JPH11149659A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup by which emission power of a light source for recording information can be stably controlled. SOLUTION: This pickup has two light sources of a semiconductor laser 1 being a light source for recording and a semiconductor laser 2 being a light source for reproducing, light beams from these semiconductor lasers 1, 2 are made incident on a prism member 7, while a laser beam from the semiconductor laser 1 reflected by an incident surface 11e on which a laser beam from the semiconductor laser 1 of this prism member 7 is made incident on the tilt is made incident on a forward monitor 33 and emission power of the semiconductor laser 1 is monitored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup for recording and reproducing information on a recording medium such as an optical card and an optical disk.

[0002]

2. Description of the Related Art Conventionally, an optical pickup is used to record information on a recording medium such as an optical card or an optical disk, and to reproduce the recorded information. Using two independent semiconductor lasers for reproduction and a common objective lens, using a tracking error signal detected from a light beam of one of the semiconductor lasers for recording and reproduction, both beams for recording and reproduction are used. The one disclosed in Japanese Patent Application Laid-Open No. 63-71945 is known as a two-light source pickup for controlling the temperature.

FIG. 10 shows an optical system of a two light source pickup, in which a semiconductor laser 81 is used as a light source for information recording and a light emitting diode 85 is used as a light source for information reproduction. Then, the recording light 91 emitted from the semiconductor laser 81 is converted into parallel light by the collimator lens 82,
After passing this parallel light through the polarizing beam splitter 83, it is irradiated onto the recording medium 90 by the objective lens 84, and the reproduction light 92 emitted from the light emitting diode 85 is converted into a parallel light by the collimator lens 86. After passing the parallel light through the non-polarizing beam splitter 87, the parallel light is guided to the polarizing beam splitter 83, is combined on the same optical path as the recording light 91 in the polarizing beam splitter 83, is reflected, and is reflected on the recording medium 90 by the objective lens 84. Irradiate. Then, the reflected light 93 from the recording medium 90 by the reproduction light 92 is reflected by the polarizing beam splitter 83 and the non-polarizing beam splitter 87 sequentially through the objective lens 84 to form the condensing lens 8.
8 so that the light is received by the photodiode 89.

In order to monitor the light intensity of the recording light 91 emitted from the semiconductor laser 81 in such an optical system of the two light source pickup, as shown in FIG.
A part of the recording light 91 emitted from the semiconductor laser 81 is reflected in the polarization beam splitter 83 to obtain a light beam 94,
By arranging the photodetector 95 on the optical path of the light beam 94, the light intensity of the recording light 91 emitted from the semiconductor laser 81 can be monitored.

[0005]

However, in such a configuration in which the photodetector 95 is arranged to monitor the output power of the semiconductor laser 81 as the information recording light source, the light emitting diode as the information reproducing light source is used. When the reproduction light 92 emitted from the light 85 passes through a part of the light beam without being completely reflected in the polarization beam splitter 83, the light becomes stray light, and is reflected on the same optical path as the light 94 reflected by a part of the recording light 91. It may enter the light receiving surface of the detector 95. Also,
When a part of the reproduction light 92 is multiple-reflected and transmitted in the polarization beam splitter 83, or is reflected on the surface of the polarization beam splitter 83, and is reflected and scattered inside a housing for housing a series of optical components to become stray light. , May also enter the light receiving surface of the photodetector 95.

In this way, when stray light due to the light beam emitted from the light emitting diode 85 as the information reproducing light source enters the light receiving surface of the photodetector 95 which monitors only the output power of the information recording light source, the information recording is performed. Offset occurs in the proportional relationship between the output power of the light source for light and the output value of the photodetector 95, and furthermore, the amount of stray light varies due to variations in the output power of the light emitting diode 85, which is an information reproducing light source. The amount also fluctuates.

