JP2002237085A - Optical pickup and optical information reproducing device or recording device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup which is used in common for DVD/CD and manufactured at greatly reduced cost while maintaining special properties of small size and simple configuration realized by mounting a semiconductor laser module. SOLUTION: In an optical pickup which requires a plurality of laser beam sources like the optical pickup used in common for DVD/CD, the number of components and cost are decreased since optical detection systems can be put together in one system by using a semiconductor laser module for one of the laser beam sources and normal semiconductor laser beam sources for others, making light beams which are emitted by the normal semiconductor laser beam sources and reflected by an optical disk incident on the semiconductor laser module, and using an optical detector provided in the module as an optical detector for the laser beams emitted by the normal semiconductor laser beam sources.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device used for reproducing a data signal recorded on an optical information recording medium (hereinafter, referred to as an optical disk). The present invention is effective for simplifying and reducing the price of a compatible optical pickup device that enables reproduction.

[0002]

2. Description of the Related Art Recently, for the purpose of miniaturizing and simplifying an optical pickup device, an optical pickup device equipped with a semiconductor laser module in which a semiconductor laser chip and a photodetector having a predetermined light receiving surface shape are sealed in the same housing has been developed. Spreading rapidly. These semiconductor laser modules include only an objective lens for condensing laser light on the semiconductor laser module and an optical information recording medium (hereinafter, simply referred to as an optical disk) and an actuator for controlling the position of the objective lens. Thus, the optical pickup device can be basically configured, which is very advantageous for miniaturization and simplification of the device.

On the other hand, recently, as one type of high-density information recording medium, an optical disk generally called a DVD has attracted attention.
Already in the market, it is rapidly spreading along with existing optical disks such as CD, CD-ROM, and CD-R. Therefore, an optical pickup device for reproducing data signals from these various optical disks is preferably a so-called compatible optical pickup that can reproduce both types of optical disks such as a CD and a DVD with one device.
In response to such demands, conventionally, a composite type including a semiconductor laser having a wavelength of 660 nm for recording or reproducing a DVD disc and a semiconductor laser having a wavelength of 780 nm for recording or reproducing a CD disc has been conventionally used. This has been addressed by using an optical pickup. However, such a compound optical pickup device needs to be newly provided with a plurality of semiconductor laser light sources and an optical element for synthesizing or separating the laser light beams emitted from these light sources. Larger, more complex and more expensive than pickups. In view of the above, recently, the development aiming at further miniaturization and simplification of the optical pickup has been promoted by adopting the above-described semiconductor laser module in the composite optical pickup.

An optical pickup device equipped with a semiconductor laser module is disclosed, for example, in Japanese Patent Laid-Open No.
Many publicly known examples such as 624 are disclosed. Also, typical known examples of the composite optical pickup as described above include JP-A-8-55363 and JP-A-9-54977.

[0005]

However, the above-mentioned semiconductor laser module is one kind of integrated semiconductor device, and its manufacture requires advanced semiconductor integration technology and manufacturing equipment. Further, since special optical components such as hologram elements are required, at present, the manufacturing cost is relatively high compared with ordinary optical pickup optical components. Therefore, when this semiconductor laser module is used in a composite optical pickup, two or more semiconductor laser modules must be mounted in one optical pickup, which is extremely disadvantageous in cost. Will happen.

A composite optical pickup in which one laser light beam optical system is constituted by a semiconductor laser module and the other laser light beam is constituted by an optical system composed of individual optical components similar to the conventional one is also conceivable. However, in such a configuration, an optical system similar to the conventional optical pickup exists in addition to the semiconductor laser module in one optical pickup, and the characteristics of the small size and simplification of the semiconductor laser module can be sufficiently obtained. I can't make the most of it.

In view of the above circumstances, it is an object of the present invention to realize a significant reduction in manufacturing cost of a compact DVD / CD shared optical pickup using a semiconductor laser module, while maintaining the characteristics of compactness and simplification. To provide an improved optical pickup.

[0008]

In order to achieve the above object, the present invention provides a semiconductor device in which at least one semiconductor laser light source and a photodetector having a plurality of divided detection surfaces are arranged in the same housing. A laser module, a second semiconductor laser light source that emits a laser light beam having a different wavelength from the laser light beam emitted by the semiconductor laser light source in the semiconductor laser module, and a laser light beam emitted from each of the semiconductor laser light sources. In an optical pickup having an objective lens having a function of irradiating a predetermined optical disk with an independent light spot, the optical disk emits each of the semiconductor laser light sources in an optical path from the objective lens to the semiconductor laser module, and Each reflected laser light beam is arranged in the semiconductor laser module, respectively. It was placed optical means having a function of guiding to a predetermined position on the optical detection surface. That is, the semiconductor laser module includes one semiconductor laser module and one semiconductor laser module, and the laser light beam emitted from the semiconductor laser module is reflected after the optical disk reflection, as in the optical pickup using the conventional semiconductor laser module.
Various signals are detected by being incident on the photodetector in the original semiconductor laser module, and the laser light beam emitted from the other semiconductor laser light source is also incident on the photodetector in the semiconductor laser module after reflection from the optical disk. Then, the configuration is such that various signals are detected from the photodetector. With such a configuration, the photodetector in one semiconductor laser module is also used as a photodetector for each laser light beam emitted from a separately provided semiconductor laser light source. The optical components for one semiconductor laser module excluding the laser light source can be omitted.

In this optical pickup, each of the semiconductor laser light sources is emitted by using a predetermined signal detected on a light detection surface in the semiconductor laser module, and each of the light beams condensed on the optical information recording medium. It has a function of independently detecting a focus error signal and a tracking error signal of a spot and reproducing an information signal recorded on each optical information recording medium.

