JP2000123433A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pickup device for a magneto-optical disk in which the size is small, the optical utilization efficiency is high, the degree of freedom in designing is high and the mass-productivity and the precision in processing are superior. SOLUTION: A beam splitter 2 is provided between a semiconductor laser 1 that is a light source, a collimating lens 10 which is a converging means to converge light beams emitted from the laser 1 on a magneto-optical recording medium 12 and an objective lens 11. The beam splitter 2 is mainly made of optical crystal having a parallelogram cross section and polarizes and separates the reflected light beams from the medium 12. A photodetector 7 is provided on a stem 8 being the same as the laser 1 to detect the reflected light beams that are branched by the beam splitter 2 from the medium 12. A first diffraction element 6 is arranged between the beam splitter 2 and the photodetector 7 to diffract a portion of the reflected light beams that are separated by the beam splitter 2 from the medium 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical disk drive, and more particularly to an optical pickup device used for a magneto-optical disk drive.

[0002]

2. Description of the Related Art Conventionally, as an optical pickup device for a magneto-optical disk, for example, the one shown in FIGS. 10 and 11 is disclosed in Japanese Patent Application Laid-Open No. 8-329544.

In this optical pickup device, a Si substrate 102 is disposed inside an optical module 101, and a semiconductor laser 103 as a light emitting element and photodetectors 104, 105, and 112 as light receiving elements are provided thereon. .
A transparent substrate 106 made of glass or resin is disposed so as to hermetically seal the inside of the optical module 101, and a focus of ± 1st-order diffracted light diffracted by approximately 5 ° to 20 ° is provided on a surface facing the semiconductor laser 103. Holographic diffraction element (diffraction grating) 107 having a lens effect at different positions
Is provided. On the other surface of the transparent substrate 106, 3
Prism 10 in which three triangular prisms 108P, 108Q, 108R and thin polarization splitter 109 are combined
8 are arranged. This thin polarization separation element 109 is
For example, it is a polarization separation / diffraction element made of lithium niobate. The incident light is separated into two linearly polarized light components orthogonal to each other, and one linearly polarized light component is defined as a zero-order light and the other linearly polarized light component is defined as a ± first-order light. It has the function of emitting light. An objective lens 110 is arranged between the optical module 101 and the magneto-optical recording medium 111.

[0004] The basic operation of the conventional optical pickup device for a magneto-optical disk thus configured will be described below.

[0005] P-polarized light emitted from the semiconductor laser 103 passes through a transparent substrate 106 provided with a hologram diffraction element 107, and is polarized by a polarization separation surface 1 of a polarizing prism 108.
08a. In this polarization separation surface 108a, the transmittance of P-polarized light is approximately 70%, the reflectance of P-polarized light is approximately 30%, and S
Since the reflectance of the polarized light is set to approximately 100%, approximately 70% of the light is transmitted and condensed on the magneto-optical recording medium 111 by the objective lens 110. Then, the magneto-optical recording medium 1
In No. 11, the plane of polarization of the light is rotated by about 0.5 ° by the recorded magnetic signal, and a small S
The light having the polarized component is reflected. This magneto-optical recording medium 1
The light reflected by the light 11 passes through the objective lens 110 again and passes through the polarization separation surface 10 of the polarization projection rhythm 108.
Return to 8a. At this time, since the transmittance of the P-polarized light is set to approximately 70%, the reflectance of the P-polarized light is set to approximately 30%, and the reflectance of the S-polarized light is set to approximately 100% on the polarization separating surface 108a as described above, About 70% of the component is transmitted, and 3
0% and 100% of the S-polarized light component which is a magneto-optical signal component is reflected.

The light reflected by the polarization separation surface 108a is separated into two linearly polarized light components orthogonal to each other by the thin polarization separation element 109, one of which is emitted as 0-order light, and the other is emitted as ± 1st-order light. Are reflected by the reflection surface 108b. Then, the + 1st-order diffracted light is output from the photodetector 11 shown in FIG.
On 2a, the 0th-order diffracted light is focused on the photodetector 112b, and the -1st-order diffracted light is focused on the photodetector 112c. Assuming that the electric signal outputs of the photodetectors 112a, 112b, 112c at this time are S1, S2, S3, respectively, the magneto-optical signal MO is obtained by MO = S1 + S3-S2.

