JP5954060B2 - Optical pickup - Google Patents

Description

  The present invention relates to an optical pickup.

  Conventionally, an optical recording medium is irradiated with light and reflected light (returned light) reflected by the optical recording medium is received to read information recorded on the optical recording medium or write information on the optical recording medium. Optical pickups are known. A typical example of the optical recording medium is an optical disc such as a BD (Blu-ray Disc; registered trademark), a DVD (Digital Versatile Disc), or a CD (Compact Disc).

  Some conventional optical pickups include, for example, a plurality of light sources that emit light having different wavelengths in order to support a plurality of types of optical disks. In such an optical pickup, for example, with the aim of reducing the number of optical components, the optical axes of light emitted from a plurality of light sources coincide with each other until the light emitted from each light source reaches the optical disk. It is often configured to.

  Patent Document 1 discloses an optical pickup in which a laser beam from two laser light sources is irradiated onto a disk-shaped recording medium (optical disk) by matching the optical axes by optical axis matching means. The optical axis matching means includes a first flat plate optical element and a second flat plate optical element having the same plate thickness. A laser beam emitted from one of the two laser light sources sequentially refracts and transmits the first flat plate optical element and the second flat plate optical element. The laser beam emitted from the other light source is reflected by the second flat plate optical element. The optical axes of the laser beams emitted from the two laser light sources coincide with each other from the second flat plate optical element to the optical disk. According to the configuration of Patent Document 1, there are advantages that the number of components constituting the optical pickup can be reduced and expensive optical components can be omitted.

Japanese Patent Laid-Open No. 2001-6205

  However, in the case of the configuration of Patent Document 1, since the first flat plate optical element and the second flat plate optical element are arranged at different angles around different axes, the light condensed on the optical disc There is a concern that large coma will occur. In order to cancel the coma aberration, for example, it is conceivable to use a tilt angle correction unit that adjusts the tilt angle of the objective lens. However, there are concerns that the cost may increase and the coma aberration may not be corrected reliably. The aforementioned objective lens is a condensing lens that condenses the light from the light source on the recording surface of the optical disc.

  In view of the above points, an object of the present invention is to provide an optical pickup capable of reducing component cost and suppressing deterioration in performance.

  In order to achieve the above object, an optical pickup according to the present invention includes a light path including a forward path that guides light from a light source to an optical recording medium, and a return path that guides reflected light reflected by the optical recording medium to a light receiving element. In the pickup, the light source includes a first light source and a second light source that emit light having different wavelengths, and the first wavelength light emitted from the first light source is included in the forward path. And optical axis matching means for matching the optical axes of the second wavelength light emitted from the second light source, and the optical axis matching means includes a first optical element and a second optical element. The first optical element includes a first reflecting surface that reflects a part of the first wavelength light and reflects at least a part of the second wavelength light. The second optical element has a second reflecting at least part of the first wavelength light. An optical axis of the first wavelength light reflected in the order of the second reflecting surface and the first reflecting surface after passing through the first reflecting surface, and the second reflecting surface. After passing through the reflecting surface, the optical axis of the second wavelength light reflected by the first reflecting surface is the same (first configuration). The forward path and the return path are words that specify the type of the optical path.

  According to this configuration, the optical axis of the light emitted from the first light source and the light emitted from the second light source using the two optical elements that can be manufactured at low cost are matched in the forward path It has become. For this reason, it is possible to avoid using expensive parts such as a dichroic prism. That is, according to this configuration, it is possible to reduce the cost of the optical pickup. Further, in this configuration, the amount of astigmatism and coma aberration can be suppressed by devising the configuration and arrangement of the first optical element and the second optical element used as the optical axis matching means. is there. That is, according to this configuration, it is possible to improve the performance of reproduction and the like for a plurality of types of optical recording media (for example, BD, DVD, CD, etc.) and to improve the ability to cope with poor quality optical recording media. Is possible.

  In the optical pickup having the first configuration, the first optical element and the second optical element have an angle formed by the first reflecting surface and the second reflecting surface arranged to face each other. The first light source is incident on the first reflection surface at an incident angle of 0 ° when the first wavelength light is transmitted through the first reflection surface. The second light source is arranged such that an incident angle of the second wavelength light to the first reflecting surface is a second angle, and the first angle is It is preferable that the configuration is a half value of the angle of 2 (second configuration). According to this configuration, it is easy to suppress the amount of astigmatism and coma generated while reducing the cost required for the optical axis matching means.

