JPH06333251A - Device for detecting tracking error of optical head - Google Patents

Abstract

PURPOSE:To prevent the interference, to eliminate the occurrence of offset of a tracking error signal due to a tangential skew of a disk and to provide the stable tracking error signal by constituting to scatter or absorb an incident light beam on the electrode surface of an optical head after reflected by the disk. CONSTITUTION:A beam is emitted from a semiconductor laser chip 32. The beam is reflected by an etching mirror 35, and is reflected by a disk through a diffracted grating, a hologram and an optical system incorporating an objective lens, and whose sub beam is made incident on the electrode surface 40 of the semiconductor laser chip 32 also as an incident luminous flux 42a. A wire 39 for supplying power source to the semiconductor laser chip 32 is bonded to an incident area. Thus, the incident luminous flux 42a is reflected by a dome shape on a wire bonding part 41 to become a scattered beam 43. The scattered beam flares to an angle remarkably larger than the incident luminous flux 42a, and the light quantity again returning to the disk becomes nearly zero, and thus, the interference is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking error detecting device for an optical head used in an optical recording device and a reproducing device.

[0002]

2. Description of the Related Art Recently, an optical head having a light source and a photodetector integrated therein has been proposed, as disclosed in Japanese Patent Laid-Open No. 64-35737. 14 and 15 show a perspective view of the optical head and a conceptual view of the optical system. As shown in FIG. 14, the optical head device 1a has first and second semiconductor substrates 2 and 8 each having five regions on the semiconductor substrate 8.
The light receiving elements 9 and 10 are formed and the second semiconductor substrate 8 is mounted on the first semiconductor substrate 2. A semiconductor laser element (hereinafter referred to as a semiconductor laser chip) 5 is attached to the second semiconductor substrate 8, and a monitor light receiving element 4 is formed.

A prism is formed on the first semiconductor substrate 2.
11 are installed. The prism 11 has a substantially trapezoidal cross section, the inclined surface 11a serves as a mirror, and the vertical surface 11b faces the emission surface of the semiconductor laser chip 5 mounted on the second semiconductor substrate 8. The upper surface 11c of the prism 11 is the first diffraction grating 1
It is said to be 2. A second diffraction grating 13 is arranged above the first diffraction grating 12.

To explain the outline of the operation, the beam emitted from the semiconductor laser chip 5 shown in FIG. 14 is reflected by the inclined surface 11a of the prism 11 and enters the first diffraction grating 12.
It is divided into a 0th-order beam for reading information and a ± 1st-order beam for detecting a tracking error signal, and the second diffraction grating 13 is set to 0.
Next, the light is transmitted, and is condensed on the disk 19 by the objective lens 18 shown in FIG. 0th order and ± 1 focused on this disk 19
The secondary beam is reflected by the disk 19, passes through the objective lens 18, enters the second diffraction grating 13, and is divided into ± first-order beams and guided to the first and second light receiving elements 9 and 10.

Here, the first and second light receiving elements 9 and 10
Is arranged so that it is displaced before and after the converging position as shown in the cross-sectional view of the optical head in FIG. 16, and the size of the spot on the light receiving element that changes with the focus movement of the disk changes oppositely. Then, the focus error is detected by the beam size method. The tracking error is detected by the three-beam method using the ± 1st order beams for detecting the tracking error signal generated by the first diffraction grating 12.

In the optical head in which the above-mentioned light source and photodetector are integrated, further miniaturization is carried out, and when the semiconductor laser chip 5 and the prism 11 are arranged close to each other, the disk 19
One of the ± first-order beams for detecting the tracking error signal reflected by is transmitted through the second diffraction grating 13 at the 0th order, is incident on the surface of the semiconductor laser chip 5 facing the second diffraction grating 13, and is reflected. I will return to the disc again. In this way, when the ± first-order beams for detecting the tracking error signal reflected by the disk enter the vicinity of the light emitting element, are reflected there and return to the disk again, the beam and the ± for detecting the tracking error signal are detected. The primary beam causes interference, and an offset occurs in the tracking error signal due to the tangential skew of the disk.
No. 61-24031. In addition, JP-A-61-240
As a countermeasure against this, Japanese Patent Laid-Open No. 31-31 proposes a method of providing a light shield that scatters or absorbs light on the emission end face of the semiconductor laser element.

