JPH1049904A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact optical pickup capable of dealing with different kinds of optical disks and securing sufficient signal intensity. SOLUTION: This optical pickup device includes two semiconductor lasers 1 and 2 for emitting identical or different wavelength laser light, a photodetector 8 composed of a plurality of light receiving elements, a heat sink 9 having two semiconductor lasers 1 and 2 and the photodetector 8, a housing having a laser light transmitting window while sealing the heat sink 9, two polarized beam splitters 3 and 4, a reflection mirror 5, a 1/4 wavelength plate 6 and a grating 7. The light separating surfaces of the two polarized beam splitters 3 and 4 and the reflection surface of the reflection mirror 5 are placed in parallel to each other, the housing 2, the polarized beam splitters 3 and 3, the reflection mirror 5, the 1/4 wavelength plate 6 and the grating 7 are integrally provided and thus, difference kinds of optical disk are dealt with and sufficient signal intensity is secured by a compact form.

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 on an optical disk.

[0002]

2. Description of the Related Art With respect to a conventional optical pickup, an optical pickup which emits laser light and detects reflected light thereof will be described. FIG. 7 is a diagram illustrating a conventional optical element.

In FIG. 7, a semiconductor laser 21 for emitting a laser beam, a diffraction grating 22 for dividing the light of the semiconductor laser into three beams, and a light reflected from a disk are detected by a photodetector 2.
A hologram 23 having two regions for leading to 4;
It consists of a photodetector 24 of a five-division light-receiving element for detecting light reflected from the disk. The semiconductor laser 21 and the photodetector 24 are sealed in a housing, and are integrally formed by bonding and fixing a cover glass 25 having a hologram 23 formed on a light emitting surface on the housing.

Light emitted from a semiconductor laser 21 is split into three beams by a diffraction grating 22, transmitted through a hologram 23, emitted from an optical element, and reaches a disk by optical components described later. The three beams are 2 of the hologram 23
The light is diffracted in each of the two regions, guided to the five-division light receiving element, and received. In this optical element, focus detection is performed by a known Foucault method, and track detection is performed by a known three-beam method.

FIG. 8 is a structural view of a conventional optical pickup. In FIG. 8, light from a semiconductor laser 31 is reflected by a half mirror 32, becomes parallel light by a collimator lens 33, is reflected by a rising mirror 34, and is condensed on an optical disk 36 by an objective lens 35. You. The reflected light from the optical disk 36 is collected again by the objective lens 35, reflected by the rising mirror 34, and transmitted through the collimator lens 33. Collimator lens 33
Is transmitted through the detection lens 37 and is received by the photodetector 38. In the conventional optical pickup, focus detection is performed by a known astigmatism method, and track detection is performed by a known phase difference method. For this reason, the photodetector 38 is composed of a plurality of light receiving elements.

[0006]

However, in the conventional optical pickup, the emitted light of the laser for focusing on the optical disk passes through the hologram, and the primary diffracted light of the hologram is detected for detecting the reflected light from the optical disk. Is used, the signal light intensity is reduced.

Further, the wavelength of the semiconductor laser light used is a single wavelength, and recording / reproducing of a write-once type optical disc having a different wavelength cannot be performed.

Further, in the conventional optical pickup, the optical components are constituted by discrete components, and the arrangement of the semiconductor laser, the half mirror and the light receiving element is determined by the range in which the focus error is drawn, making it difficult to miniaturize the optical pickup. It is.

The present invention solves the above-mentioned conventional problems, and is an optical pickup which emits a laser beam and detects the reflected light thereof, which is compatible with different types of optical discs, and which is small and has sufficient signal strength. It is an object of the present invention to provide an optical pickup that can perform the optical pickup.