On the other hand, the light transmitted through the polarization splitting surface 108a is reflected by the hologram diffraction element 1 formed on the transparent substrate 106.
07. Then, the + 1st-order diffracted light is applied to the photodetector 10
4, the -1st-order diffracted light enters the photodetector 105. At this time, the hologram diffraction element 107 has a lens effect such that the focal positions of the ± 1st-order diffracted lights are different.
7, and the -1st-order light is focused farther from the hologram diffraction element 107 than the photodetector 105.
When the light converged by the objective lens 110 on the magneto-optical recording medium 111 is correctly focused on the medium, FIG.
As shown in FIG. 1, the diameters of the light spots on the photodetector 104 and the photodetector 105 become equal,
The electric signal outputs of a to 104f are S4 to S9, and the photodetector 1
Assuming that the electric signals 05a to 105f are S10 to S15, the focus error signal FE is FE = (S4 + S6 + S7 + S9 + S11 + S14)-
(S5 + S8 + S10 + S12 + S13 + S15).

Also, portions 104a to 104a of the photodetector 104
By arranging the optical pickup device such that the dividing line that separates 04c from 104d to 104f is parallel to the information track direction on the magneto-optical recording medium 111, the tracking error signal TE can be obtained based on the so-called push-pull method. , TE = (S4 + S5 + S6 + S13 + S14 + S15)
− (S7 + S8 + S9 + S10 + S11 + S12)

On the other hand, Japanese Patent Application Laid-Open No. 9-44893 discloses a package 210 in which a hologram 217 is arranged on photodiodes 213, 214, and 215 integrated with a semiconductor laser 212 as shown in FIG. An optical pickup device in which a polarizing beam splitter 218 and a quarter-wave plate 219 are bonded and fixed in this order is disclosed.

In this optical pickup device, light emitted from a semiconductor laser 212 passes through a beam splitter 218 and is converted into circularly polarized light by a １ ／ wavelength plate 219, and thereafter, is converted into a circularly polarized light by an objective lens 204. It is collected. The light reflected by the information recording medium 205 is 1
The light is converted into linearly polarized light having a different direction by 90 ° by the ゜ wavelength plate 219. The light is reflected 100% by the beam splitter 218, reaches the hologram 217, is diffracted, and then enters the photodiodes 213, 214, and 215.

[0011]

However, in the optical pickup device for a magneto-optical disk disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-329544, the hologram diffraction element 107 includes the semiconductor laser 103 and the magneto-optical recording medium 111.
Therefore, the following problems occur.

First, since the amount of light reaching the magneto-optical recording medium 111 is reduced by being diffracted by the hologram diffraction element 107, a semiconductor laser having a higher output is required.

Next, when the light emitted from the semiconductor laser 103 and diffracted by the hologram diffraction element 107 enters the objective lens 110, it is reflected by the magneto-optical recording medium 111 and projected on the photodetectors 104 and 105. Therefore, false signals are generated in the focus error signal and the tracking error signal. In order to prevent this, the present inventors have proposed
As disclosed in Japanese Patent No. 3703, the formation area of the hologram diffraction element 107 may be limited. However, as the wavelength of light becomes shorter, the grating pitch of the hologram diffraction element 107 becomes shorter in proportion thereto. It becomes difficult to manufacture at low cost.

Since the size of the polarizing prism 108 is 2 mm to 5 mm due to restrictions on the arrangement and manufacturing, the distance from the light detector 104 to the light detector 112 is also 2 mm to 5 mm.
5 mm, which is 2 to 5 times the size of a normal Si substrate 1
02 is required, so that the cost of the photodetector increases.

In addition, the polarizing prism 108 is polished 3
Two triangular prism-shaped glass members (triangular prism) 108P,
108Q, 108R) and a strip-shaped thin polarizing beam splitter 10
9 is bonded and polished and cut, so that only about 10 to 20 pieces can be processed at a time, which is disadvantageous in cost and accuracy.

Further, since the photodetectors 104 and 105 are arranged near the semiconductor laser 103, the transparent substrate 10
The radiated light from the semiconductor laser 103 reflected at 6 is incident on these photodetectors, and a false servo signal is likely to be generated.

On the other hand, in the optical pickup device disclosed in Japanese Patent Application Laid-Open No. 9-44893, since the hologram 217 is not disposed between the semiconductor laser 212 and the information recording medium 205, the amount of light reaching the information recording medium 205 Is not reduced, and the light diffracted by the hologram 217 does not enter the information recording medium 205 to generate a false signal. Also, since the formation area of the photodiodes 213 to 215 is not related to the size of the beam splitter,
The area of the substrate can be reduced. Further, since the photodiodes 213 to 215 are not in the vicinity of the semiconductor laser 212, the radiated light of the semiconductor laser 212 does not enter these photodiodes to generate a false signal.

