JPH0244552A - Optical pick-up - Google Patents

Abstract

PURPOSE:To cause an optical pick-up to be compact and light by causing a light incident through a first hologram to a second hologram and separating the light to plural optical beams for information signal detection and control signal detection with the second hologram CONSTITUTION:The light from a semiconductor laser 1 passes through a first hologram 5 and it is focused on the recording surface of a recording medium 3. A reflected light is incident to the hologram 5 and diffracted in a direction which is different from the layer 2. Then, the reflected light is passed through a 1/2 wavelength board 6 and incident to a second hologram 7. When the rotation of a polarizing surface is not received in the medium 3, intensity goes to be equal for the P-polarizing component and S-polarizing component of the light which is incident to the hologram 7. The P-polarizing component to transmit a half circle part 7a of the hologram 7 is photodetected by an optical detector S2 and the S-polarizing component to be diffracted by 1/4 circle parts 7b and 7c is photodetected by optical detectors S1 and S3 respectively. Then, a focus error signal is obtained by the detector S2 and a tracking error signal is obtained by the difference signal of the detectors S1 and S3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical optical pickup using a small program.

[Problems that conventional technology and inventions attempt to solve] Near [
, Information-related industries are making remarkable progress, and the amount of information being handled is also on the rise. For this reason, instead of recording or reproducing devices that use conventional magnetic heads to record or reproduce information, it is possible to record information at high density on a recording medium by irradiating a light beam. Optical information recording and reproducing apparatuses that can reproduce information recorded on a medium at high density at high speed are now being installed.

In addition, as a rewritable recording method, ``Y''C information is recorded on the recording medium according to the direction of magnetization (upward and downward), and ↑I'i information is reproduced using magneto-optical effects such as the Kerr effect. The magneto-optical method is attracting attention.

The magneto-optical method described in IVI requires an optical pickup capable of reading the rotation of the plane of polarization.

For example, patent application No. 62-3364 filed earlier by the applicant
In the optical pickup shown in Book 39, Mei ItiII, information signals are obtained in the following manner. That is, for example, P(
The recording medium is irradiated with the Q light, and the reflected light from the surface of the recording medium undergoes rotation of the plane of polarization due to the Kerr effect and becomes a light beam P1 or P2 having an S polarization component. This light is transmitted through a half-wave plate with an azimuth angle of 22.5 degrees, the plane of polarization is rotated by 45 degrees, and the light is made incident on a polarizing beam splitter, where it is split into two parts: reflected light and transmitted light. The reflected light and transmitted light are emitted in parallel by a bristle, received by a two-split photodetector, and converted into electrical signals. Then, in the differential circuit, J is used to calculate the difference between the outputs of each detection core of the two-split photodetector. (The &'F train is now running off the coast of Japan.

However, conventional optical pickups have the following disadvantages in obtaining information signals: 4) The optical system has a large number of optical and electronic parts, making it difficult to downsize and integrate into the IY system. There is also the problem that the adjustment of optical parts is
! ! was necessary.

In addition, conventional optical pickup requires an a+II control optical system for focus detection and tracking detection, and a difference fJ+ optical system divided into two, which increases the number of photodetectors.
In addition, especially) if the critical angle method is used for A-scatter detection and the focus A-cast error signal and 1 to racking error signal are detected by 4-split light detection, an error will occur, but it will not be separated. , there is a risk that they may overload each other and cause malfunction.

However, recently, in order to make the optical pickup smaller and lighter, an optical system using a hologram has been proposed.

For example, JP-A-62-120640 discloses that, although not for magneto-optical use, a t-phase type hologram, a surface relief type hologram, and a λ/4 plate are used to detect the emitted light from a light source.
An optical pickup is provided to separate the reflected light from the recording medium.

In addition, Japanese Patent Application Laid-Open No. 63-7/1149J'3 describes a magneto-optical optical pickup that focuses light directed from a light source toward a recording medium onto the recording medium, such as Hole 1-1. A jl-logogram that diffracts the OJ light toward the photodetector side is arranged by hand, and a third hologram for guiding the signal light to the two photodetectors is arranged between the two holograms and the two light beams. An optical pickup between the detector and the detector is disclosed.

Furthermore, as a related technique, Japanese Patent Laid-Open No. 62-249107 discloses a polarizing beam splitter using a phase-type diffraction grating that shifts the polarization property to the right.