This means that the monitor photodetector 95 cannot accurately obtain an output value corresponding to the emission power of the semiconductor laser 81 as the information recording light source. There is a problem that the emission power of the semiconductor laser 81, which is a light source, cannot be stably controlled. The present invention has been made in view of the above circumstances, and has as its object to provide an optical pickup capable of stably controlling the emission power of an information recording light source.

[0008]

According to the first aspect of the present invention,
It has two light sources, a first semiconductor laser as a recording light source and a second semiconductor laser as a reproduction light source, and irradiates laser light from these first and second semiconductor lasers onto a recording medium, thereby obtaining information. An optical pickup for performing recording and reproduction of a laser beam having a combining surface for combining respective laser beams from the first and second semiconductor lasers so as to be substantially on the same optical path; Optical means having an incident surface on which the laser light is incident obliquely, and receiving the laser light from the first semiconductor laser reflected by the incident surface of the optical means and monitoring the output of the first semiconductor laser And light detecting means.

According to a second aspect of the present invention, in the first aspect of the present invention, there is further provided a light shielding means provided so as to cover the light detecting means and for shielding stray light due to laser light from the second semiconductor laser. Provided.

According to a third aspect of the present invention, in the second aspect of the present invention, the optical means and the light detecting means are held and fixed to a housing for housing the optical means and the light detecting means, and It is formed integrally with the housing or a cover member provided in the housing.

As a result, according to the first aspect of the present invention,
It is possible to prevent stray light generated by the light beam from the second semiconductor laser passing through the optical means from entering the light detecting means. According to the second aspect of the present invention, by covering the light detection means with the light shielding means, it is possible to prevent stray light reflected and scattered at various places from entering, and also to prevent other stray light shielding means from entering obliquely. According to the third aspect of the present invention, by forming the light shielding means integrally with the housing or the cover member provided on the housing, an increase in the number of components can be minimized.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1 and 2 show a schematic configuration of an optical pickup to which the present invention is applied. FIG. 1 is a plan view, and FIG. 2 is a partial side view of FIG.

The optical pickup according to the first embodiment is an integrated type in which the entire housing can be moved in the seek direction, and has a semiconductor laser as a recording light source and a semiconductor laser as a reproduction light source. Irradiating the optical card with the light beam from these semiconductor lasers by a common objective lens, and recording and reproducing information while performing tracking control and focusing control with the light beam from one of the semiconductor lasers. 2 shows a two light source pickup to be performed.

In FIG. 1, reference numeral 1 denotes a semiconductor laser serving as a recording light source, and a light beam 50a from the semiconductor laser 1 is provided.
1 (linearly polarized light parallel to the paper surface in FIG. 1) is incident on a diffraction grating 6 as a parallel light flux by a collimator lens 5, where it is diffracted to produce a 0th-order light (recording beam) and ± 1st-order diffracted light (tracking beam). These three beams are obtained, and these light beams are made to enter the prism member 7.

On the other hand, reference numeral 2 denotes a semiconductor laser which is a light source for reproduction. A light beam 51a (linearly polarized light parallel to the paper surface in FIG. 1) from the semiconductor laser 2
Then, the polarization plane is rotated by 90 ° by the half-wave plate 9 so as to enter the diffractive optical member 10.

The diffractive optical member 10 has, for example, different diffraction gratings 10a and 10b on both the entrance and exit surfaces of a glass substrate, respectively. A light beam is obtained, and these two beams are diffracted by the diffraction grating 10b on the emission side to obtain three light beams of 0-order light and ± 1st-order diffracted light, respectively, that is, a total of six light beams. And these light beams are
Is made to enter.

The prism member 7 includes a light beam 50a from the semiconductor laser 1 and a light beam 51a from the semiconductor laser 2.
And a function of separating return light from the optical card 4 described later from the outward path.
A first prism 7a having an incident surface 11c on which a light beam 50a from the semiconductor laser 2 is incident, a second prism 7b having an incident surface 11e on which a light beam 51a from the semiconductor laser 2 is incident, and the first and second prisms. A first polarizing film 11a for beam synthesis provided on the joint surface of the prisms 7a and 7b,
And a second polarizing film 11b for reciprocating path separation provided on the other surface of the prism 7b. The first polarizing film 11a here has, for example, a P-polarized light transmittance Tp of 100%,
The S-polarized light reflectance Rs is set to 100%, and the second polarizing film 11b
Is, for example, Tp = 70% and Rs = 60%.

