JPH06111409A - Optical information reproducing device - Google Patents

Abstract

PURPOSE:To reproduce recording information recorded on an optical recording medium with a low cost and a simple constitution. CONSTITUTION:The optical system of an optical head 4 is provided with comprizes a light emitting element 21 for emitting a light beam, an optical element 22 transmitting the light from the light emitting element 21, a collimator lens 23 for making the transmitted light through the optical element 22 parallel and supplying the light to an objective lens. The returned light from the objective lens transmits through the collimator lens 23, reflected by the coating surface 24 provided on the optical element 22 at the right angle and is made incident on a light receiving element 7. The light emitted from the light emitting element 21 is linearly polarized and the polarization direction is inclined by 45 degrees to the P polarization on the optical element 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an optical information reproducing device,
In particular, it relates to an optical information reproducing apparatus for reproducing magneto-optical recording information.

[0002]

2. Description of the Related Art In recent years, with the development of information technology, an optical information recording / reproducing device has attracted attention as a large capacity information storing / reproducing device. Among the optical information recording / reproducing apparatuses, the magneto-optical method has received particular attention because it is rewritable. In this magneto-optical recording, a magneto-optical disk in which a magnetic film having an easy axis of magnetization in a direction perpendicular to the film surface is formed on a transparent substrate is used as a recording medium, and the magnetic film has regions (marks) having different magnetization directions. Information is stored by forming pits.

As a method for forming marks having different magnetization directions as described above, there are a magnetic field modulation method and a light beam modulation method. These methods differ only in the modulation method,
In principle, the recording light beam is irradiated onto the magnetic film as a light spot by an objective lens, etc., and the coercive force is lowered by raising the temperature of the light spot and the magnetic film in the vicinity thereof, and the magnetic field is externally applied by a magnetic head. Recording is performed by applying.

Regarding reproduction of information, the polarization direction of the reflected light from the magneto-optical disk is rotated by + θk or -θk due to the Kerr effect due to the polarity of the mark. By separating and detecting this reflected light into S-polarized light and P-polarized light,
This detection signal is subtracted to obtain a reproduction signal.

[0005]

However, in such a conventional magneto-optical recording type optical information recording / reproducing apparatus, in addition to the detection of defocus, track deviation, and pre-pit signal, the magneto-optical signal, that is, the optical signal is detected. Since it is necessary to detect the polarization direction, many optical elements such as a polarization beam splitter and a half-wave plate are used. Therefore, the overall shape of the optical head that emits a light beam and detects reflected light is There is a problem that it is large and heavy. Furthermore, the large number of parts complicates assembly and adjustment,
There is also the problem of cost.

The present invention has been made in view of the above circumstances, and provides a low-cost optical information reproducing apparatus capable of reproducing magneto-optical recording information recorded on a magneto-optical disk with a simple structure. Has an aim.

[0007]

The optical information reproducing apparatus of the present invention has a light emitting element 21 as a light emitting means for emitting light.
And an objective lens 6 as a condenser for collecting light from the light emitting element 21 on the magneto-optical disk 3 as an optical recording medium and receiving return light from the magneto-optical disk 3.
The light emitting element 2 is arranged on the optical path between the light emitting element 21 and the objective lens 6, and reflects or transmits the return light to thereby cause the light emitting element 2
1, an optical element 22 as a separating means for separating the return light from the optical axis of the light from 1 to the magneto-optical disk 3, and the optical element 22.
The optical element 22 includes an a region 26 and a b region 27 as two polarization regions for reflecting or transmitting light of polarization components orthogonal to each other. Consisting of a light receiving element 7
Is a light receiving area 28 as a plurality of light receiving areas for respectively receiving lights of polarization components orthogonal to each other separated by reflecting or transmitting the a area 26 and the b area 27.
And b light receiving area 29.

In the optical information reproducing apparatus of the present invention, the optical element 22 is composed of a transparent substrate 62 as a flat plate-shaped transparent plate, and two polarizing regions are formed on at least one of the front and back surfaces of the transparent substrate 62. Can be configured.

