JP2006053993A - Optical element for optical pickup, and optical pickup using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element for an optical pickup which can be easily and highly accurately assembled and assures favorable optical characteristics, and an optical pickup using the same. <P>SOLUTION: The optical element 10 for the optical pickup has an objective lens 1 for converging luminous flux, an aberration correction means 2 for correcting aberration, and a holder 6 for fixing the relative position of the objective lens 1 and the aberration correction means 2. The aberration correction means 2 includes an aberration correction element which does not completely cover a hole 14 for the passing of the luminous flux formed in the holder 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical element for an optical pickup provided in an optical disc drive apparatus for optically recording / reproducing information, and an optical pickup using the optical element.

  In recent years, in order to increase the recording capacity of an optical disk drive device, a CD using a laser beam having a wavelength of 780 nm, a DVD using a laser beam having a wavelength of 650 nm, and a disc using a laser beam having a wavelength of 405 nm have been adopted. In addition, higher density is being promoted by shortening the wavelength.

  In such an optical disc drive apparatus, in order to make use of the past assets, even a disc apparatus using a laser beam with a wavelength of 405 nm, a DVD using a laser beam with a wavelength of 650 nm, or a CD using a laser beam with a wavelength of 780 nm. It is desirable to be able to record and reproduce.

  By the way, an optical pickup that irradiates a recording medium with laser light to perform recording and reproduction is mounted on the optical disk drive device, and an objective lens that condenses the laser light onto the recording medium is attached to the optical pickup. ing.

  This optical pickup and objective lens are designed to be dedicated to one wavelength, and by mounting a plurality of optical pickups and objective lenses, it is easy to cope with recording and reproduction of disks of various wavelengths.

  However, mounting an optical pickup corresponding to each wavelength in this way is disadvantageous for downsizing and cost reduction of the apparatus, so that one optical pickup is required to support a plurality of wavelengths. . The objective lens mounted on the optical pickup is not equipped with a plurality of objective lenses corresponding to each wavelength, and they are used by switching them according to the wavelength, but a single objective lens can handle a plurality of wavelengths. It is demanded.

  However, when the wavelength is shortened, the allowable amount of optical characteristics with respect to various aberrations is reduced, and it becomes difficult to handle a plurality of wavelengths with only one objective lens. For this reason, in addition to the objective lens that collects light, an aberration correction element that corrects aberrations caused by different wavelengths is required. In addition, this aberration correction element needs to align its optical axis with the optical axis of the objective lens with high accuracy in order to ensure the optical performance of the optical pickup.

On the other hand, as a conventional optical pickup, for example, a focusing means for condensing a light beam on the signal recording surface of an optical disc, and one of the ordinary light component and abnormal light component of the light beam is transmitted and the other component is diffracted. And a polarizing hologram element that converges and a holding means for fixing the relative position of these elements are known (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 10-3690

  If the technique disclosed in Patent Document 1 is applied and the polarizing hologram element is replaced with an aberration correction element, the relative position between the aberration correction element and the objective lens as the focusing means can be accurately maintained by the holding means. It is possible to secure good optical characteristics. To that end, however, it is necessary to hold the aberration correction element and the objective lens with a positional accuracy of the order of μm by the holding means, and to ensure assemblability. In order to achieve this, it is necessary to devise the shape.

  However, the above Patent Document 1 does not disclose the specific shape of the holding means for fixing the relative position between the focusing means and the polarizing hologram element, and is difficult to realize.

  Accordingly, an object of the present invention made in view of the above circumstances is to provide an optical element for an optical pickup having an objective lens and an aberration correction element that can be easily assembled with high accuracy and ensure good optical characteristics, and an optical pickup using the same. Is to provide.

The invention according to claim 1, which achieves the above object, comprises: an objective lens that focuses a light beam; an aberration correction unit that corrects aberration; and a holder that fixes the relative positions of the objective lens and the aberration correction unit. An optical element for pickup,
The aberration correction means includes an aberration correction element that does not completely cover the hole for passing the light beam provided in the holder.

  According to a second aspect of the present invention, in the optical element for an optical pickup according to the first aspect, when the cross section is taken along a plane that passes through the aberration correction element and is perpendicular to the optical axis, the aberration correction element and the holder A gap exists between the hole for allowing the light beam to pass or the side surface of the space connected to the hole.

  According to a third aspect of the present invention, in the optical element for an optical pickup according to the first aspect, the aberration correcting element is applied to the holder in a direction parallel to the optical axis, and the optical axis including the applied surface is applied. When a cross section is taken on a vertical plane, a gap exists between the aberration correction element and a hole portion through which the luminous flux of the holder passes or a side surface of a space connected to the hole portion. .

  According to a fourth aspect of the present invention, in the optical element for an optical pickup according to any one of the first to third aspects, the aberration correction means includes a plurality of aberration correction elements, and at least one aberration correction element. Is not completely covering the hole through which the light beam provided in the holder passes.

  According to a fifth aspect of the present invention, in the optical element for an optical pickup according to any one of the first to third aspects, the aberration correction unit includes a plurality of aberration correction elements, and all of the aberration correction elements are the above-described aberration correction elements. It is characterized by not completely covering the hole portion through which the light beam provided in the holder passes.

  According to a sixth aspect of the present invention, in the optical element for an optical pickup according to any one of the first to fifth aspects, the aberration correction means includes a plurality of aberration correction elements, and at least two of the aberration correction elements. Are arranged so as to have portions that do not overlap when viewed from a direction parallel to the optical axis.

  According to a seventh aspect of the present invention, in the optical element for an optical pickup according to the sixth aspect, each of the at least two aberration correction elements has a rectangular shape when viewed from a direction parallel to the optical axis. The longitudinal directions are not parallel but are arranged to have an angle.

  The invention according to claim 8 is the optical element for optical pickup according to claim 7, wherein the angle is 90 degrees.

  According to a ninth aspect of the present invention, in the optical element for an optical pickup according to the sixth aspect, each of the at least two aberration correction elements has a square shape when viewed from a direction parallel to the optical axis. The sides are not parallel but have an angle.

  According to a tenth aspect of the present invention, in the optical element for an optical pickup according to the ninth aspect, the angle is 45 degrees.

  The invention according to claim 11 is the optical element for optical pickup according to any one of claims 1 to 10, wherein the holder has an abutment surface for abutting the aberration correction element in a direction parallel to the optical axis. And having a space that enables adjustment of movement of the aberration correction element along the attachment surface.