  In the optical pickup having the first or second configuration, the first optical element and the second optical element are provided in a parallel plate shape, and the second optical element is incident on the second wavelength light. A configuration in which the angle is inclined so as to be a predetermined angle larger than 0 ° (third configuration) is preferable. Here, the predetermined angle is preferably an angle that can cancel or reduce the astigmatism of the second light source. According to this configuration, it is easy to provide an optical pickup having good performance at low cost.

  In the optical pickup having any one of the first to third configurations, the first reflected light that is emitted from the first light source and reflected by the optical recording medium, and the second reflected light source that is emitted from the second light source. It is preferable that the second reflected light reflected by the optical recording medium has a configuration (fourth configuration) that passes through the first optical element and reaches the light receiving element. According to this configuration, the first optical element used as a part of the optical axis matching means in the forward path can be effectively used in the return path. For example, the first optical element can be used as astigmatism applying means that enables generation of a focus error signal by the astigmatism method in the return path.

  The optical pickup having any one of the first to fourth configurations includes an objective lens that condenses light from the light source on the optical recording medium, and an optical path between the optical axis matching means and the objective lens. And a collimating lens that is movable in the optical axis direction (fifth configuration). This configuration is suitable for an optical pickup that requires correction of spherical aberration (for example, an optical pickup that can handle BD).

  ADVANTAGE OF THE INVENTION According to this invention, while being able to reduce component cost, the optical pick-up which can suppress a performance fall can be provided.

1 is a schematic perspective view showing an external configuration of an optical pickup according to an embodiment of the present invention. 1 is a schematic plan view showing an optical configuration of an optical pickup according to an embodiment of the present invention. 1 is a schematic plan view showing a configuration of an outward path of an optical pickup according to an embodiment of the present invention. 1 is a schematic plan view showing a configuration of a return path of an optical pickup according to an embodiment of the present invention. Schematic plan view showing a first modification of the optical pickup according to the embodiment of the present invention Schematic plan view showing a second modification of the optical pickup according to the embodiment of the present invention.

  Hereinafter, embodiments of an optical pickup according to the present invention will be described in detail with reference to the drawings. The optical pickup according to the embodiment will be described by taking an optical pickup capable of reading and / or writing information on two types of optical discs such as BD and DVD as an example. It is not intended to limit the scope of the invention.

  FIG. 1 is a schematic perspective view showing an external configuration of an optical pickup 1 according to an embodiment of the present invention. As shown in FIG. 1, the optical pickup 1 includes a pickup base 10. Various members constituting the optical pickup 1 are mounted on the pickup base 10. Bearing portions 10 a and 10 b are provided at the left and right ends of the pickup base 10. The pickup base 10 is slidably supported on a guide shaft (not shown) using the bearing portions 10a and 10b.

  The guide shaft here is provided in an optical disc device (a device capable of reproducing and / or recording an optical disc). The optical pickup 1 mounted on the optical disc apparatus accesses a desired address of the rotating optical disc while moving along the guide shaft. The optical pickup 1 that has accessed a desired address irradiates the optical disc with light, reads information recorded on the optical disc, and writes information on the optical disc.

  FIG. 2 is a schematic plan view showing an optical configuration of the optical pickup 1 according to the embodiment of the present invention. As shown in FIG. 2, the optical pickup 1 includes a first semiconductor laser 11, a second semiconductor laser 12, a first optical element 131 and a second optical element 132 that constitute the optical axis matching means 13. A collimating lens 14, a rising mirror 15, an objective lens 16, and a light receiving element 17. These members are mounted on the pickup base 10 described above.

  The optical pickup 1 includes an outward path (forward optical path) that guides light from the first semiconductor laser 11 and the second semiconductor laser 12 to the optical disk, and a return path (recovery path) that guides reflected light reflected by the optical disk to the light receiving element 17. Optical path). Hereinafter, the configuration of the optical pickup 1 will be described separately for the forward path and the return path.

  FIG. 3 is a schematic plan view showing the configuration of the forward path 1a of the optical pickup 1 according to the embodiment of the present invention. As shown in FIG. 3, members constituting the forward path 1 a of the optical pickup 1 include a first semiconductor laser 11, a second semiconductor laser 12, a first optical element 131, and a second optical element 132. A collimating lens 14, a raising mirror 15, and an objective lens 16.