Further, in the optical information reproducing apparatus of the present invention, the transparent substrate 100 in which the optical element 22 is a flat transparent plate.
And a region 104, a region b 105, a region c 106, and a region 107 as two reflection polarization regions for reflecting lights of polarization components orthogonal to each other are formed on both surfaces of the transparent substrate 100. 7 are a region 104, b region 105 formed on both front and back surfaces of the transparent substrate 100,
The c-region 106 and the d-region 107 are composed of A-region 109, B-region 110, and C-region 111 as a plurality of light-receiving regions that respectively receive the lights of the polarization components orthogonal to each other separated by reflecting the returning light. Can be configured to.

[0010]

In the optical information reproducing apparatus having the above construction, a
In the light receiving area 28 and the b light receiving area 29, the a area 26 and the b area
Since the lights of the polarization components orthogonal to each other separated by being reflected or transmitted through the area 27 are received, the magneto-optical recording information recorded on the magneto-optical disk 3 can be reproduced with a simple structure.

When two polarizing regions are formed on at least one of the front and back surfaces of the transparent substrate 62, the magneto-optical recording information recorded on the magneto-optical disk can be reproduced with a simple structure, and at the same time, it is simple. A polarizing region can be formed in

Further, on both surfaces of the transparent substrate 100, a regions 104, b regions 105, and c regions 10 as two reflection polarization regions for reflecting lights having polarization components orthogonal to each other are provided.
6, d region 107 is formed, and a region 104 and b region 10 are formed.
5, the light of the polarization components orthogonal to each other separated by reflecting the return light in the c region 106 and the d region 107 is A
When the regions 109, B 110 and C 111 are configured to receive light, the magneto-optical recording information recorded on the magneto-optical disk can be reproduced with a simple configuration, and the polarization direction of the returning light is not uniform. Even if there is a magneto-optical recording (M
O) The signal can be corrected.

[0013]

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

1 to 4 relate to the first embodiment of the present invention, FIG. 1 is a block diagram showing the configuration of a magneto-optical information recording / reproducing apparatus, and FIG. 2 is a block diagram showing the configuration of the optical head of FIG. FIG. 3 is an explanatory view explaining the light incident on the light receiving element of FIG. 1, and FIG.
FIG. 7 is an explanatory diagram illustrating a modified example of the light receiving element in FIG. 1.

As shown in FIG. 1, in a magneto-optical information recording / reproducing apparatus 1 of this embodiment, an optical head 4 is arranged so as to face an optical disk 3 which is rotationally driven by a spindle motor 2. VCM (Voice coil motor) 5
It is provided movably in the radial direction of the magneto-optical disk 3 by a head feeding mechanism such as.

The optical head 4 condenses a light beam from an optical system (not shown) described later by an objective lens 6 to form a light spot on the recording surface of the magneto-optical disk 3. The light reflected by the magneto-optical disk 3 is guided to the light receiving element 7 through the objective lens 6 and the above-mentioned optical system (not shown), and is photoelectrically converted by the light receiving element 7. The photoelectrically converted signal is input to the recording / reproducing processing circuit 8 and the control circuit 9. During recording, the optical head 4 irradiates the optical disc 3 with a light beam of a predetermined level to raise the recording surface of the magneto-optical disc 3 to a recordable temperature and magnetically modulates it by a magnetic head (not shown). A mark is formed on the magneto-optical disk 3 to record information.

The recording / reproducing processing circuit 8 processes the signal from the light receiving element 7 so that the optical disk 3 is processed.
The information recorded on the track is reproduced. Further, the information to be recorded is subjected to modulation processing or the like to drive and control a magnetic head (not shown), and the optical head 4 is controlled to record information. Although the recording method is the magnetic modulation method in this embodiment, the magneto-optical information recording / reproducing apparatus may be configured to record information by the optical modulation method.