  According to a twelfth aspect of the present invention, in the optical element for an optical pickup according to the eleventh aspect, the holder has a convex portion that restricts the movement of the aberration correction element along the abutting surface. To do.

  The invention according to claim 13 is the optical element for optical pickup according to any one of claims 1 to 10, wherein the holder is a convex portion or a concave portion that positions the aberration correction element in a direction perpendicular to the optical axis. It is characterized by having.

  According to a fourteenth aspect of the present invention, in the optical element for an optical pickup according to the thirteenth aspect, the distance between the wall portions of the holder facing each other for positioning the convex portion or the concave portion, and the portion fixed to the distance. The difference from the length of the corresponding portion of the aberration correction element is less than 10 μm.

  The invention according to claim 15 is the optical element for optical pickup according to any one of claims 1 to 14, wherein the numerical aperture of the objective lens is 0.75 or more. .

  According to a sixteenth aspect of the present invention, in the optical element for an optical pickup according to any one of the first to fifteenth aspects, the aberration correction element is a diffraction grating.

  According to a seventeenth aspect of the present invention, in the optical element for an optical pickup according to any one of the first to sixteenth aspects, the aberration correction element is an element that corrects chromatic aberration due to wavelength variation of the light beam. It is what.

  According to an eighteenth aspect of the present invention, in the optical element for an optical pickup according to any one of the first to seventeenth aspects, an aberration that occurs when the aberration correction element makes light of a different wavelength incident on the objective lens. It is an element which correct | amends.

  The invention according to claim 19 is the optical element for optical pickup according to any one of claims 1 to 18, wherein the objective lens and the holder are integrally formed of a synthetic resin. To do.

  The invention according to claim 20 is the optical element for optical pickup according to any one of claims 1 to 10, 15 to 19, wherein the aberration correction element and the holder are integrally formed of a synthetic resin. It is a special removal.

  Furthermore, the invention of an optical pickup according to a twenty-first aspect that achieves the above object is characterized in that the optical element for an optical pickup according to any one of the first to twentieth aspects is mounted.

  According to the present invention, in an optical element for an optical pickup having an objective lens that focuses a light beam, an aberration correction unit that corrects aberrations, and a holder that fixes them, the light beam that the aberration correction unit is provided on the holder passes. Therefore, since the aberration correction element that does not completely cover the hole is included, it can be easily assembled with high accuracy and good optical characteristics can be ensured. Further, by mounting this optical element for an optical pickup on the optical pickup, the performance of the optical pickup can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
1 to 7 show a first embodiment of the present invention. FIG. 1 and FIG. 2 are perspective views showing an optical element unit set as an optical element for an optical pickup, and FIG. 3 is an exploded perspective view. 4 is a top view, FIG. 5 is a cross-sectional view taken along the line AA in FIG. 4, FIG. 6 is a partial top view of the optical pickup on which the optical element unit set of the present embodiment is mounted, and FIG. It is a conceptual diagram of the optical pick-up shown with a BB cross section.

  6 and 7, a holder 51 made of a synthetic resin such as a liquid crystal polymer has an objective lens 1, an aberration correction element 2 as aberration correction means, and an optical element for an optical pickup having a lens barrel 6 as a holder. The element unit set 10 is bonded and fixed. The optical element unit set 10 will be described in detail later. Focus coils 52 a and 52 b and tracking coils 53 a to 53 d are bonded to the holder 51. Also, one end of four wire springs 54a to 54d (54a not shown) made of beryllium copper is bonded to the holder 51. Further, one end of wire springs 54a to 54d and terminals of focus coils 52a and 52b and tracking coils 53a to 53d are connected to the substrates 55a and 55b fixed to the holder 51 (terminals are not shown).

  The other ends of the wire springs 54a to 54d are bonded to the spring spacer 56, whereby the holder 51 is supported so as to be movable in the vertical direction (Z direction) and the radial direction (X direction) of the recording medium 59 via the wire springs 54a to 54d. Will be. A substrate 57 is fixed to the spring pocket 56, and the other ends of the wire springs 54 a to 54 d are soldered to the substrate 57. The wire springs 54a to 54d are further connected to an external electric circuit via a flexible substrate (not shown). The spring bush 56 is fixed to a bent up part 61 a of an iron base 58. Magnets 62a and 62b for generating a magnetic field are also fixed to the bending rising portions 61a and 61b. The mechanism for moving the optical element assembly 10 assembled on the base 58 is referred to as the lens actuator 60. In FIG. 7, only this lens actuator 60 is shown by the BB cross section of FIG. 6, and other optical components etc. are shown as conceptual diagrams.

  Next, the optical element unit set 10 will be described in detail with reference to FIGS.

  An objective lens 1 and an aberration correction element 2 are bonded and fixed to a lens barrel 6 made of a synthetic resin such as a liquid crystal polymer containing carbon fibers. The objective lens 1 is made of glass, and is a lens optimized for a recording medium having a cover glass thickness of 0.1 mm, a wavelength of 405 nm, and a numerical aperture of 0.85. The aberration correction element 2 is made of synthetic resin, and an annular diffraction grating is formed in the central region 3.

  The aberration correction element 2 is an objective lens for a DVD having a cover glass thickness of 0.6 mm, a wavelength of 650 nm, and a numerical aperture of 0.6, and a CD having a cover glass thickness of 1.2 mm, a wavelength of 780 nm, and a numerical aperture of 0.45. Since 1 is not optimized and an aberration occurs, the aberration is corrected by a diffraction grating using a difference in diffraction due to a difference in wavelength.

  As shown in FIGS. 3 and 5, the lens barrel 6 has a hole 14 through which light passes from the aberration correction element 2 to the objective lens 1, and the objective lens 1 is shown in FIGS. 2 and 5. Further, it is bonded to the lens barrel 6 so as to completely cover the hole portion 14.

  On the other hand, as shown in FIG. 4, when viewed from the Z direction parallel to the optical axis, the aberration correction element 2 has a rectangular shape, and the hole 14 of the lens barrel 6 has a circular shape. Here, the length of the short side of the aberration correction element 2 is shorter than the diameter of the hole 14 and does not completely cover the hole 14, and there are gaps 4 a and 4 b as shown in FIGS. 1 and 4. The inside of the hole portion 14 is connected to the external space through the gaps 4a and 4b.

  The aberration correcting element 2 has its Z + end face abutted against the Z-end abutting surfaces 11a and 11b of the lens barrel 6, and is fixed along the X and Y directions within the abutting faces 11a and 11b. The position adjustment is performed by being moved, and after the position adjustment is completed, the adhesives 16a and 16 are applied and fixed.

