JP2012089185A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup device that reads out signals recorded on optical disks of different standards by using laser beams having different wave lengths.SOLUTION: The optical pickup device includes a second polarization beam splitter 7 on which a laser beam emitted from a two-wavelength laser diode 3 is incident through a divergence lens 5 and which guides the laser beam emitted from the two-wavelength laser diode 3 toward an objective lens and guides a laser beam reflected from a signal recording layer of each optical disk toward a photodetector 16. The optical axis misalignment of the divergence lens 5 is corrected by displacing the second polarization beam splitter 7 in directions of the optical axes of a reflected second laser beam and a reflected third laser beam.

Description

  The present invention relates to an optical pickup device that performs reading operation of a signal recorded on an optical disc and recording operation of a signal on an optical disc by laser light.

  2. Description of the Related Art Optical disk apparatuses that can perform signal reading operation and signal recording operation by irradiating a signal recording layer of an optical disk with laser light emitted from an optical pickup device have become widespread.

  As an optical disk apparatus, an apparatus using an optical disk called a CD or a DVD is generally widespread. Recently, an optical disk with improved recording density, that is, an apparatus using a Blu-ray standard optical disk has been developed.

  As a laser beam for performing a read operation of a signal recorded on a CD standard optical disc, an infrared light having a wavelength of 785 nm is used. As a laser beam for performing a read operation of a signal recorded on a DVD standard optical disc, , Red light having a wavelength of 655 nm is used.

  Further, the thickness of the transparent protective layer provided between the signal recording layer and the surface of the optical disc in the CD standard optical disc is 1.2 mm, and is used to read out signals from the signal recording layer. The numerical aperture of the objective lens to be set is set to 0.47. The thickness of the transparent protective layer provided between the signal recording layer in the DVD standard optical disc and the surface of the optical disc is 0.6 mm, and is used to read out signals from the signal recording layer. The numerical aperture of the objective lens to be set is set to 0.6.

  For such CD standard and DVD standard optical disks, the laser light for performing the read operation of the signals recorded on the Blu-ray standard optical disk is a laser light having a short wavelength, for example, a blue-violet light having a wavelength of 405 nm. in use.

  The thickness of the protective layer provided on the upper surface of the signal recording layer in the Blu-ray standard optical disc is 0.1 mm, and the aperture of the objective lens used to read out signals from the signal recording layer The number is set to 0.85.

  The diameter of a laser spot generated by reading a signal recorded on a signal recording layer provided on a Blu-ray standard optical disc or by condensing a laser beam to record a signal on the signal recording layer Need to be small. The objective lens used to obtain a desired laser spot shape has a feature that not only the numerical aperture is increased but also the focal length is shortened, so that the radius of curvature of the objective lens is reduced.

An optical disc apparatus capable of reading and recording signals recorded on all the optical discs of the CD standard, the DVD standard, and the Blu-ray standard described above has been commercialized, and is incorporated into such an optical disc apparatus. As an optical pickup device, a laser diode that emits a first laser beam that performs an operation of reading a signal recorded on a Blu-ray standard optical disc, and the first laser beam emitted from the laser diode is condensed on a signal recording layer. Two wavelengths for emitting a first objective lens, a second laser beam for performing a read operation of a signal recorded on a DVD standard optical disc, and a third laser beam for performing a read operation of a signal recorded on a CD standard optical disc Laser diode, and second and third laser beams Optical pickup device in which the second objective lens is incorporated for converging the signal recording layer of the click is generally employed (see Patent Document 1.).

JP 2010-61781 A

  A laser diode that emits a laser beam of one wavelength, a two-wavelength laser diode that emits a laser beam of two wavelengths, and a reading operation of signals recorded on three optical discs of different standards by two objective lenses In the optical pickup apparatus configured as described above, when an optical path is provided for each laser beam, many optical parts are required, which is not only expensive, but also cannot be reduced in size.

  As a method for solving such a problem, the optical paths of the first laser light, the second laser light, and the third laser light are made common. A conventional optical pickup device having such a configuration will be described with reference to FIGS.