The light beam 50a from the semiconductor laser 1 having passed through the diffraction grating 6 is incident on the first polarizing film 11a as P-polarized light via the first prism 7a, passes through the first polarizing film 11a, and Laser 2 having passed through diffractive optical member 10
Is incident on the first polarizing film 11a as S-polarized light via the second prism 7b, and is reflected by the first polarizing film 11a. Thus, the light beam 50a from the semiconductor laser 1 and the light beam 51a from the semiconductor laser 2 are combined by the first polarizing film 11a so as to have substantially the same optical path, and are emitted from the second polarizing film 11b. become.

The light beam emitted from the second polarizing film 11b of the prism member 7 is raised by the mirror 12 shown in FIG.
, The light is reflected in the direction perpendicular to the plane of the paper, and is irradiated onto the optical card 4 by the objective lens 3 as shown in FIG.

The return light reflected by the optical card 4 is incident on the second polarizing film 11b of the prism member 7 via the objective lens 3 and the rising mirror 12, where the return light separated from the outward path is converted. The light passes through the condenser lens 13 and is incident as convergent light on a parallel plate 14 arranged at an angle of 45 ° with respect to the optical axis and also at an angle of 45 ° with respect to the track direction. Astigmatism for detection is generated, and the light enters the photodetector 16 via the concave lens 15.

FIG. 3 shows the relative positional relationship between the spot formed by the light beam from the semiconductor laser 1 and the spot formed by the light beam from the semiconductor laser 2 and the track formed on the optical card 4 in such a configuration. It is shown.

In this case, a number of guide tracks 4b are arranged in the optical recording area of the optical card 4 in parallel, and a track 4a is formed between the guide tracks 4b. 40a
40c to 40c indicate spots formed by the light beam from the semiconductor laser 1;
And spots 40b and 40
c indicates spots of the diffraction grating 6 due to the ± 1st-order diffracted light, respectively.

The spots 41a to 41f are spots formed by the light beam from the semiconductor laser 2. Among the spots 41a to 41c, the ± 1st-order diffracted light of the diffraction grating 10a, for example, the 0th-order diffracted light is A spot 41a is a spot formed by a light beam separated into light and ± 1st-order diffracted light, a spot 41a is a spot formed by a 0th-order light, and spots 41b and 41c are spots formed by ± 1st-order diffracted light. 41f are spots formed by respective light beams obtained by separating the -1st-order diffracted light of the diffraction grating 10a into 0th-order light and ± 1st-order diffracted light by the diffraction grating 10b. Reference numerals 41e and 41f indicate spots due to ± first-order diffracted light, respectively.

The spots 40a to 40c by the light beam from the semiconductor laser 1 are changed to the desired tracks 4a of the optical card 4 by the tracking control.
In the state where it is located above, the spots 40b and 40c are
The guide track 4b is located at an edge on one side and an edge on the other side of the guide track 4b several tracks before and after the desired track 4a.

The spots 41a to 41c by the light beam from the semiconductor laser 2 are positioned on three sequential tracks on one side including the desired track 4a where the spot 40a is located, and the spots 41d to 41f
Are located on three sequential tracks on the other side including the desired track 4a where the spot 40a is located.

The spots 41a to 41c by the light beam from the semiconductor laser 2 are positioned on one of the three successive tracks including the desired track 4a on which the spot 40a is located, and the spots 41d to 41f are
The spot 40a is located on three sequential tracks on the other side including the desired track 4a where the spot 40a is located.