  Convex portions 13 a to 13 d are formed integrally with the lens barrel 6 on the abutting surfaces 11 a and 11 b of the lens barrel 6. The protrusions 13a to 13d do not limit the movement of the aberration correction element 2 in the X direction, but limit the movement amount of the movement in the Y direction. Here, the Y-direction interval 15 of the convex portions 13a to 13d is about 0.5 to 1 mm larger than the Y-direction dimension 3 ′ of the aberration correction element 2, and the aberration correction element 2 is set to Y within this gap. You can also adjust the direction.

  The aberration correction element 2 is moved in position by grasping the side surfaces 5a and 5b in the Y direction with an adjustment jig. The adjustment jig is inserted into the hole 14 in the Z direction from the gaps 4a and 4b and is gripped not only on the Z-side of the side surfaces 5a and 5b but also in the entire Z direction (see FIG. 1 for the side surface 5a). A range 17 shown by hatching.The side surface 5b is a range symmetrical to the range 17). As a result, the aberration correction element 2 can be gripped more firmly than the Z-side alone, and the rigidity of the gripped portion can be increased, so that it can be moved more precisely and the adjustment accuracy can be improved. .

  In the present embodiment, the positions in the Z direction of the Z-end surfaces 12a and 12b of the lens barrel 6 where the aberration correction element 2 is not fixed are the abutting surfaces 11a and 11b where the aberration correction element 2 is fixed. Although they are the same, they need not be the same.

  Next, an optical system other than the optical element unit set 10 will be described along an optical path from the laser diode 63 that emits laser light having a wavelength of 405 nm to the optical element unit set 10 with reference to FIG.

  Laser light from the laser diode 63 enters the collimator lens 64. The collimator lens 64 is adjusted in position in the optical axis direction so that incident laser light is emitted as parallel light. The laser light that has passed through the collimator lens 64 passes through a dichroic prism 65 that synthesizes the laser light and laser light having a wavelength of 650 nm, and further passes through a dichroic prism 66 that synthesizes the laser light and laser light having a wavelength of 780 nm. / 4 wavelength plate 68 is joined to polarization beam splitter 67. The laser light emitted from the laser diode 63 follows the above path, and then passes through the relay lens system including the concave lens 69 and the convex lens 70 that slightly converges or diverges the parallel light, and enters the optical element group 10. To reach.

  A part of the laser light emitted from the laser diode 63 is reflected by the polarization beam splitter 67. A photodetector 71 is disposed at a position where the reflected light travels. Further, the return light from the recording medium is reflected by the polarization beam splitter 67 and reaches the photodetector 73 via the condenser lens 72.

  In addition to the laser diode 63, a laser diode 74 that emits laser light having a wavelength of 650 nm and a laser diode 76 that emits laser light having a wavelength of 780 nm are also arranged.

  Laser light having a wavelength of 650 nm from the laser diode 74 is incident on the collimator lens 75. The collimator lens 75 is adjusted in position in the optical axis direction so that incident laser light is emitted as parallel light. The laser light that has passed through the collimator lens 75 is incident on the dichroic prism 65 that combines the laser light and the laser light having a wavelength of 405 nm and is reflected. Thereafter, the laser beam having a wavelength of 405 nm follows the same optical path and reaches the optical element unit set 10.

  Laser light having a wavelength of 780 nm from the laser diode 76 enters the collimator lens 78 via the grating 77 in order to detect a tracking error by the three-beam method. The collimator lens 78 is adjusted in position in the optical axis direction so that incident laser light is emitted as parallel light. The laser light that has passed through the collimator lens 78 is incident on the dichroic prism 66 that combines the laser light, the laser light having a wavelength of 405 nm, and the laser light having a wavelength of 650 nm, and is reflected. Thereafter, the laser beam having a wavelength of 405 nm follows the same optical path and reaches the optical element unit set 10.

  The photodetector 71 and the photodetector 73 are shared by all wavelengths. In addition, each of the optical elements described above is fixed to a housing (not shown) via an appropriate holder or mounting plate.

  Next, the operation of the embodiment configured as described above will be described.

  When a recording medium 59 corresponding to a laser beam having a wavelength of 405 nm is used, the laser diode 63 is caused to emit light. The laser light emitted from the laser diode 63 enters the collimator lens 64 to be converted into parallel light, and passes through the dichroic prisms 65 and 66, the polarization beam splitter 67, the quarter wavelength plate 68, and the relay lenses 69 and 70. Then, a spot is formed on the recording medium 59 by the objective lens 1 through the aberration correction element 2 of the optical element group 10.

  Part of the laser light incident on the polarization beam splitter 67 is reflected and received by the photodetector 71, and the light emission amount of the laser diode 63 is adjusted based on the output.

  The reflected light (returned light) from the recording medium 59 passes through the objective lens 1 again, and reaches the polarization beam splitter 67 along a path opposite to the forward path. Here, the return light is reflected and received by the photodetector 73 through the condenser lens 72, and the focus error, tracking error and recording signal are detected based on the output. Further, spherical aberration is also detected.

  When a focus error is detected, the holder 51 is driven in a direction perpendicular to the recording medium 59 by passing a current through the focus coils 52a and 52b. When a tracking error is detected, current is passed through the tracking coils 53a to 53d to drive the holder 51 in a direction crossing the track of the recording medium 59. When the recording medium 59 is a disk, it is driven in the radial direction. Further, when accessing different tracks, the holder 51 together with the housing is driven in a direction crossing the track of the recording medium 59 by a driving means (not shown). As described above, the holder 51 and the optical element group 10 fixed thereto are subjected to focus control, tracking control, and access control.

  When the spherical aberration generated due to the variation in the cover glass thickness of the recording medium 59 is detected, the lens 69 and / or 70 constituting the relay lens system is driven to correct the spherical aberration. In this method, by moving the lens 69 and / or 70, the convergence / divergence of light that is originally parallel light incident on the optical element unit set 10 is changed, and spherical aberration that changes thereby is used.

  In the present embodiment, the aberration correction element 2 does not completely cover the hole 14 through which the light beam provided in the lens barrel 6 that fixes the relative position between the aberration correction element 2 and the objective lens 1 passes. 4b, an adjustment jig or device for holding the aberration correction element 2 and fixing it to the lens barrel 6 by using a part of the gap 4a, 4b can be used. The aberration correction element 2 can be well fixed to the lens barrel 6. In addition, since the aberration correction element 2 can be easily grasped with an adjustment jig or device, the workability of assembling the optical element can be improved. Thereby, it is possible to obtain an optical element with high accuracy and good workability.