  In FIG. 3, reference numeral 1 denotes a laser diode that generates and emits first laser light having a wavelength of 405 nm, for example, blue-violet light, and 2 denotes a first diffraction grating on which the first laser light emitted from the laser diode 1 is incident. There is a diffraction grating section 2a that separates laser light into zero-order main beam, + 1st-order light, and two sub-beams that are −1st-order light, and 1 that converts incident laser light into linearly polarized light in the S direction. / 2 wavelength plate 2b.

  3, for example, a first laser element that generates and emits second laser light that is red light having a wavelength of 655 nm and a second laser element that generates and emits third laser light that is infrared light of 785 nm are housed in the same case. This is a two-wavelength laser diode.

  Reference numeral 4 denotes a second diffraction grating on which the second laser light emitted from the first laser element incorporated in the two-wavelength laser diode 3 and the third laser light emitted from the second laser element are incident. A diffraction grating portion 4a that separates light into a main beam that is zero-order light, two sub-beams that are + 1st-order light, and two sub-beams that are −1st-order light, and a ½ wavelength that converts incident laser light into linearly polarized light in the S direction It consists of a plate 4b.

  Reference numeral 5 denotes a divergence lens provided at a position where the second laser light and the third laser light emitted from the two-wavelength laser diode 3 are incident through the second diffraction grating 4, and is incident divergent light. It functions to adjust the divergence angle of the laser beam. Such a divergence lens 5 is a lens that functions to set the optical magnification of the forward path by adjusting the divergence angle, and is generally called a power lens.

  Such a power lens is designed to have a positive power in order to increase the laser output on the surface of the optical disk.

Reference numeral 6 denotes a first laser beam, a second laser beam, and a third laser beam that reflect the S-polarized light of the first laser beam incident through the first diffraction grating 2 and reflected from the optical disk through an optical path to be described later. It is a first polarization beam splitter that transmits P-polarized light that is return light. 7 reflects the S-polarized light of the second laser light and the third laser light incident through the second diffraction grating 4 and the divergence lens 5 and is reflected by the first polarizing beam splitter 6 and incident first. This is a polarization beam splitter that transmits laser light and transmits P-polarized light that is return light of the first laser light, the second laser light, and the third laser light reflected from the optical disk.

  In the second polarizing beam splitter 7 having such a configuration, a part of the S-polarized light of the second laser light and the third laser light incident through the second diffraction grating 4 and the divergence lens 5 is transmitted and the first polarized beam is transmitted. A part of the S-polarized light of the first laser light reflected and incident from the splitter 6 is reflected. A front monitor 8 is provided at a position where the first laser beam reflected by the second polarization beam splitter 7, the second laser beam transmitted through the second polarization beam splitter 7, and the third laser beam are irradiated. It is a diode and is configured to output a detection signal corresponding to the output of each laser beam. That is, the laser output can be controlled to a desired laser output by using the detection signal obtained from the front monitor diode 8.

  Reference numeral 9 is provided at a position where the first laser light transmitted through the second polarizing beam splitter 7, the second laser light reflected by the second polarizing beam splitter 7 and the third laser light are incident. A three-wavelength compatible quarter wavelength that converts incident laser light corresponding to two different wavelengths of laser light from linearly polarized light to circularly polarized light, and vice versa. It is a board.

  Reference numeral 10 denotes a collimating lens that receives the first laser light, the second laser light, and the third laser light transmitted through the quarter-wave plate 9 and converts the incident laser light into parallel light. The spherical aberration generated based on the thickness of the protective layer of the optical disc by the displacement operation in the direction of the optical axis of 10 is corrected.

  Reference numeral 11 denotes a first objective lens for condensing the first laser beam on the signal recording layer L1 provided on the first optical disc D1 (see FIG. 4), and reference numeral 12 denotes a second laser beam provided on the second optical disc D2. The second objective lens focuses light on the signal recording layer L2 and focuses the third laser light on the signal recording layer L3 provided on the third optical disc D3.

  In such a configuration, the first objective lens 11 and the second objective lens 12 are, for example, displaced by a four support wires in a focusing direction perpendicular to the surface of the optical disc and in a radial direction of the optical disc. It is mounted on a member called a lens holder that is supported so that it can be displaced in the direction.