The control circuit 9 generates a tracking error signal and a focus error signal from the signal from the light receiving element 7 and performs tracking control so that the light beam applied to the optical disc 3 tracks a target track. Focus control is performed so that the light beam with which the optical disc 3 is irradiated maintains the focus state.

As shown in FIG. 2A, the optical system of the optical head 4 includes a light emitting element 21 for emitting a light beam, an optical element 22 for transmitting the light from the light emitting element 21, and the optical element. And a collimator lens 23 that collimates the light that has passed through 22 and supplies the collimated light to the objective lens 6.
The return light from the objective lens 6 passes through the collimator lens 23, is reflected by a coating surface 24 provided on the optical element 22 and having a reflectance described later at 90 degrees, and is incident on the light receiving element 7. The light emitted by the light emitting element 21 is linearly polarized light, and its polarization direction has an angle of 45 degrees with respect to the P polarized light in the optical element 22.

The coating surface 24 provided on the optical element 22 is, as shown in FIG. 2B, an a region 26 that reflects only P-polarized light (reflectance of P-polarized light: Rpa = 10).
50%, reflectance to S-polarized light: Rsa = 0%, and b region 27 that reflects only S-polarized light (reflectance to P-polarized light: Rpb = 0%,
Reflectance against S-polarized light: Rsb = 10 to 50%), and the light-receiving element 7 also has the coating surface 24.
It is divided into an a-light receiving area 28 and a b-light receiving area 29 so as to respectively receive the light reflected by the a area 26 and the b area 27 (see FIG. 2A). The area a 26
The dividing line of the area b and the area b is provided in the direction perpendicular to the track groove of the magneto-optical disk 3.

The polarization direction of the light emitted from the light emitting element 21 has an angle of 45 degrees with respect to the P polarized light in the optical element 22 (reference numeral 41), as shown in FIG. The return light from 3 is + θk due to the Kerr effect, depending on the direction of magnetization of the recording mark of the magneto-optical disk 3.
It can be rotated by -θk (θk: Kerr rotation angle) (reference number 4)
2, 43). This return light is reflected by the a-region 26 and the b-region 27 of the coating surface 24, is divided into P-polarized component light 44 and S-polarized component light 45 according to the reflectance, and is divided into two light receiving elements 7. The light is incident on the a light receiving area 28 and the b light receiving area 29. a light receiving area 28, b light receiving area 29
Respectively photoelectrically convert the received P-polarized component light 44 and S-polarized component light 45 and transmit them to the recording / reproducing processing circuit 8. The recording / reproducing processing circuit 8 uses the a-light receiving area 28 and the b-light receiving area 29.
By taking the difference between the signals obtained in step 3, the magneto-optical recording (M
O) Reproduce signal.

Therefore, according to the magneto-optical information recording / reproducing apparatus 1 of the present embodiment, the optical element 22 is provided with the coating surface 24 including the a region 26 and the b region 27 having a predetermined reflectance, so that the structure is simple. The magneto-optical recording (MO) information recorded on the magneto-optical disk 3 can be reproduced.

The size of the optical head is determined by the distance between the light emitting element and the collimating lens (or the objective lens). In this embodiment, the optical element 22 is provided between the light emitting element 21 and the collimating lens 23. Since the necessary optical system can be configured by arranging, the small-sized optical head 4 close to the limit can be realized.

Further, since the dividing line of the a region 26 and the b region 27 is provided in the direction perpendicular to the track groove of the magneto-optical disk 3, the magneto-optical recording is not affected by the diffracted light by the track groove. (MO) information can be reproduced.

The light receiving element 7 is formed by a dividing line provided in the direction perpendicular to the track groove of the magneto-optical disk 3
Although it is assumed that the light receiving region 28 and the b light receiving region 29 are configured to have two light receiving regions, the invention is not limited to this, and the light receiving region may be configured as shown in FIG.