[0007]

As described above, the light source,
When the optical head with the integrated photodetector is downsized, the tangential skew of the disk causes an offset in the tracking error signal. In addition, JP-A-61-24
Japanese Patent Laid-Open No. 031 discloses a method of providing a light shield that scatters or absorbs light on the emitting end face of a semiconductor laser element, but in a small optical head that integrates the above-mentioned light source and photodetector, a disk is used. One of the reflected ± 1st-order beams for tracking error signal transmission passes through the second diffraction grating 13 at the 0th order and sandwiches the surface of the semiconductor laser chip 5 facing the second diffraction grating 13 and / or the mirror. Since the light is incident on the surface opposite to the diffraction grating on the side opposite to the semiconductor laser chip 5, the effect of preventing interference by providing a light shield for scattering or absorbing light on the emission end surface of the semiconductor laser chip as described above Can't get

The present invention has been made in view of the above problems, and an object of the present invention is to provide a tracking error detecting device for an optical head, which integrates a light source and a photodetector to obtain a stable tracking error signal. To do.

[0009]

In order to achieve the above object, the present invention provides a light beam reflected by a mirror which is close to a semiconductor laser device and reflects a laser light beam emitted from the semiconductor laser device to deflect an optical path. Is incident on the optical recording medium. The 0th and ± 1st order luminous fluxes of the diffraction grating emitted from the deflection optical element through which the 0th order ± 1st order luminous fluxes emitted from the diffraction grating pass are converged on the optical recording medium. A zero-order and ± first-order light flux of the diffraction grating reflected by the optical recording medium passes through the objective lens, is incident on the deflection optical element, and is further deflected by the deflection optical element. A photodetector for receiving the luminous flux is provided, an optical output corresponding to the ± first-order luminous flux is obtained from the photodetector, and a tracking error signal is obtained based on a difference between outputs corresponding to the ± first-order luminous flux. In the tracking error detecting device for an optical head, the at least one of the ± first-order light fluxes reflected by the optical recording medium and passing through the objective lens, the deflection optical element, and the diffraction grating is Without passing through the mirror, the light is incident on the surface of the semiconductor laser element that faces the diffraction grating and / or the surface of the semiconductor laser element that faces the diffraction grating on the side opposite to the semiconductor laser element. Is configured to scatter or absorb light.

[0010]

According to the tracking error detecting device of the optical head of the present invention, the sub-beam generated by the diffraction grating 36a of FIG. 3 is reflected by the disk 38, passes through the objective lens 37, and the hologram 36b and the diffraction grating 36a are zero order. The light is transmitted and is incident on the surface of the semiconductor laser chip 32 facing the transmissive optical element 36. By making the incident region scatter or absorb light, interference can be prevented, and therefore, the occurrence of offset in the tracking error signal due to the tangential skew of the disk can be eliminated.

[0011]

【Example】

(Embodiment 1) FIG. 1 is a front view showing an arrangement of a semiconductor laser chip and a photodetector of an optical head according to a first embodiment of the present invention, and FIG. 2 is an A of a semiconductor laser chip mount portion in the optical head of FIG. FIG.

As shown in FIGS. 1 and 2, a semiconductor substrate
Above the 31 are photodetectors 33, 34, each consisting of 5 regions.
Then, an etching mirror 35 is formed by chemically anisotropically etching the semiconductor substrate 31, and a semiconductor laser chip 32 is mounted in the vicinity of the etching mirror 35.

The feature of this embodiment is that a wire 39 is bonded to the electrode surface 40 of the semiconductor laser chip 32 and a wire bonding portion 41 is formed.

Next, the operation will be described with reference to the schematic view of the tracking error detecting device of the optical head shown in FIGS. 1, 2 and 3 and the diffraction grating and hologram of the optical head shown in FIG.

The beam emitted from the semiconductor laser chip 32 is reflected by the etching mirror 35 as shown by the arrow in FIG. 2, and the diffraction grating formed on the lower surface of the transmissive optical element 36 shown in FIGS. 3 and 4. It is incident on 36a and diffracted, and is divided into a main beam for reading information and two sub-beams for tracking error detection, and transmits the hologram 36b formed on the upper surface of the transmission type optical element 36 in the 0th order. It converges to 38. The converged light is reflected by the disk 38, passes through the objective lens 37, enters the hologram 36b, is diffracted, and is divided into ± first-order lights and guided to the photodetectors 33 and 34.

