JP4072776B2 - Optical pick-up module and magneto-optical signal recording / reproducing apparatus - Google Patents

Description

  The present invention relates to an optical pickup module and a magneto-optical signal recording / reproducing apparatus, and is intended to enable control and information signals to be formed with particularly high accuracy.

  Conventionally, as shown in FIG. 15, an optical pickup 1 used in a magneto-optical disk apparatus converts laser light emitted from a laser diode 2 as a light source into a grating element 3, a beam splitter 4, a collimator lens 5, and an objective lens. 6 is sequentially collected on the magneto-optical disk 11, and the reflected light is passed through the objective lens 6, the collimator lens 5, the beam splitter 4, the Wollaston prism 7 and the multi-lens 8 in order and connected to the photodetector 9. The thing of the structure which is imaged is used.

  However, the optical pickup 1 having this configuration has a configuration in which a plurality of optical components are individually combined. Therefore, there is a problem that it is difficult to reduce the size of the entire apparatus and to improve reliability.

  Therefore, in the case of a magneto-optical disk reproducing apparatus, it is desired to realize a small and highly reliable optical pickup like the optical pickup 20 shown in FIG. 16 used in a compact disk reproducing apparatus.

  The optical pick-up 20 has an optical pick-up module 21, and laser light emitted from a laser diode LD provided as a light source in a housing 22 of the optical pick-up module 21 is formed on a slope of a trapezoidal glass prism 23. The light is reflected by the translucent film 24 attached to the surface, and sequentially passes through the transparent cover plate 25, the reflection mirrors 26 and 27, and the objective lens 28 to irradiate the optical disk 29, and the reflected light is reflected on the objective lens 28 and the reflection. The light passes through the mirrors 27 and 26 sequentially and is guided to the translucent film 24 as return light.

  The glass prism 23 is provided on the semiconductor substrate 30 together with the laser diode LD, introduces return light that has passed through the semitransparent film 24 into the glass prism 23, and adheres between the bottom surface of the glass prism 23 and the semiconductor substrate 30. The reflected light is reflected so as to be folded back between the translucent film 31 and the total reflection film 32 attached to the upper surface of the glass prism 23 and the semitransparent film 31 on the bottom surface.

  Thus, the return light introduced into the glass prism 23 is transmitted to the two photodetectors PD1 and PD2 provided on the semiconductor substrate 30 at the front and rear positions sandwiching the total reflection film 32 that is conjugate to the laser diode LD. Thus, information detection signals are output from the photodetectors PD1 and PD2.

  Since the optical pickup module 21 having this configuration forms a non-polarization optical system as a whole, it cannot be used for reproducing a magneto-optical signal. However, an optical pickup for a magneto-optical disk is configured with the same configuration. If possible, it is considered that further downsizing can be realized as compared with the optical pickup currently used.

  The present invention has been made in view of the above points, and aims to realize an optical pickup and a magneto-optical signal recording / reproducing apparatus that are smaller and more reliable than those of the prior art.

In order to solve such a problem, in the present invention, on a semiconductor substrate, first and second planes made of a birefringent material made of a uniaxial crystal or a biaxial crystal and parallel to each other, and the first and second planes. An optical pickup module in which a prism-shaped polarization separation element having a slope formed in a direction oblique to the second plane and a light-emitting element serving as a light source are integrally mounted and formed on a semiconductor substrate. The return light from the magneto-optical disk enters from the inclined surface of the polarization separation element and is bent in the direction of the first plane on the semiconductor substrate side of the polarization separation element, whereby the first part of the return light is separated while being separated. A first light receiving unit group for detecting a part of the return light when transmitted through a semi-transmissive film provided below the plane of the second plane, and the other part of the return light reflected by the semi-transmissive film is a second plane. Reflected by the reflective layer provided on the The second and second beams are detected below the first plane by being bent in the direction of the first plane and separating the first and second separated light beams when the other part of the return light is incident on the slope. The optical axis of the uniaxial crystal is set in a plane perpendicular to the normal line of the reflecting surface, or the optical axis of the uniaxial crystal is the main axis to the uniaxial crystal. It is set in a plane parallel to the normal of the light incident surface and the normal of the reflecting surface, or the orientation with respect to the refractive index having a large difference from the intermediate refractive index among the orientations of the refractive indices of the biaxial crystal is The orientation corresponding to the refractive index which is set in a plane perpendicular to the normal line of the reflecting surface or has a larger difference from the intermediate refractive index among the orientations of the refractive indices of the biaxial crystal is the biaxial property. An optical pickup module set in a plane parallel to the normal of the principal ray to the crystal and the normal of the reflecting surface is used.