That is, as shown in FIG.
The light receiving element 7a as a modified example of No. 1 has a dividing line parallel to the track groove of the magneto-optical disk 3 and a of the coating surface 24.
The area 26 and the area b are divided into four areas (area a, area b, area c, area d) by dividing lines that are parallel to the dividing lines, and the return light at the defocus position is divided into these four areas. You may make it inject into the center of. In this case, the recording / reproducing processing circuit 8 uses the photoelectric conversion signals a from the four areas (a area, b area, c area, d area).
A reproduction signal = (a + b)-(c + d) and a track error signal = (a + c)-(b + d) are obtained from b, c, and d.

As shown in FIG. 4B, the light receiving element 7b according to the second modification has two dividing lines parallel to the track grooves of the magneto-optical disk 3 and an a region 26 of the coating surface 24. And the dividing line parallel to the dividing line of the b region 27, the six regions (a region, b region, c region, d region, e
Area, f area), and the return light at the defocus position may enter the center of these six areas. In this case, the recording / reproducing processing circuit 8 uses the photoelectric conversion signals a, b, c, d, e, from the six areas (a area, b area, c area, d area, e area, f area).
From f, reproduction signal = (a + b + c)-(d + e + f) Track error signal = (a + d)-(c + f) Focus error signal = (a + d + c + f)-(b + e)

Further, as shown in FIG. 4 (c), the third
The light receiving element 7c as a modified example of No. 2 has a dividing line parallel to the track groove of the magneto-optical disk 3 and a of the coating surface 24
The area is divided into 6 areas (a area, b area, c area, d area, e area, f area) by two dividing lines parallel to the dividing lines of the area 26 and the b area 27, and the defocus position is set. It is also possible to have the return light in (4) enter the centers of these six regions. In this case, the recording / reproducing processing circuit 8
Are photoelectric conversion signals a, b, c from these six areas (area a, area b, area c, area d, area e, area f).
From d, e, and f, reproduction signal = (a + b)-(e + f) track error signal = (a + c + e)-(b + d + f) focus error signal = (a + b + e + f)-(c + d).

Next, a second embodiment will be described. 5 to 7 relate to the second embodiment, FIG. 5 is a configuration diagram showing the configuration of the optical head, FIG. 6 is an explanatory diagram for explaining the coating characteristics of the coating surface of the optical element of FIG. 5, and FIG. FIG. 5 is an explanatory diagram illustrating light incident on the light receiving element of FIG.

Since the second embodiment is almost the same as the first embodiment and only the configuration of the optical element is different, the same components are designated by the same reference numerals and only different points will be described.

As shown in FIG. 5, the optical element 6 of the present embodiment.
In No. 1, the transparent substrate 62 is also provided with a coating surface 63 having different reflection characteristics depending on the incident angle. The reflection characteristic of the coating surface 63 is as shown in FIG.
When the incident angle is 45 degrees or less, the incident light is reflected regardless of the polarization characteristic, and when the incident angle is 45 degrees or more, only the S-polarized light is reflected. The light incident on the coating surface 61 is reflected according to the incident angle, and the light receiving element 7
(See FIG. 2). Further, since the light receiving element 7 is divided into the a light receiving area 28 and the b light receiving area 29,
One region, for example, the a light receiving region 28 receives light regardless of the polarization characteristics, and the other region, the b light receiving region 29, receives the light of the S polarization component.

That is, as shown in FIG.
For the light 81 emitted by the optical disc 1, the Kerr effect causes + θk, − depending on the direction of magnetization of the recording mark of the magneto-optical disk 3.
The return light 82 rotated by θk (θk: Kerr rotation angle) is a
The S-polarized light component of the return light 82 received by the light receiving area 28 is received by the b light receiving area 29. The recording / reproducing processing circuit 8 detects the ratio of the signal of the b light receiving area 29 to the signal of the a light receiving area 28 to detect the magneto-optical recording (MO).
Play the signal.

Other configurations and operations are the same as those in the first embodiment.

Therefore, in this embodiment, in addition to the effect of the first embodiment, it is not necessary to divide the coating surface and the coating surface 62 of the optical element 61 can be easily formed.

Next, a third embodiment will be described. FIG. 8 is a configuration diagram showing the configuration of the optical head according to the third embodiment.

