JP2006209814A - Optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform focus signal processing by detecting two laser beams from a proximate 2-wavelength 1-package laser with a photodetector. <P>SOLUTION: The light receiving element of the photodetector 12 is divided into 6, i.e., 3 in a horizontal direction and 2 in a vertical direction. First light emitted from a proximate 2-wavelength 1-package laser 11 and reflected on an optical disk 13 is converged on the center of one cross division of the 6-divided elements of the photodetector 12, and second light is converged on the center of the other cross division of the 6-divided light receiving elements of the photodetector 12. Thus, servo signal processing such as focus servo is performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical pickup apparatus for recording or reproducing information using two types of light having different wavelengths with respect to an optical disc having wavelength dependency.

  In recent years, the capacity of optical disks has been increasing as a recording medium, and accordingly, the wavelength of light sources used for optical pickups has been shortened. In general, the size of the light spot on the optical disk is proportional to the wavelength of the light source, and the capacity of the optical disk increases in inverse proportion to the square of the wavelength.

  However, some conventional optical disks have a strong wavelength dependency on light reflectance, recording power, etc., and the wavelength of light used for recording on a certain optical disk is the same as the wavelength of light used for other optical disks. If they are different from each other, there is a problem that recording cannot be performed on the optical disc with the light of the wavelength for the other optical disc. Therefore, in order to make it possible to use one optical pickup together with a normal optical disk and an optical disk suitable for increasing the capacity, light having a wavelength that is normally used and light having a wavelength shorter than the wavelength of the light, for example, There is a need for an optical disc apparatus capable of reproducing or recording information on two types of optical discs using light having a wavelength of 780 nm and light having a wavelength of 650 nm.

  FIG. 14 is a schematic diagram showing a general optical configuration of an optical pickup device having a two-wavelength one-package laser capable of emitting light of two different wavelengths. This optical pickup has, as a light source, a two-wavelength one-package laser 1 that emits two wavelengths, for example, a first wavelength (780 nm) and a second wavelength (650 nm). The first light emission point) is on the optical axis, and the light emission point having the second wavelength (second light emission point) is located at a position about 110 μm away from the first light emission point.

  The light of the first wavelength emitted from the first emission point on the optical axis in the two-wavelength one-package laser 1 passes through the diffraction grating 9 and the quarter-wave plate 8 and then bends the optical path by the beam splitter 7. And collimated by the collimating lens 5. Then, the light is condensed on the optical disk 3 by the objective lens 4, and information is reproduced and recorded on the optical disk 3 by the condensed light spot. Further, the light of the first wavelength reflected by the optical disk 3 is made into substantially parallel light by the objective lens 4 and becomes focused light by the collimating lens 5. Then, after passing through the beam splitter 7, the light is condensed on the light receiving area for the first wavelength in the photodetector 2 by the condenser lens 6. The information signal and the servo signal are detected based on the amount of light received by the photodetector 2.

  On the other hand, the light of the second wavelength emitted from the second light emitting point outside the optical axis proceeds as shown by the dotted line in the figure, as in the case of the light of the first wavelength, and the photodetector 2 is focused on the second wavelength light receiving region. The photodetector 2 has two light receiving regions for the first wavelength and the second wavelength, separated by about 110 μm to 200 μm. Note that the wavelength of light used is appropriately selected depending on the type of the optical disk.

  However, the conventional optical pickup having a two-wavelength one-package laser capable of emitting light of two different wavelengths has the following problems.

  That is, as described above, when the normal two-wavelength one-package laser 1 is used, the second light emitting point is disposed outside the optical axis of the first light emitting point, and thus the light collecting point on the optical disc 3 is collected. The aberration of the light spot increases. Therefore, the information signal received by the photodetector 2 and the servo signal are deteriorated. In particular, when information is recorded on the optical disc 3, the deterioration of the servo signal is an important problem because it leads to a decrease in recording quality and a recording failure.

  Currently, a proximity two-wavelength one-package laser having a light-emitting point interval between two wavelengths of light of 5 μm to 20 μm has been developed. When this laser is used, since the amount of optical axis deviation at the second light emitting point is small, the increase in aberration at the focused spot on the optical disk is small, and a good information signal or servo signal is received by the photodetector. It becomes possible.

However, when the proximity two-wavelength one-package laser is used, the interval between two light spots on the photodetector is about 5 μm to 40 μm. For this reason, the two light condensing spots almost overlap on the photodetector, and there is a problem that servo signal processing such as focus servo cannot be performed with a normal four-divided light receiving element. In this case, if the size of the light receiving spot on the photodetector is reduced, the condensed spot of light of two wavelengths can be separated. However, when the spot size is reduced, the positional accuracy of the photodetector becomes strict, and a fine positional shift causes deterioration of the received light signal. The light receiving spot size in a normal optical pickup is generally about 70 μm to 100 μm, and making it smaller than this is not preferable because it causes deterioration of the light receiving signal.
JP 2002-298425 A JP 2001-297473 A

  Accordingly, an object of the present invention is to provide an optical pickup equipped with a photodetector that enables servo signal processing based on two laser beams emitted from a proximity two-wavelength one-package laser having a distance between two emission points of 5 μm to 20 μm. It is to provide.