  Further, since the hole portion 14 is not sealed, moisture does not accumulate inside, and it is possible to avoid problems such as dew condensation or to perform cleaning by blowing air to the hole portion 14.

  In the present embodiment, the aberration correction element 2 is applied to the application surfaces 11a and 11b of the lens barrel 6 in a direction parallel to the optical axis, and the position is adjusted in the X and Y directions along the surfaces. . As a result, variations due to dimensional tolerances of components can be absorbed, and an optical element with higher accuracy and better performance can be obtained. For this fine adjustment, it is necessary to pick the aberration correction element 2 with high accuracy and high rigidity. However, by providing the gaps 4a and 4b, the surrounding space is widened. The degree of freedom is increased, and the effect is demonstrated more.

  Further, since the convex portions 13 a to 13 d are provided on the lens barrel 6 to limit the adjustment movement amount of the aberration correction element 2, the deviation amount when the aberration correction element 2 is first placed on the lens barrel 6 is reduced. Therefore, the workability is improved by shortening the adjustment time.

  Note that various roles can be considered for the objective lens 1 and the aberration correction element 2. In the present embodiment, an optical element for three wavelengths has been described, but it may be for two wavelengths or one wavelength. In the case of dealing with a plurality of wavelengths, it is necessary to increase the positional accuracy between the objective lens 1 and the aberration correction element 2, so that the present invention can be effectively applied and the effect is great.

  Further, even in the case of supporting one wavelength, for example, when the objective lens 1 is made to correspond to a recording medium having a cover glass thickness of 0.1 mm, a wavelength of 405 nm, and a numerical aperture of 0.85, the wavelength is short and the numerical aperture is large. When the aberration correction element 2 has a role of correcting the chromatic aberration due to the decreasing wavelength of the laser diode, it is necessary to increase the positional accuracy between the objective lens 1 and the aberration correction element 2, and thus the present invention is effective. The effect is great.

  Various combinations of cover glass, wavelength, and numerical aperture can be considered. For example, it may correspond to a recording medium having a cover glass thickness of 0.6 mm, a wavelength of 405 nm, and a numerical aperture of 0.65. However, the smaller the cover glass thickness, the shorter the wavelength, and the larger the numerical aperture, the smaller the optical tolerance, the greater the need for the aberration correction element 2, and the higher accuracy in mounting the aberration correction element 2. Therefore, the effects of the present invention can be further exhibited. In particular, when the numerical aperture is 0.75 or more, such as the numerical aperture 0.85 as in the present embodiment, the required accuracy is extremely high, and the effect of the present invention is also enhanced.

  In the optical pickup, the performance can be improved by providing the optical element unit set 10 having the objective lens 1 having the above characteristics, the aberration correction element 2, and the lens barrel 6.

(Second Embodiment)
FIGS. 8 and 9 show a second embodiment of the present invention. FIG. 8 is a perspective view of an optical element unit set as an optical element for an optical pickup, and FIG. 9 is a top view thereof. The same parts as those in the first embodiment are denoted by the same reference numerals.

  In the present embodiment, the shape of the lens barrel 6 is different from that of the first embodiment. That is, the Z-end surface 18 of the lens barrel 6 is a simple flat surface, and the convex portions 13a to 13d are not provided. The aberration correction element 2 is adjusted in the X direction and the Y direction along the surface 18, and is fixed to the lens barrel 6 with adhesives 16a and 16b. Other configurations and operations are substantially the same as those in the first embodiment.

  Also in the present embodiment, the aberration correction element 2 does not completely cover the hole 14 through which the light beam provided in the lens barrel 6 that fixes the relative position of the aberration correction element 2 and the objective lens 1 passes. Since the gaps 4a and 4b exist, it is possible to use an adjustment jig or device for holding the aberration correction element 2 and fixing it to the lens barrel 6 by using a part of the gaps 4a and 4b. The aberration correction element 2 can be fixed to the lens barrel 6 with high accuracy. In addition, since the aberration correction element 2 can be easily grasped with an adjustment jig or apparatus, assembly workability can also be improved.

  Further, since the surface 18 of the lens barrel 6 has no projection, the shape of the lens barrel 6 can be simplified and the cost can be reduced, and the accuracy of the surface 18 can be easily improved. The degree of freedom in designing jigs and devices increases, and assembly accuracy and workability can be improved.

(Third embodiment)
FIGS. 10 and 11 show a third embodiment of the present invention. FIG. 10 is a perspective view of an optical element unit set as an optical element for an optical pickup, and FIG. 11 is a top view thereof. The same parts as those in the first embodiment are denoted by the same reference numerals.

  This embodiment also differs from the first embodiment in the shape of the lens barrel 6. That is, as shown in FIG. 10, a concave portion 21a (shown by a broken line because it is a hidden portion) is provided in the Z-end surface 20a of the lens barrel 6. Similarly, the surface 20b is also provided with a recess 21b (not shown).

  As shown in FIG. 11, the distance 25 between the surfaces 22a and 22b facing the X direction of the recesses 21a and 21b is several μm larger than the distance 8 between the X direction both end faces 7a and 7b of the aberration correction element 2 shown in FIG. It has become. Similarly, the distance 26 between the surfaces 23a and 23b and the surfaces 24a and 24b facing the Y direction of the recesses 21a and 21b shown in FIG. 11 is the distance between the Y direction both end surfaces 5a and 5b of the aberration correction element 2 shown in FIG. It is several μm larger than the distance 9.

  As a result, the region formed by the recesses 21a and 21b is slightly larger than the aberration correction element 2, and the aberration correction element 2 is accommodated in this portion and is fixed by adhesion. The adhesive is applied between the recesses 21 a and 21 b and the aberration correction element 2. At this time, the position of the aberration correction element 2 is not adjusted in the X and Y directions, but is positioned by the recesses 21a and 21b.

  Further, the surfaces 19a and 19b between the surfaces 20a and 20b of the lens barrel 6 have a shape having a step with the surfaces 20a and 20b in the Z + direction, and do not overlap the aberration correction element 2 in the Z direction. . Thereby, the space around the surfaces 5a and 5b of the aberration correction element 2 is widened, and it becomes easy to grip the aberration correction element 2 with an adjustment jig or device. Of course, depending on the jig for adjustment and the configuration of the apparatus, the step between the surfaces 20a and 20b and the surfaces 19a and 19b may partially overlap the aberration correction element 2 in the Z direction, or the surfaces 20a and 20b. , 19a, 19b may be the same plane. Other configurations and operations are substantially the same as those in the first embodiment.