According to the present invention, the prism-shaped polarization separation element is a uniaxial crystal or a birefringent material alone made of a biaxial crystal, and the optical axis of the uniaxial crystal is perpendicular to the normal line of the reflecting surface. Or the optical axis of the uniaxial crystal is set in a plane parallel to the normal of the incident surface of the principal ray to the uniaxial crystal and the normal of the reflective surface, or The orientation with respect to the refractive index having the larger difference from the intermediate refractive index among the orientations of the refractive indices of the biaxial crystal is set in a plane perpendicular to the normal line of the reflecting surface, or the birefringence of the biaxial crystal The orientation corresponding to the refractive index having the larger difference from the intermediate refractive index among the orientations of the refractive indices is in a plane parallel to the normal of the principal ray to the biaxial crystal and the normal of the reflecting surface. By being set , control and information signals can be formed with high accuracy from the return light from the magneto-optical disk.

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

(1) Optical Pickup (1-1) Birefringence An optical pickup according to an embodiment of the present invention is used as a polarization separation element and is bonded to a single birefringent material (with different axial orientations of refractive index ellipsoids representing the properties). And the incident light is reflected at least once in the element.

For this reason, the polarized light is normally separated by transmitting the light incident on the element without reflecting it inside. In the case of this embodiment, as shown in FIG. 1, it is an important item that the refraction direction at the interface varies depending on the difference in the electric field density vector D (that is, the direction of the wavefront normal line k varies). As a result, incident light is separated into ordinary light (o-ray) and extraordinary light (e-ray without walk-off). FIG. 1 shows a case where convergent light is incident from the air on a uniaxial crystal YVO ₄ (ne = 2.1893 and no = 1.9734 at λ = 780 [nm]), and o-ray is a light beam according to Snell's law. E-ray represents a ray that does not follow Snell's law.

  On the other hand, in the case of this embodiment, the light ray incident in the element is reflected one or more times, and birefringence is an important item. This birefringence means that if the oscillation direction of the electric field density vector D is different even if the wavefront normal vector k is the same inside the crystal, the light ray (direction in which the energy of light travels) vector S (= electric field vector E of light wave × magnetic field of light wave) A phenomenon in which the vector H) is different. Hereinafter, birefringence will be described.

As shown in FIG. 2, the refractive index for the light beam traveling in the birefringent crystal is two ellipses formed when the refractive index ellipsoid is cut by a plane perpendicular to the wavefront normal vector k of the light beam and passing through the origin. It can be expressed by the length of the axis, that is, the vectors D1 and D2, and the direction of the axis at that time is the direction of the electric field density vector D corresponding to the refractive index. Incidentally, if the polarized light is incident so as to be approximately 45 ° with respect to the vectors D1 and D2 in FIG. 2, a magneto-optical signal can be obtained by the difference between the two components after polarization separation.

In short, this difference in refractive index is the difference in wavefront normal vector k in FIG. 1 (difference between ordinary ray (o-ray) and extraordinary ray (e-ray without walk-off)). However, strictly speaking, since the refractive index changes depending on the difference of the wavefront normal vector k, it is necessary to consider the refractive index change.
Thus, the wavefront normal vector k generated by the difference in refractive index can be determined by the combination of the refractive index and the intrinsic polarization vector D using the fact that the wavefront normal vector k follows Snell's law. .