In order to solve the above problems, an optical pickup device of the present invention is
A proximity two-wavelength one-package laser that emits two types of laser light having different wavelengths from a first light emitting point and a second light emitting point separated from each other by a distance of 5 μm or more and 20 μm or less;
An emission optical system for condensing the first laser beam emitted from the first emission point and the second laser beam emitted from the second emission point in the proximity two-wavelength one-package laser onto an optical disc;
A photodetector for detecting each of reflected light from the optical disk of the first laser light and the second laser light;
A detection optical system for condensing the reflected light on the photodetector,
The photodetector has a light receiving region divided into six parts by two parallel dividing lines extending in one direction and a dividing line extending in another direction perpendicular to the one direction,
The detection optical system reflects the reflected light of the first laser beam between one of two dividing lines extending in the one direction in the light receiving region and a dividing line extending in the other direction. While condensing on the intersection, the reflected light of the second laser light is the other of the two dividing lines extending in the one direction in the light receiving region and the dividing line extending in the other direction. It is characterized by being focused on the intersection.

  According to the above configuration, the reflected light of the first laser light is generated by either one of the two dividing lines extending in the one direction in the light receiving region and the dividing line extending in the other direction. It is condensed on the intersection. Therefore, the light receiving region divided into six is composed of four partial light receiving regions which are so-called cross-divided by the one dividing line extending in the one direction and the dividing line extending in the other direction. As a result, an output signal is acquired, and focus servo signal processing can be performed based on the acquired four output signals.

  On the other hand, the reflected light of the second laser beam is collected at the intersection of the other of the two dividing lines extending in the one direction and the dividing line extending in the other direction in the light receiving region. Lighted. Therefore, the light receiving region divided into six is composed of four partial light receiving regions which are so-called cross-divided by the other dividing line extending in the one direction and the dividing line extending in the other direction. As a result, an output signal is acquired, and focus servo signal processing can be performed based on the acquired four output signals.

  That is, according to the present invention, it is possible to provide an optical pickup equipped with a photodetector that enables focus servo signal processing based on two laser beams emitted from the proximity two-wavelength one-package laser.

The optical pickup device of the present invention is
A proximity two-wavelength one-package laser that emits two types of laser light having different wavelengths from a first light emitting point and a second light emitting point separated from each other by a distance of 5 μm or more and 20 μm or less;
An emission optical system for condensing the first laser beam emitted from the first emission point and the second laser beam emitted from the second emission point in the proximity two-wavelength one package laser on the optical disc; ,
A photodetector for detecting each of reflected light from the optical disk of the first laser light and the second laser light;
A detection optical system for condensing the reflected light on the photodetector,
The photodetector has a light receiving region divided into four parts, a parting line extending in one direction and a parting line extending in another direction perpendicular to the one direction,
The detection optical system includes a reflected light of the first laser light and a reflected light of the second laser light, a dividing line extending in the one direction and a dividing line extending in the other direction in the light receiving region. It includes an optical axis adjusting optical element for condensing light at an intersection of the two.

  According to the above configuration, the reflected light of the first laser light and the reflected light of the second laser light both extend in the one direction in the light receiving region and in the other direction. It is condensed on the intersection with the dividing line. Therefore, in any case of the first laser light and the second laser light, output signals from four partial light receiving areas obtained by so-called cross-dividing the light receiving area are detected, and the detected four output signals are detected. Focus servo signal processing can be performed based on the above.

  That is, according to the present invention, it is possible to provide an optical pickup equipped with a photodetector that enables focus servo signal processing based on two laser beams emitted from the proximity two-wavelength one-package laser.

The optical pickup device of the present invention is
A proximity two-wavelength one-package laser that emits two types of laser light having different wavelengths from a first light emitting point and a second light emitting point separated from each other by a distance of 5 μm or more and 20 μm or less;
An emission optical system for condensing the first laser beam emitted from the first emission point and the second laser beam emitted from the second emission point in the proximity two-wavelength one package laser on the optical disc; ,
A photodetector for detecting each of reflected light from the optical disk of the first laser light and the second laser light;
A detection optical system for condensing the reflected light on the photodetector,
The photodetector has two sets of light receiving regions divided into four parts by a dividing line extending in one direction and a dividing line extending in another direction perpendicular to the one direction,
The detection optical system collects the reflected light of the first laser beam at an intersection of a dividing line extending in the one direction and a dividing line extending in the other direction in any one of the light receiving regions. For reflecting the reflected light of the second laser light on the intersection of the dividing line extending in the one direction and the dividing line extending in the other direction in the other light receiving region. An optical axis adjusting optical element is included.

  According to the above configuration, the reflected light of the first laser beam is condensed on the intersection of the dividing line extending in the one direction and the dividing line extending in the other direction in the one set of light receiving regions. Is done. Therefore, it is possible to detect output signals from the four partial light receiving areas obtained by so-called cross-dividing the one set of light receiving areas, and perform focus servo signal processing based on the detected four output signals.

  On the other hand, in the case of the reflected light of the second laser beam, the light is collected at the intersection of the dividing line extending in the one direction and the dividing line extending in the other direction in the other light receiving area of the other set. Lighted. Therefore, it is possible to detect output signals from four partial light receiving areas formed by so-called cross-dividing the other light receiving area and perform focus servo signal processing based on the detected four output signals.

  That is, according to the present invention, it is possible to provide an optical pickup equipped with a photodetector that enables focus servo signal processing based on two laser beams emitted from the proximity two-wavelength one-package laser.

In the optical pickup device of one embodiment,
The optical axis adjusting optical element is a diffraction grating.

