JPH1153756A - Prism, integrated optical element, optical head and magneto-optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a prism, an integrated optical element, an optical head and a magneto-optical disk device wherein sure polarized light separation is performed, high reliability is provided for recording/reproducing and the degree of designing freedom is increased. SOLUTION: This integrated optical element 10 is provided with a light emitting element 18, a prism 15 for reflecting a light from the light emitting element 18 toward a magneto-optical disk and separating a returning light R from the magneto-optical disk into a normal light O and an abnormal light E, a first light receiving element 12 for detecting one of the normal and abnormal lights O and E, and a second light receiving element 13 for detecting the other light. The prism 15 includes a first surface 15a where the returning light R is made incident and a second surface 15b formed obliquely to the first surface, one of the normal and abnormal lights O and E is transmitted through the second surface 15b, and the other is full-reflected on the second surface 15b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a prism for recording and reproducing information on a magneto-optical disk, an integrated optical element, an optical head, and a magneto-optical disk device.

[0002]

2. Description of the Related Art An integrated optical element for recording and reproducing information on and from a magneto-optical disk is disclosed in Japanese Patent Application Laid-Open No. 7-3119.
Japanese Patent Application Publication No. 90-90 proposes a device that performs polarization separation using a prism made of a birefringent crystal as shown in FIG.

As shown in FIG. 11, the integrated optical element 100 includes a first semiconductor substrate 101, a second semiconductor substrate 102 disposed on the first semiconductor substrate 101, and a second semiconductor substrate 102. A semiconductor laser 103 disposed above,
The photodetector 7 includes a prism 104 disposed on the first semiconductor substrate 101 and made of uniaxial birefringent crystal lithium niobate.

The prism 104 has a first surface 1
A polarizing film 106 having a characteristic in which the reflectance of the S-polarized component is 50% or more and the transmittance of the P-polarized component is 80% or more is provided on 04a. This polarizing film 106 is formed by the semiconductor laser 1
02 is reflected by the polarizing film 106 in a direction substantially normal to the first semiconductor substrate 101 toward the magneto-optical disk.

The return light reflected by the magneto-optical disk is incident on the polarizing film 106 of the integrated optical element via an objective lens (not shown). This return light is applied to the prism 104
Is refracted and transmitted through the first surface 104a, and is separated into ordinary light and extraordinary light. The separated ordinary light and extraordinary light are incident on the second surface 104b, and are separately detected by the photodetectors 105 disposed adjacent to the second surface 104b. For example, as shown in FIG.
5b, and the extraordinary light is detected by the photodetector 105a.

[0006]

However, in such an integrated optical element, as described above, polarization separation of ordinary light and extraordinary light is performed by using only the birefringence of the crystal constituting the prism. Normally, the light separation of these two components is small. Therefore, it has been difficult to separate the ordinary light and the extraordinary light with high accuracy. In addition, in order to reliably separate and detect the received light and the extraordinary light, the integrated optical element needs to accurately manufacture the positional relationship between the light receiving element and the light emitting element such as a semiconductor laser. There is an inconvenience that strict manufacturing accuracy is required and the degree of freedom in design is reduced.

Therefore, the present invention has been proposed in view of the conventional situation, and performs polarization separation using a crystal having birefringence, enables reliable polarization separation, and achieves high reliability in recording and reproduction. It is an object of the present invention to provide a prism, an integrated optical element, an optical head, and a magneto-optical disk device which can realize the performance and have a large degree of freedom in design.

[0008]

A prism according to the present invention completed to achieve the above object has a first surface and a second surface formed obliquely with respect to the first surface. Having a predetermined incident angle with respect to the first surface, separates the light into ordinary light and extraordinary light, one of the ordinary light and the extraordinary light passes through the second surface, and the other It is characterized by being totally reflected by the second surface.

In the prism according to the present invention configured as described above, the return light is separated into ordinary light and extraordinary light, and one of the ordinary light and extraordinary light is transmitted through the second surface on the second surface. In addition, since the other is totally reflected by the second surface, the ordinary light and the extraordinary light can be reliably separated.

The integrated optical element according to the present invention, which has been completed to achieve the above-described object, irradiates light to a magneto-optical disk and also returns light reflected by the magneto-optical disk and returned. An integrated optical element to be detected.

Further, the integrated optical element includes a light emitting element, a prism for reflecting light from the light emitting element toward the magneto-optical disk and separating return light from the magneto-optical disk into ordinary light and extraordinary light. It comprises a first light receiving element for detecting one of the ordinary light and the extraordinary light, and a second light receiving element for detecting the other of the ordinary light and the extraordinary light.

