JP3668422B2 - Optical pickup device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical pickup device that emits a plurality of laser beams having different wavelengths and reads information recorded on optical discs of different types and standards.
[0002]
[Prior art]
An optical pickup device used for reading information recorded on an optical disc such as a compact disc (abbreviation: CD) and a digital versatile disc (abbreviation: DVD) and recording information on a recordable CD and DVD Two laser beams having different wavelengths that are optimum for each optical disc are used.
[0003]
FIG. 7 is a schematic configuration diagram showing an optical pickup device 1 disclosed in International Publication No. WO98 / 19303, which is a prior art. FIG. 8 is a side view showing the optical pickup device 1. The optical pickup device 1 includes a semiconductor laser light source 2, a flat beam splitter 3, a collimator lens 4, a rising mirror 5, a wavelength selective aperture 6, a condensing lens 7, and a light receiving element 8.
[0004]
The semiconductor laser light source 2 includes semiconductor laser elements 2a and 2b having different oscillation wavelengths. One semiconductor laser element 2a emits an infrared laser beam having a wavelength of 780 nm. The other semiconductor laser element 2b emits a red laser beam having a wavelength of 650 nm. The semiconductor laser elements 2a and 2b are arranged parallel to the information recording surface 9a of the optical disk 9, that is, horizontally, and the horizontal width of the laser elements 2a and 2b is 100 μm. The plate beam splitter 3 matches the optical axes of the beam lights having different wavelengths emitted from the semiconductor laser elements 2a and 2b. The collimator lens 4 converts the light incident on the collimator lens 4 into parallel light and emits it. The rising mirror 5 reflects a light beam incident in the horizontal direction in the vertical direction or reflects a light beam incident in the vertical direction in the horizontal direction. The wavelength selective aperture 6 changes the numerical aperture (abbreviation: NA) of the condenser lens 7. The light receiving element 8 detects incident light rays and converts them into electrical signals.
[0005]
A laser beam having a wavelength of 780 nm emitted horizontally from one semiconductor laser element 2 a is reflected horizontally by the front surface 3 a of the flat plate beam splitter 3. The laser beam having a wavelength of 650 nm emitted horizontally from the other semiconductor laser element 2 b is transmitted through the front surface 3 a of the flat plate beam splitter 3, is reflected by the rear surface 3 b of the flat plate beam splitter 3, and is again returned to the front surface of the flat beam splitter 3. It passes through 3a. The optical axes of the laser beams emitted from the semiconductor laser elements 2a and 2b coincide with each other by the flat beam splitter 3.
[0006]
The two laser beams whose optical axes are matched by the flat beam splitter 3 are converted into parallel light by the collimator lens 4. The two laser beams converted into the parallel light are reflected vertically upward by the rising mirror 5. The two laser beams reflected by the standing mirror 5 pass through the wavelength selective aperture 6 and are condensed on the information recording surface 9 a of the optical disk 9 by the condenser lens 7. The reflected light from the information recording surface 9 a of the optical disk 9 passes through the condenser lens 7, is reflected in the horizontal direction by the rising mirror 5, and passes through the collimator lens 4.
[0007]
Of the reflected light from the optical disk 9 that has passed through the collimator lens 4, the reflected light of the laser beam emitted from one semiconductor laser element 2a is partially reflected by the front surface 3a of the flat beam splitter 3 to reduce the amount of light, and the rear surface 3b. Is completely transmitted and condensed on the light receiving element 8. Of the reflected light from the optical disk 9 that has passed through the collimator lens 4, the reflected light of the laser beam emitted from the other semiconductor laser element 2b is completely transmitted through the front surface 3a of the flat beam splitter 3 and partially reflected at the rear surface 3b. As a result, the amount of light is reduced, transmitted through the rear surface 3 b, and condensed on the light receiving element 8. The two reflected lights are transmitted through the plate beam splitter 3 in a state where the optical axes coincide with each other.