By the way, in optical pickup, in addition to information No. 53, control rs for focus error signal and tracking error signal is used.
i: It is necessary to detect the number, but the
No. 20640 does not discuss detection of this control signal. -1, 1111, 14 questions, 1983-
Publication No. 7/1149 describes that the deviation in the A-scrap direction and the track direction can be detected by a third hoop (by devising the method of creating one gram), but the specifics are not disclosed. The method has not been disclosed.

In order to control the control signal with a lever, special bi1 1986~
As shown in Japanese Patent No. 277635e, it is conceivable to interpose a hologram in the optical path from the light source to the recording medium to separate the reflected light from the recording medium into beams for detecting control signals.

However, in this case, the diffraction efficiency decreases,
The amount of light irradiated onto the recording medium decreases, and the control 111
There is a problem in that the light reception on the photodetector for signal detection is reduced, resulting in deterioration of performance.

[1'1 Aspects of the Invention] The present invention has been made in view of the above circumstances, and has the following features: ! The purpose of the present invention is to provide an optical pickup that can efficiently convert 2Y information signals and υ control signals into 10 signals.

[Means for Solving the Problems] The optical pickup of the present invention includes a light source that emits light that illuminates a magneto-optical recording medium, and a light source that emits light that illuminates a magneto-optical recording medium. a first hologram that guides the reflected light from the recording medium in a direction different from the light source, and an optical path of the reflected light from the recording medium that has passed through the first hologram, Disposed outside the optical path from the light source to the recording medium, and reflecting light from the recording medium.

For information signal detection and control? a second hologram having a polarization property that allows molecules to be split into a plurality of optical beams for detecting 2n 4R, and information signal detection and control signals that receive each of the light beams separated by the second hologram. It is equipped with a photodetector for detection.

[Function] In the present invention, the light emitted from the light source passes through the first hologram and is irradiated onto the magneto-optical recording medium, and the plane of polarization is rotated according to the direction of magnetization of the magneto-optical recording medium. reflected. This reflected light passes through the first hologram, enters the second hologram, and is transmitted to the second hologram into a plurality of light beams for information signal detection and control No. 18 detection. Separated. This light beam is then received by a photodetector for information signal detection and control signal detection, and an information signal q and a control signal 19 are obtained.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

Figures 1 to 6 relate to the first embodiment of the present invention.
2 is an explanatory diagram showing the configuration of the optical pickup, FIG. 2 is an explanatory diagram showing the second hologram in FIG. 1, and FIG. 3 is an explanatory diagram showing the configuration of the optical pickup in a modification of the embodiment.
Figure 4 is a circuit diagram showing the circuit for generating information signals and control 211ft numbers, Figure 5 is an explanatory diagram showing the method for creating the first hologram, and Figure 6(a) is the second hologram. FIG. 6(b) is a polygonal explanatory diagram showing the method of creating the second hologram, and FIG. 6(b) is a polygonal explanatory diagram showing the irradiation area of the six lights on the dry plate during the creation of the second hologram.

As shown in FIG. 1, an optical pickup 11.1 for recording, reproducing, and erasing information on the magneto-optical recording medium 3, and a semicircular semiconductor laser 2 as a light source are emitted from the semiconductor laser 2. a first diffracting beam that diffracts and focuses the light onto the recording surface of the magneto-optical recording medium 3, and diffracts the reflected light from the recording medium 3 in a direction different from that of the semiconductor laser 2; E[Jgram 5, the first hologram 5
On the optical path of the reflected light from the recording medium 3 that has passed through,
1111 note 1/2 wavelength plate 6 and second hologram 7 arranged outside the optical path from the conductor laser 2 to the recording medium 3
and three photodetectors 31. which receive the light beam emitted from the second phonogram 7. S2. It is equipped with S3.

The semiconductor laser 2 emits linearly polarized light, for example, P-polarized light, and this light enters the first hologram 5 from an oblique direction. As this light passes through the first U-1 gram 5, the diameter of the ellipse in the short axis direction is expanded, the beam shape is shaped into a substantially circular shape, and the beam is focused, so that it is
Focus on the recording surface. In this recording medium 3, information J is recorded in the upward magnetization and the downward magnetization.

Therefore, the P-polarized light incident on the recording medium 3 has a magnetic light γ effect (Kerr effect) depending on the magnetization direction of the recording medium.
The plane of polarization rotates. For example, for upward magnetization, 3.
If the plane of polarization is rotated by θ degrees, then the plane of polarization is rotated by θ degrees for downward magnetization.