  According to this embodiment, the reflected light of the first laser light and the reflected light of the second laser light from the optical disc extend in the one direction in the light receiving region by the action of the diffraction grating. The light is condensed on the intersection of the dividing line and the dividing line extending in the other direction. Alternatively, due to the action of the diffraction grating, the reflected light of the first laser light from the optical disk causes a dividing line extending in the one direction and a dividing line extending in the other direction in the one set of light receiving regions. On the other hand, the reflected light of the second laser light from the optical disc extends in the other direction and the dividing line extending in the one direction in the other light receiving region. It is condensed on the intersection with the dividing line.

In the optical pickup device of one embodiment,
The optical axis adjusting optical element is a spectroscopic prism.

  According to this embodiment, the reflected light of the first laser light and the reflected light of the second laser light from the optical disk extend in the one direction in the light receiving region by the action of the spectral prism. The light is condensed on the intersection of the dividing line and the dividing line extending in the other direction. Alternatively, due to the action of the spectroscopic prism, the reflected light of the first laser light from the optical disc has a dividing line extending in the one direction and a dividing line extending in the other direction in the one set of light receiving regions. On the other hand, the reflected light of the second laser light from the optical disc extends in the other direction and the dividing line extending in the one direction in the other light receiving region. It is condensed on the intersection with the dividing line.

In the optical pickup device of one embodiment,
The optical axis adjusting optical element is a direct-view spectroscopic prism.

  According to this embodiment, the reflected light of the first laser light and the reflected light of the second laser light from the optical disk extend in the one direction in the light receiving region by the action of the direct-view spectral prism. The light is condensed on the intersection of the dividing line that extends and the dividing line extending in the other direction. Alternatively, due to the action of the direct-view spectroscopic prism, the reflected light of the first laser light from the optical disk is divided in the one set of light receiving regions in the one direction and in the other direction. The reflected light of the second laser light from the optical disc is focused on the intersection with the line, and the dividing line extending in the one direction and the other direction in the light receiving area of the other set It is condensed on the intersection with the dividing line.

In the optical pickup device of one embodiment,
The optical axis adjusting optical element is a lotion prism.

  According to this embodiment, the reflected light of the first laser light and the reflected light of the second laser light from the optical disk extend in the one direction in the light receiving region by the action of the lotion prism. The light is condensed on the intersection of the dividing line and the dividing line extending in the other direction.

In the optical pickup device of one embodiment,
The optical axis adjusting optical element is a Wollaston prism.

  According to this embodiment, due to the action of the Wollaston prism, the reflected light of the first laser light from the optical disc is separated from the dividing line extending in the one direction in the one light receiving area and the other. It is condensed on the intersection with the dividing line extending in the direction. On the other hand, the reflected light of the second laser light from the optical disc is condensed on the intersection of the dividing line extending in the one direction and the dividing line extending in the other direction in the other pair of light receiving regions. Is done.

In the optical pickup device of one embodiment,
The optical axis adjusting optical element is a wedge half mirror that reflects the laser light from the proximity two-wavelength one-package laser toward the optical disc, and transmits the reflected light from the optical disc toward the photodetector. .

  According to this embodiment, the reflected light of the first laser light and the reflected light of the second laser light from the optical disk extend in the one direction in the light receiving region by the action of the wedge half mirror. The light is condensed on the intersection of the dividing line that extends and the dividing line extending in the other direction. Alternatively, due to the action of the wedge half mirror, the reflected light of the first laser light from the optical disc is divided in the one set of light receiving regions in the one direction and in the other direction. The reflected light of the second laser light from the optical disc is focused on the intersection with the line, and the dividing line extending in the one direction and the other direction in the light receiving area of the other set It is condensed on the intersection with the dividing line.

  As is clear from the above, the optical pickup device of the present invention is a light receiving device divided into six by two parallel dividing lines extending in one direction and a dividing line extending in the other direction perpendicular to the one direction. A photodetector having a region, and a detection optical system for condensing the reflected light from the optical disk of the first and second laser beams of two kinds of wavelengths emitted from the proximity two-wavelength one-package laser on the photodetector The detecting optical system reflects the reflected light of the first laser beam with any one of two dividing lines extending in the one direction in the light receiving region and a dividing line extending in the other direction. So that the light receiving region divided into six is divided into four so-called cross-divided portions by the one dividing line extending in the one direction and the dividing line extending in the other direction. The output signal is taken as if it is composed of partial light receiving areas. Thus, focus servo signal processing can be performed based on the obtained four output signals.

  Further, the detection optical system may reflect the reflected light of the second laser light between the other of the two dividing lines extending in the one direction in the light receiving region and the dividing line extending in the other direction. Since the light is condensed on the intersection, the six divided light receiving regions are so-called cross-divided four partial light receiving portions by the other dividing line extending in the one direction and the dividing line extending in the other direction. An output signal can be acquired by assuming that the area is configured, and focus servo signal processing can be performed based on the acquired four output signals.

  That is, according to the present invention, it is possible to provide an optical pickup equipped with a photodetector that enables focus servo signal processing based on two laser beams emitted from the proximity two-wavelength one-package laser. Therefore, the quality of the focused spot on the optical disk when using the proximity two-wavelength one-package laser can be increased, and the manufacturing yield and reliability can be improved.

  An optical pickup device according to the present invention includes a photodetector having a light receiving region divided into four parts by a dividing line extending in one direction and a dividing line extending in another direction perpendicular to the one direction, and a proximity 2 And a detection optical system for condensing the reflected light from the optical disk of the first and second laser beams of two types of wavelengths emitted from the wavelength 1 package laser, on the photodetector. An optical axis adjusting optical element for condensing the reflected light of the first and second laser beams on the intersection of the dividing line extending in the one direction and the dividing line extending in the other direction in the light receiving region; Therefore, in both cases of the first laser light and the second laser light, output signals from four partial light receiving areas formed by so-called cross-dividing the light receiving area are detected, and the detected 4 Focus servo signal processing based on one output signal It can be carried out.