For this reason, if only the polarized light is separated, the difference in the wavefront normal vector k is sufficient. However, in order to accurately grasp how the separated light beam travels, the wavefront normal vector k and the light vector S It is necessary to take into account the fact that it is off (ie Walk-off).
This ray vector S is calculated by the following equation. First, the electric field vector E in the birefringent material satisfies D = εE, and D and ε are known (since the refractive index ellipsoid is known, ε is also known from n ² = ε / ε ₀ ). To obtain the electric field vector E as ε ⁻¹ D.

Further, as shown in FIG. 3, the magnetic field vector H and the magnetic flux density vector B have H // B // k × D, and the direction of the magnetic field vector H is also known. From E, S = E × H.
This formula also holds for reflection. The birefringent crystal is generally separated in two directions at the interface, as described above, based on the fact that the refractive index differs depending on the ray wavefront vector k and the eigenvector D.
Considering these things, the case of ray tracing is the e-ray (with walk-off) in FIG. Incidentally, FIG. 1 is a diagram in the case where no reflection occurs in the crystal.

(1-2) Polarization separation element (Y direction separation type)
Next, the configuration of the polarization separation element according to the present invention will be described. As shown in FIG. 4A, the uniaxial crystal is set in a plane perpendicular to the normal line of the reflecting surface as a polarization separation element 41 that passes the reflected light twice by reflecting it twice. To do. At this time, the P-polarized light and the S-polarized light are separated in the y-axis direction as indicated by the spot groups “ooo” and “eeee” in FIG.

  In the case of this polarization separation element, the optical characteristics of the crystal are suppressed so that there is no phase difference and reflectance difference between the P-polarized light and the S-polarized light before and after reflection. In this way, the relationship between the intrinsic polarization vector D and the S and P polarizations is preserved before and after the reflection, and the intrinsic refractive index also agrees before and after the reflection. Therefore, no separation of rays other than the spot groups “ooo” and “eeee” occurs at the reflection interface, and only two spot groups “ooo” and “eeee” are completely separated on the two photodetectors separated from each other. And condensed.

In FIG. 4B, the spot group “ooo” indicates that when incident light passes through the first, second, and third times, no movement occurs as an ordinary ray “o” at all passages. .
On the other hand, the spot group “eeee” moves as the extraordinary ray “e” by the vector e1 in the y direction for the first time when the incident light passes the first time, the second time, and the third time, and then the second time. In the third pass, it indicates that the vector e2 and e3 have moved in the x direction as an extraordinary ray “e”.

  Incidentally, even if the phase difference and the reflectance difference are generated before and after the reflection and the spots are separated, the spot light to be sequentially separated spreads a little after the subsequent reflection, but finally the spot group is maintained. A magneto-optical signal can be obtained if a differential output is obtained from two spot groups that are clearly divided among the eight spot groups considered in this way.

  The polarization separation element described above is a case where the crystal is a uniaxial crystal. However, when the crystal is a biaxial crystal, the refraction having the larger difference from the intermediate refractive index in the refractive index orientation of the crystal is larger. The direction corresponding to the rate may be set in a plane perpendicular to the normal line of the reflecting surface. In this case as well, incident light is reflected at least once in the crystal. In the case of this example, if two of the three refractive indexes that are close to the refractive index are considered as no, and the remaining one as ne, it is easy to cope with them.

Furthermore, in this configuration, if the azimuth corresponding to the intermediate refractive index among the three refractive index azimuths of the crystal is set to an azimuth parallel to the normal line of the reflecting surface, the difference between no and ne will increase. (The separation angle of light can be increased), and a polarization separation element close to actual use can be obtained.
In the case of these biaxial crystals, the same effect as in the case of the uniaxial crystals can be obtained, whereby a polarization separation element having a wide selection range of crystal materials and a large degree of design freedom can be obtained.

(1-3) Polarization separation element (X direction separation type)
As shown in FIG. 5A, the polarization separation element 41 has an optical axis of a uniaxial crystal in a plane parallel to the normal line of the principal ray incident on the crystal and the normal line of the reflection surface. Set. At this time, the P-polarized light and the S-polarized light are separated in the x-axis direction as two spots “oeo” and “eoe” as shown in FIG.