However, in this conventional technique, a magneto-optical signal cannot be detected, so that the magneto-optical disk cannot be reproduced, and cannot be used as an optical pickup device for a magneto-optical disk as in the present invention. .

The adhesive for fixing the beam splitter 218 is composed of the hologram 217 and the beam splitter 21.
8 may deteriorate the optical characteristics due to bubbles of the adhesive. Furthermore, beam splitter 2
Since the prism 18 has a prism having a triangular cross section and a prism having a parallelogram cross section, there is a problem in processing accuracy and cost.

The present invention has been made to solve such problems of the prior art, and is small in size, has high light use efficiency, can improve the degree of freedom in design, has good optical characteristics, and can be mass-produced. It is an object of the present invention to provide an optical pickup device for a magneto-optical disk which is excellent in performance and processing accuracy.

[0021]

An optical pickup device according to the present invention comprises: a light source; a light condensing means for condensing light emitted from the light source on a magneto-optical recording medium; A beam splitter that is disposed on an optical path leading to the optical path and is mainly made of an optical crystal having a parallelogram cross-section and that separates polarized light from reflected light from the magneto-optical recording medium; and a beam splitter disposed in the same package as the light source A light detector that detects reflected light from the magneto-optical recording medium separated by the light source, deviates from an optical path from the light source to the magneto-optical recording medium, and moves from the beam splitter to the light detector. A first diffraction element for diffracting a part of the reflected light from the magneto-optical recording medium separated by the beam splitter is arranged on the optical path, thereby achieving the above object.

The beam splitter has a first reflecting surface for reflecting a part of the reflected light from the magneto-optical recording medium;
A second reflecting surface for reflecting light reflected from the first reflecting surface in the direction of the photodetector.

The beam splitter is a polarizing beam splitter for splitting reflected light from the magneto-optical recording medium into two polarized components orthogonal to each other on an optical path from the first reflecting surface to the second reflecting surface. May be provided.

It is preferable that the package has a plurality of mounting surfaces having different heights, and the first diffraction element and the beam splitter are mounted on different mounting surfaces.

A second diffraction element for splitting light from the light source into three or more lights may be arranged on an optical path from the light source to the beam splitter.

[0026] The second diffractive element may be formed on the same substrate as the first diffractive element.

[0027] The second diffraction element may be formed on the same surface of the substrate as the first diffraction element.

The operation of the present invention will be described below.

In the present invention, a beam splitter is provided between the light source and the condensing means, and a first diffraction element is provided between the beam splitter and the photodetector.
Since the first diffraction element is out of the optical path from the light source to the magneto-optical recording medium, the quantity of light from the semiconductor laser does not decrease due to diffraction, and is transmitted to the magneto-optical recording medium with less loss. Further, there is no need to consider that the diffracted light from the first diffractive element does not enter the condensing means, and the degree of freedom in designing the diffractive element is improved. Further, since the diffraction angle may be small, the grating interval of the diffraction element can be kept large even if the wavelength of light becomes short. Therefore,
For example, the first diffraction element can be manufactured by a method such as contact exposure.

Since the arrangement of the photodetectors is not related to the size of the beam splitter as in the conventional optical pickup device, the area of the Si substrate on which the photodetectors are formed can be reduced. In addition, since the photodetector and the semiconductor laser can be arranged apart from each other, there is no possibility that the emitted light from the semiconductor laser is incident on the photodetector and a false servo signal is generated.

Since the beam splitter is mainly made of an optical crystal having a parallelogram cross section and is basically of a parallel plate type, it is possible to improve mass productivity and improve accuracy by cutting a large substrate after laminating it. Can be improved.

The beam splitter has a first reflecting surface that reflects a part of the reflected light from the optical recording medium, and a second reflecting surface that reflects the reflected light from the first reflecting surface toward the photodetector. By providing the surface, the photodetector and the semiconductor laser can be arranged in the same package to reduce the size.

Further, a polarization splitting element for splitting the reflected light from the optical recording medium into two polarization components orthogonal to each other is arranged on the optical path from the first reflection surface to the second reflection surface of the beam splitter. Thereby, the number of parts can be reduced.

A plurality of mounting surfaces having different heights are formed on the package, and the substrate on which the first diffraction element is formed and the beam splitter are mounted on different mounting surfaces, whereby the positions of the two can be adjusted independently. It becomes possible. In this case, since the adhesive or the like does not enter between them unlike the conventional optical pickup device, the optical characteristics do not deteriorate.