  The first laser light, the second laser light, and the third laser light transmitted through the collimator lens 10 are configured to be guided to the first objective lens 11 and the second objective lens 12 by the optical system shown in FIG. . In FIG. 4, reference numeral 13 denotes a wavelength selective element, which is configured to transmit the first laser light and reflect the second laser light and the third laser light toward the second objective lens 12. Reference numeral 14 denotes a rising mirror that reflects the first laser light transmitted through the wavelength selective element 13 toward the first objective lens 11. Such a configuration is the same as the technique described in Patent Document 1, and a description thereof will be omitted.

  In such a configuration, the first laser light transmitted through the collimator lens 10 is transmitted through the wavelength selective element 13, reflected by the rising mirror 14, and incident on the first objective lens 11. Thus, the first laser light incident on the first objective lens 11 is condensed on the signal recording layer L1 provided on the first optical disc D1 by the condensing operation of the first objective lens 11. Become.

The second laser light transmitted through the collimator lens 10 is reflected by the wavelength selective element 13 and is incident on the second objective lens 12. Thus, the second laser light incident on the second objective lens 12 is condensed on the signal recording layer L2 provided on the second optical disc D2 by the condensing operation of the second objective lens 12. Become. Then, the third laser light transmitted through the collimating lens 10 is reflected by the wavelength selective element 13 and is incident on the second objective lens 12. Thus, the third laser light incident on the second objective lens 12 is condensed on the signal recording layer L3 provided on the third optical disc D3 by the condensing operation of the second objective lens 12. Become.

  In such a configuration, the first laser light emitted from the laser diode 1 is transmitted through the first diffraction grating 2, the first polarization beam splitter 6, the second polarization beam splitter 7, the quarter wavelength plate 9, the collimating lens 10, and the wavelength. After being incident on the first objective lens 11 via the selective element 13 and the rising mirror 14, the light is condensed on the signal recording layer L1 provided on the first optical disc D1 by the light collecting operation of the first objective lens 11. Although it is irradiated as a spot, the first laser light irradiated to the signal recording layer L1 is reflected as return light by the signal recording layer L1.

  The second laser light emitted from the first laser element of the two-wavelength laser diode 3 is a second diffraction grating 4, a divergence lens 5, a second polarizing beam splitter 7, a quarter-wave plate 9, a collimating lens 10, and After being incident on the second objective lens 12 via the wavelength selective element 13, the signal recording layer L2 provided on the second optical disc D2 is irradiated as a focused spot by the focusing operation of the second objective lens 12. However, the second laser light applied to the signal recording layer L2 is reflected as return light by the signal recording layer L2.

  The third laser light emitted from the second laser element of the two-wavelength laser diode 3 is a second diffraction grating 4, a divergence lens 5, a second polarizing beam splitter 7, a quarter-wave plate 9, a collimating lens 10, and After being incident on the second objective lens 12 via the wavelength selective element 13, the signal recording layer L3 provided on the third optical disc D3 is irradiated as a focused spot by the focusing operation of the second objective lens 12. However, the third laser light applied to the signal recording layer L3 is reflected as return light by the signal recording layer L3.

  The return light of the first laser beam reflected from the signal recording layer L1 of the first optical disc D1 is a first objective lens 11, a rising mirror 14, a wavelength selective element 13, a collimating lens 10, a quarter wavelength plate 9, and The light is incident on the first polarizing beam splitter 6 through the second polarizing beam splitter 7. The return light incident on the first polarizing beam splitter 6 in this way is changed to linearly polarized light in the P direction by the phase changing operation by the quarter wavelength plate 9. Therefore, the return light of the first laser beam is not reflected by the first polarization beam splitter 6 but is transmitted through the first polarization beam splitter 6 as a control laser beam.

