JP2005327388A - Optical pickup, optical disk unit, and optical axis tilt correcting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save the space for an optical system which records and reproduces CDs, DVDs, and BDs by correcting an optical axis tilt resulting from a different light emission point position without causing light quantity loss nor characteristic deterioration when an LD capable of emitting two-wavelength or three-wavelength lasers having a long light emission point interval is used. <P>SOLUTION: An optical system put in an optical pickup includes a one-wavelength laser diode 11 dedicated for DBs, a two-wavelength laser diode 28 dedicated to both CDs and DVDs, and an objective 23 exclusively for DBs, and an objective 24 exclusively for both CDs and DVDs, and an optical path change angle for making a laser beam of 780 nm in wavelength incident on the objective for both CDs and DVDs is set to such an angle that an optical axis tilt of the laser beam of 780 nm in wavelength being eliminated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical pickup and an optical disc apparatus capable of recording / reproducing three types of discs, CD, DVD and BD, and in particular, laser light emitted from laser diodes having two or three wavelengths whose emission points are separated from each other. The present invention relates to an optical axis collapse correction method for correcting the optical axis collapse.

  In recent years, CDs and DVDs for recording and reproducing video information and music information have become widespread, but in order to meet the demand for further improvement in recording density and capacity, BD (Blu-ray) using laser light with a wavelength of 407 nm in the blue wavelength region is used. Disk) has appeared.

  Accordingly, an optical disc apparatus for recording and reproducing three types of discs, CD, DVD and BD, has been developed and commercialized. In such an optical disc apparatus, it is sufficient to mount a pickup that is used for both CD and DVD and two pickups dedicated to BD, or a single pickup that can record and reproduce CD, DVD, and BD. It is very natural to mount a pickup capable of recording and reproducing a single CD, DVD, and BD (see Patent Document 1).

When recording and reproducing this CD, DVD, and BD with a single pickup, in order to reduce the size and weight of the pickup, 2w1canLD (laser diode) capable of emitting lasers of two wavelengths, CD and DVD, and a BD only 1 It is essential to save space in the optical system by using a combination with 1w1canLD that emits a laser with a wavelength, or using 3w3canLD with 3 wavelengths for CD, DVD, and BD.
Japanese Patent Laid-Open No. 2003-323735 (page 9, FIG. 1)

  However, in an LD that can emit a laser having two or three wavelengths by one laser, the interval between the light emitting points is different for each wavelength, so that the optical axis is tilted by the subsequent optical system. When this optical axis tilt occurs, off-axis light with respect to the objective lens leads to characteristic deterioration, and there is a demand to use it on the axis as much as possible. To deal with this problem, conventionally, it has been used whether the characteristics are deteriorated or an element for correcting the optical axis (optical axis combining element: for example, HOE) is mounted. However, when an optical axis synthesizing element such as HOE is used, characteristic deterioration due to loss of light amount and aberration of the element itself cannot be avoided.

  The present invention has been devised in view of the above circumstances, and the object of the present invention is to reduce the amount of light loss and the characteristics when using an LD capable of emitting a laser with two or three wavelengths whose emission points are separated. A compact and lightweight optical pickup capable of correcting the optical axis tilt of a laser beam caused by a difference in the light emitting point position without causing deterioration to a normal state and recording / reproducing BD, DVD or CD, and the optical pickup It is an object of the present invention to provide an optical disk device mounted and an optical axis tilt correction method for correcting the optical axis tilt of the laser beam.

  In order to achieve the above object, the present invention condenses laser light emitted from a single-wavelength laser light source dedicated to the first disk onto the first disk, and receives and receives the reflected light from the first disk. The first disk optical system that leads to the element, and either one of the laser light emitted from the second disk or the dual-wavelength laser light source that also serves as the third disk is used as the second disk or the third disk. A second disc or a third disc optical system that collects light on the disc, receives reflected light from any one of the second disc and the third disc, and guides it to the light receiving element; And an optical system for one disk and a shared part of the second disk or the third optical disk system.