The optical means for emitting each laser light beam emitted from each of the semiconductor laser light sources and reflecting each of the laser light beams reflected from the optical disk to a predetermined position on the light detection surface arranged in the semiconductor laser module includes: The semiconductor laser module is constituted by a diffraction grating in which concave and convex grating grooves are provided at a predetermined pitch on a transparent substrate disposed at a window of the semiconductor laser module.

Alternatively, the optical means emits a semiconductor laser light source in the semiconductor laser module and diffracts the first laser light beam having a predetermined polarization direction with a predetermined diffraction efficiency, A first polarizing diffraction grating having a diffraction efficiency of about 0% for a second laser light beam having a polarization direction substantially perpendicular to the first light beam; Contrary to the lattice, the first
And a second polarization diffraction grating having a function of diffracting the laser light beam at a predetermined diffraction efficiency with respect to the second laser light beam. Is done.

Alternatively, the optical means emits a semiconductor laser light source in the semiconductor laser module and diffracts the first laser light beam having a predetermined polarization direction with a predetermined diffraction efficiency, A first polarizing diffraction grating having a diffraction efficiency of about 0% for a second laser light beam having a polarization direction substantially perpendicular to the first laser light beam; Contrary to the diffraction grating, the diffraction efficiency is almost 0% for the first laser light beam.
And a second polarization diffraction grating having a function of diffracting the second laser light beam at a predetermined diffraction efficiency, and a second polarization diffraction grating having a function of diffracting the second laser light beam. Also includes a predetermined wave plate or a phase conversion element that functions as a substantially half wave plate.

Alternatively, the optical means emits a semiconductor laser light source in the semiconductor laser module and diffracts the first laser light beam having a predetermined polarization direction with a predetermined diffraction efficiency. A first polarizing diffraction grating having a diffraction efficiency of approximately 0% for a second laser light beam having a polarization direction perpendicular to the first laser light beam; Contrary to the grating, the first laser light beam has a diffraction efficiency of about 0%, and has a function of diffracting the second laser light beam with a predetermined diffraction efficiency. The second polarization diffraction grating functions as a substantially quarter-wave plate for one of the first and second laser light beams, and functions as a substantially half-wave plate for the other. A predetermined wave plate or Composed of a phase converting element.

Alternatively, the optical means emits a semiconductor laser light source in the semiconductor laser module and diffracts the first laser light beam having a predetermined wavelength with a predetermined diffraction efficiency. A first wavelength-selective diffraction grating that emits a second semiconductor laser light source and has a diffraction efficiency of about 0% for a second laser light beam having a wavelength different from that of the first laser light beam; Contrary to the first wavelength selective diffraction grating, the diffraction efficiency of the first laser light beam is substantially 0%, and the diffraction efficiency of the second laser light beam is predetermined. It comprises a second wavelength-selective diffraction grating having a function of diffracting a beam.

According to another aspect of the present invention, a first semiconductor laser light source for emitting a laser light beam of a predetermined wavelength and a second semiconductor laser for emitting a laser light beam of a different wavelength from the first semiconductor laser light source A semiconductor laser module in which a light source and a photodetector having a plurality of divided detection surfaces are arranged in the same housing; and a predetermined optical information recording medium for condensing each laser light beam emitted from each of the semiconductor laser light sources. And an objective lens having a function of irradiating independent light spots to each other, wherein the first semiconductor laser light source emits the first laser light beam having a predetermined polarization direction with a predetermined diffraction. The laser light beam is diffracted with an efficiency, and the diffraction efficiency is increased for a second laser light beam having a polarization direction perpendicular to the first laser light beam. A first polarizing diffraction grating having a diffraction efficiency of about 0%, and a diffraction efficiency of the first laser light beam, which is opposite to the first polarizing diffraction grating, is substantially 0%; A second polarization diffraction grating having a function of diffracting the laser light beam with a predetermined diffraction efficiency with respect to the light beam, and one of the first and second laser light beams for the laser light beam; Functions as a substantially quarter-wave plate, and approximately one-half for the other laser light beam.
A predetermined wave plate or a phase conversion element functioning as a wave plate was arranged.

Further, as another configuration of the present invention, a first semiconductor laser light source emitting a laser light beam of a predetermined wavelength and a second semiconductor laser emitting a laser light beam of a different wavelength from the first semiconductor laser light source A semiconductor laser module in which a light source and a photodetector having a plurality of divided detection surfaces are arranged in the same housing; and a predetermined optical information recording medium for condensing each laser light beam emitted from each of the semiconductor laser light sources. And an objective lens having a function of irradiating independent light spots, wherein a predetermined diffraction efficiency is obtained for a first laser light beam having a predetermined wavelength emitted from the first semiconductor laser light source. Diffracts the laser light beam at a second laser light beam emitted from the second semiconductor laser light source and having a different wavelength from the first laser light beam. , A first wavelength-selective diffraction grating having a diffraction efficiency of approximately 0%, and, contrary to the first wavelength-selective diffraction grating, a diffraction efficiency of approximately 0% for the first light beam. %, And a second wavelength-selective diffraction grating having a function of diffracting the second light beam with a predetermined diffraction efficiency.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic front view showing the configuration of the first embodiment of the optical pickup of the present invention.