The tracking error signal is the disc 38
The sub-beam generated by the diffraction grating 36a reflected by the photodetector 33a, 33c, 34a, 34c shown in FIG. 1 is detected,
The so-called three-beam method is used by calculating the intensity difference between the sub-beams. Therefore, the photodetectors 33a, 33c, 34
When the outputs of a and 34c are G, H, I and J, the tracking error signal TE can be obtained by TE = (G + I)-(H + J).

In FIGS. 1 to 3, the disk 38 is shown.
One incident light beam 42a of the sub-beam reflected by the diffraction grating 36a passes through the objective lens 37, passes through the hologram 36b and the diffraction grating 36a in the 0th order, and reaches the transmission type optical element 36 of the semiconductor laser chip 32. It is incident on the opposing electrode surface 40. The wire 39 for supplying power to the semiconductor laser chip 32 is bonded to the incident area of the electrode surface 40 which is the P or N type electrode surface of the semiconductor laser chip 32 as described above. The wire 39 may be bonded to any part of the electrode surface 40, considering only the function of power supply.

Usually, it is bonded near the center. However, in the case of the present embodiment, as shown in FIG. 2, the incident light beam 42a is reflected by the dome shape of the wire bonding part 41 by adjusting the wire bonding part 41 to the area where the incident light beam 42a enters, and scattered light 43 Becomes

This scattered light 43 is more than the incident light beam 42a.
Since the divergence angle is very large, the amount of scattered light 43 passing through the objective lens 37 and returning to the disk 38 is almost zero. Therefore, the incident light beam 42a is reflected by the electrode surface 40 facing the transmissive optical element 36 of the semiconductor laser chip 32, and the amount of light returning to the disk 38 is very small, so that the interference which is a problem in the conventional example is prevented. be able to.

In the tracking error detecting device, when the focus error is detected, the hologram 36b is used.
If is configured to give uneven lens power to the ± 1st order light, the spots incident on the photodetectors 33 and 34 will have focal positions before and after the photodetectors 33 and 34, and the disc will be defocused. Focus error detection is performed by utilizing the fact that the sizes of the spots on the photodetector change when they are changed. Therefore, the photodetectors 33d, 33e, 33
The outputs of f, 34d, 34e, and 34f are A, B, C, D, and
Letting E and F be, the focus error signal FE can be obtained by FE = (A + C + E)-(B + D + F).

In the present embodiment, as described above, the sub-beam which causes the interference incident on the semiconductor laser chip 32 is scattered by wire bonding, but the means for scattering or absorbing the incident light is not limited to this. The same effect can be obtained by such means.

(1) As shown in the sectional view of FIG. 5, a reflection-free coating portion 101a is formed on the incident surface of the sub-beam on the semiconductor laser chip 32 so as to prevent reflection.

(2) As shown in the sectional view of FIG. 6, a dome-shaped convex portion 102a is formed on the incident surface of the sub-beam on the semiconductor laser chip 32, and incident light is scattered or absorbed in the convex portion. As a means for realizing such a structure, it can be configured by potting a resin or wire-bonding separately from the power supply.

(3) As shown in the sectional view of FIG. 7, a prism-shaped convex portion 103a is formed on the incident surface of the sub-beam on the semiconductor laser chip 32, and the incident light is scattered (reflected in an unaffected direction). Alternatively, it is absorbed in the convex portion. As means for realizing such a structure, a fine prism may be bonded onto the semiconductor laser chip 32, or the semiconductor laser chip 32 itself may be etched.

(4) As shown in the cross-sectional view of FIG. 8, a grating-shaped uneven portion 104a (A is an enlarged view) is formed on the incident surface of the sub-beam on the semiconductor laser chip 32, and the incident light is diffracted and scattered. Let As a means for realizing such a structure, it can be constituted by fixing a plate on which a grid-like concavo-convex portion is formed in advance on the semiconductor laser chip 32 or by etching the semiconductor laser chip 32 itself in a grid pattern.

(5) As shown in the sectional view of FIG. 9, the semiconductor laser chip 32 itself is inclined and fixed to form an inclined portion 105a,
Scatters incident light (reflects it in a direction that does not affect it). As means for realizing such a structure, when fixing the semiconductor laser chip 32, the solder layer is melted and solidified while the semiconductor laser chip 32 is tilted, or the semiconductor laser chip is interposed via the triangular spacer 106. It can be configured by fixing 32.