In particular, the prism in the integrated optical element according to the present invention has a first surface on which return light is incident, and a second surface formed obliquely with respect to the first surface. First
The return light incident on the surface is separated into ordinary light and extraordinary light, and one of the ordinary light and extraordinary light is transmitted through the second surface and the other is totally reflected by the second surface. It is a feature.

Here, the first light receiving element detects light transmitted through the second surface of the prism out of the ordinary light and the extraordinary light. On the other hand, the second light receiving element detects, among the ordinary light and the extraordinary light, light totally reflected by the second surface of the prism.

According to the integrated optical device of the present invention configured as described above, the prism separates the incident return light into ordinary light and extraordinary light, and one of the ordinary light and extraordinary light becomes the second light. And the other is totally reflected by the second surface, so that ordinary light and extraordinary light can be reliably separated.

An optical head according to the present invention that achieves the above-described object is an integrated optical element that irradiates light to a magneto-optical disk and detects return light reflected back by the magneto-optical disk, And an objective lens for condensing the light from the integrated optical element on the signal recording surface of the magneto-optical disk.

In this optical head, the integrated optical element emits light, and the light from the light emitting element is reflected toward the magneto-optical disk, and the return light from the magneto-optical disk is incident on the optical head. It includes a prism for separating ordinary light and extraordinary light, a first light receiving element for detecting the ordinary light, and a second light receiving element for detecting the extraordinary light.

In particular, the prism used in the integrated optical element of the optical head according to the present invention is a prism for receiving the return light.
And a second surface formed obliquely with respect to the first surface. The return light incident on the first surface is separated into ordinary light and extraordinary light. It is characterized in that one of them is transmitted through the second surface and the other is totally reflected by the second surface.

Here, the first light receiving element is disposed adjacent to the second surface of the prism, and one of the return lights incident from the first surface of the prism that transmits through the second surface. Is detected. In addition, the second light receiving element is one of the return lights incident from the first surface of the prism.
The other light totally reflected on the second surface is detected.

According to the optical head configured as described above, one of the return lights incident on the prism is transmitted and the other is totally reflected on the second surface of the prism. Thereby, ordinary light and extraordinary light can be reliably separated.

According to another aspect of the present invention, there is provided a magneto-optical disk drive for rotating a magneto-optical disk, and an optical disk on a recording surface of the magneto-optical disk rotated by the rotary drive. And an optical head for detecting return light and a signal processing circuit for processing a signal detected by the optical head.

Here, the optical head irradiates light to the magneto-optical disk, detects the return light reflected back by the magneto-optical disk, and the light from the integrated optical element. And an objective lens for condensing light on the signal recording surface of the magneto-optical disk.

The integrated optical element is a light-emitting element that emits light, and reflects light from the light-emitting element toward the magneto-optical disk, and receives return light from the magneto-optical disk so that the return light is ordinary light. A prism that separates the light into extraordinary light, a first light receiving element that detects the ordinary light, and a second light receiving element that detects the extraordinary light.

In particular, the prism in the magneto-optical disk drive according to the present invention has a first surface on which return light is incident, and a second surface formed obliquely with respect to the first surface. The return light incident on the first surface is separated into ordinary light and extraordinary light, and one of the ordinary light and the extraordinary light is transmitted through the second surface and the other is totally reflected by the second surface. It is characterized by having.

Here, the first light receiving element is disposed adjacent to the second surface of the prism and detects light transmitted through the second surface. Further, the second light receiving element detects light totally reflected on the second surface.

According to the magneto-optical disk drive configured as described above, the prism used in the integrated optical element is configured so that one of the return lights is transmitted and the other is totally reflected on the second surface. Therefore, ordinary light and extraordinary light can be reliably separated.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, FIG. 1 shows a prism to which the present invention is applied.

As shown in FIG. 1, the prism 1 returns after the light applied to the magneto-optical disk is reflected on the magneto-optical disk and is incident as return light R at a predetermined incident angle. It is an optical element that separates light R into ordinary light O and extraordinary light E. The prism 1 is formed of a birefringent material such as a uniaxial crystal LN (LiNbO ₃ ) or rutile (TiO).

The prism 1 has a first surface 1a on which the return light R is incident, a second surface 1b formed obliquely with respect to the first surface 1a, and first and second surfaces. And a third surface 1c formed obliquely with respect to 1a and 1b.

In particular, in the prism 1 used in the present invention, one of the ordinary light O and the extraordinary light E among the return light R incident from the first surface 1a is incident and transmitted on the second surface 1b. And the other is totally reflected. Then, on the third surface 1c, the extraordinary light E totally reflected on the second surface 1b is incident and transmitted.

In the following, a case will be described in which the ordinary light O is transmitted and the extraordinary light O is totally reflected on the second surface 1b. As described above, the extraordinary light E is transmitted on the second surface 1b. At the same time, the ordinary light O may be totally reflected.