Reference numeral 1 denotes a semiconductor in which a semiconductor laser light source having a wavelength of 650 nm provided for recording or reproducing a DVD disc and a photodetector having a photodetection surface divided into a plurality of regions are contained in the same package. It is a laser module. This semiconductor laser module 1 is, for example, as shown in a schematic sectional view of FIG. 2 and a schematic plan view of FIG.
A semiconductor laser chip 101 serving as a light source and a photodetector 102 having a photodetection surface divided into strips on a base 100.
Further, a photodetector 107 for monitoring the light output of the semiconductor laser chip 101 is arranged, and these are sealed with a cover 106. The transparent substrate 1 is provided on the upper window of the cover 106.
A laser beam emitted from the semiconductor laser chip 101 is applied to the lower surface of the transparent substrate 103 to record / reproduce a signal, detect a focus control signal by a known method such as a knife edge method, or perform a differential phase detection. Into a main light beam used for detecting a tracking control signal already known, such as an operation method, and two sub-light beams used for detecting a tracking control signal according to a known method, such as a three-beam system or a differential push-pull system. Grating 1 for
And a hologram element 105 for guiding the reflected light beam from the optical disk onto the multi-divided detection surface of the photodetector 102 on the upper surface. This hologram element 105
Are three regions 1 as shown in the schematic plan view of FIG.
05a, 105b, and 105c, and a linear or curved diffraction grating groove is provided in each region in a predetermined direction. Note that the semiconductor laser module used in the present invention is not limited to the configuration described with reference to FIGS. 2 to 4 as described above, and the semiconductor laser chip, the photodetector, and the laser Any module may be used as long as it is a semiconductor laser module having a diffraction grating or a hologram element having a function of leading to a photodetector.

In the optical pickup according to the first embodiment, as shown in FIG. 1, in addition to a semiconductor laser module 1, a semiconductor laser light source 2 of a 780 nm wavelength band provided for recording or reproduction of a CD-based disc, Lattice 2
0, a wavelength-selective mirror 3, a correcting lens 4, a collimating lens 5, a rising mirror 6, an objective lens 7, and the like. The wavelength-selective mirror 3 is, for example, almost 100% for a laser light beam having a wavelength of 650 nm.
And has a function of a half mirror that reflects a part of the light amount and exceeds the remaining light amount with respect to the laser light beam in the 780 nm wavelength band. The diffraction grating 20 is composed of a main light beam used for recording / reproducing a laser light beam emitted from the semiconductor laser light source 2 and two beams used in a known tracking control signal detection method such as a three-beam method or a differential push-pull method. It has the function of splitting into sub light beams. Further, the correction lens 4 has a function of correcting a wavefront aberration generated when the divergent light beam emitted from the semiconductor laser light source 2 passes through the wavelength-selective mirror 3, and a laser light focused on the optical disk 8 by the objective lens 7. This lens has a function of improving the light beam transmission efficiency. The objective lens 7 is provided with an actuator 9, and a photodetector 10 in the semiconductor laser module 1 is provided.
The position control of the objective lens 7 is performed using the focus control signal and the tracking control signal obtained from Step 2.

Next, with reference to FIGS. 5 to 9, the function of each optical component in the optical pickup of the first embodiment at the time of recording or reproducing a DVD-based disc and a CD-based disc will be described.

First, when recording or reproducing data on a DVD-based optical disk such as a DVD-ROM or DVD-RAM, the semiconductor laser chip 101 in the semiconductor laser module 1 is turned on as shown in FIG. The laser beam of 650 nm wavelength emitted from the semiconductor laser module 1 is reflected by the wavelength-selective mirror 3 and then collimated by the collimator lens 5.
Is converted into parallel light, and is condensed on a predetermined recording track in the optical disk 8 by the objective lens 7 via the rising mirror 6. Then, the laser light beam reflected from the optical disk 8 reverses the same optical path as the outward path, returns to the semiconductor laser module 1 via the objective lens 7, the rising mirror 6, the collimator lens 5, and the wavelength selective mirror 3, and returns to the semiconductor laser module 1. The light enters the hologram element 105. As shown in FIG. 6, for example, the hologram element 105 divides the optical disk reflected light beam 200 incident on the hologram element 105 into three regions 105a, 105b, and 105c, and diffracts the light beam in a predetermined direction. Light is focused on different detection surfaces in the detector 102.

FIG. 7 is a schematic plan view showing an example of a state where the laser light beam diffracted and separated by the hologram element 105 is applied to each detection surface of the photodetector 102. Of the optical disk reflected light beam 200 incident on the hologram element 105, the half beam incident on the area 105a is condensed as a light spot 301a on a division line of a two-part detection surface provided at the center of the photodetector 102. Area 10
The 1/4 light beam incident on 5b is condensed on an independent predetermined detection surface as light spot 301b, and the 1/4 light beam incident on region 105c is condensed on an independent predetermined detection surface as light spot 301c. You. On the other hand, the two sub-light beams diffracted and separated by the diffraction grating 104 in the semiconductor laser module 1 on the outward path also reach the hologram element 105 after the reflection of the optical disk 8 like the main light beam,
The hologram element 105 divides the light into three parts. Of these, the 1/4 light beam incident on the area 105b is the light spot 3
The incident light beams 02b and 303b are respectively incident on the independent light detection surfaces, and the １ ／ light beams incident on the region 105c are incident on the independent light detection surfaces as the light spots 302c and 303c. Then, by performing predetermined arithmetic processing as shown in the figure on the detection signals from these light detection surfaces, a focus control signal is detected by a known focus control signal detection method such as a knife edge method, Further, a tracking control signal can be detected by a known tracking control signal detection method such as a differential phase detection method, a three-beam method, or a differential push-pull method, and an information signal recorded on the optical disk 8 can be reproduced. Since a specific method of detecting each of the control signals is already known, a detailed description thereof will be omitted. Further, the configuration and arrangement of the hologram element 105 and the photodetector 102 in the present invention are not limited to the above-described embodiment, and any configuration may be used.