  The return light of the second laser light reflected from the signal recording layer L2 of the second optical disc D2 is the second objective lens 12, the wavelength selective element 13, the collimator lens 10, the quarter wavelength plate 9, and the second polarization. The light enters the first polarizing beam splitter 6 through the beam splitter 7. The return light incident on the first polarizing beam splitter 6 in this way is changed to linearly polarized light in the P direction by the phase changing operation by the quarter wavelength plate 9. Therefore, the return light of the second laser light is not reflected by the first polarization beam splitter 6 but is transmitted through the first polarization beam splitter 6 as control laser light.

The return light of the third laser beam reflected from the signal recording layer L3 of the third optical disc D3 is the second objective lens 12, the wavelength selective element 13, the collimator lens 10, the quarter wavelength plate 9, and the second polarization. The light enters the first polarizing beam splitter 6 through the beam splitter 7. The return light incident on the first polarizing beam splitter 6 in this way is changed to linearly polarized light in the P direction by the phase changing operation by the quarter wavelength plate 9. Accordingly, the return light of the third laser light is not reflected by the first polarization beam splitter 6 but is transmitted through the first polarization beam splitter 6 as control laser light.

  Reference numeral 15 denotes an anamorphic lens to which the control laser beam transmitted through the half mirror 6 is incident, and has an action of shaping the control laser beam so as to have a size and a spot shape suitable for generating a focus error signal or the like. It is to be made.

  Reference numeral 16 denotes a photodetector that is irradiated with control laser light through the anamorphic lens 15 and is provided with a well-known quadrant sensor or the like, and a signal recorded on the signal recording layer of the optical disc by the main beam irradiation operation. A focus error signal generation operation for performing a signal generation operation associated with the readout operation of the lens, a focusing control operation by the astigmatism method, and a tracking error signal generation operation for performing the tracking control operation by the irradiation operation of the two sub beams It is configured. Since such control operations for generating various signals are well known, the description thereof is omitted.

  As described above, the first laser light emitted from the laser diode 1 goes to the signal recording layer L1 of the first optical disc D1, and the second laser light emitted from the second wavelength laser diode 3 records the signal on the second optical disc D2. When comparing the forward path to the layer L2 and the forward path of the third laser light emitted from the two-wavelength laser diode 3 to the signal recording layer L3 of the third optical disc D3, the path from the second polarization beam splitter 7 to the wavelength selective element 13 is compared. It can be seen that the optical path is also used.

  Then, the return path of the return light of the first laser light reflected from the signal recording layer L1 of the first optical disk D1 to the photodetector 16, the return of the second laser light reflected from the signal recording layer L2 of the second optical disk D2 Comparing the return path of the light to the photodetector 16 and the return path of the return light of the third laser light reflected from the signal recording layer L3 of the third optical disc D3 to the photodetector 16, the light detection from the wavelength selective element 13 It can be seen that the optical path to the device 16 is also used.

  In such a configuration, the optical axis LA of the first laser light reflected by the first polarizing beam splitter 6 and the optical axes LB of the second laser light and the third laser light reflected by the second polarizing beam splitter 7. Is designed to be coaxial.

  The conventional optical pickup device shown in FIG. 3 uses the first laser light emitted from the laser diode 1 and the second laser light and the third laser light emitted from the two-wavelength laser diode 3 on the signal recording layer of each optical disc. Since the return path that guides the return light reflected from the signal recording layer of each optical disk to the optical detector 16 is also used, the number of optical components can be reduced, and as a result, the manufacturing price can be reduced. In addition, there is an advantage that the optical pickup device can be miniaturized.

  In the optical pickup device having such a configuration, if the optical magnification in the forward path and the optical magnification in the backward path are greatly different, a positional deviation between the light receiving unit such as a four-divided sensor incorporated in the photodetector 16 and the spot of the return light occurs. There is a problem that it is easy. In the conventional example described above as a method for solving such a problem, the divergence lens 5 is provided in the forward path of the second laser light and the third laser light emitted from the two-wavelength laser diode 3. That is, by adjusting the optical magnification with such a divergence lens 5, it is possible to suppress the occurrence of spot displacement, but there is a problem that workability is poor because the divergence lens 5 needs to be fixed and adjusted accurately. .