Thus, in the information recording mode, the semiconductor laser 1 emits a light beam that changes from a predetermined reproducing power to a recording power according to information to be recorded, and the semiconductor laser 2 emits a light beam having a predetermined reproducing power. A light beam is emitted, tracking control is performed based on the return light from the spots 40b and 40c, and, depending on the moving direction of the optical card 4, for example, at the preceding spot 41c or 41e,
While performing a blank check of a track to be recorded and a defect detection, information is recorded on a desired track 4a by a spot 40a, and the recorded information is transferred to a rear spot 41e.
Alternatively, verification is performed based on the return light from the return light from 41c.

In the information reproducing mode, the semiconductor lasers 1 and 2 emit light beams of a predetermined reproducing power, respectively, and perform the tracking control based on the return light from the spots 41b and 41c, while controlling the spots 41a to 41c.
Based on the return light from the spots 41c and the spots 41d to 41f, multi-track reading for simultaneously reproducing five tracks is performed. The spots 41c and 41e
Is located on the simultaneous track 4a, so that the track 4a is reproduced based on the return light from one of the spots.

Returning to FIG. 1, the holding means for holding the optical components of the first embodiment in the housing 34 will be described with reference to the partial side view of FIG. In this case, the prism member 7 holds the first and second prisms 7a and 7b by bonding a surface orthogonal to the joining surface to a flat surface (not shown) formed on the housing 34 and parallel to the xy plane. doing. The rising mirror 12 is held by bonding the surface opposite to the anti-slope surface of the light beam to a flat surface (not shown) inclined at an angle of 45 ° with respect to the xy plane formed in the housing 34. doing.

The semiconductor laser 1 is press-fitted into a hole formed substantially in the center of the plate 17 and is mounted on a contact surface provided on a side surface on the outer periphery of the housing 34. Similarly, the semiconductor laser 2 also has a hole 21 formed substantially in the center of the plate 21.
a, and is attached to a contact surface provided on the outer peripheral side surface of the housing 34.

The collimator lens 5 is bonded and fixed inside a cylindrical lens frame 18 having a flat surface on the outer periphery, and the diffraction grating 6 is bonded and fixed to the end surface of the lens frame 18 on the prism member 7 side. By bonding multiple optical components to one lens frame, the number of components is reduced.

In this case, the housing 34 to which the lens frame 18 is attached extends in the direction parallel to the optical axis direction of the collimator lens 5 as shown in FIG. It has an abutment surface parallel to the y plane, and the lens frame 18 can be moved in the optical axis direction of the collimator lens 5 between these abutment surfaces, so as to regulate the movement in a direction orthogonal to the optical axis. The leaf spring 19 is elastically pressed and held.

The leaf spring 19 has one end portion of the housing 3.
4 with a screw 20, and the other end portion is provided with one projection 1 so as to press the lens frame 18 near the center in the optical axis direction.
91 are formed.

Similarly, the collimator lens 8 is bonded and fixed inside a cylindrical lens frame 22 having a flat surface on the outer periphery. Also, a housing 34 for attaching the lens frame 22
Extends in a direction parallel to the optical axis direction of the collimator lens 8 to form a contact surface erected in the z direction and a contact surface parallel to the xy plane, and the lens is disposed between these contact surfaces. The frame 22 can be moved in the optical axis direction of the collimator lens 8,
It is elastically pressed and held by a leaf spring 23 so as to restrict movement in a direction perpendicular to the optical axis.

Similarly to the leaf spring 19, one end of the leaf spring 23 is engaged with the housing 34 and fixed with the screw 24. The other end of the leaf spring 23 is located near the center in the optical axis direction. One protrusion 231 is formed so as to press.

Half-wave plate 9 and diffractive optical member 10
Are bonded and fixed to both end surfaces of a hollow cylindrical frame 25 having a flat portion on the outer periphery. The housing 34 to which the frame 25 is attached has a contact surface extending in a direction parallel to the optical axis direction of the collimator lens 8 and standing in the z direction and a contact surface parallel to the xy plane. The leaf spring 26 is elastically pressed and held between these contact surfaces.

