JPH06314448A - Optical pickup device - Google Patents

Abstract

PURPOSE:To take out high-grade magneto-optical recording signals with simple constitution. CONSTITUTION:A magneto-optical recording disk 1 is irradiated with the laser beams emitted from a laser diode 2 after the laser beam on the right side of the optical axis as a boundary is optically rotated by a prescribed angle by a dextrorotatory plate 5R of an optically rotary plate 5 and after the laser beam on the left side is optically rotated by a prescribed angle by a levorotatory plate 5L. The reflected light relating to the laser beam via the dextrorotatory plate 5R is made incident on the levorotatory plate 5L and is further optically rotated by the prescribed angle in a right direction. The reflected light relating to the laser beam via the levorotatory plate 5L is made incident on the dextrorotatory plate 5R and is further optically rotated by the prescribed angle in a left direction. This reflected light is bent in its optical path by as much as the prescribed component by a hologram film 4 and is transmitted through a polarization beam splitter 3. A first photocletector 7 for detecting servo signals is irradiated with this light. The reflected light is also reflected by the polarization beam splitter 3 and a second photodetector 8 for detecting the magneto- optical recording signals is irradiated with this light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device suitable for use as an optical system such as a magneto-optical disk recording / reproducing apparatus for recording / reproducing desired recording information on / from a magneto-optical disk.

[0002]

2. Description of the Related Art Today, large storage capacity,
Magneto-optical discs have come to be widely used for recording / reproducing recorded data because of the good preservation of the recorded data and the fact that they can be easily rewritten.

An optical pickup device provided in a magneto-optical disk recording / reproducing apparatus for recording / reproducing recorded data on / from the magneto-optical disk includes, for example, a semiconductor laser and a collimator lens for collimating emitted light from the semiconductor laser. , Is provided between the semiconductor laser and the objective lens, which is provided between the objective lens that collects the emitted light that is collimated by the collimator lens and irradiates the recording surface of the magneto-optical disk, and is reflected by the recording surface of the magneto-optical disk. A first polarization beam splitter for separating a part of the reflected light thus reflected, an analyzer for detecting a part of the reflected light separated by the first polarization beam splitter, and a level of light transmitted through the analyzer It is composed of a photo detector or the like for detecting the.

The optical pickup device having such a structure condenses the laser beam emitted from the semiconductor laser, irradiates the recording surface of the magneto-optical disk with the reflected light, and reflects one of the reflected lights on the recording surface. The part is separated by the first polarization beam splitter, and the level of a component having a predetermined polarization plane, that is, a predetermined light oscillation plane, out of a part of the separated reflected light is detected by the photodetector. The recorded data recorded on the magneto-optical disk is reproduced.

As the above-mentioned analyzer, a "sheet analyzer" is generally used, but this sheet analyzer has a problem that the S / N ratio is low because the "extinction ratio" is low. For this reason, a half-wave plate is provided in place of the above-mentioned analyzer in the optical pickup device which is currently the mainstream.

In the optical pickup device provided with the half-wave plate, the reflected light separated by the first polarization beam splitter is further reflected by the half-wave plate and the second polarization beam splitter by P Separated into wave component and S wave component,
The levels of the P-wave component and the S-wave component are detected by two photodetectors, and the difference between these levels is detected by a differential amplifier, whereby the recorded data recorded on the magneto-optical disk is reproduced. ing.

[0007]

However, the optical pickup device provided with the above-mentioned half-wave plate must be provided with a total of two polarization beam splitters, that is, the first and second polarization beam splitters. There was a problem that the number of points increased and the production cost increased.

Further, since the reflected light separated by the first polarization beam splitter is further separated into two components by the second polarization beam splitter, it is necessary to establish an optical path for each component. However, there is a problem that the device itself becomes large in size in addition to the troublesome alignment.

The present invention has been made in view of the above-mentioned problems, and relates to an optical pickup device capable of reducing the number of parts to be manufactured in a small size and at a low cost and reducing troublesome alignment. .