  Further, according to the present invention, one of the three types of laser light emitted from the three-wavelength laser light source also serving as the first disk, the second disk, or the third disk is used as the first disk, the second disk, or the third disk. A first disk that receives light reflected from any one of the first disk, the second disk, and the third disk and guides it to the light receiving element; 2 disc or a third disc combined optical system.

  The present invention also relates to an optical disk apparatus for condensing a laser beam from an optical pickup onto a disk and receiving reflected light from the disk with the optical pickup to record and reproduce data. For the first disk, which condenses the laser light emitted from the one-wavelength laser light source dedicated to the first disk onto the first disk, receives the reflected light from the first disk, and guides it to the light receiving element. Laser light emitted from an optical system and a two-wavelength laser light source also serving as a second disk or a third disk is condensed on the second disk or the third disk, and the second disk or the third disk A second disk or third disk optical system that receives reflected light from the light and guides it to the light receiving element, and the first disk optical system and the second disk or third disk optical system Characterized by the and a communal area.

  The present invention also relates to an optical disc apparatus for condensing laser light from an optical pickup onto an optical recording medium and receiving reflected light from the optical recording medium with the optical pickup to record and reproduce data. The optical pickup collects laser light emitted from the first disk, the second disk, or the third-wavelength laser light source also serving as a third disk on the first disk, the second disk, or the third disk. A first disc, a second disc, or a third disc optical system that emits light, receives reflected light from the first disc, the second disc, or the third disc and guides it to a light receiving element. It is characterized by that.

  The present invention also relates to an optical axis tilt correction method for correcting the optical axis tilt of a laser beam, the optical path changing angle for making the first laser beam incident on the objective lens for one wavelength, or the second or third. One or both of the optical path changing angles for making the laser beam incident on the dual-wavelength objective lens have the optical axis tilt of the first laser light or the second or third laser. The angle is such that the optical axis collapse of light is eliminated.

  The present invention is also an optical axis tilt correction method for correcting an optical axis tilt of a laser beam, and is a one-wavelength objective lens that focuses the first laser beam on a first disk, or a second or third lens. The arrangement angle of one or both of the dual-wavelength objective lenses for condensing the laser beam on the second or third disk is set so that the optical axis of the first laser beam is tilted or the second or third lens is used. The angle is such that the tilt of the optical axis of the laser beam is eliminated.

  As described above, according to the present invention, a single wavelength laser light source dedicated to the first disk (for example, BD), a dual wavelength laser light source also used for the second disk (for example, DVD) or the third disk (for example, CD), A space-saving optical system including the disc objective lens and the second disc or the third disc objective lens is stored in the optical pickup, or the first disc, the second disc, or the third disc. By storing a further space-saving optical system having a dual-wavelength laser light source, a first disk objective lens, and a second disk or third disk objective lens in an optical pickup, The optical pickup can record / reproduce three types of the first disc, the second disc, or the third disc, and the optical pickup is small and lightweight. It can be achieved.

  Further, an optical path changing angle for entering the first laser beam (for example, laser beam having a wavelength of 407 nm) into the first objective lens (for example, objective lens for BD) or the second laser beam (for example having a wavelength of 650 nm). Laser beam) is incident on the second objective lens (for example, a CD or DVD objective lens), either one of the optical path change angles or both optical path change angles are set to either the first or second laser light. Alternatively, the angle may be such that both optical axis tilts are eliminated, or the first objective lens for condensing the first laser light on the first disk or the second laser light is condensed on the second disk. The position of the light emitting point is determined by setting the angle of arrangement of either one or both of the second objective lenses to be such that the tilt of the optical axis of either one or both of the first or second laser beams is eliminated. Different The inclination optical axis of the laser beam caused by Rukoto can be corrected to the normal state.