[0008]
FIG. 9 is a schematic configuration diagram showing an optical pickup device 11 disclosed in Japanese Unexamined Patent Publication No. 2000-99983, which is another conventional technique. The optical pickup device 11 includes a semiconductor laser light source 12, a parallel plate 13, a beam splitter 14, a collimator lens 15, a condenser lens 16 and a light receiving element 17.
[0009]
The semiconductor laser light source 12 has two semiconductor laser elements having different oscillation wavelengths. One semiconductor laser element emits a laser beam having a wavelength of 780 nm. The other semiconductor laser element emits a laser beam having a wavelength of 650 nm.
[0010]
The parallel plate 13 includes two glass substrates 13a and 13b, a first wavelength selection film 18 and a second wavelength selection film 19. The first wavelength selection film 18 is in close contact with one surface of one glass substrate 13a, the second wavelength selection film 19 is in close contact with the other surface of one glass substrate 13a, and the other glass substrate 13b is in contact with one glass substrate. The laminated structure is in close contact with the second selection film 19 in close contact with the substrate 13a. The first wavelength selection film 18 transmits a laser beam having a wavelength of 780 nm emitted from one semiconductor laser element and reflects a laser beam having a wavelength of 650 nm emitted from the other semiconductor laser element. The second wavelength selection film 19 reflects a laser beam having a wavelength of 780 nm emitted from one semiconductor laser element.
[0011]
The laser beam having a wavelength of 780 nm emitted from one of the semiconductor laser elements is refracted by the first wavelength selection film 18 of the parallel plate 13, passes through the first glass substrate 13a, is reflected by the second wavelength selection film 19, and again. The light passes through the first glass substrate 13a, is refracted by the first wavelength selection film 18, and enters the beam splitter 14 in a direction perpendicular to the incident direction. A laser beam having a wavelength of 650 nm emitted from the other semiconductor laser element is reflected by the first wavelength selection film 18 of the parallel plate 13 and enters the beam splitter 14 in a direction perpendicular to the incident direction. Due to the parallel plate 13, the optical axes of the two laser beams incident on the beam splitter 14 coincide.
[0012]
Two laser beams having the same optical axis incident on the beam splitter 14 are transmitted through the beam splitter 14, converted into parallel light by the collimator lens 15, and condensed on the information recording surface 9 a of the optical disk 9 by the condenser lens 16. Is done. Reflected light from the information recording surface 9 a of the optical disk 9 passes through the condenser lens 16 and the collimator lens 15, is reflected by the beam splitter 14, and enters the light receiving element 17.
[0013]
[Problems to be solved by the invention]
In the optical pickup device 1 which is the above-described prior art, the two semiconductor laser elements 2 a and 2 b are arranged in parallel with the information recording surface 9 a of the optical disk 9. In the optical pickup device 11, the two semiconductor laser elements are arranged in parallel. The distance between the light emitting portions of these semiconductor laser elements is not less than the horizontal width of each semiconductor laser element, that is, not less than 100 μm, and the optical axis of the laser light emitted from each semiconductor laser element is also separated by not less than 100 μm.
[0014]
As described above, when two laser beams whose optical axes are largely separated are condensed on the information recording surface 9a of the optical disk 9 by the same condenser lens, the optical axis does not pass through the center of the condenser lens, and the aberration increases. . When the distance between two parallel optical axes is 30 μm or more, a beam matching optical element that matches the optical axes of the two laser beams, such as the flat plate beam splitter 3 of the optical pickup device 1 and the parallel flat plate 13 of the optical pickup device 11 Is required.
[0015]
In an optical pickup device that reads information recorded on different types of optical discs such as CDs and DVDs, such a beam matching optical element is required, so that it is difficult to assemble and adjust the optical pickup. Since the beam matching optical element has to be fixed at a predetermined angle with respect to the optical axis, it is very difficult to adjust. It is not easy to integrate the beam matching optical element with other optical elements.
[0016]
In addition, since two laser beams having different wavelengths are received by the same light receiving element, there is a problem that when the structure of the light receiving element is matched with the laser beam of one wavelength, the characteristics with respect to the laser beam of the other wavelength are deteriorated.