[0010]

An optical pickup device according to the present invention has a laser beam emitting means for emitting a laser beam having a first polarization direction for irradiating a magneto-optical disk, and a first polarization direction. A polarization beam splitter that transmits a laser beam included therein and reflected light generated by irradiating the magneto-optical disk with the laser beam, and reflects the laser beam having a second polarization direction orthogonal to the first polarization direction and the reflected light. The laser beam transmits as the 0th-order light, and the reflected light as the 1st-order diffracted light is emitted by bending the optical path by a predetermined amount, and the incident laser beam and the reflected light are rotated by a predetermined angle. The first optical rotator that emits the laser beam and the incident laser beam and the reflected light that rotatively emits the laser beam and the reflected light by a predetermined angle contrary to the first optical rotator. And optical rotation portion, and optical rotation means provided in the boundary of the optical axis of the laser beam and the reflected light,
Converging means for converging the laser beam from the laser beam emitting means and irradiating the magneto-optical disc, and reflected light of the laser beam whose optical path is bent by the hologram film, transmitted through the polarization beam splitter. Of the reflected light reflected by the polarization beam splitter, the first light detecting means for receiving the light and detecting the tracking error and the focus error, and the first light detecting means for detecting the tracking error and the focus error. A first light receiving unit that receives reflected light emitted through the optical rotatory unit and detects the level thereof, and a reflected light emitted through the second optical rotator of the optical rotator receives the level thereof. Second to detect
Second light for detecting a magneto-optical recording signal recorded in the magneto-optical recording medium by detecting a difference in level of each of the reflected lights detected by each of the light receiving sections. The above-mentioned problems are solved by having a detection means.

Further, in the optical pickup device according to the present invention, the hologram film emits the laser beam from the laser beam emitting means of the polarization beam splitter and the reflected light of the laser beam enters the hologram film. The optical rotation means is provided adjacent to the surface, and the optical rotation means is provided between the magneto-optical disk and the hologram film to solve the above problems.

Further, in the optical pickup device according to the present invention, the optical rotation means emits the laser beam from the laser beam emitting means of the polarization beam splitter and makes the reflected light of the laser beam incident. The hologram film is provided adjacent to the surface, and the hologram film is provided between the magneto-optical disk and the optical rotation means, thereby solving the above-mentioned problems.

[0013]

In the optical pickup device according to the present invention, for example, S
The laser beam of the polarized component is emitted from the laser beam emitting means. The S-polarized component laser beam is incident on the polarization beam splitter. The polarization beam splitter has a characteristic that the S-polarized component laser beam is transmitted as it is and the P-polarized component laser beam that is a polarization component orthogonal to the S-polarized component is reflected. Therefore, the S-polarized component laser beam from the laser beam emitting means is transmitted through the polarization beam splitter. The laser beam transmitted through this polarization beam splitter is incident on the hologram film.

The hologram film transmits the laser beam as zero-order light, and the reflected light generated by irradiating the magneto-optical disk with the laser beam is emitted as first-order diffracted light by bending its optical path by a predetermined amount. It is a characteristic. Therefore, the laser beam incident on the hologram film from the polarization beam splitter is emitted without the optical path thereof being bent. The laser beam emitted from this hologram film is incident on the optical rotation means.

The optical rotator is formed by, for example, a right optical rotator which is the first optical rotator on the right side and a left optical rotator which is the second optical rotator on the left side of the optical axis of the laser beam, and the hologram is used. Among the laser beams from the film, the right side laser beam with an optical axis as a boundary is rotatively emitted by the right optical rotator at a predetermined angle, and the left side laser beam with the optical axis as a boundary is emitted by the left optical rotator. In contrast to the right optical rotatory plate, the light is rotatably emitted at a predetermined angle.

As a result, although apparently a single laser beam, laser beams having different optical rotation angles are formed on the right and left sides of the optical axis. This laser beam is converged by the converging means and applied to the magneto-optical disk.

Next, the laser beam is applied to the magneto-optical disk through the converging means to generate reflected light. Of this reflected light, the reflected light relating to the laser beam emitted through the right optical rotation plate in the optical rotation means is incident on the left optical rotation plate in the optical rotation means and emitted through the left optical rotation plate in the optical rotation means. The reflected light of the generated laser beam is incident on the right optical rotatory plate in the optical rotator.