Next, a CD such as a CD-ROM or CD-R
FIG. 8 shows a case where recording or reproduction is performed on a system optical disc.
This will be described with reference to FIG. In this case, the wavelength 780
The semiconductor laser light source 2 that emits a laser light beam in the nm band is turned on. 780 nm wavelength emitted by the semiconductor laser light source 2
After the laser light beam in the band is split by the diffraction grating 20 into a main light beam and two sub-light beams for tracking control signal detection, as shown in FIG.
The light enters the objective lens 7 via the collimator lens 5 and the rising mirror 6. This objective lens 7 has a wavelength of 650 nm.
And a laser beam having a wavelength of 780 nm is used for a CD-based optical disc having a substrate thickness of 1.2 mm. It also has the function of condensing light well on the recording track. Therefore,
The laser light beam emitted from the semiconductor laser light source 2 and reaching the objective lens 7 is favorably focused on a predetermined recording track of the CD-type optical disk 8.

The laser beam reflected from the optical disk 8 follows the same optical path as the outward path, and reaches the wavelength selective mirror 3 via the objective lens 7, the rising mirror 6, and the collimator lens 5. At this time, a part of the light amount of the laser beam reaching the wavelength-selective mirror 3 is reflected by the wavelength-selective mirror 3 and enters the semiconductor laser module 1. The light beam is diffracted by the hologram element 105 in the semiconductor laser module 1 in the same manner as the laser light beam in the wavelength band of 650 nm described above, and the light beam cross section is divided into three sections. And the focus control signal and the tracking control signal are detected, and the information signal recorded on the optical disk 8 is reproduced, similarly to the laser light beam in the 650 nm wavelength band described above.

The point to be noted in this case is that
The laser light beam for recording / reproducing a DVD-based optical disk of 650 nm band emitted from the semiconductor laser module 1 and the laser light beam for recording / reproducing of a CD-based optical disk of 780 nm wavelength emitted from the semiconductor laser light source 2 have mutually different wavelengths. Due to the difference, the diffraction angle at the hologram element 105 is different, and when the light is incident on a predetermined light detection surface in the light detection surface 102, the incident positions are shifted from each other. Even in such a case, for example, as shown in FIG. 9, a strip shape is used so that each light spot is correctly incident on a predetermined detection surface and a focus control signal and a tracking control signal can be correctly detected for both laser light beams. The detection surface is substantially radially arranged, and the direction of the division line of the two-part detection surface for focus control signal detection is focused on this division line. That the diffraction direction of the laser beam, it is necessary to devise on the detection surface arranged such predetermined angle tilt.

With the above configuration, the DV
In a composite optical pickup (two-laser optical pickup) that can be used for both D / CD, the photodetector in one semiconductor laser module is used for both recording or reproducing of a DVD optical disc and recording or reproducing of a CD optical disc. I can do it. As a result, one semiconductor laser module or one photodetection system can be eliminated from a conventional composite optical pickup or a composite optical pickup in which two semiconductor laser modules are mounted.

The present invention is not limited to the configuration of the first embodiment described with reference to FIGS. For example, in the first embodiment, a semiconductor laser light source for emitting a laser light beam of a wavelength of 650 nm for a DVD optical disk is stored in a semiconductor laser module, and a semiconductor laser for emitting a laser light beam of a wavelength of 780 nm for a CD optical disk. The light source is arranged separately and independently from the semiconductor laser module, but of course, on the contrary, a semiconductor laser light source for emitting a laser light beam having a wavelength of 780 nm for a CD optical disk is used. A semiconductor laser light source that emits a laser light beam in the wavelength band of 650 nm for a DVD-based optical disk and that is stored in the semiconductor laser module may be arranged separately and independently from the semiconductor laser module. Further, the configuration of the optical system shown in FIG. 1 may be replaced with the configuration of the semiconductor module 1, the semiconductor laser light source 2, and the diffraction grating 20.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a schematic front view showing an optical system configuration according to the second embodiment of the present invention. Note that the same optical components as those of the first embodiment shown in FIG.

In this embodiment, the semiconductor laser module 1
Has a configuration in which the polarization directions of the emitted laser light beam and the laser light beam emitted from the semiconductor laser light source 2 are orthogonal to each other, and the hologram shown in FIG. Instead of the element 105, a polarizing hologram element 10 having a polarizing property as described later is provided, and a second polarizing hologram element 11 having a polarizing property different from that of the polarizing hologram element 10 is disposed thereon. I have.

The laser light beam emitted from the semiconductor laser module 1 is, for example, linearly polarized in a direction parallel to the paper surface as shown in FIG. 10, and the laser light beam emitted from the other semiconductor laser light source 2 is perpendicular to the paper surface. Linearly polarized light. Then, the polarizing hologram element 10 diffracts and separates the + 1st-order or -1st-order diffracted light with a predetermined diffraction efficiency for the laser light beam in the polarization direction parallel to the paper surface. Has the characteristic of transmitting light as it is at almost 100% efficiency. On the other hand, the polarizing hologram element 11 transmits the laser light beam in the polarization direction parallel to the paper surface as it is opposite to the polarization hologram element 10 at almost 100% efficiency, and conversely, the laser light beam in the polarization direction perpendicular to the paper surface. The beam has a characteristic of diffracting and separating + 1st-order or -1st-order diffracted light at a predetermined diffraction efficiency.

With such a configuration, the DVD laser light beam emitted from the semiconductor laser module 1 reflects on the optical disc, reflects off the wavelength-selective mirror 3, and returns to the semiconductor laser module 1 again. (A)
As shown in (1), the light is diffracted only by the polarization hologram element 10 and guided to the detector 102 in the semiconductor laser module 1. On the other hand, when the CD laser light beam emitted from the semiconductor laser light source 2 is reflected by the optical disc and then reflected by the wavelength-selective mirror 3 to travel to the semiconductor laser module 1, the laser light beam shown in FIG.
As shown in (b), the light is diffracted only by the polarization hologram element 11 and guided to the detector 102 in the semiconductor laser module 1 like the laser light beam for DVD. Therefore,
By independently designing the hologram patterns of the polarizing hologram elements 10 and 11 independently, even if there is a difference in wavelength between the laser light beam emitted from the semiconductor laser module 1 and the laser light beam emitted from the semiconductor laser light source 2, for example, FIG. 12, light spot 501a shown in FIG.
501b, 501C, 502b, 502C, 503b,
As in 503c, each light spot can be applied to substantially the same position in a predetermined detection plane. Therefore, the first
The problem of displacement of the light spot irradiation position due to the difference in wavelength which must be considered in the second embodiment is eliminated, and as a result, the size of the detection surface of the photodetector 102 can be made smaller than in the first embodiment. There is an advantage that the detection surfaces need not be specially arranged as in the first embodiment, and may be simply arranged in parallel.