The ordinary light O thus separated passes through the second surface 1b and is detected by a first light receiving element (not shown). On the other hand, the extraordinary light E is detected by a second light receiving element (not shown) after passing through the third surface 1c.

Here, the prism 1 used in the present invention
Adjusts the angle at which the first surface 1a, the second surface 1b, and the third surface 1c intersect, and the refractive index of the prism itself to reduce the difference between the intrinsic refractive indices of the ordinary light O and the extraordinary light E. make use of,
On the second surface 1b, it becomes possible to transmit the ordinary light O and totally reflect the extraordinary light E as described above.

As described above, the prism 1 to which the present invention is applied is configured so that the ordinary light O of the separated return light R is transmitted and the extraordinary light E is totally reflected on the second surface 1b. Therefore, the ordinary light O and the extraordinary light E can be reliably separated, and high reliability can be obtained in terms of recording and reproduction. Moreover, according to this prism,
Since the beam separation between the ordinary light O and the extraordinary light E is large, the polarization separation can be performed more effectively, and the degree of freedom in design and manufacture is high.

In the area where the ordinary light O is incident on the second surface 1b, the reflection of the ordinary light O is suppressed and the extraordinary light E
-Polarized light component generated when the light is totally reflected on the surface 1b
It is preferable to provide an optical thin film that suppresses the deviation of the phase difference from the polarization component.

As shown in FIG. 2, the prism 2 to which the present invention is applied has a first surface 2a on which return light R is incident.
And the second surface 2b on which the return light R formed obliquely to the first surface 2a and separated by the prism is incident.
And a third surface 2 formed obliquely with respect to the second surface 2b.
c and a fourth surface 2d opposed to the second surface 2b and formed obliquely with respect to the first surface 2a. In particular, in the prism 2, the auxiliary prism 3 is further disposed on the first surface 2a, and the auxiliary prism 4 is further disposed on the third surface 2c. As a material for the auxiliary prisms 3 and 4, an isotropic medium such as glass is preferable.

In the following, a case will be described in which the ordinary light O is transmitted and the extraordinary light O is totally reflected on the second surface 1b. As described above, the extraordinary light E is transmitted on the second surface 1b. At the same time, the ordinary light O may be totally reflected.

In this prism 2, the return light R incident from the first surface 2a is separated into ordinary light O and extraordinary light E,
Of the return light R, the ordinary light O is transmitted and the extraordinary light E is totally reflected on the second surface 2b. The ordinary light O transmitted through the second surface 2b is detected by a first light receiving element (not shown).

The extraordinary light E totally reflected on the second surface 2b is incident on the fourth surface 2d, is totally reflected again, and transmits through the third surface 2c. Further, this third surface 2
The extraordinary light E transmitted through c passes through the auxiliary prism 4 and
It is detected by a second light receiving element (not shown).

In this prism 2, auxiliary prisms 3, 4
, The refractive index of the prism 2 itself, the first, second,
By adjusting the angle and the like formed by each of the third and fourth surfaces 2a, 2b, 2c, and 2d, the ordinary light O of the return light is transmitted and the extraordinary light is transmitted on the second surface 2b of the prism 2. Control can be performed so that E is totally reflected. In particular, since the prism 2 includes the auxiliary prisms 3 and 4, the refractive index of the entire prism 2 can be adjusted more accurately.

Next, the integrated optical element to which the present invention is applied will be described in detail. FIG. 3 is a diagram showing an integrated optical element to which the present invention is applied.

As shown in FIG. 3, an integrated optical element 10 to which the present invention is applied has a first semiconductor substrate 11, a first light receiving element 12 and a second light receiving element 12 formed on the first semiconductor substrate 11. A light receiving element 13, a prism 15 bonded to the first semiconductor substrate 11 via an adhesive layer 14,
5, a second semiconductor substrate 17 disposed on the first semiconductor substrate 11, and a light emission for emitting laser light provided on the second semiconductor substrate 17. And an element 18. Here, as an example of the prism arranged on the inclined surface of the prism 15, a glass member 16 made of glass can be used.

The prism 15 has a first surface 15a on which a laser beam emitted from the light emitting element 18 is reflected at a predetermined incident angle as return light R from the magneto-optical disk after being reflected on the magneto-optical disk. , At least a second surface 15b formed obliquely with respect to the first surface 15a, and a third surface 15c opposed to the second surface 15b.

The prism 15 is made of, for example, TiO ₃ or the like which is a uniaxial crystal, and polarizes and separates the incident return light R from the magneto-optical disk into ordinary light O and extraordinary light E.