A second diffraction element for dividing light from the light source into three or more lights may be arranged on the optical path from the light source to the beam splitter. In this case, the tracking signal can be detected by a so-called three-beam method.

By forming the second diffraction element on the same substrate as the first diffraction element, it is possible to suppress an increase in manufacturing cost. Here, the first diffraction element and the second diffraction element may be formed on different surfaces, but by forming them on the same surface, it is possible to further suppress an increase in manufacturing cost.

[0037]

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

(Embodiment 1) FIG. 1 is a perspective view showing a schematic configuration of an optical pickup device of the present embodiment, and FIG. 2 is a sectional view thereof.

This optical pickup device includes a semiconductor laser 1 as a light source, and a collimating lens 10 and an objective lens 11 as focusing means for focusing light emitted from the semiconductor laser 1 on a magneto-optical recording medium 12. Have. On the optical path from the semiconductor laser 1 to the collimator lens 10, a beam splitter 2 for polarizing and separating the reflected light from the magneto-optical recording medium 12 is arranged. The beam splitter 2 is basically a parallel plate type, and is mainly made of an optical crystal having a parallelogram cross section. The same stem 8 as the semiconductor laser 1 is provided with a photodetector 7 for detecting the reflected light from the magneto-optical recording medium 12 separated by the beam splitter 2.

On the optical path from the beam splitter 2 to the photodetector 7, the semiconductor laser 1
And a first diffraction element (diffraction grating) 6 for diffracting a part of the reflected light from the magneto-optical recording medium 12 separated by the beam splitter 2 is provided.

A cap 9 is put on a stem 8 on which the semiconductor laser 1 and the photodetector 7 are arranged, and the light transmitting substrate 1 on which the first diffraction element 6 is formed is mounted on the cap 9.
4 and a beam splitter 2 are attached. A glass plate 15 is attached to the light passage area of the cap 9 for hermetic sealing. By hermetically sealing the inside of the package 13 including the stem 8 and the cap 9 in this manner, the relative position between the semiconductor laser 1 and the photodetector 7 can be stably maintained. As shown in FIG. 2, the cap 9 has two mounting surfaces 9a and 9b having different heights, and the light transmitting substrate 14 on which the first diffraction element 6 is formed and the beam splitter 2 have different mounting surfaces. Surface 9a, 9b
Is installed independently.

The beam splitter 2 has a first reflecting surface 3 that reflects a part of the reflected light from the magneto-optical recording medium 12.
And a second reflection surface 5 that reflects light reflected from the first reflection surface 3 in the direction of the photodetector 7. On the optical path from the first reflection surface 3 to the second reflection surface 5, there is provided a polarization separation element 4 for separating the reflected light from the magneto-optical recording medium 12 into two polarization components orthogonal to each other. . As the polarization separation element 4, for example, two optical crystal substrates having different optical axes can be used. The first reflection surface 3 has, for example, a reflectance of 30% for P-polarized light and a reflectance of 100 for S-polarized light.
Set to%. In this case, if the polarization direction of light emitted from the semiconductor laser 1 is P-polarization, the magneto-optical recording medium 12
When the reflected light from is reflected by the first reflecting surface, the apparent rotation amount of the polarization plane can be increased.

The operation of the thus-configured optical pickup device of this embodiment will be described below.

The light emitted from the semiconductor laser 1 passes through the beam splitter 2 and is focused on the magneto-optical recording medium 12 by the collimator lens 10 and the objective lens 11. The light reflected by the magneto-optical recording medium 12 has its polarization plane rotated in accordance with the direction of magnetization recorded on the magneto-optical recording medium 12, passes through the objective lens 11 and the collimator 10 again, and enters the beam splitter 2. I do. The light incident on the beam splitter 2 is reflected by the first reflection surface 3, separated into two polarization components orthogonal to each other by the polarization separation element 4, further reflected by the second reflection surface 5, and subjected to the first diffraction. The light enters the element 6.

As shown in FIG. 3, the first diffraction element 6
It has three regions 6a, 6b, 6c, and each region has a different lattice spacing. Then, the light separated into two orthogonal polarization components respectively enters as shown by a solid-line circle and a broken-line circle in FIG.

The light incident on the area 6a of the first diffraction element 6 is applied to the light detecting portion 7a of the photodetector 7 shown in FIG.
Are incident on the photodetector 7b, and the light incident on the region 6c is incident on the boundary between the photodetector 7c and the photodetector 7d. The light that has passed through the first diffraction element 6 as the 0th-order diffracted light enters the light detection units 7e and 7f.