(6) As shown in the sectional view of FIG. 10, a ground glass-like rough surface portion 107a is formed on the incident surface of the sub-beam on the semiconductor laser chip 32 to scatter the incident light. As a means for realizing such a structure, a plate on which a rough surface is formed in advance is used as a semiconductor laser chip 32.
It can be fixed on top, the semiconductor laser chip 32 itself can be roughened, or the semiconductor laser chip 32
It is configured by etching itself (for example, a gold thin film is made rough by etching with an iodine solution).

(Embodiment 2) FIG. 11 is a front view showing the arrangement of a semiconductor laser chip and a photodetector of an optical head according to a second embodiment of the present invention, and FIG. 12 is a semiconductor laser chip of the optical head shown in FIG. It is an AA sectional view of a mount part.

The feature of this embodiment is that, as shown in FIGS. 11 and 12, a non-reflective coating portion 51 is provided immediately above the semiconductor laser chip 32 mounted on the semiconductor substrate 31. Others, Etching mirror 35,4
The photodetectors 33 and 34 having two regions are the same as those in the first embodiment.

Explaining the operation based on the above configuration, the beam emitted from the semiconductor laser chip 32 is reflected by the disk 38 shown in FIG. 3, enters the hologram 36b through the objective lens 37, is diffracted, and the ± 1st order light is emitted. Split photo detector 3
Guided by 3 and 34, the tracking error signal T by the 3-beam method
The operation for obtaining E is the same as that in the first embodiment.

In the present embodiment, one incident light beam 42b of the sub-beams generated by the diffraction grating 36a reflected by the disk 38 (sub-beam on the opposite side to the first embodiment).
Passes through the objective lens 37, hologram 36b, diffraction grating 36a
Of the transmission type optical element 36 on the side opposite to the semiconductor laser chip 32 with the etching mirror 35 interposed therebetween.
Is incident on the surface 50 facing the. As shown in FIGS. 11 and 12, the incident region of the incident light beam 42b is provided with the anti-reflection coating 51, so that the incident light beam 42b is absorbed by the semiconductor substrate 31, and thus this light is reflected. Then, the amount of light passing through the objective lens 37 and returning to the disk 38 again becomes almost zero. Therefore, the incident light beam 42b sandwiches the etching mirror 35 and faces the transmissive optical element 36 on the opposite side of the semiconductor laser chip 32 from the facing surface 50 of the semiconductor substrate 31.
Since the amount of light reflected by the optical disk and returning to the disk 38 is extremely small, it is possible to prevent the interference which has been a problem in the conventional example.

Further, the focus error signal FE when the focus error is detected in the tracking error detecting device
The operation of the photodetector for obtaining is similar to that of the first embodiment.

In this embodiment, as described above, the semiconductor substrate 31
Although the sub-beam that causes interference to the incident light is absorbed by the antireflection coating portion 51, the means for scattering or absorbing the incident light is not limited to this, and the same effect can be obtained by the following means.

(1) As shown in the sectional view of FIG. 13, a wire bonding portion is formed on the incident surface of the sub beam on the semiconductor substrate 31.
41 is formed, and the incident light is diffracted and scattered in the dome shape of the wire bonding portion 41.

(2) As shown in the sectional view of FIG. 5, the anti-reflection coating 10 is formed on the incident surface of the sub-beam on the semiconductor substrate 31.
Configure 1b so that it does not reflect.

(3) As shown in the sectional view of FIG. 6, a dome-shaped convex portion 102b is formed on the incident surface of the sub-beam on the semiconductor substrate 31, and the incident light is scattered or absorbed in the convex portion.
As a means for realizing such a structure, it can be configured by potting a resin or wire-bonding separately from the power supply.

(4) As shown in the sectional view of FIG. 7, a prism-shaped convex portion 103b is attached to the incident surface of the sub-beam on the semiconductor substrate 31, and the incident light is scattered (reflected in an unaffected direction) or Absorb in the convex part. As a means for realizing such a structure, a fine prism may be bonded onto the semiconductor substrate 31 or the semiconductor substrate 31 itself may be etched.

(5) As shown in the cross-sectional view of FIG. 8, a grid-shaped uneven portion 104b (A
Form an enlarged view) and diffract and scatter the incident light.
As a means for realizing such a structure, it can be configured by fixing a plate on which a grid-shaped uneven portion is formed in advance on the semiconductor substrate 31 or by etching the semiconductor substrate 31 itself in a grid pattern.

(6) As shown in the sectional view of FIG. 9, an inclined portion 105b is formed on the sub-beam incident surface itself on the semiconductor substrate 31,
Scatters incident light (reflects it in a direction that has no effect). As a means for realizing such a structure, it can be configured by etching the semiconductor substrate 31 itself.