The prism 15 is bonded to the first semiconductor substrate 11 via the bonding layer 14 such that the second surface 15b faces the first semiconductor substrate 11. At this time, the second surface 15b is an adhesive surface with the first semiconductor substrate 11.

Further, in the prism 15 used in the present invention, the adhesive layer 1 is applied to the region 19 on the second surface 15b where the return light R incident from the first surface 15a first enters.
4 is not formed, and serves as an air layer 20.

In the prism 15 used in the present invention, in the region 19 on the second surface 15b, the first
Of the return light R from the magneto-optical disk incident from the surface 15a, the ordinary light O is transmitted, and the extraordinary light E is totally reflected toward the third surface 15c.

Further, the ordinary light O transmitted through the second surface 15b
Is detected by the first light receiving element 12. On the other hand, the second
The extraordinary light E totally reflected on the surface 15b is incident on the third surface 15c and reflected, and then detected by the second light receiving element 13.

As described above, the prism 15 used in the present invention configured as described above has the air layer 20 provided in the region 19 on the second surface 15b where the return light R is incident.
For example, a glass member 1 is formed on the first surface 15a as a prism.
6 and the angle of each surface of the prism 15 and the prism 1
5 and ordinary light O and extraordinary light E
Can be effectively used, and in the region 19 on the second surface 15b, the ordinary light O can be transmitted and the extraordinary light E can be totally reflected.

That is, the prism 1 used in the present invention
0, as shown in FIG. 4, the ordinary light O and the extraordinary light E can be reliably separated on the second surface 15b, and the recording and reproduction of the information signal can be performed with higher accuracy. . Moreover, since the ordinary light O and the extraordinary light E can be completely separated as light rays, the degree of freedom in designing can be increased.

To transmit the ordinary light O and totally reflect the extraordinary light E on the second surface 15b, the prism 15 for forming the air layer 20 in the region 19 on the second surface 15b as described above. Instead, as shown in FIG. 5, it can also be realized by a prism 26 in which an adhesive layer 27 is formed on the entire second surface 26b.

That is, in the prism 26, the refractive index of the prism 26 itself, the first surface 26a and the second surface 26b
By adjusting the angle between the second surface 26a and the angle between the first surface 26a and the third surface 26c, the ordinary light O can be transmitted on the second surface 26b and the extraordinary light E can be totally reflected. . Although the second light receiving element is not shown in FIG. 5, it may be provided at a position where the extraordinary light E totally reflected on the second surface 26b can be detected.

For example, in the prism 26, as shown in FIG. 5, the first surface 26 is adjusted by adjusting the refractive index of the prism 26.
a, the angle of incidence θb of the return light R incident on the second surface 26b can be increased, and the extraordinary light E can be reflected by the second light 26a. Control can be performed such that the light is incident on the surface 26b at an incident angle equal to or greater than the critical angle. At the same time, control can be performed such that the ordinary light O is incident on the second surface 26b at an incident angle equal to or smaller than the critical angle of the ordinary light O.

Therefore, as a result, the extraordinary light E can be totally reflected on the second surface 26b, and the ordinary light O
Can be completely separated from the ordinary light O and the extraordinary light E.

The prism 26 as shown in FIG.
The second light receiving element 13 can be formed on the first substrate 11, and the extraordinary light E is transmitted from the obliquely formed surface 26d and detected by the second light receiving element 13. . Thereby, in the prism 26, the air layer 20 arranged in the prism 15 as shown in FIG. 3 is not formed, and the adhesive layer 27 can be formed uniformly, so that the manufacturing process can be simplified. it can.

In the integrated optical element to which the present invention is applied, the reflection of the ordinary light O is suppressed and the extraordinary light E is totally reflected in the area on the second surface of the prism where the return light is incident. An optical thin film for suppressing the phase difference between the S-polarized component and the P-polarized component at that time may be provided. At this time, the second light receiving element
What is necessary is just to arrange in the position which can detect the abnormal light E. By disposing the optical thin film in this way, it becomes possible to more effectively separate the ordinary light O and the extraordinary light E.

Next, a detailed description will be given of a magneto-optical disk device incorporating an optical head having an integrated optical element configured as described above. FIG. 6 shows an embodiment of a magneto-optical disk drive to which the present invention is applied.
Here, the optical head in the figure includes the integrated optical element 10 having the above-described configuration.

The magneto-optical disk drive 11 shown in FIG.
0 is a reproducing device for detecting and reproducing the amount of polarization of the return light R;
For example, a reproducing apparatus for a magneto-optical disk will be described.

The magneto-optical disk drive 110 includes a spindle motor 112 as a rotary drive for rotating the magneto-optical disk 111, an optical head 113, a feed motor 114 as a rotary drive for the optical head 113, and a magneto-optical disk. And a recording magnetic head 115 for performing information recording on the data 111.