  The first semiconductor laser 11 is provided so as to be able to emit BD laser light (for example, laser light having a wavelength of 405 nm band). The second semiconductor laser 12 is provided so as to be capable of emitting DVD laser light (for example, laser light having a wavelength of 650 nm band).

  The first optical element 131 is provided in a parallel plate shape. A first reflective surface (reflective film) 131a is formed on one of the two plate surfaces of the first optical element 131 (the surface on the side facing the second optical element 132). The first reflecting surface 131 a reflects a part of the first wavelength light 11 a emitted from the first semiconductor laser 11 and is a part of the second wavelength light 12 a emitted from the second semiconductor laser 12. Reflect the part. The remaining light that is not reflected by the first reflecting surface 131a passes through the first reflecting surface 131a. The first reflecting surface 131a may be configured as a half mirror, for example.

  As will be described later, in the present embodiment, the light emitted from the second semiconductor laser 12 is refracted and transmitted through the first optical element 131 in the return path. For this purpose, the first reflecting surface 131 a is configured to reflect a part of the second wavelength light 12 a emitted from the second semiconductor laser 12. When the configuration in which the light emitted from the second semiconductor laser 12 does not pass through the first optical element 131 in the return path is adopted, the first reflecting surface 131a is emitted from the second semiconductor laser 12. All the second wavelength light may be reflected.

  The first semiconductor laser 11 is arranged so that the optical axis of the first wavelength light 11a emitted from the laser is orthogonal to the plate surface (first reflection surface 131a) of the first optical element 131. Yes. That is, the first semiconductor laser 11 is arranged so that light 11a emitted from the laser and transmitted through the first reflecting surface 131a is incident on the first reflecting surface 131a at an incident angle of 0 °.

  The second optical element 132 is also provided in a parallel plate shape. A second reflective surface (reflective film) 132a is formed on one surface of the two plate surfaces of the second optical element 132. The second reflecting surface 132 a reflects all the first wavelength light 11 a emitted from the first semiconductor laser 11. On the other hand, the second reflection surface 132a transmits all the second wavelength light 12a emitted from the second semiconductor laser 12. That is, the second reflecting surface 132a is configured as a dichroic mirror.

  The second reflecting surface 132a may be, for example, a half mirror instead of the dichroic mirror. When the second reflecting surface 132a is formed of a half mirror, the second reflecting surface 132a reflects part of the light emitted from the first semiconductor laser 11 and the second semiconductor laser 12. It's okay.

  As shown in FIG. 3, the second optical element 132 is inclined by an angle α with respect to the first optical element 131 (rotated by an angle α about an axis orthogonal to the paper surface). In other words, the angle formed by the first reflecting surface 131a and the second reflecting surface 132a is an angle α (corresponding to the first angle of the present invention). For this purpose, the first wavelength light 11a emitted from the first semiconductor laser 11 (light transmitted through the first optical element 131) is incident on the second reflecting surface 132a of the second optical element 132. It will be incident at α. The first wavelength light 11a reflected by the second reflecting surface 132a of the second optical element 132 is incident on the first reflecting surface 131a of the first optical element 131 at an incident angle 2α. Become.

  The second wavelength light 12a emitted from the second semiconductor laser 12 is transmitted through the second optical element 132, and is incident on the first reflecting surface 131a of the first optical element 131 at an incident angle θ (in the present invention). (Corresponding to the second angle). In the optical pickup 1 of the present embodiment, the above-described angle α is set to be a half value of the angle θ. Therefore, at the time when light is emitted from the optical axis matching means 13 toward the optical disk side, the optical axis of the first wavelength light 11a emitted from the first semiconductor laser 11 and the second semiconductor element 12 are emitted. In this state, the optical axis of the second wavelength light 12a emitted from the light beam coincides with the optical axis. In other words, the optical axes of the first wavelength light 11a and the second wavelength light 12a when they enter the collimating lens 14 are the same.

  In this case, the second wavelength light 12a emitted from the second semiconductor laser 12 enters the second optical element 132 at an incident angle α. The magnitude of the angle α is not particularly limited as long as it is set to the half value of the incident angle θ described above. However, the angle α is preferably set to a size that can cancel (or reduce) the astigmatism of the second semiconductor laser 12. Semiconductor laser elements have different vertical and horizontal ratios of the active region, and the divergence angle of the laser beam is different between the vertical direction and the horizontal direction with respect to the bonding surface, and astigmatism may occur. The above is to set the angle α so that astigmatism caused by this astigmatism difference can be canceled.