  In FIG. 5B, the spot “eoe” indicates that when the return light incident on the position “ooo” passes through the polarization separation element 41 for the first time, the second time, and the third time, the extraordinary ray “e” appears for the first time. Represents that the vector e1 moves in the x direction, and the second time does not move as the ordinary ray “o”, and the third time as the extraordinary ray “e” moves by the vector e3.

On the other hand, the spot “oeo” does not move as an ordinary ray “o” at the first time, moves only by the vector e2 as an extraordinary ray “e” at the second time, and does not move as an ordinary ray at the third time. Represents.
As a result, the two spots “eoe” and “oeo” occur in positions separated in the x direction.

In this way, even if the same uniaxial crystal is used, the polarization separation direction can be changed by simply changing the arrangement of the optical axes, so that the design range of the optical system (servo error detection method, PD division method, etc.) can be increased. You can have it.
When a biaxial crystal is used for the polarization separation element, the orientation corresponding to the refractive index having a larger difference from the intermediate refractive index among the refractive index orientations of the crystal is set to the principal ray incident on the crystal. What is necessary is just to set in the surface parallel to the normal line of an entrance plane, and the normal line of a reflective surface. Even if it does in this way, the same effect as the above-mentioned can be acquired.

Furthermore, in this configuration, the refractive index of the crystal is such that the orientation corresponding to the intermediate refractive index among the three refractive index orientations of the crystal is parallel to the normal of the principal ray incident surface and the reflective surface incident on the crystal. If the azimuth is set, the difference between no and ne is increased apparently (the light beam separation angle can be increased), and a polarization separation element close to actual use can be obtained.
In the case of these biaxial crystals, the same effect as in the case of the uniaxial crystals can be obtained, whereby a polarization separation element having a wide selection range of crystal materials and a large degree of design freedom can be obtained.

In this way, by using a single birefringent material in the above-described polarization separation element, it is possible to realize a polarization separation element with high accuracy as long as it is not necessary to worry about the bonding accuracy of the optical axis at the time of manufacture.
In addition, since the polarization separation element is formed of a single birefringent material, a polarization separation element that is not affected by changes over time can be realized.

(2) Magneto-optical signal recording / reproducing apparatus FIG. 6 shows an optical pickup using the polarization separation element described in the previous section. FIG. 7 shows an optical system of a magneto-optical signal recording / reproducing apparatus using an optical pickup, and FIG.
As shown in FIG. 6, the optical pickup 41 has a laser diode LD, a polarization separation element 43, and the like mounted on a semiconductor substrate 42 on which photodetectors PD1, PD2, and PD3 are integrated.

  The polarization separation element 43 shown in this embodiment is the birefringent crystal described in the previous section, and reflects the light beam twice in the crystal. Here, the polarization separation element 43 is processed to have a substantially trapezoidal cross section, and the laser beam is reflected by the polarization beam splitter film 44 formed on the inclined surface facing the laser diode LD, and the recording surface of the magneto-optical disk is irradiated. It is made to do. Incidentally, a polarizing beam splitter film 44 having a transmittance of, for example, Ts = 30 [%] and Tp = 65 [%] is used.

The return light of the laser beam reflected by the recording surface of the magneto-optical disk is guided into the crystal of the polarization separation element 43 through the polarization beam splitter film 44, and a part of the return light is transmitted from the bottom surface of the polarization separation element 43 to the semi-transmissive film. And output to the photo detector PD1.
On the other hand, the laser light reflected by the bottom surface of the polarization separation element 43 is reflected again by the high reflection film 46 provided on the top surface of the polarization separation element 43 and then the photodetectors PD2 and PD3 below the bottom surface of the polarization separation element 43. It is condensed to.

The electrical signals output from these photodetectors PD1 to PD3 are converted into currents and voltages via an I / V amplifier circuit 53 as shown in FIG.
The matrix amplifier circuit 54 outputs the difference between the output signals obtained from the photodetectors PD2 and PD3 as a magneto-optical signal S3, and outputs the sum of any one of the output signals obtained from the photodetectors PD1 to PD3 as a pit signal S4.