[0010]

An optical pickup according to the present invention comprises two semiconductor lasers for emitting laser beams of the same or different wavelengths, a photodetector constituted by a plurality of light receiving elements, and two semiconductor lasers. A heat sink on which a photodetector is mounted, a housing that seals the heat sink and has a transmission window for laser light, two polarization beam splitters, a reflection mirror, a quarter-wave plate, and a diffraction grating; The light separation surface of the two polarization beam splitters and the reflection surface of the reflection mirror are parallel to each other, and the housing, the two polarization beam splitters, the reflection mirror, the quarter-wave plate, and the diffraction grating are integrally formed. It is characterized by the following.

With the above arrangement, it is possible to cope with different types of optical discs, emit light without passing through the diffraction grating, and use light transmitted through the diffraction grating (zero-order diffraction light) as reflected light from the medium. Thus, an optical pickup that is small and can ensure sufficient signal strength can be provided.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 and claims 3 to 6 is an optical pickup for recording information on or reproducing information from a disk-shaped recording medium, the optical pickup having a first wavelength. A photodetector comprising a first semiconductor laser for emitting laser light, a second semiconductor laser for emitting laser light having a second wavelength, and a plurality of light receiving elements for detecting reflected light from a disk And a heat dissipation substrate member on which the first semiconductor laser, the second semiconductor laser, and the photodetector are mounted, and sealing the first semiconductor laser, the second semiconductor laser, the photodetector, and the heat dissipation substrate member. A housing having a portion through which laser light is transmitted, two light separating elements that transmit or reflect according to a polarization plane of the laser light disposed in the housing, and a photodetector that detects reflected light from a disk disposed in the housing Reflects on A projection mirror, a quarter-wave plate for changing the polarization state of laser light disposed on the light exit surface of the light separating element, and a diffraction grating having a plurality of regions for guiding the reflected light from the disk to the photodetector One light separating element is provided so that the center of the light separating element is aligned with the optical axis of the first semiconductor laser, and the center of the light separating element is aligned with the optical axis of the second semiconductor laser. A light separating element, a diffraction grating is further provided on a joint surface between the reflecting mirror and the light separating element, and the light separating surface of the two light separating elements and the reflecting surface of the reflecting mirror are parallel to each other, and the housing is provided. And two light separating elements, a reflecting mirror, a quarter-wave plate, and a diffraction grating are integrally formed, and either one of the first semiconductor laser and the second semiconductor laser emits light to the mounting surface of the heat dissipation substrate member. It is characterized by emitting in a vertical direction It is.

According to a second aspect of the present invention, there is provided an optical pickup for recording information on or reproducing information from a disk-shaped recording medium, which emits a laser beam having a first wavelength. A first semiconductor laser, a second semiconductor laser that emits a laser beam having a second wavelength, a photodetector that includes a plurality of light receiving elements for detecting reflected light from a disc, A heat radiation board member on which the semiconductor laser, the second semiconductor laser, and the photodetector are mounted;
A housing having a portion through which the semiconductor laser, the second semiconductor laser, the photodetector, and the heat dissipation substrate member are sealed and through which the laser light is transmitted, and which is transmitted or reflected according to the polarization plane of the laser light disposed in the housing. Two light separating elements, a reflecting mirror for reflecting light reflected from an optical disk disposed in a housing to a photodetector, and changing a polarization state of laser light disposed on a light emitting surface of the light separating element. A four-wave plate,
A diffraction grating having a plurality of regions for guiding the reflected light from the disk to the photodetector, and having one light separating element so that the center of the light separating element coincides with the optical axis of the first semiconductor laser. A reflection mirror is provided so that the center of the reflection surface is coincident with the optical axis of the second semiconductor laser; and a diffraction grating is provided on the joint surface between the other one light separating element and the housing.
The light separation surface of the two light separation elements and the reflection surface of the reflection mirror are parallel to each other, and the housing, the two light separation elements, the reflection mirror, the quarter-wave plate, and the diffraction grating are integrally formed. Outgoing light of any one of the semiconductor laser and the second semiconductor laser is emitted in a direction parallel to the mounting surface of the heat dissipation substrate member.