  That is, according to the present invention, it is possible to provide an optical pickup equipped with a photodetector that enables focus servo signal processing based on two laser beams emitted from the proximity two-wavelength one-package laser. Therefore, the quality of the focused spot on the optical disk when using the proximity two-wavelength one-package laser can be increased, and the manufacturing yield and reliability can be improved.

  Further, an optical pickup device of the present invention includes a photodetector having two sets of light receiving regions divided into four by a dividing line extending in one direction and a dividing line extending in the other direction perpendicular to the one direction, A detection optical system that condenses the reflected light from the optical disk of the first and second laser beams of two kinds of wavelengths emitted from a proximity two-wavelength one-package laser on a photodetector, An optical axis for condensing the reflected light of the first laser light on the intersection of the dividing line extending in the one direction and the dividing line extending in the other direction in any one of the light receiving regions. Since the adjusting optical element is included, output signals from four partial light receiving areas formed by so-called cross-dividing the one set of light receiving areas are detected, and focus servo signals are detected based on the detected four output signals. Processing can be performed.

  Further, the optical axis adjusting optical element causes the reflected light of the second laser beam to be reflected on the intersection of the dividing line extending in the one direction and the dividing line extending in the other direction in the other light receiving region. Therefore, the output signals from the four partial light receiving areas formed by dividing the other light receiving area into the so-called cross are detected, and focus servo signal processing is performed based on the detected four output signals. be able to.

  That is, according to the present invention, it is possible to provide an optical pickup equipped with a photodetector that enables focus servo signal processing based on two laser beams emitted from the proximity two-wavelength one-package laser. Therefore, the quality of the focused spot on the optical disk when using the proximity two-wavelength one-package laser can be increased, and the manufacturing yield and reliability can be improved.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

First Embodiment FIG. 1 is a schematic diagram showing an optical configuration of an optical pickup device according to the present embodiment. This optical pickup device has a proximity two-wavelength one-package laser 11 that emits two types of light having different wavelengths so that the optical pickup device can be applied to any of two types of optical disks 3 corresponding to light of two wavelengths. .

  As for the light of two types of wavelengths emitted from the proximity two-wavelength one-package laser 11, for example, the first light is light having a wavelength (first wavelength) of 780 nm, and the second light is wavelength (second wavelength). It is 650 nm light. Then, the light emitted from the proximity two-wavelength one-package laser 11 passes through the diffraction grating 19 and is circularly polarized by the quarter-wave plate 18. Thereafter, the light is reflected by the beam splitter 17 and is made substantially parallel light by the collimating lens 15. Then, the light is condensed on the optical disk 13 by the objective lens 14. Information is reproduced from and recorded on the optical disc 13 by the focused light spot. The wavelength of light used is appropriately selected depending on the type of the optical disc 13.

  On the other hand, the light reflected by the optical disc 13 is converted into substantially parallel light again by the objective lens 14, and again converged by the collimating lens 15, then transmitted through the beam splitter 17 and transmitted through the spot lens 16. The light is collected on the detector 12. Then, the signal is detected by the photodetector 12.

  FIG. 2 shows a split state and a focused spot state of the light receiving element 20 for focus servo in the photodetector 12. FIG. 2A shows the detection state of each partial light receiving element for the first light. FIG. 2B shows a detection state of each partial light receiving element for the second light. The light receiving element 20 is divided into three in the horizontal direction by two parallel dividing lines a and a ′ extending in the vertical direction in the drawing, and is divided in two in the vertical direction by a dividing line b extending in the horizontal direction. The total is divided into six. Since the proximity two-wavelength one-package laser 11 is used, the first light and the second light are collected at overlapping positions on the photodetector 12. In that case, the first light is on the intersection of the dividing line a extending in the vertical direction and the dividing line b extending in the horizontal direction in the light receiving element 20 divided into six parts of the photodetector 12. On the other hand, the second light is condensed on the intersection of the dividing line a ′ and the dividing line b in the six-divided light receiving element 20 of the photodetector 12.

  Accordingly, the calculation formula of the focus servo at that time is such that the output of the partial light receiving element 21 formed by dividing the light receiving element 20 into A, the output of the partial light receiving element 22 as B, the output of the partial light receiving element 23 as C, and the partial light reception. When the output of the element 24 is D, the output of the partial light receiving element 25 is E, and the output of the partial light receiving element 26 is F, (A + D + F) − (B + C + E) for the first light, and the second For light, (A + D + E)-(B + C + F), and focus servo is possible.

  As described above, in the present embodiment, the light receiving element 20 of the photodetector 12 is divided into three parts in the horizontal direction and two parts in the vertical direction, for a total of six parts. Then, the first light emitted from the proximity two-wavelength one-package laser 11 and reflected by the optical disk 13 is condensed in the middle of one cross division in the six-divided light receiving element 20 in the photodetector 12. On the other hand, the second light is condensed in the middle of the other cross division in the light receiving element 20 divided into six in the photodetector 12. Therefore, the focus servo can be performed by the above-described formula for focus servo.

  That is, according to this embodiment, two laser beams emitted from the proximity two-wavelength one-package laser 11 having a light emitting point interval of 5 μm to 20 μm are detected by one light receiving element 20 and servo signal processing is performed. It can be done.