  In the present embodiment, since the aberration correction element 2 is positioned in the X direction and the Y direction by the recesses 21a and 21b, adjustment of these directions can be made unnecessary. Here, the mounting accuracy of the aberration correction element 2 is determined by the dimensional difference between the recesses 21a and 21b and the aberration correction element 2, but this may be determined from an allowable amount such as optical performance, for example, less than 10 μm. Is desirable.

  In this embodiment, the dimensions of the recesses 21a and 21b are made larger than the dimensions of the aberration correction element 2, but conversely, they may be made smaller and fixed so as to press-fit the aberration correction element 2. By doing so, there is no shift due to the dimensional difference, and the accuracy can be further increased. Also in this case, if the dimensional difference is large, the aberration correction element 2 is bent at the time of fixing and the optical performance is deteriorated. Therefore, the dimensional difference between the aberration correction element 2 and the recesses 21a and 21b is set to, for example, less than 10 μm, It is desirable to do.

  In this embodiment, the concave portion 21a, 21b is provided in the lens barrel 6 and the aberration correction element 2 is fixed. However, a convex portion is provided instead of the concave portion 21a, 21b to fix the aberration correction element 2. It goes without saying that it is good.

  According to the present embodiment, the position of the aberration correction element 2 is not adjusted, but a hole through which a light beam provided in the lens barrel 6 that fixes the relative position between the aberration correction element 2 and the objective lens 1 passes. 14, the aberration correction element 2 is not completely covered, and the gaps 4a and 4b exist. Therefore, the aberration correction element 2 is grasped by using that part, for example, a part thereof is inserted into the gaps 4a and 4b. A fixing jig or device for fixing can be used. As a result, the aberration correction element 2 can be easily grasped, so that the assembling workability is improved, and assembly errors such as the aberration correction element 2 not being completely dense with the recesses 20a and 20b are prevented. Accuracy can also be improved.

  In addition to the positioning in the X direction and the Y direction, the Z direction may be adjusted using the recesses 21a and 21b as guides. In this case, the aberration correction element 2 can be easily grasped, so that the effect of improving the assembly accuracy can be further exhibited.

(Fourth embodiment)
12 to 15 show a fourth embodiment of the present invention. FIG. 12 is a perspective view of an optical element unit set as an optical element for an optical pickup, FIG. 13 is an exploded perspective view, and FIG. 14 is a top view. 15 is a cross-sectional view of the abutting surface 27 of FIG. Also in the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals.

  The optical element group 10 of the present embodiment is greatly different from the first embodiment in shape. That is, as shown in FIG. 13, the objective lens 1 is bonded and fixed to the lens barrel 6, and the objective lens 1 is bonded so as to completely cover the hole portion 14 as in the first embodiment. However, as shown in FIGS. 12 to 14, the aberration correction element 30 as the aberration correction means has a circular shape as viewed from the Z direction parallel to the optical axis, instead of a rectangular shape. As in the first embodiment, the annular diffraction grating is formed in the central region 31.

  In order to fix the aberration correction element 30, the lens barrel 6 is provided with an abutting surface 27 in the Z direction and a cylindrical side surface 28 in contact with the outer periphery. Here, as shown in FIG. 14, the diameter 35 of the surface 28 is several μm larger than the diameter 32 of the aberration correction element 30 shown in FIG.

  As shown in FIG. 13, the cylindrical side surface 28 does not exist over the entire circumference, and has notches 29a and 29b at two locations on both sides in the X direction. The shape of the notches 29a and 29b will be described in detail in the notch 29b.

  The X-direction end surface 36 of the notch 29b is located outside the circle formed by the surface 28. Further, the Z-direction end surface 33 is located on the Z + side from the abutting surface 27. The notch 29 b is connected to the hole 14. The notch 29a has a similar shape. The hole portion 14 is widened at the Z-end by the notches 29a and 29b.

  Thus, since the surfaces 36 of the notches 29 a and 29 b are outside the circle formed by the surface 28, these portions are not covered with the aberration correction element 30. Therefore, as illustrated in FIG. 15, gaps 34a and 34b are generated by the notches 29a and 29b between the lens barrel 6 and the region 32 where the aberration correction element 30 exists (in FIG. 15, the region is shown for simplicity). 32 and detailed shapes in the gaps 34a and 34b are not shown). FIG. 15 is a cross section of the abutting surface 27 as viewed from the Z direction parallel to the optical axis of the aberration correction element 30, but the optical axis passes through the aberration correction element 30 in the Z-direction. The same applies if the cross section is taken on a vertical plane.

  Further, since the surface 33 of the notches 29a and 29b is on the Z + side with respect to the abutting surface 27, the gaps 34a and 34b are connected to the hole 14 even when the aberration correction element 30 is attached to the lens barrel 6. Yes.

  Also in the present embodiment, like the gaps 4a and 4b of the first embodiment, an adjustment jig or device is arranged in the gaps 34a and 34b, and the aberration correction element 30 is gripped and bonded to the lens barrel 6. Fix it. At this time, the positioning of the aberration correction element 30 in the X direction and the Y direction uses the fact that the diameter 35 of the surface 28 is several μm larger than the diameter 32 of the aberration correction element 30 as in the third embodiment. And positioning at this part. The Z direction is performed by applying the aberration correction element 30 to the application surface 27 as described above. Other configurations and operations are substantially the same as those in the first embodiment.

  In the present embodiment, the aberration correction element is formed by the notches 29a and 29b connected to the hole part 14 through which the light beam is provided in the lens barrel 6 that fixes the relative position between the aberration correction element 30 and the objective lens 1. 30 is not completely covered and there are gaps 34a and 34b. For this purpose, for example, a part of the gaps 34a and 34b are inserted into the gaps 34a and 34b. A jig or device can be used. As a result, the aberration correction element 30 can be easily grasped, so that the assembly workability is improved, and an assembly error such as the aberration correction element 30 not being completely in close contact with the abutting surface 27 in the Z direction can be prevented. Can be improved.

  Note that the aberration correction element 30 is not circular when viewed from a direction parallel to the optical axis, and is provided with a notch as in the present embodiment, even if it is rectangular as in the first embodiment. Needless to say, the hole shape can be adapted.