Since the third embodiment is almost the same as the first embodiment and only the configurations of the optical element and the light receiving element are different, the same reference numerals are given to the same configurations and only different points will be described.

As shown in FIG. 8A, the optical element 101
Forms coating surfaces 102 and 103 on both surfaces of a transparent substrate 100 having a predetermined thickness. Coating surface 1
02 is a region 104 that reflects only P-polarized light (reflectance against P-polarized light: Rpa = 10 to 50%, reflectance against S-polarized light: Rsa =
0%) and b region 105 that reflects only S-polarized light (reflectance against P-polarized light: Rpb = 0%, reflectance against S-polarized light: Rsb = 10.
50%). Coating surface 103
Is divided into two parts facing the coating surface 102, and is composed of a c region 106 facing the a region 104 and a d region 107 facing the b region. The reflection characteristics of the c region 106 are almost the same as the reflection characteristics of the b region 105, and the reflection characteristics of the d region 107 are the a region 104.
Is almost the same as the reflection characteristic of.

That is, in the a region 104, 10 to 50% of the P-polarized component light is reflected and the rest is transmitted, but the S-polarized component of this transmitted light is reflected in the c region 106. Similarly,
In the b region 105, 10 to 50% of the S-polarized component light is reflected and the rest is transmitted, but the P-polarized component of this transmitted light is reflected in the d region 107. In this way, the return light from the magneto-optical disk 3 is reflected by the coated surfaces 102 and 10
It is reflected by 3 and enters the light receiving element 108.

As shown in FIG. 8B, the light receiving element 108 is divided into three regions, an A region 109, a B region 110 and a C region 111, and the dividing line of the region is defined by the coating surfaces 102 and 103. It is provided at the center of each reflected return light and in the direction perpendicular to the track groove of the magneto-optical disk 3. Therefore, in the area A, the light reflected by the area 104 of the coating surface 102 (P-polarized component)
Light is incident on the area B, the light reflected by the area b 105 of the coating surface 102 and the area c of the coating surface 103 (S-polarized component) is incident on the area B, and the area d on the surface 107 of the coating surface 103 is incident on the area C. The light (P-polarized component) reflected by is incident. The photoelectric conversion signals A, B, and C from these three areas, A area 109, B area 110, and C area 111 are arithmetically processed by the recording / reproducing processing circuit 8,
(A + C) -B = information is reproduced as a magneto-optical recording (MO) signal.

Therefore, in this embodiment, in addition to the effects of the first embodiment, the returning light is split into the P polarization component and the S polarization component twice by the coating surfaces 102 and 103 formed on both surfaces of the optical element 101. However, since the P-polarized component and the S-polarized component are received by the light receiving element 108 divided into three to obtain a magneto-optical recording (MO) signal, the polarization direction of the return light is not uniform. Also, (A + C) -B
= Can be corrected by using a magneto-optical recording (MO) signal.

Next, a fourth embodiment will be described. FIG. 9 is a configuration diagram showing the configuration of the optical head according to the fourth embodiment.

The fourth embodiment is almost the same as the first embodiment, and only the structure of the optical system of the optical head is different.
The same components are designated by the same reference numerals, and only different points will be described.

As shown in FIG. 9, the optical system of the optical head of this embodiment includes a light emitting element 121 for emitting a light beam and an optical element 12 for reflecting the light from the light emitting element 121 by 90 degrees.
2 and the light reflected by the optical element 122 is condensed by the objective lens 6 to form a light spot on the recording surface of the magneto-optical disk 3. The return light from the magneto-optical disk 3 is transmitted through the optical element 122 via the objective lens 6 and is incident on the light receiving element 123. The light emitted by the light emitting element 121 is linearly polarized light, and the polarization direction is the optical element 1.
It has an angle of 45 degrees with respect to the P-polarized light at 22.