The traveling direction of the reflected light incident on the optical rotation means is opposite to the traveling direction of the laser beam emitted from the laser beam emitting means. Therefore, the reflected light incident on the left optical rotatory plate is further rotated by a predetermined angle, emitted as reflected light having a polarization component intermediate between the S-polarized component and the P-polarized component, and incident on the right optical rotatory plate. The reflected light is further rotated by a predetermined angle contrary to the reflected light incident on the left optical rotatory plate, and is emitted as reflected light having a polarization component intermediate between the S polarization component and the P polarization component. .

The reflected light emitted from the left optical rotatory plate and the reflected light emitted from the right optical rotatory plate respectively have a polarization component intermediate between the S polarization component and the P polarization component. The reflected light has an optical rotation angle in the right direction and the reflected light has an optical rotation angle in the left direction. The reflected light that has passed through the optical rotation means is then incident on the hologram film.

As described above, the hologram film transmits the laser beam as the 0th order light, and the reflected light is 1st order.
The characteristic is that the optical path of the second-order diffracted light is bent by a predetermined amount and emitted. Therefore, the reflected light that has entered the hologram film 4 is emitted with its optical path bent by a predetermined amount. The reflected light whose optical path is bent is incident on the polarization beam splitter.

As described above, the left and right optical rotatory plates of the optical rotator emit, for example, reflected light having a polarization component intermediate between the S polarization component and the P polarization component. The polarization beam splitter transmits the S-polarized component and reflects the P-polarized component. Therefore, for example, 50% of the reflected light that has entered the polarization beam splitter is transmitted, and the remaining 50% of the reflected light is reflected.

The reflected light transmitted through the polarization beam splitter is applied to the first light detecting means, and the reflected light reflected by the polarization beam splitter is applied to the second light detecting means.

The first light detecting means receives the reflected light and detects a tracking error and a focus error.

The second light detecting means receives, for example, the reflected light having a right polarization angle among the reflected light reflected and emitted by the polarization beam splitter, and detects the level thereof. And a second light receiving portion that receives reflected light having a left-handed polarization angle and detects the level thereof, and the level of the reflected light received by the first light receiving portion and the second light receiving portion. By the so-called differential detection method, which detects the difference from the level of the reflected light received by the light receiving section of
The magneto-optical recording signal recorded on the magneto-optical recording medium is detected.

In this case, the optical pickup device according to the present invention comprises the laser beam emitting means, the polarization beam splitter, the hologram film, the optical rotation means and the converging means in this order. The order of providing the means is changed, that is, the laser beam emitting means,
The polarization beam splitter, the optical rotation means, the hologram film, and the converging means may be arranged in this order.

[0026]

Embodiments of the optical pickup device according to the present invention will be described below with reference to the drawings.

The optical pickup device according to the present invention can be applied as an optical system of a magneto-optical disc recording / reproducing device for recording and reproducing desired recording data on the magneto-optical disc 1 as shown in FIG. 1, for example.

In FIG. 1, the optical pickup apparatus according to the present embodiment emits a laser beam having a strong S-polarization component for recording during recording and a laser beam having a weak S-polarization component for reproduction during reproduction. A laser diode (laser beam emitting means) 2 for emitting light, and a polarization beam splitter 3 for transmitting light of S polarization component and reflecting light of P polarization component which is a polarization component orthogonal to the S polarization component. ing.

The optical pickup device is provided adjacent to a surface of the polarization beam splitter 3 from which the laser beam from the laser diode 2 is emitted and reflected light of the laser beam is incident. The laser beam from the laser diode 2 is emitted without bending its optical path, and the reflected light of the laser beam is separated from the hologram film 4 which is emitted by bending the optical path by a predetermined amount and the optical axis of the laser beam, for example. The right optical rotatory plate 5R (first optical rotator), which is provided to swirl the incident laser beam and reflected light rightward by a predetermined angle and emits the laser beam and the incident laser beam and reflected light, And a rotatory plate (optical rotator) 5 having a left rotatory plate 5L (second rotatory part) that rotates and emits in the left direction by an angle of.

The optical pickup device further comprises an objective lens (converging means) 6 for converging the laser beam from the laser diode 2 incident through the optical rotation plate 5 and irradiating the magneto-optical disc 1 with the laser beam. The hologram film 4
A first photodetector (first light detecting means) 7 for detecting the tracking error and the focus error by receiving the reflected light that has passed through the polarization beam splitter 3 among the reflected light whose optical path is bent by a predetermined amount. have.