  According to the present invention, a single-wavelength laser light source dedicated to the first disk (for example, BD), a dual-wavelength laser light source also used for the second disk (for example, DVD) or the third disk (for example, CD), A space-saving optical system including a disc-dedicated objective lens and a second disc or a third disc-use objective lens is housed in an optical pickup, or the first disc, the second disc, or the third disc A space-saving optical system comprising a dual-use three-wavelength laser light source, a first disc-dedicated objective lens, and a second disc or a third disc-use objective lens is housed in an optical pickup, and the first laser An optical path changing angle for entering light (for example, laser light having a wavelength of 407 nm) into a first objective lens (for example, objective lens for BD) or a second laser light (for example, 6 One or both of the optical path changing angles for entering the second objective lens (for example, an objective lens dedicated to CD or DVD) into the first objective lens or the second laser light. The angle is set so that the optical axis collapse of one or both of the first and second laser beams is eliminated, or the first objective lens or the second laser beam for condensing the first laser beam on the first disk is the second one. By setting the angle of arrangement of either one or both of the second objective lenses focused on the disk to an angle that eliminates the optical axis tilt of either one or both of the first or second laser beams, When using a laser diode that can emit lasers with two or three wavelengths whose emission points are separated, the optical axis tilt of the laser beam can be corrected to a normal state without causing loss of light quantity or deterioration of characteristics. Further, one optical pickup, for example, BD, CD, or the third disc recording and reproducing can and the can allow smooth access to the optical pickup BD as small and lightweight, the CD or DVD.

  When using an LD that can emit lasers with two or three wavelengths that are spaced apart from each other, the optical axis of the optical axis tilting caused by the difference in the position of the light emitting point is normal without causing loss of light quantity or deterioration of characteristics. BD-dedicated one-wavelength laser light source, BD-dedicated dual-wavelength laser light source, and BD-dedicated objective lens for the purpose of correcting the state and reducing the size and weight of an optical pickup capable of recording and reproducing BD, CD, or DVD And a space-saving optical system including a CD or DVD combined objective lens in an optical pickup, or a BD, CD or DVD combined three-wavelength laser light source, a BD dedicated objective lens, and a CD or DVD combined objective A space-saving optical system including a lens is housed in an optical pickup, and a first laser beam (for example, a laser beam having a wavelength of 407 nm) is sent to the first pair. An optical path changing angle for entering a lens (for example, an objective lens for BD) or a second laser beam (for example, a laser beam having a wavelength of 650 nm) is incident on the second objective lens (for example, an objective lens for CD or DVD) One or both of the optical path changing angles for adjusting the optical path changing angle is set to an angle that eliminates the optical axis tilt of either one or both of the first and second laser lights, or the first laser light Of the first objective lens for condensing the first laser beam on the first disk or the second objective lens for focusing the second laser beam on the second disk, or the arrangement angle of both the first and second lenses. This is achieved by setting the angle so that the tilt of the optical axis of either one or both of the laser beams is eliminated.

  FIG. 1 is a block diagram showing the configuration of the optical pickup according to the first embodiment of the present invention. The 407-nm laser light emitted from the BD laser diode 11 of the optical pickup according to the present embodiment is a half-wave plate 12, a beam splitter 13, a grating 16, a beam splitter 17, a mirror 18, a collimator lens 19, and three wavelengths. The light beam is condensed on a BD (not shown) through the beam splitter 20, the power liquid crystal 22, and the BD objective lens 23. At this time, a part of the laser light emitted from the BD laser diode 11 passes through the beam splitter 13 as it is and is condensed by the condenser lens 14 onto the front monitor photodiode IC 15. The reflected light from the BD passes through the BD dedicated objective lens 23, the power liquid crystal 22, the three-wavelength beam splitter 20, the collimator lens 19, the mirror 18, the beam splitter 17, and the hologram element 25, and is collected in the photodiode IC 27 by the multilens 26. Lighted. The above is the configuration of the optical system dedicated to BD mounted on the optical pickup of the present embodiment.