Coating surfaces 124 and 125 are formed on both surfaces of the optical element 122.
No. 4 has a characteristic that the reflectance is about 80% without polarization dependency, and the coating surface 125 transmits only S-polarized light.
The light receiving element 123 is divided into a region 126 and a b region 127 that transmits only P-polarized light. Further, the light receiving element 123 is also divided into the a region 126 and the b region 127 of the coating surface 125.
It is divided into an a light receiving region 128 and a b light receiving region 129 so as to receive the light respectively transmitted by the. The dividing line of the a region 126 and the b region 127 is provided in the direction perpendicular to the track groove of the magneto-optical disk 3.

The a light receiving area 128 and the b light receiving area 129 are
The received S-polarized component light and P-polarized component light are photoelectrically converted and transmitted to the recording / reproducing processing circuit 8. The recording / reproducing processing circuit 8 calculates the difference between the signals obtained in the a-light receiving area 128 and the b-light receiving area 129. By taking this, the magneto-optical recording (MO) signal is reproduced.

Therefore, in this embodiment, in addition to the effect of the first embodiment, the polarization direction of the projected beam is uniform within the beam, and the S / N ratio does not deteriorate.

Next, a fifth embodiment will be described. Figure 10
FIG. 9 is a configuration diagram showing a configuration of an optical head according to a fifth example.

The fifth embodiment is almost the same as the first embodiment, and only the configuration of the optical system of the optical head is different.
Only different points will be described.

As shown in FIG. 10, the optical system of the optical head of this embodiment has a light emitting element 141 for emitting a light beam and an optical element which is a ½ wavelength plate for rotating the polarization direction of transmitted light by 45 degrees. 142, the optical element 142 reflects the light from the light emitting element 141 by 90 degrees. The light reflected by the optical element 142 is condensed by the objective lens 6 to form a light spot on the recording surface of the magneto-optical disk 3. The return light from the magneto-optical disk 3 passes through the optical element 142 via the objective lens 6 and is incident on the light receiving element 143. The light emitted by the light emitting element 141 is linearly polarized light,
The polarization direction matches the S polarization direction in the optical element 142.

Coating surfaces 144 and 145 are formed on both surfaces of the optical element 142.
No. 4 is a coating property in which the transmittance Tp for P-polarized light is larger than the transmittance Ts for S-polarized light (Tp = 100%,
Ts = 10-40%), and the coated surface 145
Is divided into an a region that transmits only P polarized light and a b region that transmits only S polarized light. Further, the light receiving element 143 is also transmitted in the a region and the b region of the coating surface 145. It is divided into an a light receiving region 148 and a b light receiving region 149 so as to receive light respectively. still,
The dividing lines of the a region and the b region are provided in the direction perpendicular to the track grooves of the magneto-optical disk 3.

The a light receiving region 148 and the b light receiving region 149 are
The received P-polarized component light and S-polarized component light are photoelectrically converted and transmitted to the recording / reproducing processing circuit 8. The recording / reproducing processing circuit 8 calculates the difference between the signals obtained in the a-light receiving area 148 and the b-light receiving area 149. By taking this, the magneto-optical recording (MO) signal is reproduced.

Therefore, in this embodiment, in addition to the effect of the first embodiment, the polarization rotation angle can be apparently amplified, so that the S / N ratio is improved.

Next, a sixth embodiment will be described. Figure 11
FIG. 13 is a configuration diagram showing a configuration of an optical head according to a sixth example.

The sixth embodiment is almost the same as the fifth embodiment, and only the configuration of the optical system of the optical head is different.
Only different points will be described. That is, as shown in FIG. 11, the coating surface 161 formed on the optical element 142.
The coating characteristics of No. 5 are different from those in the fifth embodiment, and the coating surface 161 has a function as a polarization beam splitter having the coating characteristics of transmitting P-polarized light and reflecting S-polarized light. Is a first light receiving element 162 that receives the light transmitted through the coating surface 161.
And a light receiving element 163 that receives the reflected light. Then, the recording / reproducing processing circuit 8 includes the first light receiving element 162 and the second light receiving element 162.
By taking the difference between the signals obtained by the light receiving element 163,
Reproduces magneto-optical recording (MO) signal. Other configurations and operations are the same as those in the fifth embodiment.