  The collimating lens 14 is means for converting incident light into parallel light. However, in the optical pickup 1, the collimating lens 14 can be moved in the optical axis direction (left and right direction in FIGS. 2 and 3) by a lens driving device 30 (see FIG. 2). The position of the collimating lens 14 is appropriately moved according to the change of the optical disc type corresponding to the optical pickup 1 or the layer jump. The reason why the collimating lens 14 can be moved in the optical axis direction in this way is to adjust the degree of convergence / divergence of the light incident on the objective lens 16 to appropriately suppress the influence of spherical aberration.

  For example, some BDs have a plurality of information recording layers in the thickness direction. When the information recording layer to be read is different, the amount of spherical aberration generated varies due to the difference in the thickness of the cover layer. In particular, in the case of dealing with BD, if the objective lens 16 is made of resin, the variation in the amount of spherical aberration generated due to temperature change cannot be ignored. For this reason, for example, when the optical pickup 1 is compatible with BD, means for correcting spherical aberration is required. The lens driving device 30 is introduced into the optical pickup 1 as a spherical aberration correction mechanism.

  The lens driving device 30 only needs to be able to move the collimating lens 14 in the optical axis direction, and its configuration is not particularly limited. Examples of the lens driving device 30 include various known types such as a configuration in which a lead screw is rotated using a motor as a driving source, and the rotation of the lead screw is converted into a linear movement parallel to the optical axis direction. A configuration may be applied.

  The raising mirror 15 reflects the light from the collimating lens 14 and changes the traveling direction of the light. 2 and 3, the light reflected by the rising mirror 15 travels in the direction toward the front side of the drawing.

  The objective lens 16 is spaced apart from the raising mirror 15 (in FIG. 2 and FIG. 3, it is on the front side of the raising mirror 15), and the light from the raising mirror 15 is transmitted to the information recording layer (not shown) of the optical disc. Condensed to As shown in FIG. 1, the objective lens 16 is disposed on the pickup base 10 while being mounted on the objective lens actuator 20. The objective lens actuator 20 is a device that enables the objective lens 16 to move in the focus direction and the tracking direction. The focus direction is a direction in which the optical disc is in contact with or separated from the optical disc. The tracking direction is a direction parallel to the radial direction of the optical disc.

  In the optical pickup 1, when reading information or the like, it is necessary to perform focusing control so that the focal position of the objective lens 16 always matches the information recording layer of the optical disc. The optical pickup 1 performs tracking control so that the position of the light spot focused on the information recording layer of the optical disk by the objective lens 16 always follows the track of the optical disk when reading information or the like. There is a need. The objective lens actuator 20 is used, for example, when performing these focusing control and tracking control.

  As shown in FIG. 1, the objective lens actuator 20 has a lens holder 21 that holds the objective lens 16, and is configured to support the lens holder 21 with a wire 22 so as to be swingable. The objective lens actuator 20 moves the lens holder 21 with a force generated using a coil and a magnet (that is, moves the objective lens 16). Since this type of objective lens actuator is known, detailed description thereof is omitted here. The objective lens actuator may be of another type (for example, a shaft sliding type).

  Next, the configuration of the return path will be described. FIG. 4 is a schematic plan view showing the configuration of the return path 1b of the optical pickup 1 according to the embodiment of the present invention. As shown in FIG. 4, the members constituting the return path 1b of the optical pickup 1 include the first optical element 131, the collimating lens 14, the rising mirror 15, the objective lens 16, and the light receiving element 17. included. The elements other than the light receiving element 17 are shared with members constituting the forward path 1a.

  The first reflected light 11b emitted from the first semiconductor laser 11 and reflected by the optical disk and the second reflected light 12b emitted from the second semiconductor laser 12 and reflected by the optical disk have the same path. It follows the (optical path) and reaches the light receiving element 17. That is, these reflected lights 11 b and 12 b are transmitted through the objective lens 16, reflected by the rising mirror 15, and transmitted through the collimator lens 14. A part of the reflected lights 11 b and 12 b transmitted through the collimating lens 14 is refracted and transmitted through the first optical element 131 and is condensed on the light receiving element 17.