Here, as shown in FIG. 1, since the linear portion of the region 6c of the first diffraction element 6 is set in a direction orthogonal to the track direction of the magneto-optical recording medium 12, the light detecting portion 7a The radial error signal based on the push-pull method is obtained by calculating the difference between the output signal of the photodetector 7b and the output signal of the photodetector 7b.
By calculating the difference between the output signals, a focus error signal based on the Foucault method is obtained. Also, the light detection unit 7e
The magneto-optical signal is reproduced by calculating the difference between this output signal and the output signal of the photodetector 7f.

(Embodiment 2) FIG. 5 is a perspective view showing a schematic configuration of an optical pickup device of this embodiment, and FIG. 6 is a sectional view thereof. Here, for the sake of simplicity, components having the same functions as those of the first embodiment are denoted by the same reference numerals.

In this optical pickup device, the second diffraction element 6 is arranged on the optical path from the semiconductor laser 1 to the beam splitter 2, and the number of the photodetectors 2 of the photodetector 7 is increased by two. Other than that, the configuration is the same as that of the first embodiment.

The second diffraction element 16 is formed on the light transmitting substrate 14.
Are formed on the same plane as the first diffraction element 6, and are linear gratings at a constant interval as shown in FIG. The light from the semiconductor laser 1 is split by the second diffraction element 16 into a total of three beams, two tracking beams and one information reproducing beam. Accordingly, three light spots are formed on the magneto-optical recording medium 12.

The three beams reflected by the magneto-optical recording medium 12 are reflected by the first reflecting surface 3 of the beam splitter 2 and separated into two orthogonal polarization components by the polarization splitting element 4. Two beams are formed. Then, the light is reflected by the second reflection surface 5 and enters the first diffraction element 6.

The first diffraction element 6 has three regions 6a, 6b, and 6c, as in the first embodiment, and the lattice spacing is different in each region. Then, the light separated into two orthogonal polarization components is incident as shown by a solid circle and a broken circle in FIG. 8, respectively.

The photodetector 7 has a photodetector 7g as shown in FIG. 9 in addition to the photodetectors 7a to 7f shown in the first embodiment.
And 2h, and the two tracking beams transmitted through the first diffraction element as the 0th-order diffracted light are incident on the photodetectors 7g and 7h, respectively.

Therefore, by calculating the difference between the output signal of the light detection unit 7g and the output signal of the light detection unit 7h, a radial error signal based on the three-beam method is obtained, and the output signal of the light detection unit 7c and the light detection unit By calculating the difference between the 7d output signals, a focus error signal based on the Foucault method is obtained. A so-called push-pull signal is obtained by calculating the difference between the output signal of the light detection unit 7a and the output signal of the light detection unit 7b. It is used for detecting an address signal recorded in a meandering manner. Further, the magneto-optical signal is reproduced by calculating the difference between the output signal of the light detection unit 7e and the output signal of the light detection unit 7f.

[0055]

As described above in detail, in the case of the present invention, the beam splitter is provided between the light source and the condensing means, and the first diffraction element is provided between the beam splitter and the photodetector. The arrangement allows the light from the semiconductor laser to be transmitted to the magneto-optical recording medium with less loss. Since the light use efficiency can be improved, a magneto-optical signal can be detected even when a semiconductor laser having a low output is used. Further, there is no need to consider that the diffracted light from the first diffractive element does not enter the condensing means, and the degree of freedom in designing the diffractive element is improved. Furthermore, since the diffraction angle may be small, the lattice spacing of the diffraction element can be kept large even when the wavelength of light is short, and it can be manufactured by a method with high productivity such as contact exposure, for example. The manufacturing cost can be reduced.

Since the arrangement of the photodetectors is not related to the size of the beam splitter as in the conventional optical pickup device, the area of the Si substrate on which the photodetectors are formed can be reduced, and the mass productivity is improved. be able to. In addition, since the photodetector and the semiconductor laser can be arranged apart from each other, it is possible to prevent the emission light from the semiconductor laser from being incident on the photodetector and generate a false servo signal, thereby improving reliability.

Since the beam splitter is mainly made of an optical crystal having a parallelogram cross section, it can be manufactured by stacking large substrates and then cutting. Therefore, it is possible to prevent a failure at the time of assembling, thereby improving mass productivity and improving processing accuracy.