Therefore, in this embodiment, in addition to the effect of the fifth embodiment, there is almost no loss of light quantity, and the S / N ratio is further improved.

Next, a seventh embodiment will be described. 12
13 and 14 relate to the seventh embodiment, FIG. 12 is a configuration diagram showing the configuration of the optical head, and FIG. 13 is a configuration diagram showing the configuration of the light receiving element of FIG.

The seventh embodiment uses a parallel plate-shaped beam splitter as an optical element to obtain a focus error signal by utilizing the fact that the light transmitted through this optical element has astigmatism. is there.

That is, as shown in FIG. 12A, the optical system of the optical head of this embodiment comprises a light emitting element 181 for emitting a light beam and an optical element 182 which is a parallel plate beam splitter. The light from the light emitting element 181 reflected by the optical element 182 is collimated by the collimator lens 23.
Are collimated by the objective lens 6 to form a light spot on the recording surface of the magneto-optical disk 3 as described in the first embodiment. The return light from the magneto-optical disk 3 is transmitted through the optical element 182 through the objective lens 6 and the collimator lens 23 and is incident on the light receiving element 183. The light emitted by the light emitting element 181 is linearly polarized light, and its polarization direction has an angle of 45 degrees with respect to the P polarized light in the optical element 182.

Coating surfaces 184 and 185 are formed on both surfaces of the optical element 182.
No. 4 has a characteristic that the reflectance is about 80% without polarization dependence, and as shown in FIG.
Is divided into an a region 186 that transmits only S-polarized light and a b region 187 that transmits only P-polarized light. The dividing line of the a region 186 and the b region 187 is provided in the direction perpendicular to the track groove of the magneto-optical disk 3. On the other hand, the light receiving element 183 has the coating surface 18
5 so that the light transmitted through the a-region 186 and the b-region 187 may be received, and the dividing line parallel to the track groove of the magneto-optical disk 3 and the a-region 1 of the coating surface 185.
It is divided into four regions (a region, b region, c region, d region) by the dividing line parallel to the dividing line of 86 and b region 187.

Since the light beam passing through the optical element 182 has astigmatism, the light receiving element 1 is placed at a position where the cross section of this light beam is circular, as shown by the solid line in FIG.
83 is arranged. The cross section of this light beam becomes, for example, a vertically elongated ellipse when the objective lens 6 approaches the magneto-optical disk 3 and the image forming surface moves away, as shown by the broken line in FIG. When it is moved away from the area, for example, a horizontally long ellipse is formed.
The focus error signal is obtained from the photoelectric conversion signals a, b, c, d from the area) by the following: focus error signal = (a + c)-(b + d), and the recording / reproducing processing circuit 8 further reproduces the reproduction signal = (a + d)-( b + c) Track error signal = (a + b)-(c + d) can be obtained. Other functions and effects are the same as those in the first embodiment.

The reason why the light receiving element in the first embodiment differs from the reproduction signal and the track error signal in the first to third modifications is that a and c (or b and d) are due to the effect of astigmatism.
This is because the signal of is inverted.

In the magneto-optical information recording / reproducing apparatus of each of the above-mentioned embodiments, the magneto-optical disk apparatus for audio can exert more effect. That is, although the S / N ratio of the reproduced signal does not have to be so high in the magneto-optical disk device for audio, it is desired to have a low cost. Therefore, the magneto-optical recording (MO) recorded on the magneto-optical disk 3 is simple. A magneto-optical information reproducing device equipped with an optical head capable of reproducing information is optimal,
More effective.

[0063]

As described above, according to the optical information reproducing apparatus of the first aspect, the light of the polarization components orthogonal to each other is separated by reflecting or transmitting the light in the two polarizing regions. Since the light beams of the polarized light components that are orthogonal to each other are received in a plurality of light receiving regions, there is an effect that the recording information recorded on the optical recording medium can be reproduced at a low cost and with a simple configuration.