In order to set the polarization directions of the two laser light beams to be perpendicular to each other as in this embodiment, for example, either the semiconductor laser module or the semiconductor laser light source is tilted by 90 degrees around the optical axis. It can be realized by placing a wave plate such as a half-wave plate or a quarter-wave plate in the optical path.

In this embodiment, the laser light beam emitted from the semiconductor laser module 1 and the semiconductor laser light source 2
The hologram elements that diffract each beam and guide them to the photodetector 102 in the semiconductor laser module 1 are different from each other by changing the polarization direction of the laser beam emitted from the laser beam and using a polarizing diffraction grating. The characteristic of the diffraction efficiency with respect to the wavelength of the diffraction grating can be set relatively freely by optimally designing the depth of the grating groove. By utilizing this property, for example, the diffraction efficiency becomes almost 0% with respect to the wavelength (780 nm band in the above-described embodiment) of the laser beam emitted from the semiconductor laser light source 2 with the diffraction grating 10 in the configuration of FIG. The depth of the grating groove is determined so that almost all of the light quantity is transmitted as it is, and the diffraction efficiency is almost equal to the wavelength (650 nm band in the above-described embodiment) of the laser beam emitted from the semiconductor laser module 1 through the diffraction grating 11. 0
%, And the depth of the grating groove is determined so that almost all of the light quantity is transmitted as it is, as in the second embodiment described above, the semiconductor laser module 1 and the semiconductor laser light source 2
Even if the polarization directions are not perpendicular to each other, the hologram elements guided to the photodetector 102 can be made different from each other as in the second embodiment.

The second embodiment of the present invention is, of course, not limited to the embodiment shown in FIG. 10, but the polarization direction of the laser light beam emitted from the semiconductor laser module 1 and the semiconductor laser light source 2 Even if the polarization direction of the emitted laser light beam is reversed from the configuration in FIG. 10, it does not matter.
Further, similarly to the first embodiment, the polarization hologram elements 10 and 1
There is no problem even if the arrangement of 1 is changed, or if the optical system including the semiconductor laser module 1 and the polarization hologram elements 10 and 11 and the optical system including the semiconductor laser light source 2 and the diffraction grating 20 are interchanged.

Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 13 is a schematic front view showing an optical system configuration according to the third embodiment of the present invention. Note that the same optical components as those in the first and second embodiments are denoted by the same reference numerals.

In the third embodiment, the polarization hologram elements 12 and 14 having the same polarization characteristics as the polarization hologram element 10 described in the second embodiment are arranged above the semiconductor laser module 1. It has a configuration. That is, each of the polarizing hologram elements 12 and 14 diffracts and separates a + 1st-order or a -1st-order diffracted light with a predetermined diffraction efficiency with respect to a laser beam having a polarization direction parallel to the plane of the paper. The light beam has a characteristic of being transmitted as it is with almost 100% efficiency.

The polarizing hologram elements 12 and 14
Between them, there is provided a broadband half-wave plate 13 which functions as a half-wave plate for both the laser light beams in the 650 nm band and the 780 nm band. Such 2
When the direction of the principal axis of the half-wave plate is set at an inclination of 45 degrees with respect to the polarization direction of the incident laser light beam, the polarization direction of the transmitted laser light beam is 90 degrees with respect to the polarization direction of the incident laser light beam. Can be tilted. Utilizing this characteristic, the polarizing hologram elements 12 and 1 are used as described above.
When this half-wave plate 13 is installed between the four, after all,
For example, as shown in FIG. 14A, a laser beam emitted from the semiconductor laser module 1 and having a polarization direction parallel to the plane of the drawing is a polarizing hologram element 12, a half-wave plate 1, and the like.
3. After the light sequentially passes through the polarizing hologram element 14 and reflects on the optical disk 8 and reaches the polarizing hologram element 14 again, the polarization direction becomes a direction perpendicular to the paper surface and further passes through the half-wave plate 13. Is reached, the polarization direction is again parallel to the paper surface. Therefore, this light beam passes through the polarizing hologram element 14 as it is, and is diffracted only by the polarizing hologram element 12 and guided to the photodetector 102.

On the other hand, the laser light beam emitted from the semiconductor laser light source 2 also has a polarization direction parallel to the plane of the drawing, and this laser light beam is parallel to the plane of the drawing until it reflects off the optical disk 8 and reaches the polarizing hologram element 14. The polarization direction is maintained. When the light reaches the polarization hologram element 12 via the half-wave plate 13, the polarization direction is perpendicular to the paper surface. Therefore, this laser light beam is
As shown in FIG. 14B, the polarizing hologram element 14
, And is guided to the photodetector 102, and is transmitted through the polarizing hologram element 12 as it is. For this reason, even if the polarization direction of the laser light beam emitted from the semiconductor laser module 1 and the polarization direction of the laser light beam emitted from the semiconductor laser light source 2 are aligned, the photodetector 1 is provided for each light beam.
The hologram element guided to 02 can be different, and the same effect as in the second embodiment can be obtained.