(7) As shown in the cross-sectional view of FIG. 10, by forming a frosted glass-like rough surface portion 107b on the incident surface on the semiconductor substrate 31, the incident light is scattered. As a means for realizing such a structure, a plate having a rough surface formed in advance is fixed on the semiconductor substrate 31, the semiconductor substrate 31 itself is coated with a rough surface, or the semiconductor substrate 31 itself is etched (for example, gold). The surface can be made rough by etching the thin film with an iodine solution).

Although the semiconductor substrate is used as the mirror in this embodiment, the same effect can be obtained even when the mirror is made of other materials (glass, metal, ceramic, etc.).

[0042]

As described above, the tracking error detecting device for an optical head according to the present invention has the following two light beams, namely (1), in an optical head in which a light source and a photodetector are integrated and miniaturized. The sub-beam generated by the diffraction grating is reflected by the disc, passes through the objective lens, passes through the hologram and the diffraction grating in the 0th order, and is incident on the surface of the semiconductor laser chip facing the transmissive optical element. (2) Diffraction grating The sub-beam generated in step 2 is reflected by the disk, passes through the objective lens, passes through the hologram and diffraction grating in the 0th order, and then enters the surface opposite the semiconductor laser chip facing the transmissive optical element across the etching mirror. This light prevents the conventional problem of interference by causing the light to scatter or absorb in the incident area that it is incident on, and therefore the disc Eliminate the occurrence of the offset of the emission tangential skew by the tracking error signal, it is possible to obtain a stable tracking error signal.

[Brief description of drawings]

FIG. 1 is a front view showing an arrangement of a semiconductor laser chip and a photodetector of an optical head according to a first embodiment of the present invention.

2 is a cross-sectional view taken along the line AA of the semiconductor laser chip mount portion in the optical head of FIG.

FIG. 3 is a schematic diagram of a tracking error detection device for the optical head shown in FIG.

4 is a diagram showing a diffraction grating and a hologram of the optical head shown in FIG.

FIG. 5 is a sectional view showing a configuration of a semiconductor laser chip and a photodetector of the optical head according to the first and second embodiments of the present invention.

FIG. 6 is a cross-sectional view showing a configuration around a semiconductor laser chip of an optical head according to first and second embodiments of the present invention.

FIG. 7 is a cross-sectional view showing the configuration around a semiconductor laser chip of an optical head according to first and second embodiments of the present invention.

FIG. 8 is a sectional view showing a configuration around a semiconductor laser chip of an optical head according to first and second embodiments of the present invention.

FIG. 9 is a cross-sectional view showing a configuration around a semiconductor laser chip of an optical head according to first and second embodiments of the present invention.

FIG. 10 is a cross-sectional view showing a configuration around a semiconductor laser chip of an optical head according to first and second embodiments of the present invention.

FIG. 11 is a front view showing the arrangement of semiconductor laser chips and photodetectors of the optical head according to the second embodiment of the present invention.

12 is a sectional view taken along line AA of the semiconductor laser chip mount portion of the optical head shown in FIG.

FIG. 13 is a sectional view showing a structure around a semiconductor laser chip of an optical head according to a second embodiment of the present invention.

FIG. 14 is a perspective view of a conventional optical head.

FIG. 15 is a conceptual diagram of a conventional entire optical system.

16 is a cross-sectional view of the optical head of FIG.

[Explanation of symbols]

31 ... Semiconductor substrate, 32 ... Semiconductor laser chip, 33,
34 ... Photodetector, 35 ... Etching mirror, 36 ... Transmissive optical element, 36a ... Diffraction grating, 36b ... Hologram, 37
… Objective lens, 38… Disc, 39… Wire, 40
… Electrode surface, 41… Wire bonding part, 42a, 42b
… Luminous flux, 43… Scattered light, 50… Opposed surface, 51, 101a, 101b
... non-reflective coating part, 102a, 102b ... dome-shaped convex part, 103a, 103b ... prism-shaped convex part, 104a, 104b ... lattice-shaped concave-convex part, 105a, 105b ... inclined part, 106 ... solder layer spacer 107a, 107b ... rough surface.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Yoshikawa 1-1 Sachimachi, Takatsuki City, Osaka Prefecture Matsushita Electronics Industrial Co., Ltd.