  Further, the 780 or 650 nm laser beam for CD or DVD emitted from the CD / DVD laser diode 28 of the optical pickup of the present embodiment is coupled with the coupling lens 29, the mirror 30, the grating 31 and the beam splitter 32 for the wavelength. , A collimator lens 33, a three-wavelength beam splitter 20, a power liquid crystal 22, and a DVD / CD objective lens 24. At this time, a part of the laser light emitted from the CD / DVD laser diode 28 has a configuration in which the optical path is changed by 90 degrees by the beam splitter 20 and is condensed on the front monitor photodiode IC21. The reflected light from the CD or DVD passes through the CD / DVD objective lens 24, the power liquid crystal 22, the three-wave beam splitter 20, the collimator lens 33, the two-wavelength beam splitter mirror 32, the cylindrical lens 34, and the optical axis synthesizing element 35. Then, the light is focused on the photodiode IC 36. The above is the CD / DVD combined optical system housed in the optical pickup of the present embodiment. In order to cope with the recording / reproduction of CD or DVD and BD, the two-wavelength laser diode 28 for CD / DVD A BD-dedicated laser diode 11 is provided, and the optical path is switched by a three-wavelength beam splitter 20 so that CD, DVD, and BD can be recorded and reproduced with a single optical pickup. The optical system as described above is housed in a housing 38 of the optical pickup, and the housing 38 is slidably attached to a fixed shaft 39 so as to be movable in the radial direction of the optical disk.

  Next, the operation of the present embodiment will be described. When recording or reproducing BD, the above-described optical system for BD is used. When recording or reproducing a CD or DVD, for example, when recording or reproducing a CD (CDR, CDRW), a CD / DVD laser diode 28 emits a 780 nm laser beam for the CD, and the DVD (DVDR, DVDRW, When recording and reproducing (DVDRAM), a laser beam of 650 nm for DVD is emitted from the laser diode 28 for CD / DVD, and both are irradiated to the CD or DVD through the above-described optical system for both CD / DVD.

  In this case, since there are two light emitting points of the laser diode 28 and the distance between them is shifted, the optical axis collapses. The 650 nm laser beam and the 780 nm laser beam are condensed on each disk by the common CD / DVD objective lens 24. At that time, if the emission point of the 650 nm laser beam is aligned with the optical axis, the 780 nm laser beam is off the optical axis, so that the 780 nm laser beam is incident on the CD / DVD objective lens 24 at an angle. Thus, the characteristic deterioration of the CD / DVD combined objective lens 24 occurs, but in this case, since the wavelength is long, the influence of the characteristic deterioration is not so great.

  Here, FIG. 1 shows the most of 2w1canLD + 1w1canLD by one CD / DVD combined laser diode 28, one BD dedicated laser diode 11, one CD / DVD combined objective lens 24 and one BD dedicated objective lens 23. Space was saved by a practical optical configuration. However, in addition to the combination of 2w1canLD + 1w1canLD, there is a BD / DVD combined laser diode and a CD dedicated laser diode, or a BD / CD laser diode and a DVD dedicated laser diode. There is a lens and one CD objective lens, or a BD / CD objective lens and a DVD objective lens. Various combinations of laser diode types and objective lens types can be considered. It is done.

  Among them, for example, when an optical system combining a CD / DVD objective lens and a BD objective lens using a BD / DVD combined laser diode and a CD dedicated laser diode is emitted from the BD / DVD combined laser diode. Since both of the laser wavelengths are short, the influence of the characteristic deterioration of the optical system due to the tilting of the optical axis cannot be ignored.

  FIG. 2 is a block diagram showing a method of correcting the optical axis tilt in the above case. In the BD / DVD combined laser diode 60, the light emission point 61 of the laser light of 407 nm is on the optical axis. Since the light emission point 62 of 650 nm is shifted from the light emission point 61 by d, the light emission point 62 of 650 nm is naturally shifted from the optical axis by d. The 407-nm laser light emitted from the light emitting point 61 is collimated by the collimator lens 51 and is incident on the two-wavelength beam splitter 52, where it is reflected by 90 degrees and incident on the BD dedicated objective lens 53. 53 is condensed on the BD 56. In this case, the film 521 that reflects the laser beam of 407 nm is disposed at an angle of 45 degrees.

  The 650-nm laser light emitted from the light emitting point 62 is converted into parallel light by the collimator lens 51 and is incident on the two-wavelength beam splitter 52, passes there, is reflected by 90 degrees, and is a CD / DVD objective lens 55. And is condensed on the DVD 57 by the objective lens 55 for both CD / DVD. In this case, the arrangement angle θ of the mirror 54 that reflects the laser beam of 650 nm is slightly larger than 45 degrees. However, when the focal length of the collimator is fcl and the light emission point deviation amount of the LD is d, θ = 45 ° + 1/2 × arctan (d / fcl). Thus, when entering the CD / DVD combined objective lens 55, the optical axis tilt of the 650 nm laser beam is corrected and incident on the CD / DVD combined objective lens 55 from a normal direction.