Second Embodiment FIG. 3 is a schematic diagram showing an optical configuration in the optical pickup device of the present embodiment. The same members as those in the optical pickup device of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the optical pickup device in the present embodiment, a diffraction grating 32 as the optical axis adjusting optical element is disposed between a spot lens 16 and a photodetector 31. Then, the diffraction grating 32 bends the optical path of only the second wavelength (650 nm) light away from the optical path of the first wavelength (780 nm) light.

  FIG. 4 shows a split state and a focused spot state of the light receiving element 33 for focus servo in the photodetector 31 in the present embodiment. The photodetector 31 has a first light receiving element 33a for the first light disposed at a position where the first light is incident, and the second light at a position away from the first light receiving element 33a. The second light receiving element 33b for the second light disposed at the incident position. The first and second light receiving elements 33a and 33b are divided into two in the horizontal direction by dividing lines c and e extending in the vertical direction in the drawing, and by dividing lines d and f extending in the horizontal direction. It is divided into two in the vertical direction, for a total of four.

  The first light is condensed on the intersection of the dividing line c extending in the vertical direction and the dividing line d extending in the horizontal direction in the first light receiving element 33a, while the second light is collected. Is condensed on the intersection of the dividing line e and the dividing line f in the second light receiving element 33b. In this case, the focus servo calculation formula is such that the output of the partial light receiving element 34 formed by dividing the light receiving element 33a into four is A, the output of the partial light receiving element 35 is B, the output of the partial light receiving element 36 is C, and the partial light receiving element 37 While the output is D, the output of the partial light receiving element 38 formed by dividing the light receiving element 33b into four is E, the output of the partial light receiving element 39 is F, the output of the partial light receiving element 40 is G, and the output of the partial light receiving element 41 is In the case of H, (A + D) − (B + C) for the first light and (E + H) − (G + F) for the second light.

  As described above, in the present embodiment, the photodetector 31 is disposed at the first light receiving element 33a disposed at the position where the first light is incident and the incident position of the second light. The light receiving elements 33a and 33b are divided into two parts in the horizontal direction and two parts in the vertical direction, for a total of four parts. The first light emitted from the proximity two-wavelength one-package laser 11 and reflected by the optical disk 13 is collected in the middle of the first light receiving element 33a in the photodetector 31. On the other hand, the optical path of the second light is bent by the diffraction grating 32 in a direction away from the optical path of the first light, and is condensed in the middle of the second light receiving element 33 b in the photodetector 31. Therefore, the focus servo can be performed by the above-described formula for focus servo.

  That is, according to this embodiment, the optical axis shift of the two laser beams emitted from the proximity two-wavelength one-package laser 11 having a light emitting point interval of 5 μm to 20 μm is corrected by a simple optical axis adjusting optical element. In addition, servo signal processing can be performed by detection by the two light receiving elements 33a and 33b in one photodetector 31.

Third Embodiment FIG. 5 is a schematic diagram showing an optical configuration in the optical pickup device of the present embodiment. The same members as those in the optical pickup device of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the optical pickup device in the present embodiment, a diffraction grating 52 as the optical axis adjusting optical element is disposed between a spot lens 16 and a photodetector 51. The diffraction grating 52 bends the optical path of only the light of the second wavelength (650 nm) in a direction approaching the optical path of the light of the first wavelength (780 nm).

  FIG. 6 shows a split state and a focused spot state of the light receiving element 53 for focus servo in the photodetector 51 of the present embodiment. The light receiving element 53 in the photodetector 51 is divided into two in the horizontal direction by a dividing line g extending in the vertical direction in the drawing, and divided in two in the vertical direction by a dividing line h extending in the horizontal direction, for a total of 4 It is divided. Both the first light and the second light are collected on the intersection of the dividing line g extending in the vertical direction and the dividing line h extending in the horizontal direction in the light receiving element 53. In this case, the focus servo calculation formula is such that the output of the partial light receiving element 54 formed by dividing the light receiving element 53 into four is A, the output of the partial light receiving element 55 is B, the output of the partial light receiving element 56 is C, and the partial light receiving element 57 When the output is D, (A + D) − (B + C) is obtained for the first light and the second light.

  As described above, in the present embodiment, the light receiving element 53 of the photodetector 51 is divided into two parts in the horizontal direction and two parts in the vertical direction, for a total of four parts. Then, the first light emitted from the proximity two-wavelength one-package laser 11 and reflected by the optical disc 13 is collected in the middle of the cross division in the light receiving element 53 of the photodetector 51. On the other hand, the optical path of the second light is bent by the diffraction grating 52 in a direction approaching the optical path of the first light, and is condensed in the middle of the cross division in the light receiving element 53 of the photodetector 51. Therefore, the focus servo can be performed by the above-described formula for focus servo.

  That is, according to this embodiment, the optical axis shift of the two laser beams emitted from the proximity two-wavelength one-package laser 11 having a light emitting point interval of 5 μm to 20 μm is corrected by a simple optical axis adjusting optical element. In addition, servo signal processing can be performed by detecting by one light receiving element 53 in one light detector 31.

Fourth Embodiment FIG. 7 is a schematic diagram showing an optical configuration in the optical pickup device of the present embodiment. The same members as those in the optical pickup devices of the first embodiment and the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the optical pickup device in the present embodiment, a spectral prism 61 as the optical axis adjusting optical element is disposed between a spot lens 16 and a photodetector 31. The spectral prism 61 bends the optical path of only the second wavelength (650 nm) light away from the optical path of the first wavelength (780 nm) light.