Further, in the above optical pickup device, of the reflected light reflected by the polarization beam splitter 3 after the optical path is bent by the hologram film 4 by a predetermined amount, the reflected light passing through the left optical rotatory plate 5L of the optical rotatory plate 5. And a second light receiving portion 8L for receiving the reflected light from the right rotatory plate 5R of the rotatory plate 5 and detecting the level thereof. Second photodetector 8 and each light receiving portion 8 of the second photodetector 8
The differential amplifier circuit 9 detects the magneto-optical recording signal recorded on the magneto-optical recording medium by detecting the difference between the levels of the respective reflected lights detected by R and 8L.

The second photodetector 7 and the differential amplifier circuit 9 constitute second photodetection means.

The laser diode 2 and the first photodetector 7 are provided adjacent to each other in a box-shaped laser unit 11. The laser unit 11 is provided with holes 11a so as not to block the laser beam emitted from the laser diode 2 and the reflected light that is transmitted through the polarization beam splitter 3 and is applied to the first photodetector 7. Has been. It should be noted that, for example, the laser unit 11 is configured so as to shield all light except for the hole 11a.

Next, the operation of the optical pickup device according to this embodiment having the above structure will be described.

First, at the time of recording or reproducing, the laser diode 2 emits an S-polarized component laser beam as shown in FIG. 2A. The S-polarized component laser beam is incident on the polarization beam splitter 3. The polarization beam splitter 3 allows the S-polarized component laser beam to pass through as it is. The laser beam transmitted through the polarization beam splitter 3 is a hologram film 4
Is incident on.

The hologram pattern of the hologram film 4 is at the position where the laser diode 2 is provided, and
It is determined according to the positions where the first and second photodetectors 7 and 8 are provided, and is, for example, an interference fringe of a divergent spherical wave.

The hologram film 4 has such a characteristic that the laser beam is transmitted as 0th-order light and the reflected light is emitted as 1st-order diffracted light by bending its optical path by a predetermined amount. Therefore, the laser beam incident on the hologram film 4 via the polarization beam splitter 3 is emitted without bending the optical path. The laser beam emitted from the hologram film 4 is then incident on the optical rotation plate 5.

As described above, the optical rotation plate 5 is formed by the right optical rotation plate 5R on the right side and the left optical rotation plate 5L on the left side with the optical axis of the laser beam as a boundary. Therefore, the optical rotation plate 5 is
Of the laser beams incident through the hologram film 4, the laser beam on the right side of the optical axis is rotated by the right optical rotation plate 5R by a predetermined amount (+ α) to the right as shown in FIG. 2B. And emits (+ α + θk: θk = Kerr rotation angle), and the laser beam on the left side of the optical axis is a predetermined amount (-) as shown in FIG.
α) Rotate to the left and emit (-α + θk: θk =
Car rotation angle).

As a result, although apparently one laser beam, laser beams having different polarization directions on the right and left sides of the optical axis are formed. This laser beam is converged by the objective lens 6 and applied to the magneto-optical disk 1.

Next, by irradiating the magneto-optical disk 1 with the laser beam through the objective lens 6, reflected light is generated. Of this reflected light, the reflected light (+ α + θk) related to the laser beam emitted through the right rotatory plate 5R in the rotatory plate 5 is the left rotatory plate 5L in the rotatory plate 5.
The reflected light (−α + θk) related to the laser beam that is incident on the laser beam and is emitted via the left optical rotation plate 5L in the optical rotation plate 5 is
The light is incident on the right optical rotation plate 5R in the optical rotation plate 5.

The traveling direction of the reflected light incident on the optical rotatory plate 5 is opposite to the traveling direction of the laser beam emitted from the laser diode 2. Therefore, the reflected light that has entered the left optical rotation plate 5L is further rotated by a predetermined amount (+ α) to the right as shown in FIG.
α + θk), the reflected light incident on the right optical rotation plate 5R is
As shown in (e) of the figure, the light is further rotated leftward by a predetermined amount (-α) and emitted (-2α + θk).

The reflected light that has passed through the optical rotation plate 5 is then incident on the hologram film 4.