  The configuration for correcting the optical axis tilt in the optical system shown in FIG. 1 does not have a simple configuration as shown in FIG. 2, but has many optical components inserted in the optical path. If there are optical components corresponding to the two-wavelength beam splitter 52 and the mirror 54 for splitting the optical path of the laser light and making it incident on the respective objective lenses, the optical axis tilt can be corrected based on the principle described above.

  In the above embodiment, the reflection angle of the mirror 54 is adjusted. However, if the optical axis of the 407 nm laser beam is tilted, there is a configuration in which the reflection angle of the two-wavelength beam splitter 52 is adjusted. If the optical axis is tilted, the reflection angles of both the mirror 54 and the two-wavelength beam splitter 52 are adjusted.

  According to the present embodiment, one CD / DVD combined laser diode 28, one BD dedicated laser diode 11, one CD / DVD combined objective lens 24, and one BD dedicated objective lens 23 provide 2w1canLD + 1w1canLD. The optical system for both CD / DVD and part of the optical system dedicated to BD are common, so the number of optical components can be reduced and space can be saved. The pickup can be made smaller and lighter.

  Further, when the optical path of the two-wavelength laser light emitted from the two-wavelength laser diode 60 is shifted and distributed to the respective objective lenses, the optical path is split. By adjusting the angle, the arrangement angle of the mirror 54 in the above example, by aligning the optical axis of the laser beam incident on the mirror 54 due to the tilting of the optical axis with the optical axis of the CD / DVD combined objective lens 55, The optical axis collapse can be corrected. At that time, there is no deterioration in characteristics due to loss of light amount or aberration of the element itself, and no expensive parts are used, so that the optical axis tilt of the laser beam is corrected at a very low cost to obtain high quality recording / reproducing characteristics. be able to.

  As a method of correcting the optical axis tilt, the optical axes can be aligned by tilting the objective lens 55 itself shown in FIG. Also in this case, when the laser beam of 407 nm causes the optical axis to be tilted, the optical axes are aligned by tilting the objective lens 53 itself. When both the laser beams cause the optical axis to be tilted, both objective lenses are used. The optical axes are aligned by tilting 53 and 55 themselves.

  Next, the configuration of the optical pickup according to the second embodiment of the present invention will be described below. The optical pickup of this example is equipped with an optical system (not shown) having 3w1canLD that uses one BD, DVD, and CD three-wavelength laser diodes, and its configuration is more than that of the optical system shown in FIG. Further, the pickup can be simplified, and the pickup can be further reduced in size and weight.

  By the way, the laser light emitted from the laser diode for three wavelengths as described above is different in wavelength from 407, 650, and 780 nm, and its emission power is also different. Therefore, it is optimal for condensing the laser light on each disk. The optical magnification is also different: BD is 10 to 12 times, DVD is 5 times, and CD is about 4 times. Therefore, in the present embodiment, the above-described optimum optical magnification when irradiating the disk with each wavelength laser through the optical system is realized with the configuration described below.

  FIG. 3 is a block diagram showing an optical system for determining an optical magnification when condensing laser light. Laser light emitted from the laser diode 91 is converted into parallel light by the collimator lens 92, and this laser light is condensed on the disk 94 by the objective lens 93. The optical magnification β of such an optical system is expressed by β = f2 / f1 (1) where the focal length of the objective lens 93 is f1 and the focal length of the collimator lens 92 is f2. Therefore, when realizing the optimum magnification of CD, DVD, and BD, if the focal length f2 of the collimator lens 92 is made constant, the denominator of the equation (1) must be reduced as the magnification is increased. That is, when the objective lens 93 of the optical system in FIG. 3 is for BD, DVD, and CD, the focal length f1 of the objective lens 93 becomes longer in this order.