(Fifth embodiment)
FIGS. 16 to 21 show a fifth embodiment of the present invention. FIG. 16 is a perspective view of an optical element set as an optical element for an optical pickup, FIG. 17 is an exploded perspective view, and FIG. 19 is a sectional view taken along the line CC in FIG. 18, FIG. 20 is a sectional view taken along the line DD in FIG. 19, and FIG. 21 is a sectional view taken along the line EE in FIG. Also in the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals.

  As shown in FIGS. 16 to 19, the present embodiment is different from the first embodiment in that the aberration correction correction means includes two aberration correction elements 2 and 37. Further, as shown in FIG. 16, the abutting surfaces 11a and 11b and the surfaces 12a and 12b at the Z-end of the lens barrel 6 are shifted in the Z direction by more than the thickness of the aberration correcting element 2, The aberration correction element 2 is fixed to the surfaces 11a and 11b, and the aberration correction element 37 is fixed to the surfaces 12a and 12b.

  As described in the first embodiment, the aberration correction element 2 corrects the aberration caused by the difference in wavelength by using the difference in diffraction at the diffraction grating due to the difference in wavelength, and supports a plurality of wavelengths. Is to do. The other aberration correction element 37 is a diffraction grating having characteristics opposite to the change in the refraction angle due to the wavelength in the objective lens 1 and corrects chromatic aberration due to the wavelength variation of the laser diode. That is, as described in the modification of the first embodiment, the occurrence of chromatic aberration due to the wavelength variation of the laser diode cannot be ignored when the wavelength is short, and there is no problem at the wavelength of 650 nm, but it is a problem at the wavelength of 405 nm. In order to improve the characteristics at the wavelength of 405 nm, an aberration correction element 37 is added.

  The fixing of the objective lens 1 and the aberration correction element 2 to the lens barrel 6 is almost the same as in the first embodiment. As shown in FIG. 21, the aberration correction element 2 is in the region 43 and does not completely cover the hole portion 14, and there are gaps 45 a and 45 b as in the first embodiment. Although the aberration correction element 2 is located deeper than the Z-side of the lens barrel 6, the aberration correction element 2 can be easily grasped by the gaps 45a and 45b, thereby improving the workability of the aberration correction element 2. The lens barrel 6 can be adjusted and fixed with high accuracy.

  The aberration correction element 37 is fixed to the Z-side surfaces 12a and 12b from the aberration correction element 2. Like the aberration correction element 2, the aberration correction element 37 has a rectangular shape when viewed from a direction parallel to the optical axis, but is arranged so that its longitudinal direction is orthogonal to the longitudinal direction of the aberration correction element 2. ing. Other than that, it is fixed similarly to the aberration correction element 2. That is, the convex portions 13a to 13d do not limit the movement of the aberration correction element 37 in the Y direction, but restrict the movement in the X direction, contrary to the aberration correction element 2. Here, similarly to the relationship between the Y-direction dimension 3 ′ of the aberration correction element 2 and the Y-direction interval 15 of the protrusions 13 a to 13 d, the X-direction dimension 40 of the aberration correction element 37 is the X direction of the protrusions 13 a to 13 d. It is smaller than the interval 41 by about 0.5 to 1 mm. The aberration correction element 37 can also be adjusted in the X direction within this gap. The aberration correction element 37 has a diffraction grating formed in a region 38 shown in FIGS.

  As shown in FIG. 20, the aberration correction element 37 is in the region 42, does not completely cover the hole portion 14, and there are gaps 44 a to 44 d. In addition, gaps 46 a and 46 b are widened in the Z-direction of the aberration correction element 2.

  When the aberration correction element 37 is adjusted, the side surfaces 47a and 47b in the X direction shown in FIGS. 16 to 18 are firmly held by the adjustment jigs and devices using the gaps 44a to 44d, 46a and 46b. The position is moved. Accordingly, the rigidity of the gripped portion is increased, so that it can be moved more precisely and the adjustment accuracy can be improved. After the adjustment, as shown in FIG. 16 and FIG. 18, it is fixed to the lens barrel 6 with adhesives 39a and 39b.

  In assembling the optical element unit set 10, first, the objective lens 1 is fixed to the lens barrel 6, then the aberration correction element 2 is adjusted and fixed in accordance with the objective lens 1, and finally the objective lens 1. The aberration correction element 37 is adjusted and fixed in accordance with the aberration correction element 2.

  The aberration correction element 2 can be grasped by inserting a jig using the gaps 44a to 44d shown in FIG. 20 in a state where the aberration correction element 37 is present. Since it can be grasped using 46a and 46b, the aberration correction elements 2 and 37 can be grasped simultaneously. Therefore, the aberration correction elements 2 and 37 may be adjusted and fixed at the same time instead of being adjusted and fixed in order. Thus, if it adjusts simultaneously, adjustment accuracy can be raised more. In this case, as can be seen from FIG. 16 and FIG. 18, the adhesives 16a, 16b, 39a, 39b do not overlap when viewed from the Z direction, so that the adhesive fixation can be performed without any problem. Other configurations and operations are substantially the same as those in the first embodiment.

  In the present embodiment, both the aberration correction elements 2 pass through the hole 14 through which the light beam provided in the lens barrel 6 that fixes the relative position between the two aberration correction elements 2 and 37 and the objective lens 1 passes. , 37 are not completely covered and there are gaps 44a to 44d, 45a, 45b, 46a, 46b. An adjustment jig or device fixed to 6 can be used. Thereby, the aberration correction elements 2 and 37 can be fixed to the lens barrel 6 with high accuracy, and the assembly workability is also improved.

  In this embodiment, the aberration correction means is composed of two aberration correction elements. However, the present invention can be effectively applied even when the aberration correction means is composed of three or more aberration correction elements. Further, it is also possible not to completely cover the hole portions of all the aberration correction elements but to completely cover the hole portions of some of the aberration correction elements. In other words, if the number of aberration correction elements increases, the shape of the lens barrel may become complicated if the holes are not completely covered for all aberration correction elements. It is desirable that the hole portion is not completely covered only with respect to a simple aberration correction element because the configuration becomes simple.

  In this embodiment, since the aberration correction elements 2 and 37 are arranged so that there is a portion that does not overlap when viewed from a direction parallel to the optical axis, as described above, the gaps 44a to 44d and 46a. 46b can be used to grasp the aberration correction element 2 on the back side, and simultaneously adjust the position of both aberration correction elements 2 and 37, thereby improving the adjustment accuracy and providing a high-performance optical element. It can be.