[0017]
Further, when the beam splitter 14 and the collimator lens 15 are arranged between the parallel plate 13 and the condenser lens 16 as in the optical pickup device 11, the distance from the parallel plate 13 to the condenser lens 16 is increased. The device becomes larger.
[0018]
Accordingly, an object of the present invention is to provide an optical pickup device having a small size and good light receiving characteristics.
[0019]
[Means for Solving the Problems]
  The present inventionA laser light source, a beam splitter, and a mirror are arranged in order in the first direction X among the first, second, and third directions X, Y, and Z perpendicular to each other.
  The laser light source includes two semiconductor laser elements that are offset in the third direction Z and have optical axes of two laser beams having different oscillation wavelengths, and each optical axis is parallel to the first direction X. ,
  The beam splitter transmits the laser beam incident from the first direction X from the laser light source in the first direction X, and reflects the laser beam incident from the opposite direction of the first direction X from the mirror in the second direction Y. And
  In the third direction Z, a condenser lens is arranged in order of the mirror,
  The condensing lens guides and condenses the laser beam in the third direction Z from the mirror perpendicularly to the information recording surface of the optical disk, and reflects the laser beam reflected by the information recording surface in the direction opposite to the third direction Z. Led to the mirror,
  The mirror has a beam matching optical element;
  This beam matching optical element
  A wavelength selective transmission film that reflects a laser beam of one wavelength of the two laser beams and transmits a laser beam of the other wavelength;
  A parallel plate with a wavelength selective transmission film attached to one surface;
  A reflective film that is attached to the other surface of the parallel plate and reflects the laser beam of the other wavelength;
  Reflecting each of the two laser beams from the laser light source via the beam splitter to guide the optical axis in the third direction Z, and
  Reflecting each laser beam reflected by the information recording surface via the condenser lens and shifting the optical axis in the third direction Z for each wavelength, leading to the opposite direction of the first direction X,
  The light receiving means is arranged in the second direction Y in order with the beam splitter,
  The light receiving means includes two light receiving elements that are arranged to be shifted in the third direction Z and receive the laser beams for the respective wavelengths from the beam splitter.This is an optical pickup device.
[0020]
  According to the present invention, two parallel laser beams having different wavelengths emitted from each laser element are:MirrorBy beam matching opticsIn the third direction ZThe optical axes are matched and enter the optical disk. The laser beam reflected by the optical disk isThe optical axis is shifted in the third direction Z for each wavelength.Separated into two laser beams. This laser beam is received through a light receiving optical element that reflects or diffracts part of incident light, such as a beam splitter or a hologram element, and enters the light receiving element.
  ThisIn the present invention, the optical disc andmirrorSince no beam splitter or the like is provided between the two, the apparatus is not as in the second prior art described above.1 up and downThe optical pickup device can be thinned without increasing the size.
  ThisThe optical pickup apparatus of the present invention as described above can read information recorded on an optical disk or record information on an optical disk with one optical pickup apparatus for CD and DVD optical disks.
[0022]
  eachTwo parallel laser beams having different wavelengths emitted from the laser element are:MirrorThe optical axis is made coincident by the beam matching optical element so that it can enter the optical disk perpendicularly. The laser beam reflected by the optical disk isMirrorThe laser beam is separated into two laser beams by the beam matching optical element, and a part of the laser beam can be perpendicularly incident on the light receiving element by the beam splitter. That is, since the beam matching optical element of the present invention has a function as a rising mirror, the number of parts is reduced, assembly is facilitated, and the apparatus can be downsized.
[0024]
  BiSince two laser beams having different wavelengths incident on the light receiving element from the beam splitter can be incident on the light receiving elements corresponding to the wavelengths of the respective laser beams, it is necessary to use each light receiving element optimal for the laser beam. it can.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view showing an optical pickup device 51 according to an embodiment of the present invention, and FIG. 2 is a plan view showing the optical pickup device 51. The optical pickup device 51 can read information recorded on the information recording surface of two types of optical disks 100 such as a CD and a DVD, and record information on the information recording surface of the optical disk 100 such as a recordable CD and DVD. it can.