The reflected light whose polarization plane has been rotated in this way and has an S-polarized component is incident on the first hologram 5, and the semiconductor laser 2
The light is diffracted in a direction different from that of the light beam, passes through the 1/2 wavelength plate 6, and enters the second hologram 7. This second hologram 7 is shown in FIG.
One of them, the inner part 7a, becomes a surface relief type hologram having a polarization property that transmits P-polarized light.
b.

7C, each of which is a surface relief type hologram having a polarization property that diffracts S-polarized light. In addition, the surface relief type hologram l\ is a relief hot stone that uses birefringence, and the light in the direction of the relief and the downward polarization direction is reflected once, and the relief f! It transmits light with a polarization direction perpendicular to direction 4.

Also, the polarization direction of the incident light with respect to the second hologram 7 and the relief fj? of the second hologram 7? The azimuth angle of the 1/2 wave plate 6 is set to 22.5 degrees so that the angle b with the i direction is 45 degrees.

As a result, when the recording medium 3 does not receive rotation of the polarization plane LJ, the DI 1 enters the second hologram 7.
P polarization component of TM (polarized light perpendicular to the grating groove) of J light and T
The light intensity of the S-polarized component of E (polarized light parallel to the grating grooves) is made equal. Note that when the plane of polarization is rotated in the recording medium 3, the ratio of the P-polarized light component and the S-polarized light component changes depending on the upward magnetization and the downward magnetization.

P transmitted through the semicircular portion 7a of the second hologram 7
The polarized light component is received by the photodetector S2, and the 1/4 inner portion 7
The S-polarized light components diffracted by beams b and 7c are received by photodetectors Sz and 83, respectively. As shown in FIG. 4, the photodetector 82 has four divided photodetectors PjS2t, S22°S23. It has S24.

Next, a circuit for generating information and fli control signals will be described with reference to FIG.

First, regenerating the magneto-optical data section Y month, do the following.
C (!1. The adder 11 divides each of the four photodetectors S 21 , S 22 , S 2 ]
, S24 is multiplied by 1'J, and the adder C7 12 obtains a sum signal of the output signals of the photodetectors Sz and S3.

Then, the differential amplifier 13 outputs the difference signal between the outputs of the amplifier 11 and the adder 12, and the output signal of the differential amplifier 13 is used as the magneto-optical data section reproduction signal. roar. A photodetector S which is the output signal of the g adder 11
21, S22, S2], S24 correspond to the light intensity of the P-polarized component, while the output of the brightener 12, the No. 1 photodetector Sz, S:l
The sum A5 of the output signal corresponds to the light intensity of the SG light component.

Therefore, the output signal of the differential amplifier 13 corresponds to the difference between the optical intensity of the P polarization component and the optical intensity of the 5li2 optical component, and thereby 1. It is determined whether the magnetization is L direction magnetization or downward direction magnetization.

Further, the playback signal of the prepit section is transmitted to the adder 11.1.
It is obtained by the output signal of the summation device 14 which generates the sum signal of the two output signals.

Further, the focus error signal is processed as follows. That is, the Jn+C> unit 15 adds 17 to the outputs of the photodetectors S2t, S2:+, and the adder 16 adds the outputs of the photodetectors S22. A phase signal of the output signal of S24 is obtained. Then, the differential amplifier 17 generates a difference signal of 49
The output signal of this l-dynamic amplifier 17 becomes a focus error signal. In this embodiment, 1) the second hologram 7 also has a puif edge ridge function equal to J3t in the knife one-edge method, and the semicircular portion 7a of the second lli m+gram 7
In the in-focus state, the transmitted light is focused at the center of the L4-divided photodetector S2, and when the recording medium 3 approaches the in-focus position, it is focused as shown by the broken line in FIG. , photodetector S2
t, 1' circular shape on S2J side 04 L,, recording medium 3
is further away from the in-focus position u9, as shown by the solid line in FIG. It enters a semicircular shape on the S2+ side (
14. The diameter of the semicircle becomes smaller as it deviates from the focal point 1. Therefore, the differential amplifier 17 adjusts the light intensity of the photodetectors 82+ and 323 and the light intensity of the photodetector 323. A focus error signal 17 is generated by detecting the difference in light amount in S22 and S24.

In addition, the tracking J-hu signal is detected by the photodetectors S1, S]
111 by the output signal of the differential amplifier 18 which produces the difference p of the output signals of . In this embodiment, a push-pull method is used to detect the imbalance in the intensity distribution of the return light from the recording medium 3. In the A1-rack state, the incident light on the photodetector S+, S:l is fil are equal, but l−
L; L if it comes off the rack.