  When using a BD-dedicated lens and a CD / DVD combined lens to save space in an optical system having a 3w1canLD that uses a single laser diode for three wavelengths, a DVD dedicated lens and a CD / BD combined lens are used. There are three ways of using a CD-only lens and a BD / DVD combined lens, but when the optimum magnification is achieved (the common lens is an appropriate compromise magnification), the focal length of the CD-only lens is BD / The focal length of the DVD / CD objective lens is longer than the focal length of the DVD / CD objective lens. The focal length of the BD / CD objective lens is longer than the focal length of the DVD objective lens. There are three ways of longer. As described above, the relationship between the focal lengths of the dedicated lens and the dual-purpose lens is similarly applied to the configuration in which 2w1canLD + 1w1canLD shown in FIG.

  FIG. 4 is a block diagram showing a configuration of a main part of an optical disc apparatus according to the third embodiment of the present invention. The optical disk device accesses a disk type disk 202 such as DVD ± R / RW, CD-R / RW, or BD by an optical pickup 204, records and reproduces data, and drives the disk 202 to rotate. A spindle motor 203 as a driving means for driving, an optical pickup 204 for reading / writing data from / to the disk 202, a feed motor 205 as a driving means for moving the optical pickup 204 in the radial direction of the disk 202, and the entire apparatus A system controller 207 that performs control, a signal processing unit 208 that performs predetermined processing such as demodulation and error correction processing based on an output signal from the preamplifier 220, a servo control unit 209 that controls the spindle motor 203 and the feed motor 205, Each output from the optical pickup 204 A pre-amplifier 220 that generates a focus error signal, a tracking error signal, an RF signal, and the like based on the above signal, an interface 211 that connects the signal processor 208 and the external computer 230, and a laser control that drives a laser light source in the optical pickup 204. An external computer 230 that receives a signal recorded on the disk 202 as a reproduction signal, modulates the data by the signal processing unit 208 and outputs it to the laser control unit 221 to drive the laser light source in the optical pickup 204. The D / A conversion of the signal from the signal processing unit 208 or the A / D conversion of the signal from the audio / visual processing unit 213, the A / D converter 212, and the recorded or reproduced audio / video signal Audio / visual processing unit 213 for processing It is configured. Here, the optical pickup 204 houses the optical system of the first embodiment shown in FIG.

  For example, a feed motor 205 for moving to a predetermined recording track on the disk 202 is connected to the optical pickup 204. Control of the spindle motor 203, control of the feed motor 205, and control of the focusing direction and tracking direction of the biaxial actuator that holds the objective lens of the optical pickup 204 are the focus error signal input from the preamplifier 220 by the servo control unit 209, respectively. This is performed based on the tracking error signal. The laser control unit 221 controls the laser diodes 11 and 28 in the optical pickup 204, and variably controls the output power of the laser diodes 11 and 28 in the recording mode and the reproduction mode.

  According to this embodiment, since the optical pickup 204 having the optical configuration of 2w1canLD + 1w1canLD shown in the first embodiment (or the optical configuration of 3w1canLD described in the second embodiment) is mounted, It is possible to record / reproduce three types of discs, BD, DVD, and CD, and to smoothly access the target address portion of the disc 202 because of its small size and light weight.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can implement also with another various form in a concrete structure, a function, an effect | action, and an effect.

1 is a block diagram illustrating a configuration of an optical pickup according to a first embodiment of the present invention. It is the block diagram which showed the method of correct | amending optical axis fall. It is the block diagram which showed the optical system which determines the optical magnification at the time of condensing a laser beam. It is the block diagram which showed the structure of the principal part of the optical disk apparatus based on the 3rd Embodiment of this invention.

Explanation of symbols

  11, 28, 60, 91 ... Laser diode, 12 ... 1/2 wavelength plate, 13, 17, 20, 32, 52 ... Beam splitter, 14 ... Condensing lens, 15, 21, 27, 36 ... ... Photodiode IC, 16, 31 ... Grating, 18, 30, 54 ... Mirror, 19, 33 ... Collimator lens, 22 ... Power liquid crystal, 23, 24, 53, 55, 93 ... Objective lens, 25 ... Hologram element, 26 ... Multi lens, 29 ... Coupling lens, 34 ... Cylindrical lens, 35 ... Optical axis composition element, 51, 92 ... Collimator lens, 56 ... BD, 57 ... DVD, 94: Disc, 204: Optical pickup.