The polarizing hologram elements 12 and 1
As shown in FIG. 15, the quarter-wave plate 13 and the half-wave plate 13 can be integrated by laminating and bonding, and the number of components of the optical pickup can be reduced.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 16 is a schematic front view showing an optical system configuration according to the fourth embodiment of the present invention. The same optical components as those in the first, second and third embodiments are given the same reference numerals.

This embodiment is different from the second embodiment of the present invention shown in FIG.
The configuration is almost the same as that of the embodiment. However, the second
The difference from this embodiment is that the polarization directions of the laser light beam of 650 nm wavelength emitted from the semiconductor laser module 1 and the laser light beam of 780 nm wavelength emitted from the semiconductor laser light source 2 are aligned (in the embodiment shown in FIG. Is also in the direction of polarization parallel to the plane of the paper) and the wavelength 78 in the optical path from the wavelength-selective mirror 3 to the objective lens 7.
The point is that a wavelength plate 15 functioning as a 波長 wavelength plate for the laser light beam in the 0 nm band is provided. This wave plate 15 has the same function as a quarter wave plate with respect to a laser beam having a wavelength of 780 nm. Therefore, if the principal axis is arranged at an angle of 45 degrees with respect to the incident light beam, the transmitted light beam becomes circularly polarized light, and when passed again, becomes a linearly polarized light whose polarization direction is inclined by 90 degrees with respect to the initial polarization direction. . On the other hand, this wave plate has a wavelength of 6
For a laser light beam in the 50 nm band, it works almost the same as a half-wave plate. Therefore, even if the laser light beam in the 650 nm band is transmitted twice, the polarization direction is the same as the original polarization direction.

By utilizing such a property of the wave plate 15 and making an optical arrangement as shown in FIG. 16, the laser light beams emitted from each of the semiconductor laser module 1 and the semiconductor laser light source 2 are both on the paper surface, for example. Even if the semiconductor laser module 1 has a parallel polarization direction, it reflects off the optical disk 8 and, when it reaches the polarization hologram elements 11 and 10, has transmitted through the wave plate 15 twice in total, so that the semiconductor laser module 1 Although the emitted laser light beam remains in the polarization direction parallel to the paper surface, the laser light beam emitted from the semiconductor laser light source 2 is changed to the polarization direction perpendicular to the paper surface. Accordingly, the laser beam emitted from the semiconductor laser module 1 is diffracted by the polarization hologram element 10 and guided to the photodetector 102, just like the second embodiment of the present invention described with reference to FIG. The laser light beam emitted from the semiconductor laser light source 2 can be diffracted by the polarization hologram element 11 and guided to the photodetector 102. That is, the same effect as that of the second embodiment can be obtained.

The wavelength plate 15 is not limited to the above-described characteristics. For example, the wavelength plate 650 n
A wavelength plate functioning as a 波長 wavelength plate for the m-band laser light beam may be used. In this case, the wave plate 1
5 is 4 for a laser beam in the 650 nm wavelength band.
It works the same as a 1 / wave plate. Therefore, when the light is transmitted through this wave plate twice in total, the light becomes linearly polarized light whose polarization direction is inclined by 90 degrees with respect to the first polarization direction. On the other hand, wavelength 7
Since the laser light beam of the 80 nm band functions almost as a one-wavelength plate, even if the laser light beam is transmitted twice, the polarization direction does not change from the original polarization direction. Therefore, when these laser light beams reach the polarization hologram elements 11 and 10, respectively, the laser light beam emitted from the semiconductor laser module 1 is diffracted by the polarization hologram element 11, and The laser beam emitted from the semiconductor laser light source 2 and guided by the semiconductor laser light source 2 can be diffracted by the polarization hologram element 10 and guided to the photodetector 102.

In the optical pickup having such a configuration, the double-sided polarization hologram element 16 in which the polarization hologram elements 10 and 11 are bonded and integrated is arranged immediately after the semiconductor laser module 1 as shown in FIG. Accordingly, the same function as that of the embodiment of FIG. 16 can be provided, and the number of parts can be reduced.

Next, a fifth embodiment of the present invention will be described with reference to FIG.
8 and FIG. Each of the embodiments described so far is an example in which one semiconductor laser light source (chip) is housed in a semiconductor laser module. However, it goes without saying that two or more semiconductor laser light sources may be housed. FIG. 18 shows, as an example, the D in the 650 nm band.
FIG. 2 is a schematic plan view showing a configuration of a semiconductor laser module in which a semiconductor laser chip for VD 101 and a semiconductor laser chip for CD having a wavelength of 780 nm are mounted in the same package. As in the previous embodiments, a photodetector 102 having a multi-segmented photodetection surface is also mounted inside the semiconductor module 1, and as shown in FIG. Polarizing hologram elements 10 and 11 similar to those of the embodiment of FIGS. 10 and 16 are arranged. And further above that,
A wavelength plate 15 functioning as a 波長 wavelength plate for a laser beam having a wavelength of 780 nm is provided.

When such a semiconductor module 1 is used as a laser light source and a photodetector for an optical pickup, a DV having a wavelength of 650 nm emitted from the semiconductor laser chip 101 is used.
When the laser light beam for D reflects off the optical disk and returns to the semiconductor module 1 again, the laser light beam shown in FIG.
As shown in (a), the light is diffracted by the polarizing hologram element 10 and guided to a predetermined light detection surface of the light detector 102. on the other hand,
When the laser light beam for the CD in the 780 nm wavelength band emitted from the semiconductor laser chip 201 is reflected on the optical disk and returns to the semiconductor module 1 again, the laser light beam shown in FIG.
As shown in (b), the light is diffracted by the polarization hologram element 11 and guided to a predetermined light detection surface of the photodetector 102 in exactly the same manner as the DVD light beam diffracted by the polarization hologram 10 (note that each laser light The reason why the beam is selectively diffracted by the polarizing hologram elements 10 and 11, respectively, is exactly the same as that described in the embodiment of FIG. 16 and is omitted here. That is, the photodetector 102 mounted in the semiconductor laser module 1 functions as a photodetector for a laser beam emitted from each of the DVD semiconductor laser light source and the CD semiconductor laser light source also mounted in the semiconductor laser module 1. In other words, they can also be used.