  The division state of the light receiving element for focus servo and the state of the focused spot in the photodetector 31 of the present embodiment are the same as those in FIG. 4 in the second embodiment. That is, as shown in FIG. 4, the photodetector 31 includes a first light receiving element 33a for the first light and a second light receiving element 33b for the second light. The two light receiving elements 33a and 33b are divided into two parts in the horizontal direction and two parts in the vertical direction, for a total of four parts.

  The first light is collected in the middle of the cross division in the first light receiving element 33a. On the other hand, the second light is collected in the middle of the cross division in the second light receiving element 33b. The focus servo calculation formula in this case is (A + D) − (B + C) for the first light, with the outputs of the partial light receiving elements 34 to 41 being A to H, and for the second light. Becomes (E + H)-(G + F).

Fifth Embodiment FIG. 8 is a schematic diagram showing an optical configuration in the optical pickup device of the present embodiment. The same members as those in the optical pickup devices of the first embodiment and the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the optical pickup device in the present embodiment, a spectral prism 62 as the optical axis adjusting optical element is disposed between a spot lens 16 and a photodetector 51. The spectral prism 62 bends the optical path of only the light having the second wavelength (650 nm) in a direction approaching the optical path of the light having the first wavelength (780 nm).

  The division state of the light receiving element for focus servo and the state of the focused spot in the photodetector 51 of the present embodiment are the same as those in FIG. 6 in the third embodiment. That is, as shown in FIG. 6, the light receiving element 53 in the photodetector 51 is divided into two in the horizontal direction and two in the vertical direction, for a total of four. Both the first light and the second light are collected in the middle of the cross division in the light receiving element 53. The focus servo calculation formula in this case is (A + D) − (B + C) with respect to the first light and the second light, where the outputs of the partial light receiving elements 54 to 57 are A to D.

Sixth Embodiment FIG. 9 is a schematic diagram showing an optical configuration in the optical pickup device of the present embodiment. The same members as those in the optical pickup devices of the first embodiment and the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the optical pickup device according to the present embodiment, a direct-viewing spectroscopic prism 63 serving as the optical axis adjusting optical element is disposed between a spot lens 16 and a photodetector 31. The direct-view spectroscopic prism 63 bends the optical path of only the second wavelength (650 nm) light away from the optical path of the first wavelength (780 nm) light.

  The division state of the light receiving element for focus servo and the state of the focused spot in the photodetector 31 of the present embodiment are the same as those in FIG. 4 in the second embodiment. That is, as shown in FIG. 4, the photodetector 31 includes a first light receiving element 33a for the first light and a second light receiving element 33b for the second light. The two light receiving elements 33a and 33b are divided into two parts in the horizontal direction and two parts in the vertical direction, for a total of four parts.

  The first light is collected in the middle of the cross division in the first light receiving element 33a. On the other hand, the second light is condensed in the middle of the cross division in the second light receiving element 33b. The focus servo calculation formula in this case is (A + D) − (B + C) for the first light, with the outputs of the partial light receiving elements 34 to 41 being A to H, and for the second light. Becomes (E + H)-(G + F).

Seventh Embodiment FIG. 10 shows an optical configuration in the optical pickup device of the present embodiment. The same members as those in the optical pickup devices of the first embodiment and the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the optical pickup device in the present embodiment, a direct-view spectral prism 64 as the optical axis adjusting optical element is disposed between a spot lens 16 and a photodetector 51. The direct-view spectroscopic prism 64 bends the optical path of only the light having the second wavelength (650 nm) in a direction approaching the optical path of the light having the first wavelength (780 nm).

  The division state of the light receiving element for focus servo and the state of the focused spot in the photodetector 51 of the present embodiment are the same as those in FIG. 6 in the third embodiment. That is, as shown in FIG. 6, the light receiving element 53 in the photodetector 51 is divided into two in the horizontal direction and two in the vertical direction, for a total of four. Both the first light and the second light are collected in the middle of the cross division in the light receiving element 53. The focus servo calculation formula in this case is (A + D) − (B + C) with respect to the first light and the second light, where the outputs of the partial light receiving elements 54 to 57 are A to D.

Eighth Embodiment FIG. 11 shows an optical configuration in the optical pickup device of the present embodiment. The same members as those in the optical pickup devices of the first embodiment and the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the optical pickup device according to the present embodiment, a Wollaston prism 65 as the optical axis adjusting optical element is disposed between the spot lens 16 and the photodetector 31, and the diffraction grating 19 and the beam splitter 17 are disposed. A wavelength-selective half-wave plate 66 is disposed in place of the quarter-wave plate 18 and a quarter-wave plate 67 is disposed between the collimating lens 15 and the objective lens 14.

  Then, the light emitted from the proximity two-wavelength one-package laser 11 passes through the diffraction grating 19, and then functions as a half-wave plate only for the second wavelength (650 nm). The polarization direction is changed by 90 degrees only in the case of light having the first wavelength (780 nm) by the two-wave plate 66. Thereafter, after the optical path is bent by the beam splitter 17, it is collimated by the collimator lens 15, is circularly polarized by the quarter wavelength plate 67, and is then condensed on the optical disk 13 by the objective lens 14. On the other hand, the light reflected by the optical disk 13 is converted back to parallel light by the objective lens 14 and then converted into linearly polarized light by the quarter wavelength plate 67 again. At that time, the polarization directions of the first wavelength light and the second wavelength light are different from each other by 90 degrees. After that, the light is focused by the collimator lens 15, passes through the beam splitter 17, and then converged toward the photodetector 31 by the spot lens 16. At this time, the light of the first wavelength travels straight through the Wollaston prism 65, but only the light of the second wavelength is bent, and the light of the first wavelength and the light of the second wavelength are mutually connected. The light is condensed on the first light receiving element 33a for the first light (see FIG. 4) and the second light receiving element 33b for the second light (see FIG. 4) separated by a predetermined distance. .