The photodetector S1. There is a difference in the amount of light required for S:l.

Therefore, 1) the fourth λ dynamic amplifier 18 is J, and the photodetector S is
1, 2 of the output signal of S3 (J to generate No. 5:
Then, tracking error No. 9 will be sent to 411.

Next, a method for creating the first hologram 5 will be explained with reference to FIG.

First, point P1 corresponding to the position of the semiconductor laser 2 facing the dry plate where photoresist is applied to the transparent substrate.
The diverging light of the recording light 0 diverging from the recording light 0 and the convergent light of the recording light 0 converging on the point P2 corresponding to the position of the recording medium 3 are irradiated and interfere with each other. Furthermore, the diverging light of the recording light a diverging from point 1) 3 corresponding to the position of the photodetector S2 and the convergent light of the recording light A are made to intersect by 1 degree, and after exposure and development, two-handed exposure method is performed. The first hologram 5 is created by. Incidentally, this first hologram 5 is referred to as, for example, a phase type edge t1.

Next, a method for creating the second hologram 6 will be explained with reference to FIG.

First, convergent light beams of recording light beams 01, 02, and 03 are irradiated toward a dry plate made of, for example, a 1/2 wavelength plate 6 coated with photoresist to cause interference. Note that 01 is the photodetector ZS2.
02 is the light detection point ZS2.
03 is the photodetector S3.
The light is focused on point L3, which corresponds to the position of . Also,
As shown in FIG. 6(b), the 02.03 is applied to the 1/4 inner portions 7b and 7C of the second gram 7, respectively. Further, focused light of recording light 01.04 is irradiated toward the dry plate to cause interference. Note that 04 is the photodetector S1. S2. This light is focused on a point L4 corresponding to a position other than S3. Further, as shown in FIG. 6(b), the 01 is the inner part 7 of the T of the second hologram 7.
Irradiate the part a. When double exposure and development are performed in this manner, a relief pattern is formed on the end face, thereby creating a second bologram 7 which is a surface relief type hologram. The i'+if relief relief 114 is formed in a direction that transmits the P-polarized light component and diffracts and covers the S-polarized light component.

As explained above, according to Kimi/A full, since a hologram is used in the optical system, the optical pickup can be reduced to a small size.
1.11Y can be integrated, access time can be shortened, the number of parts is small, and it is accurate, so it is low cost.

Also,? 1' A hologram (second small hologram 7) for beam-separating the reflected light from the recording medium 3 for detecting information signals and control signals is interposed in the optical path leading from the recording medium 3 to the recording medium 3. ! Therefore, it is possible to increase the diffraction efficiency and greatly increase the amount of light 1 that is irradiated onto the recording medium 3. In addition, the amount of light received on the photodetector for detecting control signals can be reduced by 6 m, resulting in a high-performance optical pickup.

In addition, there is no need to provide a separate photodetector for reading areas such as the BREPIT 1~ section and the data section, and it is possible to obtain information signals from the sum signal or difference signal 8 of each REC signal.
, the number of photodetectors can be reduced and the cost can be reduced.

Furthermore, since the return light from the recording medium 3 is made into a focused light by the polarizer 11, the photodetector can be made smaller.

Furthermore, in this embodiment, by arranging the photodetector and the semiconductor laser 2, which is a light source, on the same line, they can be arranged on the same substrate.
1 gram G, transparent between the second hologram 7)
By sandwiching the 5 plates, it is possible to create a much smaller and non-adjustable optical pickup.

In this example, we used a bologram with polarization to the right.
A surface relief type hologram was used, but since this surface relief type hologram has small grating grooves that utilize birefringence, the surface needs to be covered for protection. Therefore, instead of using a surface relief type hologram, the diffraction efficiency of S-polarized light and P-polarized light varies greatly depending on the product of the spatial frequency of the diffraction grating and the wavelength used. minute 1
A polarizing beam splitter having a polarizing property using a phase grating hologram of 1111 may be used.

In addition, as a protection means for the second hologram 7, a second hologram 7 is provided on the - end face of the transparent member, and a cliff conductor laser 2 and a photodetector S1.32.83 are provided on the other end face. By bringing the packages closer together, the first hologram 5 is bonded to one end surface of another transparent member, and the first hologram 5 is bonded to the other end surface.
The protection may be achieved by bonding the two-wave plate 6 and bringing the half-wave plate 6 and the second hologram 7 close to each other. As a protection means, a 1/2 wavelength plate 6 is bonded to the end face of the transparent member, and a second hologram 7 is formed on the end face of this 1/2 wavelength plate 6. A transparent part is inserted between the detector S+ and the package of 82.33.
good.