  The light receiving element 17 functions as a photoelectric conversion unit that converts the received optical signal into an electrical signal. The electric signal output from the light receiving element 17 is sent to a signal processing unit (not shown), and the signal processing unit generates a reproduction signal, a focus error (FE) signal, a tracking error (TE) signal, and the like. The above focusing control is performed based on the FE signal, and the above tracking control is performed based on the TE signal.

  In addition, since the 1st optical element 131 formed in parallel plate shape inclines with respect to the optical axis of reflected light 11b, 12b, astigmatism is given to reflected light 11b, 12b. Due to the astigmatism given in this way, an FE signal by the astigmatism method can be obtained without arranging astigmatism applying means such as a cylindrical lens. Further, the TE signal may be obtained by a push-pull method. However, depending on the case, the TE signal may be obtained by another method by arranging a diffraction element (grating) or a hologram element in place.

  In the optical pickup 1 configured as described above, the optical axis of the light emitted from the first semiconductor laser 11 and the optical axis of the light emitted from the second semiconductor laser 12 are combined using a dichroic prism or the like. This is realized with an inexpensive optical member without using expensive optical components. For this reason, the manufacturing cost of the optical pickup can be suppressed.

  In the optical pickup 1, the light emitted from the first semiconductor laser 11 is incident on the first optical element 131 provided in a parallel plate shape at an incident angle of 0 ° (incident perpendicularly to the plate surface). It reaches the objective lens 16 without generating astigmatism or coma on the road. For this reason, the light emitted from the first semiconductor laser 11 can form a high-quality light spot on the optical disk.

  In the optical pickup 1, the second optical element 132 provided in a parallel plate shape has a normal line that is a predetermined angle (angle α) with respect to the optical axis of the light emitted from the second semiconductor laser 12. Tilted. This predetermined angle is configured to cancel or reduce the astigmatism of the second semiconductor laser 12 and is generated in the light emitted from the second semiconductor laser 11 and reaching the objective lens 16. Astigmatism can be at a desired level. Further, coma aberration is generated by tilting the second optical element 132 as described above. However, since the tilt angle required to cancel the astigmatism of the second semiconductor laser is small, the coma aberration can be generated by appropriately configuring the thickness of the second optical element 132. The amount can be kept low. That is, in the optical pickup 1, the light emitted from the second semiconductor laser 12 can also form a high-quality light spot on the optical disc.

  In the optical pick-up 1 of the present embodiment, as can be understood from the above description, it is not necessary to prepare a separate mechanism for suppressing astigmatism and coma aberration, so the number of parts can be suppressed. Further, since the parallel plate-like optical element functioning as the optical axis matching means in the forward path is used as the astigmatism providing means in the return path, it is not necessary to separately arrange a cylindrical lens or the like. Also from this point, it can be said that the optical pickup 1 can suppress the number of parts.

  As described above, the optical pickup 1 of the present embodiment can suppress the performance of the optical pickup by appropriately suppressing the influence of aberration while suppressing the component cost. Such an optical pickup 1 is convenient for the user because it can cope with a slight variation in the characteristics of the optical disk.

  The embodiment described above is an exemplification of the present invention, and the optical pickup of the present invention is not limited to the configuration of the embodiment described above, and can be appropriately changed within the scope of the technical idea of the present invention.

  For example, in the above embodiment, the objective lens 16 is provided so that it can be used in both cases corresponding to BD and DVD. However, the optical pickup of the present invention is not limited to this configuration. As shown in FIG. 5, the objective lens to be used may be different between the case of supporting BD and the case of supporting DVD (in other words, a configuration having a plurality of objective lenses included in the optical pickup). Note that, in FIG. 5, the same reference numerals are given to the portions that overlap with the embodiment described above. Explanation of overlapping parts is omitted.

  In FIG. 5, reference numeral 16a is an objective lens for BD, and reference numeral 16b is an objective lens for DVD. In the configuration of FIG. 5, there are two rising mirrors 15 a and 15 b corresponding to the fact that there are two objective lenses. The rising mirror 15a disposed below the objective lens 16a may be a dichroic mirror that reflects the laser beam for BD and transmits the laser beam for DVD. The rising mirror 15b disposed below the objective lens 16b may be a mirror that reflects all of the laser beam for DVD.