Here, the spindle motor 112 is driven and controlled by a system controller 116 and a servo control circuit 118, and is rotated at a predetermined rotation speed.

The optical head 113 irradiates light onto the signal recording surface of the rotating magneto-optical disk 111. The optical head 113 performs signal recording together with the recording magnetic head 115 on the basis of the signal from the signal modulator / demodulator and the ECC11, or detects the return light from the signal recording surface. And a reproduction signal based on the return light to the ECC 117.

Thus, the signal modulator / demodulator and the ECC 11
The recording signal demodulated by the signal demodulation unit 7 is subjected to error correction through an error correction unit.
0 to an external computer or the like. Thus, an external computer or the like can receive a signal recorded on the magneto-optical disk 111 as a reproduction signal.

For example, if the magneto-optical disk drive is for audio, the D / A and A / D converter 121
The digital-to-analog conversion is performed by the A converter to obtain an audio signal.

The optical head 113 is connected to a feed motor 114 for moving it to a predetermined recording track on the magneto-optical disk 111, for example. Control of the spindle motor 112, control of the feed motor 114,
The control of the focusing direction and the tracking direction of the biaxial actuator that holds the objective lens of the optical head 113 is performed by the servo control circuit 118.

Next, an optical head built in the above-described magneto-optical disk device and an integrated optical element used in the optical head will be described in detail.

FIG. 7 is a view showing an integrated optical element to which the present invention is applied and an optical head using this integrated optical element.

As shown in FIG. 7, an optical head 113 to which the present invention is applied has an integrated optical element 10 having the structure shown in FIG. 1 and light emitted from this integrated optical element 10 is shown in FIG. An objective lens 122 that converges on the surface of a magneto-optical disk 111 that is rotationally driven by a spindle motor 112; and two optical path bending mirrors 12 that guide the light beam emitted from the integrated optical element 10 to the objective lens 122
3 and 124.

The optical head 113 converts the light beam emitted from the integrated optical element 10 into optical path bending mirrors 123 and 12.
4 to the objective lens 122, and the objective lens 122
To focus light on the signal recording surface of the magneto-optical disk 111.

The light reflected on the signal recording surface of the magneto-optical disk 111 is transmitted to the objective lens 122 and the optical path bending mirror 1.
The light is incident on the integrated optical element 10 via 24 and 123.

Next, the integrated optical element 1 to which the present invention is applied
The calculation of the detection signal in the first and second light receiving elements 12 and 13 of 0 will be described in detail. FIG. 8 is a diagram illustrating a configuration of the first and second light receiving elements 12 and 13.

The first light receiving element 12 is
It is divided in a direction corresponding to 11 radial directions, and is composed of four light receiving element portions a, b, c and d. The first light receiving element 12 detects ordinary light from the return light from the magneto-optical disk 111. Here, the detection signals detected by the light receiving elements a, b, c, d are represented by S
a, Sb, Sc, and Sd.

On the other hand, the second light receiving element 13 is similarly divided in a direction corresponding to the radial direction of the magneto-optical disk 111, and comprises four light receiving element portions e, f, g, and h. . The second light receiving element 13 detects an abnormal light out of the return light from the magneto-optical disk 111. Here, the detection signals detected by the light receiving elements e, f, g, and h are referred to as Se, Sf, Sg, and Sh.

The detection signals Sa, Sb, Sc, Sd and Se, Sf, Sg, Sh are respectively subjected to current-voltage conversion by an amplifier (not shown) and then formed on the first semiconductor substrate 11 of the integrated optical element 10, for example. An arithmetic circuit (not shown) or an arithmetic circuit external to the integrated optical element 10 connected to each light receiving element is operated as follows, and the magneto-optical reproduction signal MO and the focus error signal F are calculated as follows.
CS and tracking error signal TRK are obtained.

That is, the magneto-optical reproduction signal MO is (Sa + S
b + Sc + Sd)-(Se + Sf + Sg + Sh).

The focus error signal FCS is ｛(Sa
+ Sd)-(Sb + Sc)｝-｛(Se + Sh)-(S
f + Sg)}.

The tracking error signal TRK is (Sa
+ Sb)-(Sc + Sd) or (Sa + Sb + Sc +
Sd)-(Sc + Sd + Se + Sf).

Hereinafter, specific examples to which the present invention is applied will be described in detail.

<Embodiment 1> As shown in FIG. 9, a prism 30 used in an integrated optical element includes, for example, a first surface 30a on which return light R from a magneto-optical disk enters, and a first surface 30a.
A second surface 30b formed obliquely at 45 ° with respect to the surface 30a, and a third surface 30c opposed to the second surface. The prism 30 having such a structure is bonded to the first semiconductor substrate 32 via the bonding layer 31.