[0028]
The optical pickup device 51 includes a laser light source 52, a collimator lens 53, a beam splitter 54 as a light receiving optical element, a rising mirror 55 having a beam matching optical element 65, a condensing lens 56, and a light receiving means 57. . The laser light source 52, the collimator lens 53, the beam splitter 54, and the rising mirror 55 are sequentially arranged in parallel in the X direction. The beam splitter 54 and the light receiving means 57 are arranged in parallel in order in the Y direction. The raising mirror 55 and the condenser lens 56 are arranged in parallel in the Z direction. The X direction, the Y direction, and the Z direction are perpendicular to each other. In the optical disc 100, the information recording surface is arranged perpendicular to the Z direction on the Z direction side of the condenser lens 56.
[0029]
FIG. 3 is a front view showing the laser light source 52. The laser light source 52 includes a first laser element 61, a second laser element 62, and a stem 63. The two laser elements 61 and 62 are semiconductor laser elements having different oscillation wavelengths. The first laser element 61 emits an infrared laser having a wavelength of 780 nm, for example. For example, the second laser element 62 emits a red laser having a wavelength of 650 nm. The stem 63 is a substantially oval substrate. The laser elements 61 and 62 are attached to one surface of the stem 63 by die bonding in parallel in a direction perpendicular to the longitudinal direction of the stem 63. In the optical pickup device 51, the laser light source 52 is such that the surface of the stem 63 to which the laser elements 61 and 62 are attached faces the collimator lens 53 in the X direction, and the first laser element 61 is on the Z direction side of the second laser element 62. Are arranged as follows. Laser beams of each wavelength are emitted from the laser elements 61 and 62 so that the optical axes of the two laser beams are parallel to each other in the X direction.
[0030]
The collimator lens 53 converts two laser beams having different wavelengths emitted from the two laser elements 61 and 62 into parallel light. The beam splitter 54 transmits the laser beam incident from the X direction in the X direction and reflects the laser beam incident from the opposite direction of the X direction in the Y direction.
[0031]
FIG. 4 is a side view showing the rising mirror 55. The rising mirror 55 has a beam matching optical element 65. The beam matching optical element 65 includes a parallel plate 66, a wavelength selective transmission film 67, and a reflection film 68. A wavelength selective transmission film 67 is attached to one surface of the parallel plate 66, and a reflection film 68 is attached to the other surface of the parallel plate 66. The wavelength selective transmission film 67 is made of an optical multilayer film. The wavelength selective transmission film 67 has a property of reflecting a laser beam having a wavelength of 780 nm and transmitting a laser beam having a wavelength of 650 nm. The reflective film 68 is made of a dielectric multilayer film and a metal film. The reflective film 68 reflects the laser beam. The thickness and refractive index of the parallel plate 66 are such that the laser beam having a wavelength of 650 nm transmitted through the wavelength selective transmission film 67 is reflected by the reflection film 68 and is transmitted again through the wavelength selective transmission film 67, that is, the laser beam having a wavelength of 650 nm. When the light passes through the beam matching optical element 65 twice, the laser beam having a wavelength of 780 nm reflected by the wavelength selective transmission film 67 is selected so as to coincide with the optical axis.
[0032]
The condensing lens 56 condenses the laser beam reflected in the Z direction by the rising mirror 55 on the information recording surface of the optical disc 100.
[0033]
The light receiving means 57 includes a first light receiving element 71 and a second light receiving element 72. The light receiving elements 71 and 72 are photodiodes in which a pn junction is formed on a Si substrate. The first light receiving element 71 is pn-junction with a junction depth optimum for receiving a laser beam having a wavelength of 780 nm. The second light receiving element 72 is pn-junction with a junction depth optimum for receiving a laser beam having a wavelength of 650 nm. In this manner, a light receiving element optimum for each wavelength of laser beam can be used. In the light receiving means 57, the first light receiving element 71 is disposed on the Z direction side with respect to the second light receiving element 72.