The matrix amplifier circuit 54 calculates and outputs a focus error signal S2 from the output signal of the photodetector PD1 and at least one of the photodetectors PD2 and PD3, and outputs a tracking error from at least one of the photodetectors PD1 to PD3. The signal S1 is calculated and output.
The demodulation / decoding circuit 55 reproduces the information recorded on the magneto-optical disk 50 based on the inputted magneto-optical signal S3 and the pit signal S4, and outputs it to the processing circuit at the subsequent stage. Here, LN (LiNbO ₃ , uniaxial crystal) or KTP (KTiOPO ₄ , biaxial crystal) can be used as the polarization separation element 43.

  According to the above configuration, the optical pickup module 41 is formed by arranging the polarization separation element 43 and the light emitting element satisfying the conditions described above on the semiconductor substrate 42 on which the light receiving element is formed, thereby detecting the magneto-optical signal. The optical pickup for use can be reduced in size and weight. By configuring the optical pickup module 41 in this way, it is possible to reduce the adjustment man-hours and improve the reliability. Further, by using such a small optical pickup, it is possible to realize a magneto-optical signal recording / reproducing apparatus that is smaller than the conventional one.

  Accordingly, by obtaining at least one sum signal of the photodetectors PD1 to PD3, a pit RF signal can be obtained even when an optical disk is used as a recording medium. Therefore, the magneto-optical optical pickup and the laser coupler manufacturing facility can be shared for the optical disk.

As a crystal capable of realizing the optical pickup module 41 of FIG. 8 , LN (LiNbO ₃ ) as shown in FIG. 10, KTP (KTiOPO ₄ ) as shown in FIG. 11, or YVO ₄ as shown in FIG. 12 is applied. In any case, a practically sufficient separation between the spot groups was obtained.
10 to 12 , 44 is a beam splitter film, 45 is a semi-transmissive film, 46 is a highly reflective film, and 47 is an antireflection film.

(3) Other Embodiments In the above-described embodiment, the case where the light beam incident on the polarization separation element is reflected twice in the crystal element is described. However, the number of reflections is not limited to this, and the number of reflections is three times or more. May be hot. Increasing the number of reflections can increase spot separation and improve manufacturing tolerances. In this case, the polarization separation element can be made thinner, and sufficient spot separation can be realized. FIG. 9 shows a polarization beam splitting element having four reflections in the crystal.

  In the above-described embodiment, the optical pickup is for a magneto-optical disk. However, the present invention is not limited to this, and information is recorded from an optical recording medium such as a rewritable compact disk (MO-CD) or optical tape. The present invention can also be applied to an optical pickup used for reading out.

  Similarly, in the above-described embodiments, the magneto-optical disk reproducing apparatus has been described as an optical pickup application apparatus, but the present invention is not limited to this, and can be applied to an optical apparatus such as an optical tape recording apparatus.

Further, the optical pickup module 41 of FIG. 6 is configured so that the inclined surface for receiving incident light is wide open in the crystal of the polarization splitting element 43. In this case, however, as shown in FIG. The direct light may be irradiated to the photodetectors PD1 to PD3 as stray light.
As a configuration for preventing this stray light, a vertical surface 43B is formed in the vicinity of the bottom surface of the incident slope 43A as shown in FIG. In this way, stray light is blocked by the vertical surface 43B so that it cannot be incident, and even if it is incident on the bottom surface, it is totally reflected by the total reflection condition, so that at least input to the photodetector can be prevented. .

Further in the optical pickup modular Yule 41 of Figure 6, the beam splitter film 44 formed on the inclined surface forming a film that satisfies conditions such as R _S> R _P. In this way, enhancement of the magneto-optical signal can be realized and the ratio to noise can be improved.