According to a seventh aspect of the present invention, in addition to the optical pickup of the first to sixth aspects, one objective lens having a predetermined focal length and a stand for reflecting the optical path of the optical pickup to the objective lens. It has an up-mirror and a semiconductor laser switching means for switching light emission between the first semiconductor laser and the second semiconductor laser, and records and reproduces data on and from different types of optical disc media.

According to an eighth aspect of the present invention, in addition to the optical pickup of the first to sixth aspects, two objective lenses having different focal lengths, and an optical path for reflecting the optical path of the optical pickup to the objective lens. Raising mirror, means for switching one of the two objective lenses into and out of an optical path between the raising mirror and the optical disk medium, and an objective lens switching means; a first semiconductor laser and a second semiconductor; And a semiconductor laser switching means for switching light emission with a laser, and recording and reproducing on and from different types of optical disc media.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a configuration diagram of an optical pickup according to Embodiment 1 of the present invention. In FIG. 1, a heat sink 9 is disposed at a predetermined distance (d) at the same oscillation wavelength as the semiconductor laser 1 and at a first semiconductor laser 1 for emitting light, a photodetector 8 for detecting light, and a laser diode. Second
And the semiconductor laser 2. On the emission surface of the laser light on the heat sink 9, the polarization beam splitter 3 for separating the light of the semiconductor laser 1, the polarization beam splitter 4 for separating the light of the semiconductor laser 2, and the light of the semiconductor laser 1 or 2 are reflected. Reflection mirror 5, semiconductor lasers 1 and 2
Quarter-wave plate 6 for converting the linearly polarized state of the light into circularly polarized light
And a diffraction grating 7 having two regions for guiding light from an optical disk to a photodetector 8.

FIG. 2 is a diagram showing a grating surface of the diffraction grating 7 of FIG. In the figure, the two regions are represented in the grid pattern of the two regions on the left and right, respectively, as the difference between the lattice planes.

FIG. 3 is a diagram showing a light receiving surface of the photodetector 8 of FIG. In FIG. 3, the center vertical line for detecting the reflected light from the optical disk is arranged so as to coincide with the optical axis of the light.
A cross-shaped quadrant light-receiving element 8-A whose division line is parallel and orthogonal to the track direction of the optical disk, and at least two or more divisional light-receiving elements 8 arranged at a required distance from the quadrant light-receiving element -B.

The above components are arranged as follows. First, a heat sink 9 made of copper and a copper alloy
The semiconductor laser 1 and the semiconductor laser 2 are soldered thereon, the photodetector 8 is adhered with a UV curing resin, and is housed in a metal crown provided with a light transmission window.

Next, a polarizing beam splitter 3 whose center is aligned with the optical axis of the semiconductor laser 1 and a polarizing beam splitter 4 whose center is aligned with the optical axis of the semiconductor laser 2 are arranged on the housing. The reflection surface of the reflection mirror 5 is arranged so as to be parallel to the light separation surfaces of the polarization beam splitter 3 and the polarization beam splitter 4.

Next, at the exit of the polarizing beam splitter 3, the plane of polarization of the quarter-wave plate 6 forms an angle of 45 ° with the plane of polarization of the semiconductor laser 1, and Is disposed at an angle of 45 ° with respect to the light separating surface of the polarizing beam splitter 3.

The heat sink 9 or the housing may include a circuit for converting a current signal obtained by the photodetector 8 into a voltage signal.

The light emitted from the semiconductor laser 2 operates in exactly the same manner as the light emitted from the semiconductor laser 1 described above. In this case, the optical path length becomes longer by the distance (d). Therefore, in the finite system of the first embodiment, any one of the semiconductor lasers is used depending on the thickness (focal length) of the optical disk.

In the first embodiment, for example, the emission wavelengths of the two semiconductor lasers are selected to be the same in the range of 635 nm to 650 nm, and the distance (d) is set to 8 mm. Alternatively, a different emission wavelength may be selected according to the medium.