[0034]
The laser beam having a wavelength of 780 nm emitted from the first laser element 61 of the laser light source 52 in the X direction and the laser beam having a wavelength of 650 nm emitted from the second laser element 62 in the X direction are converted into parallel light by the collimator lens 53. Then, it passes through the beam splitter 54 in the X direction. Thereafter, the laser beam having a wavelength of 780 nm enters the wavelength selective transmission film 67 of the beam matching optical element 65 of the rising mirror 55 and is reflected in the Z direction. The laser beam with a wavelength of 650 nm is incident on the opposite side in the Z direction from the laser beam with a wavelength of 780 nm in the beam matching optical element 65 of the rising mirror 55, and the wavelength selective transmission film 67 of the beam matching optical element 65 of the rising mirror 55. , Refracted by the parallel plate 66, reflected by the reflective film 68, refracted by the parallel plate 66 again, and converted to the same optical axis as the laser beam having a wavelength of 780 nm emitted from the first laser element 61. The light is emitted from the wavelength selective transmission film 67 in the Z direction.
[0035]
Two laser beams having the same optical axis and reflected from each other in the Z direction by the rising mirror 55 are condensed by the condenser lens 56 and incident on the information recording surface of the optical disc 100.
[0036]
Signal lights of two laser beams having different wavelengths and having the same optical axis reflected on the information recording surface of the optical disc 100 in the reverse direction in the Z direction are transmitted through the condenser lens 56 in the reverse direction in the Z direction to the rising mirror 55. Incident in the opposite direction to the Z direction. The signal light having a wavelength of 780 nm is reflected in the reverse direction by the wavelength selective transmission film 67 of the beam matching optical element 65 of the rising mirror 55. The signal light having a wavelength of 650 nm passes through the wavelength selective transmission film 67 of the beam matching optical element 65 of the rising mirror 55, is refracted by the parallel plate 66, is reflected by the reflection film 68, and is refracted by the parallel plate 66 again. The optical axis is different from that of signal light having a wavelength of 780 nm, and the light is converted into signal light parallel to the signal light having a wavelength of 780 nm. At this time, the signal light having a wavelength of 650 nm is emitted from the signal light having a wavelength of 780 nm in the reverse direction in the X direction from the signal direction having a wavelength of 780 nm in the wavelength selective transmission film 67 of the rising mirror 55.
[0037]
Two signal lights having mutually different optical axes that are reflected by the rising mirror 55 in the opposite direction of the X direction are reflected by the beam splitter 54 in the Y direction and are more than the signal light having a wavelength of 650 nm. The signal light having a wavelength of 780 nm on the Z direction side enters the first light receiving element 71 of the light receiving unit 57, and the signal light having a wavelength of 650 nm enters the second light receiving element 72 of the light receiving unit 57.
[0038]
The optical axis of the laser beam having a wavelength of 780 nm which is emitted from the first laser element 61 of the laser light source 52 and is incident on the rising mirror 55, and is emitted from the rising mirror 55 and reflected by the beam splitter 54 and reflected by the light receiving means 57. The optical axis of the signal light having a wavelength of 780 nm incident on the first light receiving element 71 exists on the same plane. Further, the optical axis of the laser beam having a wavelength of 650 nm which is emitted from the second laser element 62 of the laser light source 52 and enters the rising mirror 55, and the light receiving means which is emitted from the rising mirror 55 and reflected by the beam splitter 54. The optical axis of the signal light having a wavelength of 650 nm incident on the second light receiving element 72 of 57 exists on the same plane. These two planes are parallel to each other.