It is an approximate line sectional view used for explanation of birefringence. It is a basic diagram which shows the intrinsic polarization direction seen from the side into which a light ray enters. It is a basic diagram which shows the relationship between a wave front normal direction and the direction where the energy of a light ray advances. 4A and 4B are schematic diagrams showing spot groups of rays finally separated after being reflected in the polarization separation element. 5A and 5B are schematic diagrams showing spot groups of rays finally separated after being reflected in the polarization separation element. 6A and 6B are a schematic cross-sectional side view and a transverse cross-sectional view showing the configuration of the optical pickup module. FIG. 3 is a schematic side view showing an attachment position of an optical pickup in a magneto-optical signal recording / reproducing apparatus. 1 is a block diagram showing a configuration of a magneto-optical signal recording / reproducing apparatus according to the present invention. It is a basic diagram with which it uses for description of the polarization separation element which reflects a light ray 4 times within a crystal | crystallization. FIGS. 10A and 10B are a schematic side sectional view and a transverse sectional view showing an optical pickup module when an LN crystal is used. FIGS. 11A and 11B are a schematic side sectional view and a transverse sectional view showing an optical pickup module when a KTP crystal is used. 12A and 12B are a schematic side sectional view and a transverse sectional view showing an optical pickup module when YVO ₄ crystal is used. It is side sectional drawing with which it uses for description about a stray light. It is a sectional side view which shows the Example which solved the problem of the stray light. It is a rough-line side view which shows the optical pickup used for the reproduction | regeneration of the conventional magneto-optical signal. FIGS. 16A and 16B are schematic side sectional views showing an optical pickup used for reproducing a compact disk.

Explanation of symbols

41... Optical pick-up module, 42... Semiconductor substrate, 43... Polarization separating element, 44... Polarized beam splitter, 45. Disc, 53... I / V amplification circuit, 54... Matrix amplification circuit, 55.

Claims (15)