According to the present invention, the beam splitter includes a first reflecting surface for reflecting a part of the reflected light from the optical recording medium, and a reflected light from the first reflecting surface in a direction toward the photodetector. By providing the second reflecting surface for reflection, the photodetector and the semiconductor laser can be arranged in the same package to reduce the size. Further, by disposing a polarization separation element that separates the reflected light from the optical recording medium into two polarization components orthogonal to each other on an optical path from the first reflection surface to the second reflection surface of the beam splitter, The score can be reduced.

A plurality of mounting surfaces of different heights are formed on the package, and the substrate on which the first diffraction element is formed and the beam splitter are mounted on different mounting surfaces, whereby the positions of the two can be adjusted independently. It becomes possible. Further, since an adhesive or the like does not enter between them unlike the conventional optical pickup device, the optical characteristics are not degraded, and the reliability can be further improved.

Further, if a second diffraction element for dividing light from the light source into three or more lights is arranged on the optical path from the light source to the beam splitter, the tracking signal can be detected by the so-called three-beam method. it can. Therefore, an offset is less likely to occur in the tracking signal due to the tilt or tracking action of the magneto-optical recording medium. By forming the second diffraction element on the same surface on the same substrate as the first diffraction element, it is possible to suppress an increase in manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of an optical pickup device according to a first embodiment.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of the optical pickup device according to the first embodiment.

FIG. 3 illustrates a first example of the optical pickup device according to the first embodiment.
FIG. 4 is a plan view of the diffraction element of FIG.

FIG. 4 is a plan view of a photodetector in the optical pickup device according to the first embodiment.

FIG. 5 is a perspective view illustrating a schematic configuration of an optical pickup device according to a second embodiment.

FIG. 6 is a cross-sectional view illustrating a schematic configuration of an optical pickup device according to a second embodiment.

FIG. 7 illustrates a second example of the optical pickup device according to the second embodiment.
FIG. 4 is a plan view of the diffraction element of FIG.

FIG. 8 illustrates a first example of the optical pickup device according to the second embodiment.
FIG. 4 is a plan view of the diffraction element of FIG.

FIG. 9 is a plan view of a photodetector in the optical pickup device according to the second embodiment.

FIG. 10 is a sectional view showing a schematic configuration of a conventional optical pickup device.

FIG. 11 is a plan view showing an arrangement of a photodetector in a conventional optical pickup device.

FIG. 12 is a cross-sectional view illustrating a schematic configuration of a conventional optical pickup device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 semiconductor laser 2 beam splitter 3 first reflection surface 4 polarization separation element 5 first reflection surface 6 first diffraction element 7 photodetector 8 stem 9 cap 10 collimation 11 objective lens 12 magneto-optical recording medium 13 package 14 Light transmitting substrate 15 Glass plate 16 Second diffractive element

Claims (7)

[Claims] 1. A light source; a light condensing means for condensing light emitted from the light source onto a magneto-optical recording medium; A beam splitter, which is made of an optical crystal of a shape, and polarization-separates the reflected light from the magneto-optical recording medium; and a beam splitter disposed in the same package as the light source and reflected from the magneto-optical recording medium separated by the beam splitter. A light detector for detecting light, deviated from an optical path from the light source to the magneto-optical recording medium, and separated by the beam splitter on an optical path from the beam splitter to the photodetector. An optical pickup device in which a first diffraction element for diffracting a part of light reflected from an optical recording medium is arranged. 2. A beam splitter, comprising: a first reflecting surface that reflects a part of the reflected light from the magneto-optical recording medium; and a reflected light from the first reflecting surface in a direction toward the photodetector. The optical pickup device according to claim 1, further comprising a second reflection surface that reflects light. 3. A beam splitter, on a light path from the first reflection surface to the second reflection surface, for separating a reflected light from the magneto-optical recording medium into two polarization components orthogonal to each other. The optical pickup device according to claim 2, further comprising a separation element. 4. The package according to claim 1, wherein the package has a plurality of mounting surfaces having different heights, and the first diffraction element and the beam splitter are mounted on different mounting surfaces. An optical pickup device as described in Crab. 5. The optical system according to claim 1, wherein a second diffraction element that divides light from the light source into three or more lights is disposed on an optical path from the light source to the beam splitter. An optical pickup device as described in Crab. 6. The optical pickup device according to claim 5, wherein the second diffraction element is formed on the same substrate as the first diffraction element. 7. The optical pickup device according to claim 6, wherein the second diffraction element is formed on the same surface of the substrate as the first diffraction element.