As described above, according to the present invention, since the RF signal and the tracking error signal are detected by using the zero-order diffracted light, it is possible to provide an optical pickup which is small and can secure a sufficient signal intensity. .

(Embodiment 2) FIG. 4 is a configuration diagram of an optical pickup according to Embodiment 2 of the present invention. In FIG. 4, a heat sink 9 includes a light detector 8 for detecting light.
A first semiconductor laser 1 that emits a laser beam, and a second semiconductor laser 2 that is arranged at the same oscillation wavelength as the semiconductor laser 1 and separated by a required distance (d). On the outgoing slope of the laser light on the heat sink 9, there are provided a reflection mirror 5 for reflecting the light of the semiconductor laser 1, a polarization beam splitter 3 and a polarization beam splitter 4 for separating the laser light of the semiconductor laser 2, and the semiconductor lasers 1 and 2. A quarter-wave plate 6 for converting the linearly polarized state of the laser light into circularly polarized light and a diffraction grating 7 having two regions for guiding the reflected light from the optical disk to the photodetector 8 are arranged. Note that the configuration of the light receiving surface of the photodetector 8 is the same as that of the first embodiment, and the description will not be repeated.

The above components are arranged as follows.
First, a semiconductor laser 1 and a semiconductor laser 2 are soldered on a heat sink 9 formed of copper and a copper alloy, and a photodetector 8 is bonded with a UV curing resin to form a metal crown provided with a light transmission window. Housing.

Next, on the housing, there is provided a reflecting mirror 5 arranged so that its center coincides with the optical axis of the semiconductor laser 1.
And a polarizing beam splitter 3 whose center is aligned with the optical axis of the semiconductor laser 2 and a polarizing beam splitter 4 whose center is aligned with the photodetector 8. And the light separating surfaces of the polarizing beam splitter 3 and the polarizing beam splitter 4 are arranged so as to be parallel to each other and at an angle of 45 ° with the optical axes of the semiconductor lasers 1 and 2.

Next, at the exit of the polarizing beam splitter 4, the plane of polarization of the quarter-wave plate 6 forms an angle of 45 ° with the reflecting surface of the reflecting mirror 5, and the quarter-wave plate 6 is polarized. The 波長 wavelength plate 6 is disposed so as to be at 45 ° to the light splitting surface of the beam splitter 4.

The diffraction grating 7 is provided on the joining surface between the polarizing beam splitter 4 and the housing, and is provided on either the joining surface on the housing side of the polarizing beam splitter 4 or the joining surface on the housing side corresponding to the polarizing beam splitter 4. You may.

The polarization beam splitter 3 rotates the polarization angle of the light separation surface by 90 ° with respect to the polarization angle of the semiconductor laser 2 so that the reflection light of the semiconductor laser 1 by the reflection mirror 5 is transmitted, and The light emitted from the laser 2 can be reflected by the polarization beam splitter 4.
That is, in other words, the polarizing beam splitter 3 may use a half mirror or a half prism. For the same reason, the quarter-wave plate 6 may be omitted.

Furthermore, a circuit for converting a current signal obtained by the photodetector 8 into a voltage signal may be built in the heat sink 9 or the housing.

The light emitted from the semiconductor laser 1 is reflected by the reflection mirror 5, passes through the polarization beam splitter 3 and the polarization beam splitter 4, and the quarter-wave plate 6 converts the linear polarization of the semiconductor laser light into circular polarization. The light is emitted from the optical pickup of the embodiment 2 and reaches the optical disk through the subsequent optical components. The reflected light from the optical disk is again 1 /
The light passes through the four-wavelength plate 6 and enters the optical pickup of the second embodiment. The incident light transmitted through the wavelength plate 6 is converted into linearly polarized light orthogonal to the linearly polarized light of the light emitted from the semiconductor laser 1, reflected by the polarization beam splitter 4, and then enters the diffraction grating 7. The light transmitted through the diffraction grating 7 (0
The next-order diffracted light) reaches the cross-shaped four-piece light receiving element 8-A. On the other hand, the first-order diffracted light of the diffraction grating 7 is split into two light receiving elements 8.
-B is received.