[0078] Further, the prism 30, ordinary O fixed refractive index n _o of a 2.613, fixed refractive index n _e of the extraordinary light E is 2.909. The angle formed between the first surface 30a and the second surface 30b of the prism 30 is 45 °.

The intrinsic refractive index n for extraordinary light E
_e is the above value of 2.9 depending on the angle of incidence when entering the crystal.
09 in some cases.

Further, in the prism 30, the return light R incident from the first surface 30a is first incident on the second surface 30a.
In the region 33 on the surface 30b, the adhesive layer 31 is not formed, and the air layer 34 is formed.

A glass member 35 is disposed on the first surface 30a of the prism 30. This glass member 3
5 uses BK7 and has a refractive index of 1.517.

In the prism 30 having such a configuration, the ordinary light O is transmitted on the second surface 30b and the extraordinary light E is totally reflected.

In the prism 30 as described above, the following relational expressions hold. First, the relational expression regarding the extraordinary light E in the return light R will be described in detail. here,
When the extraordinary light E is totally reflected on the second surface 30b at the critical angle, the incident angle of the return light R, that is, ∠LER is θ ₀ . For other angles, ∠DEN is θ ₁
And ∠PDQ is θ ₂ . At this time, the following equation is derived from Snell's law.

Sin θ ₀ = 1.517 sin θ ₁ (1) Since ∠MDE = 45 ° + θ ₁ from ∠EDN = 45 ° -θ ₁ , 1.517 sin (45 ° + θ ₁ ) = 2.909 ··· (2) Also, ΔSPD = 45 ° −θ ₂ , the extraordinary light E is totally reflected on the second surface, and the refractive index of the air layer 34 is 1. From this, equation (3) is derived.

2.909 sin (45 ° −θ ₂ ) = 1 (3) From the above equations (1) to (3), θ ₂ = 24.89 °,
θ ₁ = 8.82 ° and θ ₀ = 13.45 °. Therefore,
When the extraordinary light E is totally reflected on the second surface at the critical angle, the incident angle θ _{0 at} which the return light R enters the glass member 35 is 13.4.
It turned out to be 5 °.

Next, with respect to the ordinary light O of the return light R,
The incident angle of the return light R when the light is reflected on the second surface 30b at the critical angle, that is, ΔLER is set to θ, and the calculation is performed in the same manner as described above. From the same relational expression, θ ₂ = 22.50
°, θ ₁ = -3.77 °, θ ₀ = -5.72 ° are calculated. Therefore, the incident angle of the return light R when the ordinary light O reflects on the second surface at the critical angle was found to be -5.72 °.

From the above results, in the prism 30, when the incident angle of the return light R is in the range of −5.72 ° to 13.45 °, the return light R is transmitted to the ordinary light O in the prism 30.
And the extraordinary light E, and it was found that the ordinary light O of the return light R was transmitted and the extraordinary light E was totally reflected on the second surface. In other words, -5.72 ° ~
It can be said that the ordinary light O and the extraordinary light E can be separated from the divergent and convergent light of 13.45 °.

As described above, the prism 30 has a position of -5.72.
It has been found that the degree of freedom in design and manufacturing is large because polarization separation is possible for divergent and convergent light of 〜13.45 °.

The intrinsic refractive index n for extraordinary light E
_e is 2.909 mentioned in the present embodiment as described above.
In this case, the return light R
−5.72 ° to 13.45 ° which is the degree of freedom of the incident angle of
May be slightly smaller, but it can be said that the degree of freedom in designing and manufacturing is larger than that of a conventional prism.

<Embodiment 2> As shown in FIG. 10, a prism 40 used in an integrated optical element has, for example, a first surface 40a on which return light R from a magneto-optical disk is incident, and a first surface 40a. A second surface 40b formed obliquely at an angle of 45 ° with the third surface 40c opposed to the second surface 40b
And The prism 40 having such a structure is adhered to the first semiconductor substrate 42 via an adhesive layer 41.

[0091] Further, the prism 40 is fixed refractive index n _o of the ordinary light O is 2.613, fixed refractive index n _e of the extraordinary light E is 2.909. The angle formed between the first surface 40a and the second surface 40b of the prism 40 is 45 °. The refractive index of the adhesive layer 41 is 1.
45.

In the prism 40 having such a configuration, the ordinary light O is transmitted on the second surface 40b and the extraordinary light E is totally reflected.

In the prism 40 as described above, the following relational expressions are established. First, among the return light R, the relational expression regarding the extraordinary light E is as follows. here,
When the extraordinary light E is totally reflected on the second surface 40b at the critical angle, the incident angle of the return light R, that is, ΔFGH is θ ₀ and ΔIGJ is θ ₁ . At this time, the following equation is derived from Snell's law.