On a semiconductor substrate , a birefringent material made of a uniaxial crystal and a parallel first and second planes and a slope formed in a direction oblique to the first and second planes are formed. An optical pickup module in which a prism-shaped polarization separation element having a light-emitting element as a light source is integrally attached,
The return light from the magneto-optical disk formed on the semiconductor substrate is incident from the inclined surface of the polarization separation element and is bent in the direction of the first plane on the semiconductor substrate side of the polarization separation element. A first light receiving unit group for detecting a part of the return light when the part of the return light is transmitted through a semi-transmissive film provided below the first plane while being separated;
The other part of the return light reflected by the semi-transmissive film is reflected by the reflection layer provided on the second plane and is bent in the direction of the first plane. A second and a third light receiving unit group for detecting, under the first plane, first and second separated light beams separated when incident on the slope with respect to the other part,
An optical pickup module , wherein an optical axis of the uniaxial crystal is set in a plane perpendicular to a normal line of the reflecting surface . On a semiconductor substrate, a birefringent material made of a uniaxial crystal and a parallel first and second planes and a slope formed in a direction oblique to the first and second planes are formed. An optical pickup module in which a prism-shaped polarization separation element having a light-emitting element as a light source is integrally attached,
The return light from the magneto-optical disk formed on the semiconductor substrate is incident from the inclined surface of the polarization separation element and is bent in the direction of the first plane on the semiconductor substrate side of the polarization separation element. A first light receiving unit group for detecting a part of the return light when the part of the return light is transmitted through a semi-transmissive film provided below the first plane while being separated;
The other part of the return light reflected by the semi-transmissive film is reflected by the reflection layer provided on the second plane and is bent in the direction of the first plane. Second and third light receiving unit groups for detecting the first and second separated light beams separated when incident on the inclined surface with respect to the other part, respectively, under the first plane;
With
The optical axis of the uniaxial crystal is set in a plane parallel to the normal line of the principal ray incident surface to the uniaxial crystal and the normal line of the reflection surface.
A light pickup module characterized by this. On a semiconductor substrate, a birefringent material made of a biaxial crystal and a parallel first and second planes and a slope formed in a direction oblique to the first and second planes are formed. An optical pickup module in which a prism-shaped polarization separation element having a light-emitting element as a light source is integrally attached,
The return light from the magneto-optical disk formed on the semiconductor substrate is incident from the inclined surface of the polarization separation element and is bent in the direction of the first plane on the semiconductor substrate side of the polarization separation element. A first light receiving unit group for detecting a part of the return light when the part of the return light is transmitted through a semi-transmissive film provided below the first plane while being separated;
The other part of the return light reflected by the semi-transmissive film is reflected by the reflection layer provided on the second plane and is bent in the direction of the first plane. Second and third light receiving unit groups for detecting the first and second separated light beams separated when incident on the inclined surface with respect to the other part, respectively, under the first plane;
With
The orientation with respect to the refractive index having the larger difference from the intermediate refractive index among the orientations of the refractive indices of the biaxial crystal is set in a plane perpendicular to the normal line of the reflecting surface.
A light pickup module characterized by this. On a semiconductor substrate, a birefringent material made of a biaxial crystal and a parallel first and second planes and a slope formed in a direction oblique to the first and second planes are formed. An optical pickup module in which a prism-shaped polarization separation element having a light-emitting element as a light source is integrally attached,
The return light from the magneto-optical disk formed on the semiconductor substrate is incident from the inclined surface of the polarization separation element and is bent in the direction of the first plane on the semiconductor substrate side of the polarization separation element. A first light receiving unit group for detecting a part of the return light when the part of the return light is transmitted through a semi-transmissive film provided below the first plane while being separated;
The other part of the return light reflected by the semi-transmissive film is reflected by the reflection layer provided on the second plane and is bent in the direction of the first plane. Second and third light receiving unit groups for detecting the first and second separated light beams separated when incident on the inclined surface with respect to the other part, respectively, under the first plane;
With
The orientation corresponding to the refractive index having the larger difference from the intermediate refractive index among the refractive index orientations of the biaxial crystal is the normal of the principal ray to the biaxial crystal and the method of the reflecting surface. Set in a plane parallel to the line
A light pickup module characterized by this. Of the three refractive index orientations of the biaxial crystal, the orientation corresponding to the intermediate refractive index is set to an orientation parallel to the normal of the reflecting surface.
The optical pick-up module according to claim 3. Of the three refractive index azimuths of the biaxial crystal, the azimuth corresponding to the intermediate refractive index is parallel to the incident surface of the principal ray on the biaxial crystal and the reflection surface. The refractive index orientation of the axial crystal is determined
The optical pickup module according to claim 4. Light pickup modular Yule according to any one of claims 1 to 4, characterized in that to obtain a magneto-optical signal based on the difference signal of the second and third detection signal detection part group. Obtaining a pit signal based on any one of the detection signals of the first, second, and third light receiving unit groups or the sum signal of the detection signals of the second, second, and third light receiving unit groups. The optical pickup module according to any one of claims 1 to 4, characterized in that it is characterized in that: Light pickup modular Yule according to claim 1 or 2 above polarization separating element, characterized in that a uniaxial crystal LN (LiNbO _3). The optical pickup module according to claim 3 or 4 , wherein the polarization separation element is a biaxial crystal KTP (KTiOPO ₄ ). Light pickup modular Yule according to claim 1 or 2, characterized in that the polarization separating element is uniaxial crystal YVO _4. On a semiconductor substrate , a birefringent material made of a uniaxial crystal and a parallel first and second planes and a slope formed in a direction oblique to the first and second planes are formed. An optical pickup module in which a prism-shaped polarization separation element having a light-emitting element as a light source is integrally attached,