The light emitted from the semiconductor laser 2 is reflected by the polarization beam splitter 3 and then passes through the polarization beam splitter 4 to enter the quarter-wave plate 6. The incident light is converted from the linearly polarized semiconductor laser light into circularly polarized light by the quarter wavelength plate 6, emitted from the optical pickup of the second embodiment, and reaches the optical disk through the subsequent optical components. The reflected light from the optical disk passes through the quarter-wave plate 6 again to enter the optical pickup according to the second embodiment. The incident light transmitted through the wavelength plate 6 is converted into linearly polarized light orthogonal to the linearly polarized light emitted from the semiconductor laser 2, reflected by the polarization beam splitter 4, and then enters the diffraction grating 7. The transmitted light (0th-order diffracted light) of the diffraction grating 7 reaches the cross-shaped quadrant light receiving element 8-A. On the other hand, the first-order diffracted light of the diffraction grating 7 is guided to the two-divided light receiving element 8-B and received.

The process of detection by the photodetector 8 after being incident on the diffraction grating 7 is described in the first embodiment.
The description is omitted here.

(Embodiment 3) Next, a third embodiment will be described with reference to FIG. FIG. 5 shows Embodiment 3 of the present invention.
FIG. 3 is a configuration diagram of an optical pickup unit in FIG. In the figure, the optical pickup is the same as the optical pickup described in the first embodiment. The laser light emitted from the optical pickup is switched according to the optical disk 13 to be recorded or reproduced, reflected by the rising mirror 10, and then condensed on the optical disk 13 by the objective lens 11. The reflected light from the optical disk 13 is again
And is reflected by the rising mirror 10, and then enters the optical pickup. The reflected light incident on the optical pickup can read a signal from the optical disk 13 by the operation described in the first embodiment. Note that a collimator lens may be provided in the middle of this element and the rising mirror 10, and when the quarter wavelength plate 6 is not provided in the optical pickup, a 1/4 wavelength plate is provided in the middle of the optical pickup and the objective lens 11.
Wave plate 6 may be inserted.

Further, the optical pickup according to the second embodiment may be used. Embodiment 3 configured as above
Is an optical pickup unit described in Embodiment 1 or 2 (in FIG. 5, Embodiment 1
The semiconductor laser is switched and used according to the optical disk 13.

For example, the focal length of the objective lens 11 is 3.
Set to 3mm, the distance (d) of the optical pickup is 8mm
Set to. Further, according to the optical disk 13, the wavelength of one semiconductor laser is set to 780 nm for CD and the other wavelength is set to 635 nm to 650 nm for SD.

As described above, according to the third embodiment of the present invention, since the RF signal and the tracking error signal are detected using the 0th-order diffracted light, it is possible to provide an optical pickup which is small and can secure a sufficient signal intensity. It is possible to cope with different types of optical disks by switching the light emission source according to the medium.

(Embodiment 4) Next, a fourth embodiment will be described with reference to FIG. FIG. 6 shows Embodiment 4 of the present invention.
FIG. 3 is a configuration diagram of an optical pickup unit in FIG. In the figure, one objective lens 12 is for CD, and the other objective lens 16 is for CD.
Is an objective lens for SD, which can be switched by hand changing means (not shown) according to the optical disc 13.

The optical pickup is the same as the optical pickup described in the first embodiment. The laser light emitted from the optical pickup is switched by the switching means in accordance with the optical disk 13 to be recorded or reproduced, and after being reflected by the rising mirror 10, the optical disk 1 to be reproduced.
The light is focused on the optical disk 13 by the objective lens 12 or the objective lens 16 corresponding to 3. The reflected light from the optical disk 13 passes through the objective lens 12 or 16 again, is reflected by the rising mirror 10, and then enters the optical pickup. The reflected light incident on the optical pickup can read a signal from the optical disk 13 by the operation described in the first embodiment. Note that a collimator lens may be provided in the middle of the present device and the rising mirror 10, and when the quarter wave plate 6 is not provided in the optical pickup,
1 between the optical pickup and the objective lens 12 or 16
A / 4 wavelength plate 6 may be inserted.