Sin θ ₀ = 2.909 sin θ ₁ (1) From ∠IJG = 45 ° to ∠GIK = 45 ° -θ ₁ , 2.909 sin (45 ° -θ ₁ ) = 1.45 ( ₁ ) 2) From the above equations (1) and (2), θ ₁ = 15.10 °,
θ ₀ = 49.27 °. Therefore, the incident angle of the return light R when the extraordinary light E totally reflects the second surface at the critical angle is 4
It turned out to be 9.27 °.

Next, the ordinary light O of the return light R is also
The incident angle of the return light R when reflected on the second surface 40b at the critical angle, that is, ΔFGH is set to θ ₀ , and the calculation is performed in the same manner as described above. From a similar relational expression, θ ₁ = 11.2
9 ° and θ ₀ = 34.73 °. Therefore, the critical angle at which ordinary light O is totally reflected by the second surface was found to be 34.73 °.

From the above results, in the prism 40, when the incident angle of the return light R is in the range of 34.73 ° to 49.27 °, the return light R in the prism 40 is changed to the ordinary light O.
And the extraordinary light E were completely separated, and the ordinary light O was transmitted on the second surface and the extraordinary light E was totally reflected. That is, −34.73 ° to 49.27 °
It can be said that the ordinary light O and the extraordinary light E can be separated from the divergent and convergent light of

As described above, the prism 40 is -34.7.
Polarization separation was possible for divergent and convergent light of 3 ° to 49.27 °, so that it was found that the degree of freedom in design and manufacture was large.

The polarization separation can be controlled by changing the angle of refraction of the adhesive layer 41. Also, since the inherent refractive index n _e of the extraordinary light E also for Example 2 is sometimes reduced by the angle of incidence, there is a case where the degree of freedom in some incident angle is reduced, when compared with the degrees of freedom in conventional prism It can be said that the degree of freedom in design is large.

[0099]

As described above in detail, according to the prism of the present invention, one of the ordinary light and the extraordinary light of the separated return light is transmitted through the second surface, and the other is totally transmitted. By being reflected, ordinary light and extraordinary light can be reliably separated. As a result, it is possible to provide a prism that can achieve high reliability in terms of recording and reproduction and has a large degree of freedom in design.

As described above in detail, according to the integrated optical element of the present invention, one of the ordinary light and the extraordinary light among the return light incident from the first surface is formed on the second surface of the prism. Is transmitted and the other is totally reflected toward the third surface,
The ordinary light and the extraordinary light can be surely separated. As a result, high reliability can be obtained in terms of recording and reproduction, and an integrated optical element having a large degree of freedom in design can be obtained.

According to the optical head of the present invention,
By providing an integrated optical element as described above, that is, an integrated optical element in which one of ordinary light and extraordinary light is transmitted on the second surface of the prism and the other is totally reflected, And extraordinary light can be reliably separated. As a result, it is possible to obtain an optical head having high reliability in terms of recording and reproduction, and a great degree of freedom in design.

Further, according to the magneto-optical disk drive of the present invention, the prism used for the integrated optical element is configured such that one of the ordinary light and the extraordinary light is transmitted through the second surface and the other is transmitted. Since the light is totally reflected, the ordinary light and the extraordinary light can be surely separated. As a result, a highly reliable magneto-optical disk drive can be obtained in terms of recording and reproduction, and the degree of freedom in design can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a prism to which the present invention is applied.

FIG. 2 is a schematic diagram showing another example of the prism to which the present invention is applied.

FIG. 3 is a sectional view showing an example of an integrated optical element to which the present invention is applied.

FIG. 4 is a sectional view of a main part showing an example of a prism in an integrated optical element to which the present invention is applied.

FIG. 5 is a sectional view showing another example of the integrated optical element to which the present invention is applied.

FIG. 6 is a block diagram showing an example of the overall configuration of a magneto-optical disk drive to which the present invention has been applied.

FIG. 7 is a schematic diagram illustrating an example of an optical head to which the present invention is applied.

FIG. 8 is a schematic diagram showing an example of a light receiving element used in an integrated optical element to which the present invention has been applied.

FIG. 9 is a sectional view of a main part showing an example of a prism used in the embodiment.

FIG. 10 is a sectional view of a main part showing another example of the prism used in the embodiment.

FIG. 11 is a cross-sectional view showing an example of a conventional integrated optical element.