As described above, the hologram film 4 uses the reflected light as the first-order diffracted light and bends its optical path by a predetermined amount and emits it. The amount by which the optical path of the reflected light is bent by the hologram film 4 is such that the reflected light that has passed through the polarization beam splitter 3 described below is applied to the first photodetector 7. The reflected light whose optical path is bent in this way is incident on the polarization beam splitter 3.

Of the reflected light that enters the polarization beam splitter 3, the reflected light that has passed through the left optical rotation plate 5L in the optical rotation plate 5 has an optical rotation angle of + 2α + θk as shown in FIG. 2 (d). However, this optical rotation angle is, for example, about +45 degrees, and the reflected light through the right optical rotation plate 5R has an optical rotation angle of −2α + θk as shown in FIG. However, this optical rotation angle is, for example, about −45 degrees.

Therefore, the reflected light passing through the left optical rotatory plate 5L and the reflected light passing through the right optical rotatory plate 5R have, for example, S-polarized component and P-polarized component by about 50%, respectively. Become. Further, as described above, the polarization beam splitter 3 transmits the light of the S polarization component and reflects the light of the P polarization component.

Therefore, the polarization beam splitter 3 is
When the reflected light enters from the hologram film 4, 50% of the reflected light is transmitted and the remaining 50
% Of reflected light is reflected.

The reflected light transmitted through the polarization beam splitter 3 is applied to the first photodetector 7 because its optical path is bent by the hologram film 4 by a predetermined amount.

The first photodetector 7 detects a focus error by the so-called astigmatism method and a tracking error by the so-called push-pull method based on the irradiated reflected light. Then, a focus error signal and a tracking error signal are formed, and these are supplied to a system controller (not shown). Based on the focus error signal, the system controller controls, for example, the objective lens 6 to be vertically driven so that the laser beam applied to the magneto-optical disc 1 is focused, and based on the tracking error signal. The objective lens 6 is laterally driven and controlled so that the laser beam scanning the magneto-optical disk 1 is on-track.

As a result, recording / reproduction can be performed with accurate focusing and tracking.

On the other hand, in the above polarization beam splitter 3,
The remaining 50% of the reflected light is reflected, of which the reflected light (+ 2α +) that has passed through the left optical rotation plate 5L in the optical rotation plate 5 is reflected.
θk) is reflected by the polarization beam splitter 3 to obtain sin (+ 2α + θ) as shown in FIG.
k) is irradiated to the first light receiving portion 8R in the second photodetector 8 as reflected light of the P-polarized component having the polarization angle of k),
In addition, the reflected light (-2α + θ) through the right rotatory plate 5R
k) is reflected by the polarization beam splitter 3 to produce sin (-2α + θk) as shown in FIG.
The second light receiving unit 8L in the second photodetector 8 is irradiated with the reflected light of the P-polarized component having the polarization angle of.

Therefore, the first and second light receiving portions 8R, 8
The same P-polarized component is present in L, but its optical rotation angle is shown in FIG.
As shown in (f) and (g), diametrically opposite reflected light is emitted.

The first light receiving portion 8R in the second photodetector 8 receives the reflected light of the P polarized component having the optical rotation angle of sin (+ 2α + θk), detects the level from the light receiving area, and detects it. The signal is supplied to the non-inverting input terminal (+) of the differential amplifier circuit 9. Further, the second light receiving portion 8L is
The reflected light of the P-polarized component having the optical rotation angle of sin (−2α + θk) is received, the level is detected from the light receiving area, and this is supplied to the inverting input terminal (−) of the differential amplifier circuit 9.

The differential amplifier circuit 9 detects a difference in level of reflected light supplied to the non-inverting input terminal and the inverting input terminal, and amplifies the difference to form a magneto-optical recording signal. This is supplied to a magneto-optical recording signal processing circuit (not shown) via the output terminal 10.

As described above, the so-called differential detection method for detecting the difference in the level of the light receiving area is difficult to realize unless the optical system has a high extinction ratio that determines the performance of the common mode rejection ratio. However, since the optical pickup device according to the present embodiment detects the reflected light of the laser beam using the polarization beam splitter 3, the polarization beam splitter 3 is used.
It is possible to perform in-phase removal up to the extinction ratio determined by the characteristics of. Therefore, it is possible to achieve a high-quality magneto-optical system having a high common mode rejection ratio.