Further, the optical pickup according to the second embodiment may be used. The optical pickup unit according to the fourth embodiment configured as described above uses the optical pickup described in the first or second embodiment (FIG. 6 shows the case of the optical pickup according to the first embodiment) in an optical disc. 1
In accordance with 3, the semiconductor laser and the objective lens are switched and used.

For example, according to the optical disk 13, the wavelength of one semiconductor laser is set to 780 nm for a CD, and the other wavelength is set to a range from 635 nm to 650 nm. Further, the focal length of the objective lenses 12 and 16 and the distance (d) of the optical pickup are set according to the medium source 21 and the wavelength, respectively.

Thus, according to the fourth embodiment of the present invention,
Since the RF signal and the tracking error signal are detected using the 0th-order diffracted light, it is possible to provide an optical pickup capable of acquiring a sufficient signal intensity with a ten-inch shape,
By switching the objective lens and the light emitting source according to the medium, it is possible to support different types of optical disks.

[0045]

As described above, according to the present invention, it is possible to cope with different types of optical disks, and the emitted light is emitted without passing through the diffraction grating, and the reflected light from the medium is transmitted through the diffraction grating. Since signal detection is performed using (0th-order diffracted light), it is possible to provide an optical pickup that is small and can ensure sufficient signal intensity.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical pickup according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a grating surface of the diffraction grating of FIG.

FIG. 3 is a diagram showing a light receiving surface of the photodetector in FIG.

FIG. 4 is a configuration diagram of an optical pickup according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of an optical pickup unit according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram of an optical pickup unit according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a conventional optical pickup.

FIG. 8 is a configuration diagram of a conventional optical pickup unit.

[Explanation of symbols]

 1, 2, 21 Semiconductor laser 3, 4 Polarization beam splitter 5, 34 Mirror 6 Quarter-wave plate 7, 22 Diffraction grating 8, 38 Photodetector 8-A 4-split light receiving element 8-B 2-split light receiving element 9 Heat sink Reference Signs List 10 Start-up mirror 11, 12, 16, 35 Objective lens 13 Optical disk 23 Hologram

Claims (12)