[Explanation of symbols]

1, 2, prism, 3, 16, 35 glass member, 1
0, 25 integrated optical element, 15, 26, 30, 40 prism, 14, 27, 31, 41 adhesive layer, 20, 34
Air layer, 113 optical head

Claims (11)

[Claims] A first surface formed of a medium having birefringence, a second surface formed obliquely with respect to the first surface, and a predetermined surface formed on the first surface; Light incident at an incident angle is separated into ordinary light and extraordinary light, and one of the ordinary light and extraordinary light is transmitted through the second surface, and the other is totally reflected by the second surface. A featured prism. 2. The light incident on the first surface at a predetermined incident angle is return light returned by reflection of light applied to the magneto-optical disk by the magneto-optical disk. 3. The prism according to claim 1, wherein the light is separated into ordinary light and extraordinary light. 3. An integrated optical element for irradiating light to a magneto-optical disk and detecting return light reflected and returned by the magneto-optical disk, comprising: a light emitting element; and a medium having birefringence. A first surface on which light from the light emitting element is reflected toward the magneto-optical disk and return light from the magneto-optical disk is incident; and a first surface formed obliquely with respect to the first surface. And the return light incident on the first surface is separated into ordinary light and extraordinary light. One of the ordinary light and the extraordinary light passes through the second surface and the other is the second surface. A first light receiving element that detects light transmitted through the second surface of the prism out of the ordinary light and the extraordinary light, and a prism that out of the ordinary light and the extraordinary light Detecting the light totally reflected by the second surface of the second Integrated optical device, characterized in that it comprises a light receiving element. 4. The prism has a third surface opposing the second surface, and the second light receiving element is configured to reflect ordinary light or extraordinary light totally reflected by the second surface of the prism. 4. The integrated optical element according to claim 3, wherein light emitted from the second surface after being totally reflected by the third surface is detected. 5. The prism has a third surface facing the second surface, and a fourth surface facing the first surface, wherein the second light receiving element is a prism. 4. The integration according to claim 3, wherein the ordinary light or the extraordinary light totally reflected by the second surface is detected by the light that is totally reflected by the third surface and then emitted from the fourth surface. Optical element. 6. A prism disposed on a first surface of the prism, and return light from the magneto-optical disk is transmitted through the prism disposed on the first surface. 4. The integrated optical element according to claim 3, wherein the light is incident on the surface of the integrated optical element. 7. An integrated optical element for irradiating light to a magneto-optical disk and detecting return light reflected and returned by the magneto-optical disk, and a light from the integrated optical element is transmitted to a signal of the magneto-optical disk. An objective lens for converging light on a recording surface, wherein the integrated optical element comprises a light-emitting element and a medium having birefringence, and reflects light from the light-emitting element toward a magneto-optical disk and the light. It has a first surface on which return light from the magnetic disk is incident, and a second surface formed obliquely with respect to the first surface. The return light incident on the first surface is an ordinary light. And a prism, wherein one of the ordinary light and the extraordinary light is transmitted through the second surface and the other is totally reflected by the second surface. The light transmitted through the second surface of the prism is detected. A first light receiving element, among the ordinary and extraordinary light, an optical head is characterized in that it comprises a second light receiving element for detecting light totally reflected by the second surface of the prism. 8. The prism has a third surface opposite to the second surface, and the second light receiving element is configured to reflect ordinary light or extraordinary light totally reflected by the second surface of the prism. 8. The optical head according to claim 7, wherein light emitted from the second surface after being totally reflected by the third surface is detected. 9. The prism has a third surface facing the second surface, and a fourth surface facing the first surface, wherein the second light receiving element is a prism. The optical device according to claim 7, wherein the ordinary light or the extraordinary light totally reflected by the second surface is detected by the light that is totally reflected by the third surface and then emitted from the fourth surface. head. And a prism disposed on the first surface of the prism, wherein return light from the magneto-optical disk is transmitted through the prism disposed on the first surface. 8. The optical head according to claim 7, wherein the light is incident on the surface of the optical head. 11. A rotation driving means for rotating and driving the magneto-optical disk, an optical head for irradiating a recording surface of the magneto-optical disk rotationally driven by the rotation driving means with light and detecting a return light thereof, and A signal processing circuit for processing a signal detected by the head, wherein the optical head irradiates light to the magneto-optical disk and detects return light reflected back by the magneto-optical disk. And an objective lens for condensing light from the integrated optical element on a signal recording surface of a magneto-optical disk, wherein the integrated optical element comprises: a light emitting element; and a birefringent substance; A first surface on which light from the element is reflected toward the magneto-optical disk and return light from the magneto-optical disk is incident; and a first surface formed obliquely with respect to the first surface. And the return light incident on the first surface is separated into ordinary light and extraordinary light. One of the ordinary light and the extraordinary light passes through the second surface, and the other is the second. A prism that is totally reflected by the second surface; a first light receiving element that detects light transmitted through the second surface of the prism out of the ordinary light and the extraordinary light; And a second light receiving element for detecting light totally reflected by the second surface of the prism.