By using the above-mentioned protection means, it is possible to realize (ffi-reliable optical pickup).

In this embodiment, the first hologram 5 has the functions of a collimating lens, a shaping prism, and an objective lens, but as shown in FIG. Instead of the hologram 5, a first hologram 25 having the functions of a collimator lens and a shaping prism may be provided.

In the modified example shown in Fig. 3, ? t' 6 days off lei IJ”
The light emitted from the objective lens 2 is beam-shaped by the first hologram 25 and made into a parallel beam of light, and then passes through the objective lens 2.
4, it is focused onto the recording medium 3. The reflected light from the recording medium 3 is converted into a parallel light beam by the objective lens 24, and by the first hologram 25,
1/2 wavelength plate6. It is diffracted to the second hologram 7 side.

Incidentally, when creating the first hologram 25 written in +'+rJ, parallel light may be used instead of the converging recording light beam in FIG.

The other functions and effects of the configuration 9 are the same as those of the first embodiment.

7 to 9 relate to the second embodiment of the present invention, and FIG.
The figure shows the configuration of the optical pickup.
FIG. 9 is a circuit diagram showing a circuit for generating information signals and control IT (No. 5).

In this example r G,L, the second bologram 27 is the eighth
As shown in the figure J, the whole is circular, for example, and one inner half 27a of A is a surface relief type hologram that controls polarization, transmitting P-polarized light and diffracting S-polarized light. Moreover, the other half inner part is two 1/4 inner parts 27b.
, 27c, each of which is a surface relief type hologram with polarization properties that diffract S-polarized light.

Further, the azimuth angle of the 1/2 wave plate 6 is set to 22.degree. so that the angle between the polarization direction of the incident light to the second hologram 27 and the full relief direction of the second hologram 27 is 45 degrees. 5f(i).As a result, when the recording medium 3 does not undergo rotation of the plane of polarization, the light intensity of the P-polarized component and the S-polarized component of the light incident on the second hologram 27 becomes smaller. In addition, the P polarized light component transmitted through the inner half portion 27a and the S polarized light component diffracted by the inner half portion 27a are set to be equal to each other.

In this embodiment, the half inner portion 27a of the second hologram 27
A photodetector ZSu is placed at a position where it receives transmitted light, and a photodetector S13 is placed at a position where it receives diffracted light. Also, a quarter inner portion 27b of the second hologram 27
, 27c are each provided with a photodetector SI2.812-.

As shown in FIG. 9, the photodetectors S+2.812' are each divided into two photodetectors S4.812'. t, S42, S4
3.344.

The method for creating the second hologram 27 in this embodiment is the same as that for the second hologram 7 in the first embodiment, and in FIG. light detection m
513 is placed.

Next, referring to FIG. 9, a circuit for generating information signals q and control signals will be explained.

First, the reproduction signal of the magneto-optical data section is transmitted to the photodetectors So and S.
The output signal of the photodetector 811 corresponds to 1) the optical intensity of the polarized component; The output signal of photodetector SI3 corresponds to the light intensity of the S-polarized component. Therefore, the output horn signal of the differential amplifier 31 corresponds to the difference between the light intensity of the P-polarized light component and the light intensity of the S-polarized light component. Ru.

In addition, the reproduction signal of the prepit section is transmitted to each photodetector So, S.
t3.841, 842, S+a, S4+ output signal Y) of the X-dynamic amplifier 32 which generates the phase transmission S'3 of the output signals.

In addition, the focus error signal is the following J: Unishiku 11
1 will be given. 1, that is, by the adder 33, the photodetector S
The sum signal of the outputs of ZS 41.343 is multiplied by 17, and the sum signal of the output signals 23 of photodetector ZS 42.344 is obtained by Q adder . Then, a difference signal between the output No. 3 of the adder 33 and the adder 34 is obtained at the differential amplifier 35 (J, -), and the output of the differential amplifier 35 becomes a focus error signal. In this embodiment 'C, the second hologram 27 also has a knife function for performing the knife method, and the second hologram 27 has a 1/4 inner portion 27b,
The diffracted light of 27c is focused at the center of the two-split photodetector S12 and 812' in the focused state, and when the recording medium 3 is closer than the focused position, the diffracted light is focused on the center of the photodetector S 4
4 *When the light is incident on the 843 side in a 1/4 circular shape and the recording medium 3 is farther away than the in-focus position, J shown by the broken line in Fig. 9
, sea urchin, photodetection 11Ss4. It is incident on the z and s44 sides in a 1/4 circular shape. Note that the diameter of the 1/4 circle increases as the deviation from the in-focus position increases. Therefore, the differential amplifier crystal 35 allows the photodetector S41. The light amount of S43 and the photodetector S42. By detecting the difference in light n in S44, a focus error signal 1f1 is generated.