A case where the optical axis of the divergence lens 5 is displaced in the direction of arrow A in FIG. 3 will be described with reference to FIG. When the divergence lens 5 is fixed in the housing constituting the optical pickup device while being displaced in the direction of arrow A, the optical axes of the second laser beam and the third laser beam (shown by solid lines) as shown in FIG. Deviate from the correct optical axis (indicated by a broken line).

  When the optical axes of the second laser beam and the third laser beam incident on the second polarization beam splitter 7 are shifted, the second laser beam and the third laser beam reflected from the second polarization beam splitter 7 toward the objective lens. The optical axis LB is also shifted as shown in the figure.

  When the optical axes LB of the second laser light and the third laser light reflected from the second polarizing beam splitter 7 toward the objective lens are shifted, the signal recording layer L2 of the second optical disc D2 and the signal recording layer L3 of the third optical disc D3 The optical axes of the return lights of the second laser beam and the third laser beam reflected from the laser beam are also shifted.

  Since the return light of the second laser light and the third laser light is applied to the photodetector 16 as control laser light, it is provided in the photodetector 16 by shifting the optical axis of the control laser light. The position of the spot generated by irradiating the light receiving unit is shifted from the accurate position.

  If the position of a spot generated by irradiating the light-receiving unit provided in the photodetector 16 with the control laser beam is shifted, an accurate focus error signal or tracking error signal cannot be obtained from the photodetector 16. Therefore, the signal reading operation by the optical pickup device cannot be performed.

  The operation of adjusting the position of the photodetector 16 is performed in accordance with such a shift of the optical axis, and the light receiving unit incorporated in the photodetector 16 is shared by the first laser beam and the third laser beam. In such a case, if the optical axis LB of the third laser beam is shifted from the optical axis LA of the first laser beam, the return light of the first laser beam and the third laser beam are adjusted even if the position of the photodetector 16 is adjusted. It becomes impossible to irradiate the light receiving unit with the return light of the laser beam in an optimum state.

  In order to solve such a problem, the conventional optical pickup device has a problem that it is necessary to accurately perform an adjustment operation for attaching the divergence lens 5 to the housing, and the workability is poor. In particular, when it is necessary to irradiate a signal recording layer of an optical disk with a large laser output as in an optical pickup device capable of recording a signal on an optical disk, the positive power of the divergence lens 5, so-called power lens is increased. Since this is necessary, there is a problem that the fixing and adjusting operation of the lens must be performed very accurately.

  The present invention is intended to provide an optical pickup device that can solve such a problem.

The present invention relates to a laser diode that emits a first laser beam that performs a read operation of a signal recorded on a first optical disc, which is short from the surface of the optical disc to the signal recording layer, and a distance from the surface of the optical disc to the signal recording layer. Is recorded on the third optical disc in which the distance from the surface of the optical disc to the signal recording layer is longer than that of the second optical disc and the second laser beam for performing the reading operation of the signal recorded on the second optical disc longer than the first optical disc. In an optical pickup device incorporating a two-wavelength laser diode that emits two laser beams of a third laser beam that performs a reading operation of a signal being reflected, the objective lens is reflected by reflecting the first laser beam emitted from the laser diode And the signal recording layer of the first optical disc and the second optical disc No. recording layer and the first laser beam reflected from the signal recording layer of the third optical disc, the first to transmit the second laser beam and the third laser beam to the photodetector direction
A polarizing member, a power lens to which the second laser light and the third laser light emitted from the two-wavelength laser diode are incident, and a second laser light and a third laser light incident through the power lens are reflected. The first laser beam, the second laser beam, and the third laser beam that are guided in the direction of the objective lens and reflected from the signal recording layer of the first optical disc, the signal recording layer of the second optical disc, and the signal recording layer of the third optical disc. A second polarizing member that transmits light in the direction of the light detector; and a polarization direction of the first laser light, the second laser light, and the third laser light that is provided between the second polarizing member and the objective lens. A three-wavelength-compatible quarter-wave plate that converts linearly polarized light into circularly polarized light, and circularly polarized light into linearly polarized light, and the polarizing beam splitter and objective lens And a collimating lens that adjusts and changes the transmission angle of the laser light, and the second polarizing member reflects the second polarizing member and the third laser light reflected by the second polarizing member. The optical axis shift of the power lens is corrected by displacing in the optical axis direction.