Therefore, by using the semiconductor laser module as in the present embodiment, an optical pickup for both DVD / CD is basically formed only by the semiconductor laser module, the objective lens and the actuator for controlling the objective lens. The number of parts and cost can be greatly reduced.

It should be noted that the present invention is not limited to FIG.
8, it is not limited to the embodiment shown in FIG.
For example, the wave plate 15 may be a wave plate that functions as a 波長 wave plate for a laser light beam having a wavelength of 650 nm.

In this embodiment, the wave plate 15 is used to
After reflecting the optical disk, the polarization hologram element 11
By changing the polarization direction of the laser light beam to 10,
Although the hologram elements that diffract each beam and guide them to the photodetector 102 in the semiconductor laser module 1 are different from each other, the present invention is not limited to this, and the diffraction efficiency of the diffraction grating with respect to the wavelength of the diffraction grating is naturally limited. Taking advantage of the fact that the characteristics can be set relatively freely by optimally designing the depth of the lattice groove, the laser light beam for DVD and the CD
Optimum design of the grating groove depth of each hologram element according to the wavelength of each laser light beam for use, and selectively change the hologram element that diffracts this laser light beam and guides it to the photodetector for each laser light beam Of course, any configuration is acceptable.

[0050]

According to the present invention, a light source and a light detection system for a DVD / CD shared type optical pickup can be realized by using only one semiconductor laser module and one semiconductor laser light source or only one semiconductor laser module. As seen from the configuration, the number of parts and cost of the DVD / CD common type optical pickup having high versatility can be significantly reduced.

[Brief description of the drawings]

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

FIG. 2 is a schematic sectional view showing a configuration of a semiconductor laser module used in the first embodiment.

FIG. 3 is a schematic plan view showing a configuration of a semiconductor laser module used in the first embodiment.

FIG. 4 is a schematic plan view showing an example of a grating groove pattern of a diffraction grating used in the present invention.

FIG. 5 is a schematic front view showing a traveling direction of a DVD light beam in the first embodiment of the present invention.

FIG. 6 is a schematic plan view showing a state of an optical disk reflected light beam incident on the diffraction grating in the first embodiment of the present invention.

FIG. 7 is a schematic plan view showing an irradiation state of a DVD light beam applied to a light detection surface in the first embodiment of the present invention.

FIG. 8 is a schematic front view showing a traveling direction of a CD light beam in the first embodiment of the present invention.

FIG. 9 is a schematic plan view showing an irradiation state of a CD light beam applied to the photodetection surface in the first embodiment of the present invention.

FIG. 10 is a schematic front view showing a second embodiment of the present invention.

FIG. 11 is a schematic front view of a semiconductor laser module portion for explaining a diffraction state of a light beam for DVD and a light beam for CD in a second embodiment of the present invention.

FIG. 12 is a schematic plan view showing an irradiation state of a light beam for DVD and a light beam for CD applied to the photodetection surface in the second embodiment of the present invention.

FIG. 13 is a schematic front view showing a third embodiment of the present invention.

FIG. 14 is a schematic front view of a semiconductor laser module for explaining a diffraction state of a light beam for DVD and a light beam for CD in a third embodiment of the present invention.

FIG. 15 is a schematic front view showing another configuration example regarding the polarizing hologram element and the wave plate in the third embodiment of the present invention.

FIG. 16 is a schematic front view showing a fourth embodiment of the present invention.

FIG. 17 is a schematic front view showing a fifth embodiment of the present invention.

FIG. 18 is a schematic plan view of a main part of a semiconductor laser module according to a sixth embodiment of the present invention.

FIG. 19 is a schematic front view of a semiconductor laser module part for explaining a diffraction state of a light beam for DVD and a light beam for CD in a sixth embodiment of the present invention.

[Explanation of symbols]

1. Semiconductor laser module 2: Semiconductor laser light source
7 Objective lens, 8 Optical disk, 101, 201 Semiconductor laser chip, 102 Photodetector, 105 Hologram element, 10, 11, 12, 14 Polarizing hologram element, 13, 15 Wave plate

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Katsuhiko Izumi, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Digital Media Development Division, Hitachi, Ltd. (72) Nobuyuki Maeda 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Address: Hitachi, Ltd. Digital Media Development Division (72) Inventor: Masayuki Inoue 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term: Digital Media Development Division, Hitachi, Ltd. 5D090 AA01 BB02 BB05 CC01 CC04 CC16 FF08 LL02 LL05 5D119 AA01 AA40 AA41 BA01 BB01 BB04 EC45 EC47 FA05 FA08 JA22 JA25 JA26 JA31

Claims (10)

