JP2005129100A - Optical head device, manufacturing method therefor, and information processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately perform centering of an object lens and an aberration compensation element which are used for an optical head device. <P>SOLUTION: In a construction mode in which an aperture 21 is provided in a holding member 7 for the object lens 5 and the aberration compensating element 6, for performing center alignment of the object lens 5 and the aberration compensation element 6, through holes 23 are formed over three or more parts in the holding member 7, so that the external shape of the object lens 5 can be seen from the aberration compensating element 6 side, through the through holes. In another construction mode, an aperture is formed in the aberration compensating element 6, so that the centering of the object lens 5 and the aberration compensation element 6 can be performed accurately. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for accurately performing center alignment between an objective lens and an aberration correction element in application to an apparatus for reproducing and recording information on an optical recording medium.

  In a head device (so-called optical pickup) used for information reproduction and recording on an optical recording medium, an objective lens for irradiating a light spot on an optical disk and an aberration correction element (liquid crystal) for correcting spherical aberration and the like are used. The structure provided with the element etc. is known, and the form which hold | maintained the objective lens and the aberration correction element so that it was integrally movable is mentioned (for example, refer patent document 1).

  For example, the objective lens is attached to one surface of the lens holder, the liquid crystal element is attached to the other surface of the lens holder, and an aperture is provided in the lens holder positioned between the objective lens and the liquid crystal element.

JP 2003-6902 A

  By the way, in the conventional configuration, there is a problem that it is difficult to accurately align the central axis of the objective lens and the central axis of the aberration correction element, or that it takes work time.

  For example, if the central axes of the objective lens and the liquid crystal element are aligned with high accuracy and are not attached to the lens holder, the misalignment of both causes new aberrations. Such center position shift involves both the mounting accuracy of the objective lens with respect to the lens holder and the mounting accuracy of the liquid crystal element with respect to the lens holder. Therefore, it is difficult to sufficiently reduce the error. In other words, since there is an aperture between the objective lens and the liquid crystal element, the center position of the objective lens cannot be confirmed from the liquid crystal element side. Difficult to do. Therefore, when the positional accuracy with respect to the objective lens is not sufficiently ensured with respect to the liquid crystal element provided for aberration correction, this may become a new aberration generation factor and cause a decrease in optical performance or the like.

  Therefore, an object of the present invention is to accurately perform center alignment between an objective lens and an aberration correction element used in an optical head device.

  In order to solve the above-described problems, an optical head device and an information processing device according to the present invention have a configuration shown in the following (I) or (II).

  (I) In order to align the center position of the aberration correction element with the center of the objective lens as viewed from the optical axis direction of the optical system, in the holding member of the objective lens and the aberration correction element, the mounting surface of the objective lens and the aberration correction element Through holes that communicate with the mounting surface are formed at three or more locations, and the outer shape of the objective lens is partially seen from the mounting surface side of the aberration correction element through the through holes.

  (II) An aperture is formed in the aberration correction element, rather than providing an aperture in the objective lens and the aberration correction element holding member.

  Accordingly, in the present invention, in the configuration form (I), the lens center position can be known based on the outer shape of the objective lens recognized from three or more through holes. Further, in the configuration form (II), by providing an aperture in the aberration correction element, it is freed from the problem of mounting accuracy caused by the positioning of the objective lens, the holding member, and the aberration correction element as in the conventional case. As a relative positional relationship between the objective lens and the aberration correction element, it is possible to accurately align the centers of the two.

  The method for manufacturing an optical head device according to the present invention irradiates the objective lens with coherent light from the optical recording medium side in the step of aligning the center of the aberration correction element with the center of the objective lens. The center of the light spot that has passed through the objective lens and focused on the focal point is aligned with the center of the aberration correction element.

  Therefore, according to the present invention, the presence of the aperture provided between the objective lens and the aberration correction element does not affect the accuracy of center alignment.

  According to the optical head device and the information processing device according to the present invention, the center alignment of the objective lens and the aberration correction element can be accurately performed, and the performance of the device can be improved. In addition, it does not require a complicated mechanism or adjustment equipment, which is advantageous in terms of manufacturing cost.

  In the configuration form (I), the optical influence at the time of use of the optical head device can be eliminated by closing the through hole for the purpose of shielding light after the work.

  In the configuration form (II), high positional accuracy can be obtained by using a liquid crystal element as the aberration correction element and forming an aperture with the internal electrode. In the positioning work, the electrode part that defines the aperture is made transparent, and the electrode part that defines the aperture is shielded by energization when used after the work, or the aperture is formed by using a wavelength selective member. Thus, it is possible to prevent the presence of the aperture provided in the aberration correction element from adversely affecting the center alignment operation.

  Further, in the form in which the center alignment mark is formed on the objective lens or the aberration correction element, the respective centers can be easily recognized.

  According to the method for manufacturing an optical head device according to the present invention, the center of the aberration correction element can be aligned with reference to the center of the imaging light spot that has passed through the objective lens, and the work can be performed accurately with simple equipment. It can be performed.

  FIG. 1 shows an example of the configuration of an information processing apparatus according to the present invention. The information processing apparatus 1 uses an optical recording medium 2 to irradiate light and reproduces or records information. 3 is provided. The optical recording medium 2 is, for example, a disk-shaped recording medium such as an optical disk, a magneto-optical disk, or a phase-change disk that is rotated by using a spindle motor 4. Etc. can be applied.