  In the embodiment described above, the optical pickup 1 is configured to support two types of optical discs of BD and DVD. However, the optical pickup of the present invention is not limited to this configuration, and the optical pickup of the present invention may correspond to optical discs of three or more types of standards. Further, in the case of supporting two types of optical discs, it may correspond to a combination of optical discs other than BD and DVD. If the corresponding optical disk does not include, for example, BD, the collimating lens 14 may be erased.

  FIG. 6 shows a configuration example when the present invention is compatible with optical discs of three types of standards, BD, DVD, and CD. In FIG. 6, the same reference numerals are given to the portions that overlap with the embodiment described above. Description of overlapping parts is omitted. The second semiconductor laser 12 'switches between a laser beam having a wavelength for DVD (for example, a 650 nm body) and a laser beam having a wavelength for CD (for example, a 780 nm band) to be emitted.

  The position of the light emitting point that emits the laser beam for DVD is shifted from the position of the light emitting point that emits the laser beam for CD. For this reason, the optical axes of the two laser beams are shifted until reaching the light receiving element 17. In the configuration shown in FIG. 6, the solid line corresponds to the optical axis of the DVD (partially, BD) laser light, and the broken line corresponds to the optical axis of the CD laser light. The optical axis matching means 13 has a function of matching the optical axis of the BD laser light (emitted from the first semiconductor laser 11) with the optical axis of the DVD laser light. However, the optical axis matching means 13 does not match the optical axis of the laser beam for BD with the optical axis of the laser beam for CD. In this configuration, the light emitting point that emits the laser beam for DVD corresponds to the second light source of the present invention.

  Moreover, in the above embodiment, it was set as the structure by which the two optical elements 131 and 132 which comprise the optical axis matching means 13 are formed in a parallel plate shape. However, in some cases, these optical elements may be changed to other shapes such as a trapezoidal cross-sectional shape.

DESCRIPTION OF SYMBOLS 1 Optical pick-up 1a Outbound path 1b Return path 11 1st semiconductor laser (1st light source)
11a First wavelength light 11b First reflected light 12 Second semiconductor laser (second light source)
12a Second wavelength light 12b Second reflected light 13 Optical axis matching means 14 Collimator lenses 16, 16a, 16b Objective lens 131 First optical element 131a First reflecting surface 132 Second optical element 132a Second reflection surface

Claims (5)

An optical pickup comprising an outward path for guiding light from a light source to an optical recording medium, and a return path for guiding reflected light reflected by the optical recording medium to a light receiving element,
The light source includes a first light source and a second light source that emit light having different wavelengths,
The forward path includes optical axis matching means for matching the optical axes of the first wavelength light emitted from the first light source and the second wavelength light emitted from the second light source. ,
The optical axis matching means includes a first optical element and a second optical element,
The first optical element includes a first reflecting surface that reflects a part of the first wavelength light and reflects at least a part of the second wavelength light,
The second optical element includes a second reflecting surface that reflects at least a part of the first wavelength light,
After passing through the first reflecting surface, after passing through the second reflecting surface, the optical axis of the first wavelength light reflected in the order of the first reflecting surface, and after passing through the second reflecting surface An optical pickup characterized in that an optical axis of the second wavelength light reflected by the first reflecting surface coincides. The first optical element and the second optical element are arranged such that an angle formed by the first reflecting surface and the second reflecting surface arranged to face each other is a first angle,
The first light source is disposed so as to be incident on the first reflecting surface at an incident angle of 0 ° when the first wavelength light is transmitted through the first reflecting surface.
The second light source is arranged such that an incident angle of the second wavelength light to the first reflecting surface is a second angle,
The optical pickup according to claim 1, wherein the first angle is a half value of the second angle. The first optical element and the second optical element are provided in a parallel plate shape,
The optical pickup according to claim 1, wherein the second optical element is tilted so that an incident angle of the second wavelength light is a predetermined angle larger than 0 °.   The first reflected light emitted from the first light source and reflected by the optical recording medium, and the second reflected light emitted from the second light source and reflected by the optical recording medium, 4. The optical pickup according to claim 1, wherein the optical pickup passes through the first optical element and reaches the light receiving element. 5. An objective lens for condensing the light from the light source onto the optical recording medium;
The collimating lens which is arrange | positioned on the optical path between the said optical axis matching means and the said objective lens, and can move to an optical axis direction is further provided. Optical pickup.

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