  The present invention is provided so that the second laser beam and the third laser beam emitted from the two-wavelength laser diode are incident through the power lens and reflect the second laser beam and the third laser beam toward the objective lens. Since the optical axis shift of the power lens is corrected by displacing the polarizing member in the optical axis direction of the reflected light, the laser spot irradiated and generated on the signal recording layer of the optical disk can be made into an optimum shape. In addition, the position of the laser spot generated from the return light with respect to the light receiving unit incorporated in the photodetector can be set to an optimum position.

  The optical pickup device of the present invention has an advantage that the assembling work is simplified because the optical lens misalignment of the power lens can be corrected by a simple configuration in which the polarizing member is displaced in the optical axis direction.

  Further, in the present invention, since the polarizing member is configured to be displaced in the optical axis direction of the first laser beam, it has no influence on the first laser beam, so that it is recorded on the optical disk by the first laser beam. It has an advantage that it does not adversely affect the characteristics such as the signal reading operation.

It is the schematic for demonstrating operation | movement of the optical pick-up apparatus based on this invention. It is the schematic for demonstrating operation | movement of an optical pick-up apparatus. It is the schematic which shows the optical system of an optical pick-up apparatus. It is the schematic which shows the optical system of an optical pick-up apparatus.

  Using a laser diode that generates a single laser beam and a two-wavelength laser diode that generates two laser beams of different wavelengths, it is recorded on a signal recording layer provided on an optical disc of a different standard. It is related with the optical pick-up apparatus comprised so that the read-out operation | movement of the signal may be performed.

  In the schematic diagram shown in FIG. 3, the optical pickup device of the present invention emits light in the direction of arrow B, which is the same direction as the optical axis LB direction of the reflected light of the second laser beam and the third laser beam. It is characterized in that it can be displaced with respect to the housing constituting the pickup device.

As shown in FIG. 2, the optical axes LB of the second laser light and the third laser light reflected by the control film 7a provided on the second polarizing beam splitter 7 due to the optical axis shift of the divergence lens 5 are indicated by broken lines. A correction operation when the position is shifted from the correct position to the position indicated by the solid line will be described.

  As indicated by the solid line in FIG. 2, when the optical axes LB of the second laser beam and the third laser beam reflected by the control film 7a of the second polarization beam splitter 7 are shifted from the correct positions, An operation for displacing the beam splitter 7 downward, that is, in the direction of the arrow B1, is performed.

  FIG. 1 shows a state in which the second polarizing beam splitter 7 is displaced in the direction of the arrow B1, and the control film 7a of the second polarizing beam splitter 7 is displaced from the position indicated by the broken line to the position indicated by the solid line. When the control film 7a is displaced to the position indicated by the solid line, the incident points, that is, the reflection points, of the second laser light and the third laser light incident through the divergence lens 5 with respect to the control film 7a are moved.

  When the reflection point with respect to the control film 7a moves, the optical axes LB of the second laser light and the third laser light are moved in the direction of arrow C as shown in FIG. 1, and the optical axis LB is indicated by a broken line in FIG. It can be moved to the correct position.

  When the optical axes LB of the second laser light and the third laser light are moved to the correct positions, the position of the optical axis LA of the first laser light coincides with the position of the optical axis LB as shown in FIG. . Accordingly, since the optical axes of all of the first laser beam, the second laser beam, and the third laser beam coincide with each other, the optical axes of all the laser beams that pass through the quarter-wave plate 9 and the collimating lens 10 are changed. Can be coaxial.

  Thus, even if the optical axis shift occurs due to the shift of the fixed position of the divergence lens 5, the optical axis shift can be corrected by displacing the second polarization beam splitter 7 in the optical axis LB direction of the reflected light. The fixing operation of the divergence lens 5 can be easily performed. When the second polarization beam splitter 7 is displaced in the direction of the optical axis LB and the optical axis LB is moved to the correct position, the first laser can be obtained by fixing the second polarization beam splitter 7 to the housing. The optical axes of the common optical paths through which all of the light, the second laser light, and the third laser light pass can be matched.