Claims (11)

A first disk optical system that condenses laser light emitted from a single-wavelength laser light source dedicated to the first disk onto the first disk, receives reflected light from the first disk, and guides it to the light receiving element. When,
The laser light emitted from the dual-wavelength laser light source also used as the second disk or the third disk is condensed on the second disk or the third disk, and the reflected light from the second disk or the third disk is received and received. A second disc or a third disc combined optical system leading to the element;
A shared portion of the first disk optical system and the second disk or third disk combined optical system;
An optical pickup comprising:   The first disk-dedicated objective lens and the second disk are arranged in a shared portion for condensing laser light and receiving reflected light from the first disk optical system and the second disk or the third disk-combined optical system. 2. The optical pickup according to claim 1, further comprising a dual-disc or third-disc objective lens. The laser light emitted from the three-wavelength laser light source also serving as the first disk, the second disk, or the third disk is condensed on the second disk, the third disk, or the first disk, and the first disk, the first disk, A first disk, a second disk, or a third disk combined optical system that receives reflected light from the second disk or the third disk and guides it to the light receiving element;
An optical pickup characterized by that.   4. The light according to claim 3, wherein the first disk, the second disk, or the third disk combined optical system includes a first disk dedicated objective lens and a second disk or a third disk combined objective lens. pick up.   The first optical element that changes the optical path in order to make the first disc laser beam incident on the objective lens dedicated to the first disc, or the second disc or the third disc laser beam is used as the second disc. Alternatively, the optical path changing angle of either one or both of the second optical elements that change the optical path so as to be incident on the third objective lens also serves as an angle that eliminates the optical axis tilt of the laser light. The optical pickup according to claim 2, wherein:   One or both of the objective lens dedicated to the first disk, the second disk, and the third disk objective lens are arranged so that the optical axis tilt of the laser beam is eliminated. The optical pickup according to claim 2 or 4.   7. The optical disc apparatus according to claim 1, wherein the first disc is a BD, the second disc is a DVD, and the third disc is a CD. An optical disc apparatus for condensing a laser beam from an optical pickup onto a disc, and receiving reflected light from the disc with the optical pickup to record and reproduce data.
The pickup condenses laser light emitted from a single-wavelength laser light source dedicated to the first disk onto the first disk, receives reflected light from the first disk, and guides it to the light receiving element. The laser light emitted from the optical system for the disc and the two-wavelength laser light source also serving as the second disc or the third disc is condensed on the second disc or the third disc, and from the second disc or the third disc A second disc or a third disc-use optical system that receives the reflected light and guides it to the light receiving element, a shared portion of the first disc optical system and the second disc or the third disc-use optical system,
An optical disc apparatus comprising: An optical disc apparatus that collects laser light from an optical pickup onto an optical recording medium and receives reflected light from the optical recording medium by the optical pickup to record and reproduce data. The pickup includes: The laser light emitted from the three-wavelength laser light source also serving as the first disk, the second disk, or the third disk is condensed on the first disk, the second disk, or the third disk, and the first disk, the second disk, A first disk, a second disk, or a third disk combined optical system that receives reflected light from the second disk or the third disk and guides the reflected light to the light receiving element;
An optical disc device characterized by the above. An optical axis collapse correction method for correcting an optical axis collapse of a laser beam,
Either or both of the optical path changing angle for entering the first laser beam into the one-wavelength objective lens and the optical path changing angle for entering the second or third laser beam into the dual-wavelength objective lens An optical axis tilt correction method, wherein an optical path change angle is set to an angle that eliminates the optical axis tilt of the first laser beam or the optical axis tilt of the second or third laser beam. An optical axis collapse correction method for correcting an optical axis collapse of a laser beam,
Either a one-wavelength objective lens that focuses the first laser beam on the first disk, or a dual-wavelength objective lens that focuses the second or third laser beam on the second or third disk Alternatively, both arrangement angles are set such that the optical axis tilt of the first laser beam or the optical axis tilt of the second or third laser beam is eliminated. Method.

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