The leaf spring 26 is provided with urging portions at both ends, and one of these urging portions is formed with one projection 261 so as to press the frame 25.
One projection 262 is formed so as to also press 8. The leaf spring 26 is fixed to the housing 34 with screws 27, and a single urging member presses a plurality of lens frames to reduce the number of components.

The condenser lens 13 has a cylindrical lens frame 28.
It is glued and fixed inside. The lens frame 28 is formed on the abutting surface formed on the housing 34 in the z-direction and the abutting surface parallel to the xy plane by the leaf spring 26 described above.
It is elastically pressed and held.

The parallel plate 14 and the concave lens 15 are integrally held by a common frame 29 and
The position of the concave lens 4 and the concave lens 15 in the optical axis direction with respect to the condenser lens 13 can be adjusted. This frame 29 is
4 is elastically pressed and held by the leaf spring 30 fixed to the housing 34 with screws 31 against the contact surface that stands in the z direction and the contact surface that is parallel to the xy plane.

The concave lens 15 held by the frame 29
Has its optical axis inclined with respect to the optical axis of the condenser lens 13 in order to correct coma caused by the parallel flat plate 14. Also, the leaf spring 30 has one protruding portion 301 formed at the end so as to press the frame 29, similarly to the above-described leaf spring.

The photodetector 16 is mounted on the surface of the hard substrate 32. The hard substrate 32 is attached to a contact surface provided on the outer peripheral side surface of the housing 34. By the way, when controlling the emission power of the semiconductor laser by switching between the information recording mode and the reproduction mode, a part of the light beam from the semiconductor laser is separated from the optical path for guiding the light to the recording medium. A photodetector (hereinafter referred to as a front monitor) for detecting the output power may be used.

However, as described above, in a two-light source pickup using two independent semiconductor lasers 1 and 2 for recording and reproduction, it will be described later to control the emission power of the semiconductor laser 1 for recording. When the front monitor 33 is easily arranged, unnecessary stray light due to the light beam from the semiconductor laser 2 for reproduction enters the light receiving surface of the front monitor, whereby the output power of the semiconductor laser 1 for recording and the output of the front monitor are output. An offset depends on the proportionality of the value, and the offset amount fluctuates due to a variation in the emission power of the semiconductor laser 2 for reproduction. That is,
The output value of the front monitor according to the output power of the recording semiconductor laser 1 cannot be obtained due to stray light due to the light beam from the reproducing semiconductor laser 2, and the output power of the recording semiconductor laser 1 cannot be stably controlled. Sometimes.

Therefore, in such a configuration,
In order for the front monitor 33 to receive only a part of the light beam 50a from the semiconductor laser 1 for recording, the front monitor 33 needs to have one of the light beams 50a in the optical path before being combined with the light beam 51a from the semiconductor laser 2 for reproduction. It is necessary to separate the front monitor 33 on the separated optical path from the optical path leading to the optical card 4.

As a specific example, as shown in FIG. 5A, the light beam 50a from the semiconductor laser 1 is
Since the light passes through the incident surface 11c of the prism member 7, the first polarizing film 11a, and the second polarizing film 11b and is guided onto the optical card 4, the light beam 50a is transmitted through the first polarizing film 11a.
Is reflected to obtain a reflected light 50c.
If the front monitor 33 is disposed on the optical path of the reflected light 50c so that c is transmitted through the transmission surface 11d of the prism member 7, the front monitor 33 can be easily configured without providing another optical member. .

However, as shown in FIG. 5B, the optical path of the light beam 51a from the semiconductor laser 2 to the optical card 4 is such that the light beam 51a from the semiconductor laser 2 is incident on the incident surface 11e of the prism member 7. Through the first polarizing film 1
The light beam 51a is reflected by the first polarizing film 11a, is transmitted through the second polarizing film 11b, and is guided onto the optical card 4. However, the light beam 51a at this time cannot be completely reflected by the first polarizing film 11a, and is not reflected by the first polarizing film 11a. The portion transmits through the first polarizing film 11a and the transmission surface 11d, and becomes stray light 51b. The path of the stray light 51b is the same as the path of the reflected light 50c in which a part of the light beam 50a is reflected by the first polarizing film 11a.
With 0c, the light directly enters the light receiving surface of the front monitor 33.