The return light from the magneto-optical disk formed on the semiconductor substrate is incident from the inclined surface of the polarization separation element and is bent in the direction of the first plane on the semiconductor substrate side of the polarization separation element. A first light receiving unit group for detecting a part of the return light when the part of the return light is transmitted through a semi-transmissive film provided below the first plane while being separated;
The other part of the return light reflected by the semi-transmissive film is reflected by the reflection layer provided on the second plane and is bent in the direction of the first plane. A second and a third light receiving unit group for detecting, under the first plane, first and second separated light beams separated when incident on the slope with respect to the other part,
The optical axis of the uniaxial crystal is set in a plane perpendicular to the normal of the reflecting surface;
Irradiation light flux emitted from the light emitting element is applied to the magneto-optical disk, and the reflected light is incident on the polarization separating element of the optical pickup module as the return light, and the first, first, A control and information signal is formed based on detection signals obtained from the second and third light receiving unit groups. On a semiconductor substrate, a birefringent material made of a uniaxial crystal and a parallel first and second planes and a slope formed in a direction oblique to the first and second planes are formed. An optical pickup module in which a prism-shaped polarization separation element having a light-emitting element as a light source is integrally attached,
The return light from the magneto-optical disk formed on the semiconductor substrate is incident from the inclined surface of the polarization separation element and is bent in the direction of the first plane on the semiconductor substrate side of the polarization separation element. A first light receiving unit group for detecting a part of the return light when the part of the return light is transmitted through a semi-transmissive film provided below the first plane while being separated;
The other part of the return light reflected by the semi-transmissive film is reflected by the reflection layer provided on the second plane and is bent in the direction of the first plane. Second and third light receiving unit groups for detecting the first and second separated light beams separated when incident on the inclined surface with respect to the other part, respectively, under the first plane;
With
An optical axis of the uniaxial crystal is set in a plane parallel to a normal line of an incident surface of a principal ray to the uniaxial crystal and a normal line of the reflection surface;
Irradiation light flux emitted from the light emitting element is applied to the magneto-optical disk, and the reflected light is incident on the polarization separating element of the optical pickup module as the return light, and the first, Control and information signals are formed based on detection signals obtained from the second and third light receiving unit groups.
A magneto-optical signal recording / reproducing apparatus. On a semiconductor substrate, a birefringent material made of a biaxial crystal and a parallel first and second planes and a slope formed in a direction oblique to the first and second planes are formed. An optical pickup module in which a prism-shaped polarization separation element having a light-emitting element as a light source is integrally attached,
The return light from the magneto-optical disk formed on the semiconductor substrate is incident from the inclined surface of the polarization separation element and is bent in the direction of the first plane on the semiconductor substrate side of the polarization separation element. A first light receiving unit group for detecting a part of the return light when the part of the return light is transmitted through a semi-transmissive film provided below the first plane while being separated;
The other part of the return light reflected by the semi-transmissive film is reflected by the reflection layer provided on the second plane and is bent in the direction of the first plane. Second and third light receiving unit groups for detecting the first and second separated light beams separated when incident on the inclined surface with respect to the other part, respectively, under the first plane;
With
The orientation with respect to the refractive index having the larger difference from the intermediate refractive index among the orientations of the refractive indices of the biaxial crystal is set in a plane perpendicular to the normal line of the reflecting surface,
Irradiation light flux emitted from the light emitting element is applied to the magneto-optical disk, and the reflected light is incident on the polarization separating element of the optical pickup module as the return light, and the first, Control and information signals are formed based on detection signals obtained from the second and third light receiving unit groups.
A magneto-optical signal recording / reproducing apparatus. On a semiconductor substrate, a birefringent material made of a biaxial crystal and a parallel first and second planes and a slope formed in a direction oblique to the first and second planes are formed. An optical pickup module in which a prism-shaped polarization separation element having a light-emitting element as a light source is integrally attached,
The return light from the magneto-optical disk formed on the semiconductor substrate is incident from the inclined surface of the polarization separation element and is bent in the direction of the first plane on the semiconductor substrate side of the polarization separation element. A first light receiving unit group for detecting a part of the return light when the part of the return light is transmitted through a semi-transmissive film provided below the first plane while being separated;
The other part of the return light reflected by the semi-transmissive film is reflected by the reflection layer provided on the second plane and is bent in the direction of the first plane. Second and third light receiving unit groups for detecting the first and second separated light beams separated when incident on the inclined surface with respect to the other part, respectively, under the first plane;
With
The orientation corresponding to the refractive index having the larger difference from the intermediate refractive index among the orientations of the refractive indices of the biaxial crystal is the normal of the principal ray to the biaxial crystal and the method of the reflecting surface. Set to a plane parallel to the line,
Irradiation light flux emitted from the light emitting element is applied to the magneto-optical disk, and the reflected light is incident on the polarization separating element of the optical pickup module as the return light, and the first, Control and information signals are formed based on detection signals obtained from the second and third light receiving unit groups.
A magneto-optical signal recording / reproducing apparatus.

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