  The division state of the light receiving element for focus servo and the state of the focused spot in the photodetector 31 of the present embodiment are the same as those in FIG. 4 in the second embodiment. That is, as shown in FIG. 4, the photodetector 31 includes a first light receiving element 33a for the first light and a second light receiving element 33b for the second light. The two light receiving elements 33a and 33b are divided into two parts in the horizontal direction and two parts in the vertical direction, for a total of four parts.

  The first light is collected in the middle of the cross division in the first light receiving element 33a. On the other hand, the second light is condensed in the middle of the cross division in the second light receiving element 33b. The focus servo calculation formula in this case is (A + D) − (B + C) for the first light, and (A + D) − (B + C) for the first light, and (A + D) for the first light. E + H)-(G + F).

Ninth Embodiment FIG. 12 shows an optical configuration in the optical pickup device of the present embodiment. In addition, the same number is attached | subjected to the same member as the optical pick-up apparatus of the said 1st Embodiment, 3rd Embodiment, and the said 8th Embodiment, and detailed description is abbreviate | omitted.

  In the optical pickup device according to the present embodiment, a lotion prism 68 as the optical axis adjusting optical element is disposed between the spot lens 16 and the photodetector 51, and 1 between the diffraction grating 19 and the beam splitter 17. A wavelength selective half-wave plate 66 is disposed in place of the quarter-wave plate 18, and a quarter-wave plate 67 is disposed between the collimating lens 15 and the objective lens 14. Here, the behavior of the light emitted from the proximity two-wavelength one-package laser 11 is substantially the same as in the eighth embodiment, but the lotion prism 68 causes the first wavelength (780 nm) to be The difference is that light of two wavelengths (650 nm) is arranged so as to be condensed at substantially the same place on the light receiving element 53 (see FIG. 6) in the photodetector 51.

  The division state of the light receiving element for focus servo and the state of the focused spot in the photodetector 51 of the present embodiment are the same as those in FIG. 6 in the third embodiment. That is, as shown in FIG. 6, the light receiving element 53 in the photodetector 51 is divided into two in the horizontal direction and two in the vertical direction, for a total of four. Both the first light and the second light are collected in the middle of the cross division in the light receiving element 53. The focus servo calculation formula in this case is (A + D) − (B + C) with respect to the first light and the second light, where the outputs of the partial light receiving elements 54 to 57 are A to D.

Tenth Embodiment FIG. 13 shows an optical configuration of the optical pickup device according to the present embodiment. In addition, the same number is attached | subjected to the same member as the optical pick-up apparatus of the said 1st Embodiment and 3rd Embodiment, and detailed description is abbreviate | omitted.

  In the optical pickup device according to the present embodiment, a wedge beam splitter 69 serving as the optical axis adjusting optical element is disposed between the spot lens 16 and the collimator lens 15 instead of the beam splitter 17. Then, the light emitted from the proximity two-wavelength one-package laser 11 is transmitted through the diffraction grating 19 and the quarter-wave plate 18, reflected by the wedge beam splitter 69, then collimated by the collimator lens 15, The light is condensed on the optical disk 13 by the lens 14. On the other hand, the light reflected by the optical disk 13 is converted into parallel light by the objective lens 14 and then converted into focused light by the collimating lens 15. Thereafter, when the light passes through the wedge beam splitter 69, the light having the first wavelength (780 nm) and the light having the second wavelength (650 nm) are different from each other in the light receiving element 53 (see FIG. 6)).

  The division state of the light receiving element for focus servo and the state of the focused spot in the photodetector 51 of the present embodiment are the same as those in FIG. 6 in the third embodiment. That is, the light receiving element 53 in the photodetector 51 is divided into two in the horizontal direction and two in the vertical direction, for a total of four. Both the first light and the second light are collected in the middle of the cross division in the light receiving element 53. The focus servo calculation formula in this case is (A + D) − (B + C) with respect to the first light and the second light, where the outputs of the partial light receiving elements 54 to 57 are A to D.

  In the present embodiment, the wedge beam splitter 69 is used for condensing light at the same place on the photodetector 51 by the difference in refraction angle. However, the light detection as shown in FIG. It can also be used for condensing the first light receiving element for the first light and the second light receiving element for the second light.

  As described above, according to each of the above embodiments, an optical pickup equipped with a photodetector capable of receiving two laser beams emitted from a proximity two-wavelength one-package laser having an emission point interval of 5 μm to 20 μm. Servo signal processing such as focus servo in the case of using the two laser beams can be performed.