[0039]
In the optical pickup device 51 of the present embodiment, the distance between the laser beam emission point of the first laser element 61 of the laser light source 52 and the laser beam emission point of the second laser element 62 is the width of each laser element 61, 62. Therefore, the two laser beams (signal light) incident on the light receiving elements 71 and 72 of the light receiving means 57 are also separated by about 100 μm. Accordingly, the light receiving elements 71 and 72 of the light receiving means 57 must be arranged about 100 μm apart. On the Si substrate on which the light receiving means 57 is formed, in addition to the light receiving elements 71 and 72, electronic circuits such as a signal amplification amplifier and a signal processing circuit are integrated. Yes. Therefore, if the distance between the two light receiving elements 71 and 72 is about 100 μm, they can be easily integrated and integrated on one Si substrate.
[0040]
One of the two laser elements 61 and 62 is used depending on the type of the optical disk 100 from which information is to be read. Specifically, when the optical disc 100 is a CD, a laser beam having a wavelength of 780 nm is used. Therefore, when the first laser element 61 is used and the optical disc 100 is a DVD, a laser beam having a wavelength of 650 nm is used. The second laser element 62 is used. Therefore, the two light receiving elements 71 and 72 do not receive signal light at the same time, and only one set of signal processing circuits is required, and the Si substrate on which the signal integrated circuit is integrated does not increase even if one light receiving element is added.
[0041]
  FIG. 5 illustrates the present invention.Reference exampleIt is a top view which shows 51 A of optical pick-up apparatuses which are. The optical pickup device 51A is a partial modification of the configuration of the optical pickup device 51, and includes a two-wavelength hologram laser 81, a collimator lens 53, a rising mirror 55 having a beam matching optical element 65, and a condenser lens 56. Consists of.
[0042]
FIG. 6 is a perspective view showing the two-wavelength hologram laser 81. The two-wavelength hologram laser 81 includes a hologram element 82, which is a light receiving optical element, a first laser element 61A, a second laser element 62A, a first light receiving element 71A, and a second light receiving element 72A. The hologram element 82 has a diffraction grating, transmits a laser beam incident from one side, and diffracts the laser beam incident from the other side by the diffraction grating. The diffraction angle varies depending on the wavelength of the laser beam. A technique similar to a laser light source using such a hologram element is disclosed in, for example, Japanese Patent Laid-Open No. 6-5990.
[0043]
In the optical pickup device 51A, the two-wavelength hologram laser 81, the collimator lens 53, and the rising mirror 55 are sequentially arranged in parallel in the X direction. At this time, the laser beam incident / exit surface of the hologram element 82 of the two-wavelength hologram laser 81 is arranged facing the collimator lens 53 in the X direction. In the two-wavelength hologram laser 81, the first laser element 61A is disposed on the Z direction side of the second laser element 62A, and the first light receiving element 71A is disposed on the Y direction side of the second light receiving element 72A. The rising mirror 55 and the condensing lens 56 are sequentially arranged in parallel in the Z direction. The X direction, the Y direction, and the Z direction are perpendicular to each other. In the optical disc 100, the information recording surface is arranged perpendicular to the Z direction on the Z direction side of the condenser lens 56.
[0044]
The laser beam having a wavelength of 780 nm emitted from the first laser element 61A of the two-wavelength hologram laser 81 in the X direction and the laser beam having a wavelength of 650 nm emitted from the second laser element 62A in the X direction are transmitted through the hologram element 82. Thus, the collimator lens 53 makes the light parallel. Thereafter, the laser beam having a wavelength of 780 nm enters the wavelength selective transmission film 67 of the beam matching optical element 65 of the rising mirror 55 and is reflected in the Z direction. The laser beam with a wavelength of 650 nm is incident on the opposite side in the Z direction from the laser beam with a wavelength of 780 nm in the beam matching optical element 65 of the rising mirror 55, and the wavelength selective transmission film 67 of the beam matching optical element 65 of the rising mirror 55. , Refracted by the parallel plate 66, reflected by the reflecting film 68, refracted by the parallel plate 66 again, and converted to the same optical axis as the laser beam having a wavelength of 780 nm emitted from the first laser element 61A. The light is emitted from the wavelength selective transmission film 67 in the Z direction.