The problem that such stray light 51b directly enters the light receiving surface of the front monitor 33 is that the reflected light 50c received by the front monitor 33 is obtained by using the first polarizing film 11a for beam synthesis. It is caused by that. Further, the light beam 51a from the semiconductor laser 2 is multiple-reflected inside the prism member 7 to generate stray lights 51c and 51d, and these stray lights are reflected and scattered inside the casing 34 formed by aluminum die casting or the like. The light enters the light receiving surface of the front monitor 33.

Therefore, in the first embodiment, the surface reflection on the incident surface 11c of the prism member 7 is performed without using the first polarizing film 11a for beam combining in the prism member 7, A part of the light beam 50a from the semiconductor laser 1 is guided to the light receiving surface of the front monitor 33, and a light shielding cover is provided to cover a part other than the light receiving surface of the front monitor 33.

Referring to FIG. 6 and FIG.
3 will be described. In this case, as shown in FIG. 6, a part of the light beam 50a from the semiconductor laser 1 is surface-reflected by the incident surface 11c of the prism member 7, and a reflected light 50b is obtained. Monitor 3
3 are arranged.

At this time, the front monitor 33 is moved along the optical axis of the reflected light 50b so that the reflected light 50b is reflected by the light receiving surface of the front monitor 33 and the package surface and does not enter the incident surface 11c of the prism member 7 again. With respect to the xy plane.

As a result, it is possible to prevent stray light 51b generated by transmitting a part of the light beam 51a from the semiconductor laser 2 through the first polarizing film 11a from directly entering the light receiving surface of the front monitor 33. The front monitor 33 can be easily arranged without providing any special optical member. Further, since the front monitor 33 is inclined with respect to the optical axis of the reflected light 50b, it is possible to prevent stray light from being generated on the photodetector 16.

On the other hand, as shown in FIG.
Are mounted on the hard substrate 35 such that the center of the light receiving surface and the optical axis of the reflected light 50b coincide with each other in the z direction. Then, the front monitor 33 is assembled from the rear side of the housing 34 while being mounted on the hard board 35.

The housing 34 is integrally formed with a light-shielding cover 34a that covers the outer periphery of the front monitor 33. The light-shielding cover portion 34a is formed integrally with the housing 34 by aluminum die casting or the like, and forms a part of the reinforcing rib 34f inside the housing 34. The light-shielding cover portion 34a has a through hole 34b on the back surface of the housing 34. By fitting the front monitor 33 into the through hole 34b, the front monitor 33 can be positioned with respect to the housing 34. In this case, the front monitor 33 is
When inserted into the opening 4b, a concave portion 34d (FIG. 6) is provided inside the opening 34c so that the package surface corresponding to the light receiving portion of the front monitor 33 is not damaged by burrs at the mouth of the through hole 34b or irregularities on the inner peripheral surface. (See FIG. 3) so as not to contact the surface of the front monitor 33.

The light shielding cover 34a has the reflected light 5
Aperture 3 opening along optical path 0b and also in z direction
4c. Further, the side surface 34e of the reinforcing rib 34f that is opposed to the transmitting surface 11d of the prism member 7 and stands upright in the z direction has a stair-like surface, and stray light 51b transmitted through the transmitting surface 11d of the prism member 7; Even if the light 51c is irradiated, the light is reflected and scattered on the surface of the side surface 34e, and attenuates the amount of stray light incident again on the prism member 7.

Further, since the outer periphery of the front monitor 33 is covered by the light-shielding cover portion 34a, the stray light 51c reflected and scattered inside the housing 34 can be prevented from entering, and the stray light 51d can be obliquely projected on the front monitor 33. Can be prevented, and the offset of the output value of the front monitor 33 caused by the stray light entering the front monitor 33 can be effectively reduced.