Further, the reflection film of the ordinary beam splitter needs to be mass-produced in consideration of the optical phase characteristic (retardation), but the cost is high. However, the optical pickup device according to the present embodiment has the above-mentioned polarization. Beam splitter 3
Therefore, retardation does not occur. Therefore, it is possible to contribute to cost reduction because it is not necessary to mass-produce the retardation.

Further, the polarization beam splitter 3 is used to detect only the light quantity of the reflected light, and the light quantity of the outward path is 10
Since 0% is transmitted, the coupling efficiency can be improved.

Further, the rotation angles of the right rotatory plate 5R and the left rotatory plate 5L are arbitrarily set and the first and second photodetectors 7 and 8 are irradiated without affecting the outward coupling efficiency. The amount of reflected light can be set arbitrarily.

Specifically, by changing the rotation angles of the right rotatory plate 5R and the left rotatory plate 5L to 0 to 45 degrees, respectively, the reflected light emitted to the first and second photodetectors 7 and 8 is changed. It is possible to change the amount of light of 0% to 100%.

Therefore, it is possible to increase the degree of freedom in designing an amplifier circuit in the subsequent stage such as an amplifier circuit for the magneto-optical recording signal, the focus error signal and the tracking error signal. Therefore, the amplification factor of the amplification circuit in the latter stage can be set so that the amplification degree is appropriate according to the signal, and the S / N ratio can be improved.

Further, the polarization beam splitter 3 can be used for forming the magneto-optical recording signal, and it is possible to handle the magneto-optical recording signal even in the converging light without degrading the quality of the magneto-optical recording signal. Therefore, a magneto-optical laser coupler can be realized.

Further, the optical rotation plate 5 only changes the rotation angle, and does not change the phase difference unlike the wave plate. Therefore, it is not affected by the variation in the oscillation wavelength of the laser diode 2. Therefore, it is possible to handle laser beams having two or more wavelengths in the same optical system.

Further, in the optical rotation plate 5, even if the right optical rotation plate 5R and the left optical rotation plate 5L have different optical rotation angles,
As for the two reflected lights, the laser beam is the right optical rotation plate 5R.
And the left optical rotatory plate 5L are formed in order, and the laser beam is formed via the left optical rotatory plate 5L and the right optical rotatory plate 5R in order, so that the levels of the two reflected lights can be made equal. Therefore, it is possible to increase the degree of freedom in the specifications of each element used in the optical pickup device.

The polarization beam splitter 3 can be manufactured at a lower cost than a magneto-optical beam splitter provided in a normal optical pickup device. Further, the optical pickup device according to the present embodiment uses only one polarization beam splitter. Moreover, since only one polarization beam splitter is used, the optical path can be greatly shortened. Furthermore, the optical rotation plate 5
Can also be manufactured at a lower cost than the Wollaston prism.

Therefore, it is possible to reduce the size of the optical pickup device itself and to reduce the cost, and it is possible to reduce troublesome positioning work.

In the description of the above embodiment, the hologram film 4 is provided on the laser beam emitting surface of the polarization beam splitter 3 (which is also the incident surface of reflected light), and the hologram film 4 is adjacent to the hologram film 4. Although the optical rotator 5 is provided, as shown in FIG. 3, the optical rotator 5 is provided on the emitting surface of the laser beam of the polarization beam splitter 3, and the hologram film 4 is provided adjacent to the optical rotator 5. The arrangement may be changed, that is, the order of providing the optical rotation plate 5 and the hologram film 4 may be changed.

Also in this case, the operation and effect of each section are the same as those in the above-mentioned embodiment. Therefore, the detailed description of the optical pickup device according to FIG. 3 will be omitted by giving the same reference numerals as the optical pickup device according to the embodiment shown in FIG.

Further, in the above description of the embodiment, the optical rotation plate 5 in which the right optical rotation plate 5R and the left optical rotation plate 5L are combined is used as the optical rotation means, but this changes the optical axis of the 1/2 wavelength plate. You may make it use what combined two sheets.