[0045]
Two laser beams having the same optical axis and reflected from each other in the Z direction by the rising mirror 55 are condensed by the condenser lens 56 and incident on the information recording surface of the optical disc 100.
[0046]
Signal lights of two laser beams having different wavelengths and having the same optical axis reflected on the information recording surface of the optical disc 100 in the reverse direction in the Z direction are transmitted through the condenser lens 56 in the reverse direction in the Z direction to the rising mirror 55. Incident in the opposite direction to the Z direction. The signal light having a wavelength of 780 nm is reflected in the reverse direction by the wavelength selective transmission film 67 of the beam matching optical element 65 of the rising mirror 55. The signal light having a wavelength of 650 nm is transmitted through the wavelength selective transmission film 67 of the beam matching optical element 65 of the rising mirror 55, refracted by the parallel plate 66, reflected by the reflection film 68, and again by the parallel plate 66. The light is refracted and converted into signal light having a wavelength of 780 nm and signal light having a different optical axis and parallel to signal light having a wavelength of 780 nm. At this time, the signal light having a wavelength of 650 nm is emitted from the signal light having a wavelength of 780 nm in the reverse direction in the X direction from the signal direction having a wavelength of 780 nm in the wavelength selective transmission film 67 of the rising mirror 55.
[0047]
Two signal lights having mutually different optical axes and reflected from the rising mirror 55 in the opposite direction in the X direction are incident on the hologram element 82 of the two-wavelength hologram laser 81. The signal light having a wavelength of 780 nm that is closer to the Z direction than the signal light having a wavelength of 650 nm is diffracted by the diffraction grating of the hologram element 82, and the first light receiving element 71 </ b> A on the Y direction side of the second light receiving element 72 </ b> A of the two-wavelength hologram laser 81. Is incident on. The signal light having a wavelength of 650 nm is diffracted by the diffraction grating of the hologram element 82 and is incident on the second light receiving element 72 A of the two-wavelength hologram laser 81.
[0048]
When the two-wavelength hologram laser 81 is viewed from the X direction as shown in FIG. 6, the dimension in the Z direction can be reduced by making the Y wavelength direction into a substantially oval shape with the Y direction as the longitudinal direction.
[0049]
According to the optical pickup devices 51 and 51A of the present embodiment, two laser beams having different wavelengths emitted from the laser elements 61 and 62; 61A and 62A are parallel to each other. , The optical axes are matched and enter the optical disc 100. The laser beam reflected by the optical disc 100 is separated by the beam matching optical element 65 into two laser beams whose optical axes are parallel to each other. This laser beam is incident on the light receiving elements 71 and 72; 71A and 72A by reflecting or diffracting a part of the incident light by the beam splitter 54 or the hologram element 82 which is a light receiving optical element. As described above, in the present invention, since no light receiving optical element is provided between the optical disc 100 and the beam matching optical element 65, the size of the optical pickup devices 51 and 51A in the Z direction is increased without increasing the size of the device. Without this, it is possible to read information recorded on the optical disk and record information on the optical disk with a single optical pickup device for CD and DVD optical disks.
[0050]
Further, two laser beams having different wavelengths emitted from the laser elements 61 and 62; 61A and 62A and having mutually different optical axes are perpendicularly incident on the optical disc 100 with the optical axes being matched by the beam matching optical element 65. can do. The laser beam reflected by the optical disc 100 is separated into two laser beams whose optical axes are parallel by the beam matching optical element 65, and a part of the laser beam is received by the beam splitter 54 or the hologram element 82 which is a light receiving optical element. 72; It can enter perpendicularly into 71A and 72A. That is, the beam matching optical element 65 of the present invention is configured integrally with the rising mirror 55. This reduces the number of parts, facilitates assembly, and enables downsizing of the apparatus.
[0051]
Two laser beams having different wavelengths incident on the light receiving elements 71 and 72; 71A and 72A from the beam splitter 54 or the hologram element 82, which are light receiving optical elements, are converted into light receiving elements corresponding to the wavelengths of the respective laser beams. Since it can enter, each light receiving element can use the most suitable for a laser beam.
