to 13D. The zero-order light beam LA is obtained by diffracting the obtained deflected incident beam LA12.
A deflecting element 16 for forming a diffracted light beam LA15 composed of the primary light beam LA14 and the primary light beam LA14, rotating the polarization direction of the primary light beam substantially 90 degrees, and further deflecting the primary light beam LA14 in the scanning direction; The diffracted light beam LA15 is converted to the zero-order light beam LA13.
And a plurality of light sources based on the multi-light beam LA18 for light intensity detection, and a polarization beam splitter 17 for splitting into a multi-light beam LA18 for light intensity detection and a multi-light beam LA16 for scanning, respectively. A plurality of light intensity detection signals S11A to S11D for controlling the light intensities of the elements 13A to 13D to predetermined values, respectively, and the optical recording medium is scanned by a scanning multi-light beam LA16. To do it.

F action The deflecting element 16 diffracts the deflected incident beam LA12 to form the zero-order light beam LA13 and the primary light beam LA14, and splits the same at the polarizing beam splitter 17, thereby converting the zero-order light beam. A plurality of light intensity detection signals corresponding to the light intensity of the scanning multi-light beam obtained based on the primary light beam can be easily obtained by effectively using the light beam.

In this case, the zero-order light beam cannot be used as a scanning light beam, but is used as a light intensity detection light beam by a simple configuration using an optical system for forming a scanning multi-light beam LA16. In this case, the light energy can be used more effectively, so that the light energy use efficiency can be further enhanced.

G Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

1 and 2, reference numeral 11 denotes a multi-beam light source. As shown in FIG. 3, a plurality of light source elements such as four light source elements are arranged on the XY plane of the substrate 12 at predetermined intervals in the Y-axis direction.
A laser diode array 14 including one laser diode 13A, 13B, 13C, and 13D is provided.

The luminous flux emitted from the laser diodes 13A to 13D is a laser luminous flux linearly polarized in the X-axis direction. Is incident on.

Here, the correction optical system 15 includes a collimator lens system that converts each laser light beam of the laser beam LA11 into a parallel light beam, and an expander that shapes the parallel light beam into a light beam having an elliptical cross-section having a long axis in the X direction. And emits this elliptical light beam as a deflected incident beam LA12.

The deflection element 16 is an anisotropic Bragg diffraction acousto-optic deflection element 16
A, and an anisotropic Bragg diffraction acousto-optic deflecting element 16A provided by an electric drive signal supplied to a transducer 16B.
In the direction toward the absorbing member 16C, that is, the scanning direction d.
Is formed in a lattice-like vibration pattern that travels in the direction of.

Thus, the deflected incident beam LA12 that has entered the deflecting element 16 is diffracted by the deflecting element 16, and the zero-order light beam LA13 that passes through the deflecting element 16 as it is and the deflected primary light beam LA12
The diffracted light beam LA15 consisting of 14 is deflected by the beam splitter 17
Is incident on.

By the way, the deflecting surface of the first-order light beam LA14 is rotated by 90 ° with respect to the polarization plane of the zero-order light beam LA13 due to such a diffractive action of the deflecting element 16, and thus the polarizing beam splitter 17 is rotated.
Is a multi-beam scanning laser beam LA15 which allows the primary light beam LA14 of which the polarization plane has been rotated out of the diffracted light beam LA15 to pass through as it is.
At the same time, the light exits as 16 and reflects the zero-order light beam LA13 to enter the correction optical system 18 as a reflected light beam LA17.

Thus, the multi-light beam LA18 for light intensity detection is incident on the photodetector 19 via the correction optical system 18.

Here, the correcting optical system 18 is configured to perform a correcting action opposite to that of the above-described correcting optical system 15, thereby returning the elliptical reflected light beam LA17 to a circular parallel light beam, and then the photodetector 19. Focus on top.

The photodetector 19 has photodetectors 20A, 20B, 20 of a photodiode configuration corresponding to the laser diodes 13A, 13B, 13C, 13D.
C, 20D arranged light detection element array 22, the light intensity detection signals S11A, S11B, S11C, S11D sent from each light detection element 20A, 20B, 20C, 20D laser diode 13A, 1
An automatic output control circuit (not shown) for 3B, 13C, and 13D is supplied.

In the above configuration, the light beam LA11 emitted from the multi-beam light source 11 is converted by the deflecting element 16 into a primary light beam LA14 having the same polarization plane as the scanning multi-light beam LA16.
And a zero-order light beam LA13 having the same polarization plane as the light intensity detection multi-light beam LA18.
When the lattice vibration wave pattern formed inside the deflecting element 16 advances in the scanning direction d,
In the direction of, thus scanning multiple light beams
LA16 scans in the scanning direction e.

Here, since the four light beams constituting the primary light beam LA14 receive substantially the same amount of deflection from the deflecting element 16, the four light beams constituting the scanning multi-light beam LA16 eventually have a predetermined distance from each other. While scanning in the direction indicated by arrow e in FIG.

On the other hand, the zero-order light beam emitted from the deflection element 16
LA13 is rotated by 90 ° with respect to the primary light beam LA14, so that the polarization beam splitter 17 causes the polarization beam splitter 17.
It is surely split from the next light beam LA14.