Claims (16)

[Claims] 1. A diffraction grating is provided in the vicinity of a semiconductor laser element, and a light flux reflected by a mirror that reflects a laser light flux emitted from the semiconductor laser element and deflects an optical path is incident, and is emitted from the diffraction grating. The objective lens for converging the 0th order and ± 1st order light flux of the diffraction grating emitted from the deflection optical element through which the 0th order ± 1st order light flux is passed to the optical recording medium, is reflected by the optical recording medium. Further, there is provided a photodetector for receiving the 0th and ± 1st-order light fluxes of the diffraction grating through the objective lens and entering the deflection optical element, and further receiving the light flux deflected by the deflection optical element. A tracking error detecting device for an optical head, which obtains an optical output corresponding to the ± 1st-order luminous flux and obtains a tracking error signal based on a difference between outputs corresponding to the ± 1st-order luminous fluxes. In at least one of the ± first-order light fluxes reflected by the optical recording medium and passing through the objective lens, the deflection optical element, and the diffraction grating, without passing through the mirror, A tracking error detection device for an optical head, which is incident on a surface facing a diffraction grating, and the incident area is an area for scattering or absorbing light. 2. The tracking error detecting device for an optical head according to claim 1, wherein the scattering or absorbing region is constituted by a wire bonding portion for supplying power to the semiconductor laser element. 3. The tracking error detecting device for an optical head according to claim 1, wherein the scattering or absorbing region is constituted by a non-reflective coating portion formed on the semiconductor laser element. 4. The tracking error detecting device for an optical head according to claim 1, wherein the scattering or absorbing region is formed by a dome-shaped convex portion formed on the semiconductor laser element. 5. The tracking error detecting device for an optical head according to claim 1, wherein the scattering or absorbing region is constituted by a prism-shaped convex portion formed on the semiconductor laser element. 6. The tracking error detecting device for an optical head according to claim 1, wherein the scattering or absorbing region is formed by a grid-shaped uneven portion formed on the semiconductor laser element. 7. The scattering region is formed by an inclined portion of the semiconductor laser device itself.
A tracking error detection device for the optical head described. 8. The tracking error detecting device for an optical head according to claim 1, wherein the scattering or absorbing region is constituted by a rough surface portion formed on the semiconductor laser element. 9. A diffraction grating is provided in the vicinity of the semiconductor laser element, into which the light flux reflected by a mirror that reflects the laser light flux emitted from the semiconductor laser element and deflects the optical path is incident, and is emitted from the diffraction grating. The objective lens for converging the 0th order and ± 1st order light flux of the diffraction grating emitted from the deflecting optical element through which the 0th order ± 1st order light flux is transmitted to the optical recording medium, is reflected by the optical recording medium. Further, there is provided a photodetector for receiving the luminous flux deflected by the deflection optical element after the 0th and ± 1st order luminous fluxes of the diffraction grating pass through the objective lens and are incident on the deflection optical element. A tracking error detecting device for an optical head, which obtains an optical output corresponding to the ± 1st-order luminous flux and obtains a tracking error signal based on a difference between outputs corresponding to the ± 1st-order luminous fluxes. In, at least one of the ± first-order light fluxes reflected by the optical recording medium and passing through the objective lens, the deflection optical element, and the diffraction grating does not pass through the mirror, and is sandwiched by the mirror. A tracking error detecting device for an optical head, characterized in that the incident area is an area which is incident on a surface facing the diffraction grating on the side opposite to the semiconductor laser element and which scatters or absorbs light. 10. The tracking error detecting device for an optical head according to claim 9, wherein the scattering or absorbing region is formed by a wire bonding portion to the incident region. 11. The tracking error detecting device for an optical head according to claim 9, wherein the scattering or absorbing region is formed of a non-reflective coating portion provided on the incident region. 12. The tracking error detecting device for an optical head according to claim 9, wherein the scattering or absorbing region is formed by a dome-shaped convex portion provided in the incident region. 13. The tracking error detecting device for an optical head according to claim 9, wherein the scattering or absorbing region is formed by a prism-shaped convex portion provided in the incident region. 14. The tracking error detecting device for an optical head according to claim 9, wherein the scattering or absorbing region is constituted by a lattice-shaped uneven portion provided in the incident region. 15. The tracking error detecting device for an optical head according to claim 9, wherein the scattering region is formed by an inclined portion of the incident region itself. 16. The rough surface portion provided in the incident area as the scattering or absorbing area.
A tracking error detection device for the optical head described.