[Claims] An optical pickup for recording information on or reproducing information from a disk-shaped recording medium, comprising: a first semiconductor laser for emitting a laser beam having a first wavelength; A second semiconductor laser that emits laser light, a photodetector that includes a plurality of light receiving elements for detecting reflected light from a disk, the first semiconductor laser, the second semiconductor laser, A heat dissipating substrate member on which a photodetector is mounted; a housing for sealing the first semiconductor laser, the second semiconductor laser, the photodetector, and the heat dissipating substrate member, and having a portion through which laser light is transmitted; Two light separating elements disposed in the housing and transmitting or reflecting according to the polarization plane of the laser light; and a reflection device disposed in the housing and reflecting light reflected from a disk to the photodetector. A quarter-wave plate arranged on the light exit surface of the light separating element to change the polarization state of the laser light; and a diffraction device having a plurality of regions for guiding the reflected light from the disk to the photodetector. A light separating element provided so that the center of the light separating element coincides with the optical axis of the first semiconductor laser, and the light separating element is disposed on the optical axis of the second semiconductor laser. The other light separation element is provided so that the centers of the light separation elements coincide with each other, and the diffraction grating is further provided on a joint surface between the reflection mirror and the light separation element. Are parallel to each other, and the housing, the two light separating elements, the reflecting mirror, the quarter-wave plate, and the diffraction grating are integrally formed, and the first semiconductor laser or the Second semiconductor laser An optical pickup characterized in that the emitted light is emitted in a direction perpendicular to the mounting surface of the heat dissipation substrate member. 2. An optical pickup for recording information on or reproducing information from a disk-shaped recording medium, comprising: a first semiconductor laser for emitting a laser beam having a first wavelength; A second semiconductor laser that emits laser light, a photodetector that includes a plurality of light receiving elements for detecting reflected light from a disk, the first semiconductor laser, the second semiconductor laser, A heat dissipating substrate member on which a photodetector is mounted; a housing for sealing the first semiconductor laser, the second semiconductor laser, the photodetector, and the heat dissipating substrate member, and having a portion through which laser light is transmitted; Two light separating elements disposed in the housing and transmitting or reflecting according to the polarization plane of the laser light; and reflections disposed in the housing and reflecting reflected light from an optical disk to the photodetector. A mirror, a quarter-wave plate arranged on a light exit surface of the light separating element for changing a polarization state of laser light, and a diffraction element having a plurality of regions for guiding reflected light from a disk to the photodetector. A grating, wherein one light separating element is provided so that the center of the light separating element coincides with the optical axis of the first semiconductor laser, and the reflection surface The reflection mirror is provided so that the centers coincide with each other, and the diffraction grating is further provided on a joint surface between the other one of the light separation elements and the housing. The reflection surfaces are parallel to each other, and the housing, the two light separation elements, the reflection mirror, the quarter-wave plate, and the diffraction grating are integrally formed, and the first semiconductor laser or the first 2 of the semiconductor laser An optical pickup characterized in that any one of the emitted lights is emitted in a direction parallel to a mounting surface of the heat dissipation board member. 3. The optical pickup according to claim 1, wherein the first wavelength and the second wavelength are the same. 4. The optical pickup according to claim 1, wherein said first wavelength and said second wavelength are different from each other. 5. The first semiconductor laser and the second semiconductor laser each have a required thickness determined based on a thickness of a medium, a focal length of an objective lens, and a wavelength of laser light emitted from the semiconductor laser. The optical pickup according to claim 1, wherein the optical pickup is separated by a separation distance. 6. The diffraction grating has two grating regions, the photodetector has two detection regions, and a first detection region is formed of a cross-shaped quadrant light receiving element. The second detection area is constituted by at least two divided light receiving elements, and further, the at least two divided light receiving elements are arranged at positions separated by a predetermined distance from the four divided light receiving elements, and are incident on the diffraction grating. 2. The light of claim 1, wherein the zero-order diffracted light is detected by the four-divided light receiving element of the photodetector, and the first-order diffracted light is detected by the two-divided light receiving element of the photodetector. An optical pickup according to claim 2 or claim 5. 7. An optical system comprising: one objective lens having a predetermined focal length; a rising mirror for reflecting an optical path of the optical pickup to the objective lens; and a first semiconductor laser and a second semiconductor laser. 7. The optical pickup according to claim 1, further comprising a semiconductor laser switching unit for switching light emission, and recording / reproducing on / from different types of optical disc media. 8. An objective lens comprising: two objective lenses having different focal lengths; a rising mirror for reflecting an optical path of the optical pickup to the objective lens; and one of the two objective lenses. An objective lens switching means for inserting and removing the light in the optical path between the rising mirror and the optical disk medium; and a semiconductor laser switching means for switching light emission between the first semiconductor laser and the second semiconductor laser. 7. The optical pickup according to claim 1, wherein recording and reproduction are performed on various kinds of optical disk media. 9. The light beam according to claim 1, wherein said diffraction grating is formed on a joint surface between said one light separating element and a reflecting mirror surface and on a side of said light separating element. pick up. 10. The optical pickup according to claim 1, wherein the diffraction grating is formed on a joint surface between the reflection mirror and the housing and on a side of the reflection mirror. 11. The optical pickup according to claim 1, wherein the diffraction grating is formed on a joint surface between the reflection mirror and the housing and on a side of the housing. 12. An optical disk device having the optical pickup according to claim 1.