Incidentally, the light beams emitted from the laser diodes 13A to 13D have a polarization plane in a direction (X direction) perpendicular to the paper surface as shown by a symbol F1 in FIG. The deflected incident beam LA12 emitted from the system 15 also has a plane of polarization in the same direction as indicated by the symbol F2. The zero-order light beam LA13 emitted from the deflecting element 16 with respect to the deflected incident beam LA12 is not rotated in the deflecting element 16 as indicated by the symbol F3, and thus has a deflecting surface in a direction perpendicular to the paper surface. . On the other hand, the primary light beam LA14 deflected by the deflecting element 16 has a polarization plane rotated by 90 ° in a direction (Y direction) along the plane of the paper, as indicated by a symbol F4.

Thus, only the primary light beam LA14 having a plane of polarization in the Y-axis direction passes through the polarizing beam splitter 17 and is transmitted as a scanning multi-beam LA16 having a plane of polarization along the plane of the paper as indicated by the symbol F5. .

On the other hand, in FIG. 1, the zero-order light beam LA13 having a plane of polarization perpendicular to the plane of the paper is reflected by the polarizing beam splitter 17, and as a result, reflected light LA17 perpendicular to the plane of the paper is obtained as indicated by the symbol F6. This is transmitted to the photodetector 19 as a light intensity detecting multi-light beam LA18 having a polarization plane perpendicular to the paper surface as indicated by a symbol F7.

With this configuration, the fact that the polarization plane of the zero-order light beam LA13 is rotated by 90 ° with respect to the polarization plane of the first-order light beam LA14 deflected by the diffraction action of the deflection element 16 is used. The light detector 19 can obtain a multi-light beam LA18 for light intensity detection. Thus, the light intensity detection multi-light beam LA18 has a light intensity corresponding to the light intensity of the scanning multi-light beam LA16, so that the light intensity detection signal S11A
Laser diodes 13A to 13 APC controlled by S11D
The light intensity of the light beam LA11 emitted from D and the light intensity of the scanning multi-light beam LA16 are maintained at a predetermined constant value.

According to the above configuration, the polarization beam splitter 17 is provided on the emission side of the deflection element 16 so that the multi-beam
By simply providing a simple configuration for taking out 18, there is no possibility that crosstalk will occur between the photodetectors 20A to 20D.
, Four light intensity detection signals S11A to S11D can be obtained.

The zero-order light beam LA13 passing through the deflecting element 16 travels straight without being deflected by the diffractive action of the deflecting element 16, and cannot be used as a scanning light beam. Usually, a method of wastefully absorbing into an absorbing material is adopted.

On the other hand, according to the configuration of the above-described embodiment, it is possible to obtain the light intensity detection signals S11A to S11D of the respective light beams by effectively using the 0th-order light beam LA13 considered to be wasteful. it can. Thus, the light intensity detection signals S11A to S11D without crosstalk can be obtained while effectively using the light energy of the light beam emitted from the multi-beam light source 11 as a whole.

In the above-described embodiment, the embodiment using the acousto-optic deflecting element as the deflecting element 16 has been described. However, the present invention is not limited to this. The same effect as in the case of can be obtained.

Further, in the above embodiment, the embodiment using the transmission type deflection element as the deflection element 16 has been described. However, a reflection type deflection element may be used instead.

In the above description, the polarization beam splitter 17 is set so as to allow the primary light beam LA14 to pass therethrough. Alternatively, the polarization beam splitter 17 may be set so as to reflect the primary light beam LA14. The same effect as in the case can be obtained.

H As described above, according to the present invention, light intensity information obtained from each light source element constituting a multi-beam light source can be detected while effectively avoiding the possibility of crosstalk, thereby enabling scanning. Ensure each light source element of multi light beam
It is possible to easily realize an optical information processing device that can perform APC control and can further improve the use efficiency of light energy generated from a multi-beam light source.

[Brief description of the drawings]

1 and 2 are a schematic plan view and a side view showing one embodiment of an optical information processing apparatus according to the present invention, FIG. 3 is a perspective view showing the configuration of the multi-beam light source, and FIGS. 5 is a schematic diagram illustrating the scanning of the optical spot on the optical recording medium, FIG. 6 is a schematic connection diagram illustrating the APC control for one laser diode, and FIG. 7 generates a multi-beam. FIG. 4 is a schematic side view for explaining a problem of a light source to be used. 11: Multi-beam light source, 12: Substrate, 13A to 13D: Laser diode, 15, 18: Correction optical system, 16: Deflection element, 17: Polarized beam splitter, 19: Photodetector ,
20A to 20D: Photodetector.

Claims (1)

(57) [Claims] 1. A light source device comprising: a plurality of light source elements; and a plurality of light beams emitted from the plurality of light source elements.
A deflecting element for forming a diffracted light beam comprising a primary light beam and a primary light beam, rotating the polarization direction of the primary light beam by approximately 90 degrees, and further deflecting the primary light beam in a scanning direction; A polarizing beam splitter that splits the light beam into a zero-order light beam and a primary light beam and emits them as a multi-light beam for detecting light intensity and a multi-light beam for scanning, respectively, based on the multi-light beam for detecting light intensity. A light detector for transmitting a plurality of light intensity detection signals for controlling the light intensities of the plurality of light source elements to predetermined values, respectively, and scanning the optical recording medium with the scanning multiple light beams. Optical information processing device characterized by the following.