  When a plurality of aberration correction elements are provided, it is not necessary to have portions that do not overlap with each other, and it is only necessary that the aberration correction elements to be adjusted do not overlap at the same time. If the aberration correction element has a rectangular shape when viewed from a direction parallel to the optical axis as in the present embodiment, the longitudinal direction is not parallel but is arranged with an angle. This is desirable when considering the shape of the entire element and the lens barrel. If there are two symmetrical aberration correction elements, it is preferable to make the longitudinal direction orthogonal as in the present embodiment, since the overall shape becomes uniform.

(Sixth embodiment)
22 to 27 show a sixth embodiment of the present invention. FIG. 22 is a perspective view of an optical element unit set as an optical element for an optical pickup, FIG. 23 is an exploded perspective view, and FIG. 25 is a sectional view taken along line FF in FIG. 24, FIG. 26 is a sectional view taken along line GG in FIG. 25, and FIG. 27 is a sectional view taken along line HH in FIG. In the present embodiment, the same parts as those in the fifth embodiment are denoted by the same numbers.

  As shown in FIGS. 22 to 24, this embodiment differs from the fifth embodiment in that the two aberration correction elements 2 and 37 constituting the aberration correction means are viewed from a direction parallel to the optical axis. Sometimes it is not rectangular but square.

  A convex portion 48 is provided on the outer peripheral portion of the lens barrel 6. Using this convex portion 48, the optical element unit set 10 is fixed to the holder 51 described in the first embodiment. Thus, by providing the convex part 48, it can fix to the holder 51 more firmly. In addition, by performing positioning in the Z direction with the convex portion 48, the mounting accuracy can be further increased depending on the shape of the holder 51. The fixing of the objective lens 1 to the lens barrel 6 is almost the same as in the first embodiment.

  The aberration correction element 2 is fixed to the abutting surfaces 11 a to 11 d provided in a concave shape from the surface 13 at the Z-end of the lens barrel 6. The abutting surfaces 11a to 11d are on the same plane. In the aberration correction element 2, the amount of movement along the abutting surfaces 11 a to 11 d is limited by a surface parallel to the optical axis connecting the abutting surfaces 11 a to 11 d and the surface 13. Here, the dimensions 3a and 3b of the square part of the aberration correction element 2 (3a = 3b because it is a square) are the distance 15a between the surfaces parallel to the optical axis connecting the abutting surfaces 11a to 11d and the surface 13 where the aberration correction elements 2 fit. , 15b is about 0.5 to 1 mm smaller. The position of the aberration correction element 2 can be adjusted along the abutting surfaces 11a to 11d within this gap.

  As shown in FIG. 27, the aberration correction element 2 is in a region 43 deeper than the Z-side of the lens barrel 6, does not completely cover the hole portion 14, and there are gaps 45a to 45d. With the gaps 45a to 45d, the side surfaces 5a to 5d of the aberration correction element 2 shown in FIG. 23 can be easily grasped with an adjustment jig or the like, and adjustment and fixing can be performed with high workability and high accuracy. . After the adjustment is completed, the abutting surfaces 11a to 11d are filled with an adhesive and fixed.

  The aberration correction element 37 is fixed to the surfaces 12 a to 12 d provided in a concave shape with respect to the Z-side surface 13 of the lens barrel 6 on the Z-side from the aberration correction element 2. The aberration correction elements 2 and 37 have a square shape when viewed from a direction parallel to the optical axis, but are arranged so that their sides intersect at 45 degrees. Other than this, it is fixed similarly to the aberration correction element 2.

  The surfaces 12a to 12d are on the same plane, and the aberration correction element 37 is limited in the amount of movement along the surfaces 12a to 12d by a surface parallel to the optical axis connecting the surfaces 12a to 12d and the surface 13. Here, the dimensions 40a and 40b of the square part of the aberration correction element 37 (40a = 40b because it is a square) are the distances 41a and 41b between the surfaces parallel to the optical axis connecting the surfaces 12a to 12d and the surface 13 in which they are accommodated. It is smaller by about 0.5 to 1 mm. The position of the aberration correction element 37 can be adjusted along the surfaces 12a to 12d within this gap.

As shown in FIG. 26, the aberration correction element 37 is in the collar region 42, does not completely cover the hole 14, and there are gaps 44a to 44h. In addition, gaps 46 a to 46 d are widened in the Z-direction of the aberration correction element 2.

  The aberration correction element 37 is moved in position by grasping the side faces 47a to 47d shown in FIG. 23 with an adjustment jig or the like using the gaps 44a to 44h and 46a to 46d. By using the gaps 44a to 44h and 46a to 46d in this way, the aberration correction element 37 can be firmly gripped and the rigidity of the gripping portion can be increased, so that it can be moved more precisely and adjustment accuracy can be improved. Can be improved. After the adjustment, the surfaces 12a to 12d are filled with an adhesive so as to be fixed to the lens barrel 6.

  The order of adjustment is the same as that of the fifth embodiment. Similarly, the aberration correction elements 2 and 37 may be adjusted simultaneously using the gaps 44a to 44h shown in FIG. Other configurations and operations are substantially the same as those in the first embodiment.

  Also in the present embodiment, both the aberration correction elements are provided with holes 14 through which light beams provided in the lens barrel 6 that fixes the relative positions of the two aberration correction elements 2 and 37 and the objective lens 1 pass. 2 and 37 are not completely covered, and there are gaps 44a to 44h, 45a to 45d, and 46a to 46d. An adjustment jig or device fixed to the cylinder 6 can be used. Thereby, the aberration correction elements 2 and 37 can be fixed to the lens barrel 6 with high accuracy, and the assembly workability can be improved.

  In the fifth embodiment, the aberration correction elements 2 and 37 are rectangular when viewed from the direction parallel to the optical axis. In the embodiment, since it has a square shape, the sides are not parallel but have an angle. In the case where two square aberration correction elements 2 and 37 are used as in the present embodiment, it is desirable that the side be 45 degrees.

  The present invention is not limited to the above-described embodiment, and various modifications or changes can be made. In particular, the configuration of the aberration correction element can be variously modified. For example, the diffraction grating provided in the aberration correction element can be provided on both sides instead of one side. However, since the center position can be adjusted by using two aberration correction elements having diffraction gratings on one side rather than using an aberration correction element having diffraction gratings on both sides, the accuracy can be further improved. . Of course, if the accuracy of the aberration correction element is high, there is no problem if a diffraction grating is provided on both sides, and a plurality of aberration correction elements provided with diffraction gratings on both sides may be used.