Further, by forming the light shielding cover 34a integrally with the housing 34, an increase in the number of parts can be minimized.
Therefore, according to this configuration, there are two light sources, a semiconductor laser 1 as a recording light source and a semiconductor laser 2 as a reproduction light source, and light beams from these semiconductor lasers 1 and 2 are incident on the prism member 7. , This prism member 7
Since the laser light from the semiconductor laser 1 reflected from the incident surface 11e where the laser light from the semiconductor laser 1 is inclined and incident is incident on the front monitor 33, the emission power of the semiconductor laser 1 is monitored. The stray light generated by the light beam from the semiconductor laser 2 passing through the prism member 7 can be prevented from entering the front monitor 33, and an accurate output value of the front monitor 33 according to the output power of the semiconductor laser 1 can be obtained. The output power of the recording semiconductor laser 1 can be controlled stably. (Second Embodiment) FIG. 8 is a perspective view showing only a portion related to a front monitor according to a second embodiment of the present invention. Shall conform to

In this case, the front monitor 33 is
5 and is fitted into a through hole 36 a provided in the housing 36. When the front monitor 3 is attached to the housing 36,
3 has a light-receiving surface protruding from the through hole 36a.

On the other hand, a light-shielding cover portion 37a for blocking stray light entering the light-receiving surface of the front monitor 33 is provided on the back side of a protective or dust-proof cover 37 for optical components covering the upper opening of the housing 36. I have. This light shielding cover 37a
It is formed integrally with the cover 37 by a resin material. Further, a circular opening 37b is provided on the side surface of the light shielding cover 37a so that a part of the light beam 50a from the semiconductor laser 1 can be irradiated on the light receiving surface of the front monitor 33. As the resin material of the cover 37, for example, a black resin is used to prevent reflection.

In this manner, unnecessary stray light due to the light beam from the semiconductor laser 2 for reproduction is prevented from entering the light receiving surface of the front monitor 33 in the same manner as described in the first embodiment. be able to. Also, the cover 37
Can be molded from a resin material such as black.
It is also possible to reduce reflection on the surface of the light-shielding cover portion 36a that covers the third light-emitting element 3. (Third Embodiment) FIG. 9 is a perspective view showing only a portion related to a front monitor according to a third embodiment of the present invention. Shall conform to

In this case, the front monitor 33 is interposed via a spacer 39 whose dimension in the z direction is determined such that the center of the light receiving surface is located at the same position as a part of the optical axis of the light beam 50a from the semiconductor laser 1. Thus, it is mounted on the hard board 35 and fitted into a through hole 38 a provided in the housing 38.

The spacer 39 is provided with a light shielding cover 39a for blocking stray light entering the light receiving surface of the front monitor 33. The light shielding cover 39a is formed integrally with the spacer 39 by a resin material. Further, a circular opening 39b is provided on the side surface of the light-shielding cover 39a so that a part of the light beam 50a from the semiconductor laser 1 can be irradiated on the light receiving surface of the front monitor 33. The resin material of the spacer 39 is, for example, a black resin to prevent reflection.

In this manner, in the same manner as described in the second embodiment, unnecessary stray light due to the light beam from the reproducing semiconductor laser 2 is prevented from entering the light receiving surface of the front monitor 33. Since the spacer 39 can be formed of a resin material such as black, the front monitor 33 can be used.
Can also reduce the reflection of stray light on the surface of the spacer 39 that covers the space. Further, the light shielding cover 39a is connected to the front monitor 3
Since the spacer also serves as a spacer for aligning the optical axis of the light beam with the center of the light receiving surface of 3, the workability in mounting the front monitor 33 can be improved.

[0062]

As described above, according to the present invention, the stray light generated by the light beam from the second semiconductor laser passing through the optical means can be prevented from entering the light detecting means. An accurate output value corresponding to the emission power of the semiconductor laser can be obtained, and the emission power of the information recording semiconductor laser can be stably controlled.