[Claims] 1. A semiconductor laser module in which at least one semiconductor laser light source and a photodetector having a plurality of divided detection surfaces are arranged in the same housing, and a laser emitted by the semiconductor laser light source in the semiconductor laser module. A second semiconductor laser light source that emits a laser light beam having a wavelength different from that of the light beam; and a laser light beam emitted from each of the semiconductor laser light sources is condensed to irradiate a predetermined optical information recording medium with an independent light spot. In an optical pickup having an objective lens having a function of performing, in an optical path from the objective lens to the semiconductor laser module, each laser light beam emitted from each of the semiconductor laser light sources and reflected by the optical information recording medium, respectively. Optics for guiding to a predetermined position on the photodetection surface arranged in the semiconductor laser module An optical pickup characterized in that a means is arranged. 2. A focus error of each light spot emitted from each of the semiconductor laser light sources and condensed on the optical information recording medium using a predetermined signal detected on a light detection surface in the semiconductor laser module. 2. The optical pickup according to claim 1, wherein the optical pickup has a function of independently detecting a signal and a tracking error signal and reproducing an information signal recorded on each optical information recording medium. 3. The optical device according to claim 1, wherein the optical means is constituted by a diffraction grating having a concave and convex lattice groove at a predetermined pitch on at least a transparent substrate disposed at a window of the semiconductor laser module. Item 1. The optical pickup according to item 1 or 2. 4. The optical means emits a semiconductor laser light source in the semiconductor laser module and diffracts the laser light beam with a predetermined diffraction efficiency with respect to a first laser light beam having a predetermined polarization direction. A first polarization diffraction grating having a diffraction efficiency of about 0% for a second laser light beam having a polarization direction substantially perpendicular to the first light beam; Contrary to the diffraction grating, a function of diffracting the first laser light beam with a diffraction efficiency of almost 0% and diffracting the second laser light beam with a predetermined diffraction efficiency is provided. 4. The optical pickup according to claim 1, wherein the optical pickup comprises a second polarization diffraction grating. 5. The optical means emits a semiconductor laser light source in the semiconductor laser module and diffracts the laser light beam with a predetermined diffraction efficiency with respect to a first laser light beam having a predetermined polarization direction. A first polarizing diffraction grating having a diffraction efficiency of about 0% with respect to a second laser light beam having a polarization direction substantially perpendicular to the first laser light beam; In contrast to the directional diffraction grating, the first
A second polarization diffraction grating having a function of diffracting the light beam with a predetermined diffraction efficiency with respect to the second laser light beam with respect to the second laser light beam. 4. The light according to claim 1, further comprising a predetermined wavelength plate or a phase conversion element that functions as a substantially half-wave plate for both the first and second laser light beams. pick up. 6. The optical means emits a semiconductor laser light source in the semiconductor laser module and diffracts the laser light beam with a predetermined diffraction efficiency with respect to a first laser light beam having a predetermined polarization direction. A first polarizing diffraction grating having a diffraction efficiency of about 0% for a second laser light beam having a polarization direction perpendicular to the first laser light beam; Contrary to the diffraction grating, the diffraction efficiency for the first laser light beam is almost 0%,
A second polarization diffraction grating having a function of diffracting the laser light beam with a predetermined diffraction efficiency with respect to the second laser light beam, and one of the first and second laser light beams. A predetermined wavelength plate or a phase conversion element that functions as a substantially quarter-wave plate and functions as a substantially half-wave plate for the other. 3. The optical pickup according to 3. 7. The optical means emits a semiconductor laser light source in the semiconductor laser module and diffracts the laser light beam at a predetermined diffraction efficiency with respect to a first laser light beam having a predetermined wavelength; Diffraction efficiency is almost 0% for a second laser light beam emitted from the second semiconductor laser light source and having a wavelength different from that of the first laser light beam.
In contrast to the first wavelength-selective diffraction grating and the first wavelength-selective diffraction grating, the diffraction efficiency for the first laser light beam is substantially 0%, and the second laser light 4. The optical pickup according to claim 1, further comprising a second wavelength-selective diffraction grating having a function of diffracting the laser beam with a predetermined diffraction efficiency with respect to the beam. 8. A first semiconductor laser light source that emits a laser light beam of a predetermined wavelength and a second semiconductor laser light source that emits a laser light beam of a different wavelength from the first semiconductor laser light source are divided into a plurality. A semiconductor laser module in which a photodetector having a detection surface is arranged in the same housing; and an independent light spot for condensing each laser light beam emitted from each of the semiconductor laser light sources and for a predetermined optical information recording medium. And an objective lens having a function of irradiating the first semiconductor laser light source in an optical path between the objective lens and the semiconductor laser module, the first laser having a predetermined polarization direction. The laser beam is diffracted at a predetermined diffraction efficiency with respect to the light beam, and a second polarization direction perpendicular to the first laser light beam is provided. A first polarizing diffraction grating having a diffraction efficiency of approximately 0% with respect to a laser light beam, and a diffraction efficiency having a diffraction efficiency with respect to the first laser light beam which is opposite to the first polarizing diffraction grating. A second polarization diffraction grating having a function of diffracting the laser light beam with a predetermined diffraction efficiency with respect to the second laser light beam; A predetermined wave plate or a phase conversion element that functions as a substantially quarter wave plate for one of the laser light beams and functions as a substantially half wave plate for the other laser light beam; An optical pickup characterized by having an arrangement. 9. A first semiconductor laser light source that emits a laser light beam of a predetermined wavelength and a second semiconductor laser light source that emits a laser light beam of a different wavelength from the first semiconductor laser light source are divided into a plurality. A semiconductor laser module in which a photodetector having a detection surface is arranged in the same housing; and an independent light spot for condensing each laser light beam emitted from each of the semiconductor laser light sources and for a predetermined optical information recording medium. And an objective lens having a function of irradiating the semiconductor laser module with a first laser beam emitted from the first semiconductor laser light source and having a predetermined wavelength in an optical path between the objective lens and the semiconductor laser module. The laser beam is diffracted at a predetermined diffraction efficiency with respect to the beam, emits the second semiconductor laser light source, and is different from the first laser beam. A first wavelength-selective diffraction grating whose diffraction efficiency is approximately 0% for a second laser light beam having a certain wavelength, and the first light that is opposite to the first wavelength-selective diffraction grating. And a second wavelength-selective diffraction grating having a function of diffracting the light beam with a predetermined diffraction efficiency with respect to the second light beam with a diffraction efficiency of approximately 0%. An optical pickup characterized by the following. 10. An optical information reproducing apparatus or a recording apparatus equipped with the optical pickup according to claim 1.