  Further, the aberration correction element does not have to have a rectangular shape, a square shape, or a circular shape as viewed from a direction parallel to the optical axis, and may have a circular shape having a convex portion.

  Furthermore, the objective lens, the aberration correction element, and the lens barrel that fixes the relative position thereof are not separate components, and the objective lens and the lens barrel are integrally formed of synthetic resin, or conversely, aberration correction. The element and the lens barrel can be integrally formed of a synthetic resin.

It is a perspective view which shows the optical element part group which is an optical element for optical pick-ups concerning 1st Embodiment of this invention. Similarly, it is a perspective view of an optical element part set. Similarly, it is an exploded perspective view. Similarly, it is a top view. It is AA sectional drawing of FIG. It is a partial top view of the optical pick-up which mounts the optical element part group of 1st Embodiment. It is a conceptual diagram of the optical pick-up which shows one part in the BB cross section of FIG. It is a perspective view of the optical element part group which is an optical element for optical pick-ups concerning a 2nd embodiment of the present invention. Similarly, it is a top view. It is a perspective view of the optical element part group which is an optical element for optical pick-ups concerning a 3rd embodiment of the present invention. Similarly, it is a top view. It is a perspective view of the optical element part group which is an optical element for optical pick-ups concerning a 4th embodiment of the present invention. Similarly, it is an exploded perspective view. Similarly, it is a top view. It is sectional drawing which looked at the abutting surface 27 of FIG. 13 from the arrow B direction. It is a perspective view of the optical element part group which is an optical element for optical pick-ups concerning a 5th embodiment of the present invention. Similarly, it is an exploded perspective view. Similarly, it is a top view. It is CC sectional drawing of FIG. It is DD sectional drawing of FIG. It is EE sectional drawing of FIG. It is a perspective view of the optical element part group which is an optical element for optical pick-ups concerning a 6th embodiment of the present invention. Similarly, it is an exploded perspective view. Similarly, it is a top view. It is FF sectional drawing of FIG. It is GG sectional drawing of FIG. It is HH sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Objective lens 2 Aberration correction element 4a, 4b Gap 6 Lens tube 10 Optical element part set 11a-11d Abutting surface 12a-12d Surface 13 surface 13a-13d Convex part 14 Hole 16a, 16b Adhesive 18 surface 19a, 19b surface 20a, 20b surface 21a, 21b recess 22a, 22b surface 23a, 23b surface 24a, 24b surface 27 abutting surface 28 surface 29a, 29b notch 30 aberration correction element 34a, 34b gap 37 aberration correction element 39a, 39b adhesive 44a ~ 44h Clearance 45a ~ 45d Clearance 46a ~ 46d Clearance 48 Projection

Claims (21)

An optical element for an optical pickup, comprising: an objective lens that focuses a light beam; an aberration correction unit that corrects aberration; and a holder that fixes a relative position of the objective lens and the aberration correction unit.
An optical element for an optical pickup, wherein the aberration correction means includes an aberration correction element that does not completely cover a hole portion through which a light beam provided in the holder passes.   When the cross section is taken along a plane perpendicular to the optical axis through the aberration correction element, there is a gap between the aberration correction element and the hole portion through which the luminous flux of the holder passes or the side surface of the space connected to the hole portion. The optical element for an optical pickup according to claim 1, wherein the optical element is present.   The aberration correction element is applied to the holder in a direction parallel to the optical axis, and when the cross section is taken along a plane perpendicular to the optical axis including the attachment surface, the aberration correction element and the light flux of the holder are The optical element for an optical pickup according to claim 1, wherein a gap exists between a hole for passing through or a side surface of a space connected to the hole.   2. The aberration correction means includes a plurality of aberration correction elements, and at least one of the aberration correction elements does not completely cover a hole through which a light beam provided in the holder passes. The optical element for optical pickups as described in any one of -3.   4. The aberration correction means includes a plurality of aberration correction elements, and all of the aberration correction elements do not completely cover a hole through which a light beam provided in the holder passes. An optical element for an optical pickup according to any one of the above.   The aberration correction means includes a plurality of aberration correction elements, and at least two of the aberration correction elements are arranged so as to have portions that do not overlap when viewed from a direction parallel to the optical axis. An optical element for an optical pickup according to any one of claims 1 to 5.   The at least two aberration correction elements are each arranged so that the shape when viewed from a direction parallel to the optical axis is rectangular, and the longitudinal directions thereof are not parallel but have an angle. The optical element for an optical pickup according to claim 6.   The optical element for an optical pickup according to claim 7, wherein the angle is 90 degrees.   The at least two aberration correction elements have a square shape when viewed from a direction parallel to the optical axis, and are arranged so that the sides are not parallel but have an angle. The optical element for an optical pickup according to claim 6.   The optical element for an optical pickup according to claim 9, wherein the angle is 45 degrees.   The holder has an abutting surface that abuts the aberration correction element in a direction parallel to the optical axis, and has a space that enables movement adjustment of the aberration correction element along the abutting surface. The optical element for optical pickups according to any one of claims 1 to 10.   The optical element for an optical pickup according to claim 11, wherein the holder has a convex portion that restricts movement of the aberration correction element along the abutting surface.   The optical element for an optical pickup according to claim 1, wherein the holder has a convex portion or a concave portion that positions the aberration correction element in a direction perpendicular to the optical axis.   The difference between the distance between the wall portions of the holder facing each other for positioning the convex portion or the concave portion and the length of the corresponding portion of the aberration correction element fixed to the portion is less than 10 μm. The optical element for optical pickup according to claim 13.   The optical element for an optical pickup according to claim 1, wherein the numerical aperture of the objective lens is 0.75 or more.   The optical element for an optical pickup according to claim 1, wherein the aberration correction element is a diffraction grating.   The optical element for an optical pickup according to claim 1, wherein the aberration correction element is an element that corrects chromatic aberration due to a wavelength variation of the light beam.   18. The optical pickup optical device according to claim 1, wherein the aberration correction element is an element that corrects an aberration generated when light having a different wavelength is incident on the objective lens. element.   The optical element for an optical pickup according to claim 1, wherein the objective lens and the holder are integrally formed of a synthetic resin.   20. The optical element for an optical pickup according to claim 1, wherein the aberration correcting element and the holder are integrally formed of a synthetic resin.   An optical pickup comprising the optical element for optical pickup according to any one of claims 1 to 20.

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