It is a figure which shows the optical structure in the optical pick-up apparatus of this invention. It is a figure which shows the division | segmentation state of the light receiving element in the photodetector in FIG. 1, and the condensing state of a condensing spot. It is a figure which shows the optical structure in the optical pick-up apparatus different from FIG. It is a figure which shows the division | segmentation state of the light receiving element in the photodetector in FIG. 3, and the condensing state of a condensing spot. It is a figure which shows the optical structure in the optical pick-up apparatus different from FIG. 1 and FIG. It is a figure which shows the division | segmentation state of the light receiving element in the photodetector in FIG. 5, and the condensing state of a condensing spot. It is a figure which shows the optical structure in the optical pick-up apparatus different from FIG.1, FIG3 and FIG.5. It is a figure which shows the optical structure in the optical pick-up apparatus different from FIG.1, FIG.3, FIG.5 and FIG. It is a figure which shows the optical structure in the optical pick-up apparatus different from FIG.1, FIG.3, FIG.5, FIG.7 and FIG. It is a figure which shows the optical structure in the optical pick-up apparatus different from FIG.1, FIG.3, FIG.5 and FIGS. 7-9. It is a figure which shows the optical structure in the optical pick-up apparatus different from FIG.1, FIG.3, FIG.5 and FIG. It is a figure which shows the optical structure in the optical pick-up apparatus different from FIG.1, FIG.3, FIG.5 and FIGS. It is a figure which shows the optical structure in the optical pick-up apparatus different from FIG.1, FIG.3, FIG.5 and FIG. It is a figure which shows the optical structure of the conventional optical pick-up apparatus which has 2 wavelength 1 package laser.

Explanation of symbols

11: Proximity 2 wavelength 1 package laser,
12, 31, 51 ... photodetector,
13 ... Optical disc,
14 ... Objective lens,
15 ... Collimating lens,
16 ... Spot lens,
17 ... Beam splitter,
18, 67 ... 1/4 wavelength plate,
19, 32, 52 ... diffraction grating,
20, 33, 53 ... light receiving element,
61,62 ... spectral prism,
63, 64 ... Direct-viewing spectroscopic prism,
65 ... Wollaston prism,
66 ... wavelength selective half-wave plate,
68 ... Lotion prism,
69 ... Wedge beam splitter.

Claims (9)

A proximity two-wavelength one-package laser that emits two types of laser light having different wavelengths from a first light emitting point and a second light emitting point separated from each other by a distance of 5 μm or more and 20 μm or less;
An emission optical system for condensing the first laser beam emitted from the first emission point and the second laser beam emitted from the second emission point in the proximity two-wavelength one-package laser onto an optical disc;
A photodetector for detecting each of reflected light from the optical disk of the first laser light and the second laser light;
A detection optical system for condensing the reflected light on the photodetector,
The photodetector has a light receiving region divided into six parts by two parallel dividing lines extending in one direction and a dividing line extending in another direction perpendicular to the one direction,
The detection optical system reflects the reflected light of the first laser beam between one of two dividing lines extending in the one direction in the light receiving region and a dividing line extending in the other direction. While condensing on the intersection, the reflected light of the second laser light is the other of the two dividing lines extending in the one direction in the light receiving region and the dividing line extending in the other direction. An optical pickup device characterized in that light is condensed on an intersection. A proximity two-wavelength one-package laser that emits two types of laser light having different wavelengths from a first light emitting point and a second light emitting point separated from each other by a distance of 5 μm or more and 20 μm or less;
An emission optical system for condensing the first laser beam emitted from the first emission point and the second laser beam emitted from the second emission point in the proximity two-wavelength one package laser on the optical disc; ,
A photodetector for detecting each of reflected light from the optical disk of the first laser light and the second laser light;
A detection optical system for condensing the reflected light on the photodetector,
The photodetector has a light receiving region divided into four parts, a parting line extending in one direction and a parting line extending in another direction perpendicular to the one direction,
The detection optical system includes a reflected light of the first laser light and a reflected light of the second laser light, a dividing line extending in the one direction and a dividing line extending in the other direction in the light receiving region. An optical pickup device comprising an optical axis adjusting optical element for condensing light on an intersection of the two. A proximity two-wavelength one-package laser that emits two types of laser light having different wavelengths from a first light emitting point and a second light emitting point separated from each other by a distance of 5 μm or more and 20 μm or less;
An emission optical system for condensing the first laser beam emitted from the first emission point and the second laser beam emitted from the second emission point in the proximity two-wavelength one package laser on the optical disc; ,
A photodetector for detecting each of reflected light from the optical disk of the first laser light and the second laser light;
A detection optical system for condensing the reflected light on the photodetector,
The photodetector has two sets of light receiving regions divided into four parts by a dividing line extending in one direction and a dividing line extending in another direction perpendicular to the one direction,
The detection optical system collects the reflected light of the first laser beam at an intersection of a dividing line extending in the one direction and a dividing line extending in the other direction in any one of the light receiving regions. For reflecting the reflected light of the second laser light on the intersection of the dividing line extending in the one direction and the dividing line extending in the other direction in the other light receiving region. An optical pickup device comprising an optical axis adjusting optical element. In the optical pickup device according to claim 2 or 3,
The optical pickup device, wherein the optical axis adjusting optical element is a diffraction grating. In the optical pickup device according to claim 2 or 3,
The optical pickup device, wherein the optical axis adjusting optical element is a spectral prism. In the optical pickup device according to claim 2 or 3,
The optical pickup device is characterized in that the optical axis adjusting optical element is a direct-view spectroscopic prism. The optical pickup device according to claim 2,
The optical pickup device, wherein the optical axis adjusting optical element is a lotion prism. The optical pickup device according to claim 3,
The optical pickup device, wherein the optical axis adjusting optical element is a Wollaston prism. In the optical pickup device according to claim 2 or 3,
The optical axis adjusting optical element is a wedge half mirror that reflects the laser light from the proximity two-wavelength one-package laser toward the optical disc, and transmits the reflected light from the optical disc toward the photodetector. An optical pickup device characterized by that.

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