  According to the present invention, as described above, the optical axis of the common optical path through which all of the first laser beam, the second laser beam, and the third laser beam pass can be matched. The position of the irradiation spot with respect to the incorporated light receiving unit can be set to an optimum position.

  In the present embodiment, the first laser beam emitted from the laser diode 1 and the second laser emitted from the two-wavelength laser diode 3 for condensing the first laser beam on the signal recording layer L1 of the first optical disc D1. The optical pickup device using the two objective lenses, the second objective lens 12 for condensing the light and the third laser light on the signal recording layer L2 of the second optical disc D2 and the signal recording layer L3 of the third optical disc D3 has been described. The first laser beam, the second laser beam, and the third laser beam are applied to the signal recording layers L1, L2, and L3 provided on the first optical disc D1, the second optical disc D2, and the third optical disc D3 with one objective lens. Needless to say, the present invention can be applied to an optical pickup device configured to collect light.

  In this embodiment, the polarizing beam splitter is used as the second polarizing member that guides the second laser light and the third laser light toward the objective lens and displaces the reflected light in the optical axis direction for adjusting the optical axis. Of course, it is possible to use a polarizing member such as a half mirror.

  Although the description has been given of the case where the optical pickup apparatus that performs the reading operation of the signal recorded on the optical disc of the CD standard, the DVD standard, and the Blu-ray standard has been described, the reading operation of the signal recorded on the optical disc of another different standard has been described. It can also be implemented in an optical pickup device that can be used.

DESCRIPTION OF SYMBOLS 1 Laser diode 3 2 wavelength laser diode 6 1st polarizing beam splitter 7 2nd polarizing beam splitter 9 1/4 wavelength plate 10 Collimating lens 11 1st objective lens 12 2nd objective lens 15 Anamorphic lens 16 Optical detector

Claims (3)

A laser diode that emits a first laser beam having a wavelength selected for performing a read operation of a signal recorded on a first optical disc having a short distance from the surface of the optical disc to the signal recording layer, and a signal recording layer from the surface of the optical disc The distance from the surface of the optical disk to the signal recording layer is the second laser beam having a wavelength selected for performing the read operation of the signal recorded on the second optical disk that is longer than the first optical disk. An optical pickup device incorporating a two-wavelength laser diode that emits two laser beams of a third laser beam having a wavelength selected for performing a read operation of a signal recorded on a third optical disc that is longer than the optical disc. Reflecting the first laser light emitted from the laser diode to the objective lens In addition, the first laser beam, the second laser beam, and the third laser beam reflected from the signal recording layer of the first optical disc, the signal recording layer of the second optical disc, and the signal recording layer of the third optical disc are transmitted toward the photodetector. A first polarizing member, a power lens into which the second laser light and the third laser light emitted from the two-wavelength laser diode are incident, and a second laser light and a third laser incident through the power lens A first laser beam, a second laser beam, which are guided in the direction of the objective lens by reflecting light and reflected from the signal recording layer of the first optical disc, the signal recording layer of the second optical disc, and the signal recording layer of the third optical disc; A second polarizing member that transmits the third laser light in the direction of the photodetector, and a second polarizing member that is provided between the second polarizing member and the objective lens. A three-wavelength-compatible quarter-wave plate for converting the polarization directions of the first laser beam, the second laser beam, and the third laser beam from linearly polarized light to circularly polarized light, and from circularly polarized light to linearly polarized light; A second laser that is provided between the polarizing beam splitter and the objective lens and that adjusts and changes the transmission angle of the laser beam, and reflects the second polarizing member by the second polarizing member. An optical pickup device, wherein the optical axis shift of the power lens is corrected by displacing the light and the third laser light in the optical axis direction. 2. The optical pickup device according to claim 1, wherein a polarizing beam splitter is used as the second polarizing member. The optical pickup device according to claim 1, wherein a half mirror is used as the second polarizing member.

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