[0052]
Further, since the two laser elements are arranged in parallel with the direction in which the beam matching optical element 65 and the optical disc 100 are arranged, that is, arranged in the Z direction, the beam matching optical element 65 and the rising mirror 55 are integrated. Accordingly, an optical pickup device having a small thickness in the Z direction can be realized.
[0053]
【The invention's effect】
  As described above, according to the present invention, an optical disc andmirrorSince no beam splitter is provided between the two, the optical pickup device can be made thinner without increasing the size of the device as in the second prior art described above. Such an optical pickup apparatus of the present invention can read information recorded on an optical disk or record information on an optical disk with a single optical pickup apparatus for CD and DVD optical disks.
[0054]
Further, according to the present invention, the number of parts is reduced, the assembly is facilitated, and the apparatus can be miniaturized.
[0055]
Further, according to the present invention, each light receiving element that is optimal for a laser beam can be used.
[0056]
Further, according to the present invention, the beam matching optical element and the rising mirror can be integrated, thereby realizing an optical pickup device with a small thickness.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an optical pickup device 51 according to an embodiment of the present invention.
FIG. 2 is a plan view showing an optical pickup device 51. FIG.
3 is a front view showing a laser light source 52. FIG.
4 is a side view showing a rising mirror 55. FIG.
FIG. 5 shows the present invention.Reference exampleIt is a top view which shows 51 A of optical pick-up apparatuses which are.
6 is a perspective view showing a two-wavelength hologram laser 81. FIG.
FIG. 7 is a configuration diagram showing an optical pickup device 1 which is a conventional technique.
FIG. 8 is a side view showing the optical pickup device 1;
FIG. 9 is a configuration diagram showing an optical pickup device 11 which is another conventional technique.
[Explanation of symbols]
51, 51A Optical pickup device
52 Laser light source
54 Beam splitter
55 Rising mirror
57 Light receiving means
61, 61A First laser element
62, 62A Second laser element
65 Beam-matching optical elements
71, 71A First light receiving element
72, 72A Second light receiving element
81 Two-wavelength hologram laser
82 Hologram element
100 optical disc

Claims (1)

A laser light source, a beam splitter, and a mirror are arranged in order in the first direction X among the first, second, and third directions X, Y, and Z perpendicular to each other.
The laser light source includes two semiconductor laser elements that are offset in the third direction Z and have optical axes of two laser beams having different oscillation wavelengths, and each optical axis is parallel to the first direction X. ,
The beam splitter transmits the laser beam incident from the first direction X from the laser light source in the first direction X, and reflects the laser beam incident from the opposite direction of the first direction X from the mirror in the second direction Y. And
In the third direction Z, a condenser lens is arranged in order of the mirror,
The condensing lens guides and condenses the laser beam in the third direction Z from the mirror perpendicularly to the information recording surface of the optical disk, and reflects the laser beam reflected by the information recording surface in the direction opposite to the third direction Z. Led to the mirror,
The mirror has a beam matching optical element;
This beam matching optical element
A wavelength selective transmission film that reflects a laser beam of one wavelength of the two laser beams and transmits a laser beam of the other wavelength;
A parallel plate with a wavelength selective transmission film attached to one surface;
A reflective film that is attached to the other surface of the parallel plate and reflects the laser beam of the other wavelength;
Reflecting each of the two laser beams from the laser light source via the beam splitter to guide the optical axis in the third direction Z, and
Reflecting each laser beam reflected by the information recording surface via the condenser lens and shifting the optical axis in the third direction Z for each wavelength, leading to the opposite direction of the first direction X,
The light receiving means is arranged in the second direction Y in order with the beam splitter,
The optical pickup device is characterized in that the light receiving means includes two light receiving elements which are arranged so as to be shifted in the third direction Z and receive the laser beams of the respective wavelengths from the beam splitter .

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