[0068]

As is apparent from the above description, in the optical pickup device according to the present invention, the laser beam emitting means, the polarization beam splitter, the hologram film, the optical rotating means, and the converging means are sequentially provided along the optical path of the laser beam. Or
A laser beam emitting means, a polarization beam splitter, an optical rotation means, a hologram film, and a converging means are provided in order along the optical path of the laser beam, and a tracking error and a focus error are detected at the irradiation position of the reflected light passing through the polarization beam splitter. And a second light detecting means for detecting a magneto-optical recording signal is provided at the irradiation position of the reflected light reflected by the polarization beam splitter. It is possible to form and output a high-quality magneto-optical recording signal by utilizing 100% of light and improving the coupling efficiency.

Moreover, since only one polarization beam splitter is used, the number of parts can be reduced, the optical path can be greatly shortened, and the optical pickup device can be made compact and low cost. You can In addition, since the optical path can be greatly shortened, it is possible to reduce the alignment of the first and second light detecting means.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment in which an optical pickup device according to the present invention is applied to an optical system of a magneto-optical disk recording / reproducing device.

FIG. 2 is a schematic diagram for explaining an optical rotation angle of a laser beam and reflected light through each part of the optical pickup device according to the above-mentioned embodiment.

FIG. 3 is a block diagram of another embodiment of the optical pickup device according to the present invention.

[Explanation of symbols]

 1 ... Magneto-optical disk 2 ... Laser diode 3 ... Polarizing beam splitter 4 ...・ ・ Holographic film 5 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Optical plate 5R ・ ・ ・ ・ ・ ・ ・ Right optical plate 5L ・ ・ ・ ・ ・ ・ ・ Left optical plate 6 ・ ・ ・ ・・ ・ ・ Objective lens 7 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ First photo detector 8 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Second photo detector 8R ・ ・ ・ ・ ・ ・ ・ ・ First photo detector 8L --- Second light-receiving section 9 --- Differential amplifier circuit 10 --- Output terminal 11 --- ..Laser unit

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[Procedure amendment]

[Submission date] March 15, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

[0013]

In the optical pickup device according to the present invention, for example, the laser beam of the P-polarized component is emitted from the laser beam emitting means. This P-polarized component laser beam is incident on the polarization beam splitter. The polarization beam splitter has a characteristic of transmitting the laser beam of the P-polarized component as it is and reflecting the laser beam of the S-polarized component which is a polarized component orthogonal to the P-polarized component. Therefore, the P-polarized component laser beam from the laser beam emitting means is transmitted through the polarization beam splitter. The laser beam transmitted through this polarization beam splitter is incident on the hologram film.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

As described above, the left and right optical rotatory plates of the optical rotator emit, for example, reflected light having a polarization component intermediate between the S polarization component and the P polarization component. Also,
The polarization beam splitter transmits the P-polarized component and transmits the S-polarized component.
The polarized component is reflected. Therefore, for example, 50% of the reflected light that has entered the polarization beam splitter is transmitted, and the remaining 50% of the reflected light is reflected.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

In FIG. 1 described above, the optical pickup device according to the present embodiment has a strong recording level P for recording.
A laser diode (laser beam emitting means) 2 which emits a laser beam of a polarization component and emits a laser beam of a P-polarization component of a weak level for reproduction, and transmits the light of the P-polarization component, and the P-polarization component. The polarization beam splitter 3 that reflects the light of the S-polarization component that is a polarization component orthogonal to
And have.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

First, at the time of recording or reproducing, the laser diode 2 emits a laser beam of a P-polarized component as shown in FIG. 2A. The P-polarized component laser beam is incident on the polarization beam splitter 3. The polarization beam splitter 3 allows the P-polarized component laser beam to pass through as it is. The laser beam transmitted through the polarization beam splitter 3 is a hologram film 4
Is incident on.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

As described above, the optical rotation plate 5 is formed by the right optical rotation plate 5R on the right side and the left optical rotation plate 5L on the left side with the optical axis of the laser beam as a boundary. Therefore, the optical rotation plate 5
Among the laser beams incident through the hologram film 4, a laser beam on the right side of the optical axis as a boundary is moved by the right polarization plate 5R by a predetermined amount (+) as shown in FIG. 2B.
α) The light beam is rotated rightward to be emitted, and the laser beam on the left side of the optical axis is rotated by a predetermined amount (−α) leftward by the left optical rotation plate 5L as shown in FIG. Emit.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Change

[Correction content]