Also, the tracking error signal is set to 1! as follows.
'7. In other words, add → 2! The sum signal of the outputs of the photodetectors S41 and 842, that is, the output signal of the photodetector S12, is added to i37, and the sum signal of the output signals of the photodetectors So and S4+ is added by m38. A sum signal, ie, the output signal of photodetector 812', is obtained.

Then, the differential amplifier 7j139 receives the side t12!
The difference 8 between the output signals of i37 and adder f3 38 is added 19,
The output signal y) of this difference OJ amplifier 39 becomes a tracking error signal. In this embodiment, the push-pull method is used to detect the imbalance in the intensity distribution of the return light from the recording medium 3. In the on-rack state, the optical detection ZS+
2.8+2- are the same, but when off-track, there will be a difference in the amount of incident light on the photodetector S12. By generating a difference signal between the output signals of S t2', a tracking signal η can be obtained.

In addition, in this embodiment, the back of the second hologram 27,
174 internal parts 27b and 27c may use a phase type hologram or the like that does not improve polarization.

Moreover, a phase grating hologram that controls polarization may be used for the inner portion 27a.

The other functions and effects of Structure 2 are the same as those of the first embodiment.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but includes, for example, 1
/2 wavelength plate 6 (instead of a second hologram 7)
．． Polarization direction of incident light to 27 and second hologram 7
．． 27) The second hologram 7.2
7 reliefs! All you have to do is decide the direction of fl'i.

Further, the first hologram 5 may be capable of transmitting either the light directed from the semiconductor laser 2 toward the recording medium 3 or the light directed from the recording medium 3 toward the second hologram.

[Effects of the Invention] As explained above, according to the present invention, by using the hologram, the optical pickup can be made smaller.

In addition, the second small program that controls polarization, which separates the light beams into multiple light beams for information signal detection and control signal detection, is placed outside the optical path from the light source to the recording medium. This arrangement has the effect of efficiently transmitting magneto-optical information signals and control signals.

[Brief explanation of the drawing]

Figures 1 to 6, 1, relating to the first embodiment of the present invention,
FIG. 1 is an explanatory diagram showing the configuration of the optical pickup, and FIG.
FIG. 3 is an explanatory diagram showing the configuration of an optical pickup according to a modification of the embodiment, FIG. 4 is a circuit diagram showing a circuit for generating information signals and control signals, and FIG. Show? I explanatory diagram, Fig. 6 (a) shows the method of creating the second hologram, J explanatory diagram, Fig. 6 (b) shows the irradiation area of 6 lights on the dry plate when creating the second hologram. FIGS. 7 to 9 are explanatory diagrams showing the second embodiment of the present invention, FIG. 7 is an explanatory diagram showing the configuration of the optical pickup, and FIG. 8 is an explanatory diagram showing the second hologram in FIG. The explanatory diagram shown in FIG. 9 is a circuit diagram showing a circuit for generating information signals and control 911 signals. 1... Optical pickup 2... Semiconductor laser 3.
...Magneto-optical U medium 5...First hologram l-6
... 1/2 wavelength plate 7... Second hologram S
z, 32.3a... Photodetector Fig. 4 Fig. 2 Fig. 3 Fig. 5

Claims (1)

[Scope of Claims] A light source that emits light to be applied to a magneto-optical recording medium, a light source that guides the light emitted from the light source to the magneto-optical recording medium, and that emits light reflected from the recording medium that is different from the light source. a first hologram that guides the direction, and a first hologram that is disposed on the optical path of the reflected light from the recording medium that has passed through the first hologram and outside the optical path from the light source to the recording medium; A second beam having polarization properties that separates the reflected light into a plurality of light beams for information signal detection and control signal detection.
An optical pickup comprising: a hologram; and a photodetector for information signal detection and control signal detection that receives each light beam separated by the second hologram.