Further, by covering the light detecting means with the light shielding means, it is possible to prevent stray light reflected and scattered at various places from entering, and also to prevent other stray light from entering obliquely from the light shielding means. Can effectively reduce the offset of the output value caused by entering the semiconductor laser, and can stably control the emission power of the semiconductor laser. Further, by integrally forming the light shielding means with the housing or the cover member provided on the housing, an increase in the number of components can be minimized.

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic configuration of a first embodiment of the present invention.

FIG. 2 is a partial side view showing a schematic configuration of the first embodiment.

FIG. 3 is a diagram showing a relative positional relationship between a spot and a track by a light beam according to the first embodiment.

FIG. 4 is a partial side view showing a schematic configuration of the first embodiment.

FIG. 5 is a diagram for explaining the operation of the first embodiment.

FIG. 6 is a diagram showing an arrangement configuration of a front monitor according to the first embodiment.

FIG. 7 is a diagram illustrating an arrangement configuration of a front monitor according to the first embodiment;

FIG. 8 is an exemplary perspective view showing only a portion related to a front monitor according to a second embodiment of the present invention;

FIG. 9 is an exemplary perspective view showing only a portion related to a front monitor according to a third embodiment of the present invention;

FIG. 10 is a diagram showing a schematic configuration of an optical system of a conventional optical pickup.

FIG. 11 is a diagram showing a schematic configuration of a monitoring optical system of a light intensity of recording light of a conventional optical pickup.

[Explanation of symbols]

 1, 2 semiconductor laser, 3 objective lens, 4 optical card, 4a track, 4b guide track, 40a to 40c, 41a to 41f spot, 5 collimator lens, 6 diffraction grating, 7 prism member 7a, 7b: prism, 8: collimator lens, 9: half-wave plate, 10: diffractive optical member, 10a, 10b: diffraction grating, 11a to 11e: polarizing film, 12: mirror, 13: condenser lens, 14 parallel plate, 15 concave lens, 16 photodetector, 17 plate, 18 lens frame, 19 leaf spring, 20 screw, 21 plate, 22 lens frame, 23 leaf spring, 24 screw , 25 ... frame, 26 ... leaf spring, 27 ... screw, 28 ... lens frame, 29 ... frame, 30 ... leaf spring, 31 ... screw, 32 ... hard board, 33 ... front monitor, 34 ... Casing, 34a: light shielding cover, 34b: through hole, 34c: opening, 34d: concave, 34e: side surface, 34f: reinforcing rib, 35: rigid substrate, 36: casing, 37: dustproof cover, 37a ... light-shielding cover part, 37b ... opening part, 38 ... housing, 38a ... through hole, 39 ... spacer, 39a ... light-shielding cover part, 39b ... opening part, 50a, 51a ... light beam, 50c ... reflected light, 51b, 51c , 51d ... Stray light.

Claims (3)

[Claims] 1. A light source comprising a first semiconductor laser as a recording light source and a second semiconductor laser as a reproduction light source, and irradiates laser light from the first and second semiconductor lasers onto a recording medium. By doing so, the optical pickup for recording and reproducing information has a combining surface for combining the respective laser beams from the first and second semiconductor lasers so as to be substantially on the same optical path, and An optical unit having an incident surface on which a laser beam from the first semiconductor laser is obliquely incident, and a first semiconductor laser receiving the laser beam from the first semiconductor laser reflected by the incident surface of the optical unit; An optical pickup comprising: a light detection unit that monitors a laser output. 2. An optical pickup according to claim 1, further comprising a light shielding means provided so as to cover said light detection means, and shielding stray light due to laser light from said second semiconductor laser. . 3. The optical means and the light detecting means are held and fixed to a housing for housing the optical means and the light detecting means, and the light shielding means is integrated with the housing or a cover member provided on the housing. The optical pickup according to claim 2, wherein the optical pickup is formed.