Next, by irradiating the magneto-optical disk 1 with the laser beam through the objective lens 6, reflected light is generated. The plane of polarization of the reflected light rotates by θk (= Kerr rotation angle) due to the phenomenon called the Kerr effect, which rotates in accordance with the direction of magnetization of the data recorded on the magneto-optical disk 1. Of the reflected light whose polarization plane is rotated by θk, the reflected light (+ α + θk) related to the laser beam emitted through the right optical rotation plate 5R in the optical rotation plate 5 is incident on the left optical rotation plate 5L in the optical rotation plate 5. The reflected light (-α + θk) of the laser beam emitted through the left optical rotation plate 5L in the optical rotation plate 5 is incident on the right optical rotation plate 5R in the optical rotation plate 5.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] 0045

[Correction method] Change

[Correction content]

Therefore, the reflected light passing through the left optical rotatory plate 5L and the reflected light passing through the right optical rotatory plate 5R have, for example, S-polarized component and P-polarized component by about 50%, respectively. Become. In addition, as described above, the polarization beam splitter 3 transmits the P-polarized component light and reflects the S-polarized component light.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0050

[Correction method] Change

[Correction content]

On the other hand, in the polarization beam splitter 3, the remaining 50% of the reflected light is reflected. Of this, the reflected light (+) that has passed through the left optical rotation plate 5L in the optical rotation plate 5 (+
2α + θk) is reflected by the polarization beam splitter 3, so that sin (+ 2α) as shown in FIG.
The reflected light of the P-polarized component having the polarization angle of + θk) is emitted to the first light receiving portion 8R in the second photodetector 8 and reflected light (−2α +) through the right optical rotation plate 5R.
θk) is reflected by the polarization beam splitter 3 to obtain sin (−2α + θ) as shown in FIG.
The second light receiving portion 8L in the second photodetector 8 is irradiated with the S-polarized light component having the polarization angle of k) as reflected light.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0051

[Correction method] Change

[Correction content]

Therefore, the first and second light receiving portions 8R,
8L has the same S-polarized component, but its rotatory angle is radiated with reflected light having opposite polarities as shown in FIGS. 2 (f) and 2 (g).

[Procedure Amendment 10]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (3)

[Claims] 1. A laser beam emitting means for emitting a laser beam having a first polarization direction for irradiating a magneto-optical disk, and a laser beam having a first polarization direction and the laser beam for irradiating the magneto-optical disk. A laser beam having a second polarization direction orthogonal to the first polarization direction and a polarization beam splitter that reflects the reflected light; and the laser beam as zero-order light. The reflected light is incident as a first-order diffracted light by bending the optical path by a predetermined amount and emitting the hologram film, and a first optical rotator that rotates the incident laser beam and the reflected light by a predetermined angle and emits the same. The second optical rotator that rotatively emits the laser beam and the reflected light by a predetermined angle, in contrast to the first optical rotator, and the optical axis of the laser beam and the reflected light. And a converging means for converging the laser beam from the laser beam emitting means to irradiate the magneto-optical disk, and a reflected light of the laser beam whose optical path is bent by the hologram film. Among these, the first light detecting means for receiving the reflected light transmitted through the polarization beam splitter and detecting the tracking error and the focus error, and the optical path bent by the hologram film, and reflected by the polarization beam splitter. Of the reflected light, a first light receiving unit that receives the reflected light emitted through the first optical rotation unit of the optical rotation unit and detects the level thereof, and a second optical rotation unit of the optical rotation unit. A second light receiving section for receiving the reflected light to be irradiated and detecting the level thereof, and detecting a level difference between the respective reflected light detected by the respective light receiving sections. It, the optical pickup apparatus characterized by comprising a second light detecting means for detecting a magneto-optical recording signal recorded on the magneto-optical recording medium. 2. The hologram film is provided adjacent to a surface of the polarization beam splitter on which the laser beam from the laser beam emitting means is emitted and reflected light of the laser beam is incident. The optical rotation means
The optical pickup device according to claim 1, wherein the optical pickup device is provided between the magneto-optical disk and the hologram film. 3. The optical rotation means is provided adjacent to a surface of the polarization beam splitter on which the laser beam from the laser beam emitting means is emitted and reflected light of the laser beam is incident. The hologram film is
The optical pickup device according to claim 1, wherein the optical pickup device is provided between the magneto-optical disk and the optical rotation means.