According to the optical information reproducing apparatus of the second aspect, since the two polarization areas are formed on at least one of the front and back surfaces of the flat transparent plate, the magneto-optical device has a simple structure. The magneto-optical recording information recorded on the disc can be reproduced, and the polarization region can be easily formed.

According to the optical information reproducing apparatus of the third aspect, two reflective polarization areas for reflecting lights of polarization components orthogonal to each other are formed on both surfaces of the flat transparent plate, and the reflection polarization area is formed. Since the light of the polarization components orthogonal to each other, which are separated by reflecting the return light in the area, is received by the plurality of light receiving areas, the magneto-optical recording information recorded on the magneto-optical disk can be reproduced with a simple configuration, Even if the polarization direction of the return light is non-uniform, it is possible to correct the magneto-optical recording (MO) signal.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of a first embodiment of a magneto-optical information recording / reproducing apparatus of the present invention.

FIG. 2 is a configuration diagram showing a configuration of the optical head of FIG.

FIG. 3 is an explanatory diagram illustrating light incident on a light receiving element of FIG.

FIG. 4 is an explanatory diagram illustrating a modified example of the light receiving element in FIG.

FIG. 5 is a configuration diagram showing a configuration of an optical head of a second embodiment of the magneto-optical information recording / reproducing apparatus of the present invention.

6 is an explanatory diagram illustrating coating characteristics of a coating surface of the optical element of FIG.

FIG. 7 is an explanatory diagram illustrating light incident on the light receiving element of FIG.

FIG. 8 is a structural diagram showing the structure of an optical head of a third embodiment of the magneto-optical information recording / reproducing apparatus of the present invention.

FIG. 9 is a configuration diagram showing a configuration of an optical head of a fourth embodiment of the magneto-optical information recording / reproducing apparatus of the present invention.

FIG. 10 is a structural diagram showing the structure of an optical head of a fifth embodiment of the magneto-optical information recording / reproducing apparatus of the present invention.

FIG. 11 is a structural diagram showing the structure of an optical head of a sixth embodiment of the magneto-optical information recording / reproducing apparatus of the present invention.

FIG. 12 is a structural diagram showing the structure of an optical head of a seventh embodiment of the magneto-optical information recording / reproducing apparatus of the present invention.

13 is a configuration diagram showing a configuration of a light receiving element of FIG.

[Explanation of symbols]

 3 Magneto-optical disk 4 Optical head 6 Objective lens 7 Light receiving element 21 Light emitting element 22 Optical element 23 Collimating lens 24 Coating surface 26 a area 27 b area 28 a Light receiving area 29 b Light receiving area

Claims (3)

[Claims] 1. A light emitting means for emitting light, a light condensing means for condensing light from the light emitting means on an optical recording medium and receiving return light from the optical recording medium, and the light emitting means. Separating means arranged on the optical path with the condensing means and separating the return light from the optical axis of the light from the light emitting means to the optical recording medium by reflecting or transmitting the return light; Light receiving means for receiving the light separated by the means, wherein the separating means is composed of two polarization regions for reflecting or transmitting the lights of the polarization components orthogonal to each other, and the light receiving means for separating the two polarization regions. An optical information reproducing device comprising a plurality of light receiving regions for respectively receiving lights of polarization components orthogonal to each other separated by being reflected or transmitted. 2. The separating means comprises a flat plate-shaped transparent plate, and the two polarization regions are formed on at least one of the front and back surfaces of the transparent plate. Optical information reproducing device. 3. The separating means is formed of a flat plate-shaped transparent plate, and forms two reflection polarization regions for reflecting lights of polarization components orthogonal to each other on both front and back surfaces of the transparent plate, The means includes a plurality of light receiving devices that respectively receive the light beams of polarization components orthogonal to each other, which are separated by reflecting the return light beams on the two reflection polarization regions formed on both front and back surfaces of the transparent plate. The optical information reproducing apparatus according to claim 1 or 2, wherein the optical information reproducing apparatus comprises a region.