  The optical head device 3 has an objective lens 5 and an aberration correction element 6 for irradiating the optical recording medium 2 with light, and these are attached to a holding member (holder) 7. A movable unit driving means 8 (so-called biaxial actuator) including the holding member 7 is provided, and the movable unit is driven and controlled in a focus direction and a tracking direction with respect to the optical recording medium 2.

  In the optical system shown in this example, the light emitted from the light emitting unit 9 including a laser diode passes through the grating 10 and the polarization beam splitter 11 and then becomes parallel light by the collimator lens 12. Then, light that has passed through the aberration correction element 6 after passing through the quarter-wave plate 13 is irradiated from the objective lens 5 toward the optical recording medium 2.

  The return light reflected by the recording layer of the optical recording medium 2 passes through the objective lens 5, the aberration correction element 6, the quarter wavelength plate 13, and the collimator lens 12 along a path opposite to the forward path, The polarization beam splitter 11 receives an optical path change of 90 °, and reaches the light receiving unit 15 via a lens 14 (so-called multi-lens).

  In this example, a configuration form (so-called discrete type) in which different elements are used for the light emitting unit 9 and the light receiving unit 15 is shown. However, the application of the present invention is not limited to such a configuration, and light emission Needless to say, the present invention can be implemented in various forms such as a configuration using an optical integrated device in which a light receiving part and a light receiving part are packaged.

  The output photoelectrically converted in the light receiving unit 15 is sent to the signal processing unit 16. For example, the output signal is processed by an internal matrix circuit or the like to generate various error signals (tracking error signal, focus error signal, etc.), and these are sent to the servo control unit 17. Further, a reproduction RF (Radio Frequency) signal is subjected to demodulation processing, error correction processing, and the like.

  For example, the signal processing unit 16 detects the amount of time-axis fluctuation (jitter amount) of the reproduction RF signal and sends the result to the aberration correction control unit 18. The aberration correction control unit 18 calculates the control amount of the aberration correction element 6 based on the detection result, and outputs a drive signal corresponding to the calculation result to the aberration correction element 6.

  The servo control unit 17 generates a drive signal to the drive unit 8 based on the error signal and supplies a current to the tracking coil and the focus coil to control the drive of the movable unit of the optical head device 3 or to perform a spindle motor. 4 is performed (note that illustration and description of known components such as a feed mechanism (so-called thread mechanism) of the optical head device 3 are omitted).

  FIG. 2 shows a main part of the configuration example 19 of the optical system of the optical head device 3, and illustrates the configuration form (I) that enables the outer shape of the objective lens 5 to be grasped. The axis “A” in the figure indicates a central axis extending in the optical axis direction through the center of the objective lens 5, and the axis “B” indicates a central axis extending in the optical axis direction through the center of the aberration correction element 6. Show.

  In the objective lens 5 shown in this example, one surface (a surface facing the optical recording medium 2) 5a is a flat surface, and the opposite convex curved surface 5b is a spherical surface or an aspheric surface.

  The holding member (lens holder) 7 is formed with a receiving recess 7a for the objective lens 5. The bottom surface of the holding member 7 is an attachment surface 7b, and the periphery of the objective lens 5 is bonded and fixed. In addition, the surface opposite to the receiving recess 7 a is an attachment surface 7 c for the aberration correction element 6.

  As for the center hole 7d formed in the holding member 7, the portion 20 located on the objective lens 5 side of the inner peripheral surface is tapered, and the inner diameter increases in the upward direction of the figure (in the direction toward the objective lens 5). Has been increased. An aperture 21 is formed by the smallest diameter portion, and a larger diameter portion 22 is formed closer to the aberration correction element 6 than the portion.

  Thus, in the present example, the positional relationship is such that the aperture 21 in the holding member 7 is provided between the objective lens 5 and the aberration correction element 6.

  The holding member 7 is formed with a plurality of through holes 23, 23,... That connect the mounting surface 7 b and the mounting surface 7 c, and a part of the outer shape of the objective lens 5 passes through these through holes. It is comprised so that it can be seen from the attachment surface 7c side. That is, when the center position of the objective lens 5 and the aberration correction element 6 is aligned, it is necessary to grasp the center position of the objective lens 5, but the objective lens 5 is passed through each through hole 23 formed in the holding member 7. The center position of the objective lens 5 can be specified by optically recognizing the outer shape of the objective lens 5 from the aberration correction element 6 side. For example, when the outer shape of the objective lens 5 is circular, if three different positions can be detected, the circle passing through these points is uniquely located, so that the center of the circle can be detected. That is, the outer shape of the objective lens is known, and generally three or more through holes are formed, and the outer periphery of the objective lens can be partially detected through these holes.

  As the aberration correction element 6, for example, a liquid crystal element is used, and a drive signal from the aberration correction control unit 18 is supplied to the connection part (external electrode part) 6a. It is also possible to use a hologram element or the like. In any case, since the center position of the element can be specified with sufficient manufacturing accuracy, the center axis B can be accurately aligned with the center axis A of the objective lens 5 described above.

  After the center of the aberration correction element 5 is positioned with respect to the center of the objective lens 5 and each part is attached to the holding member 7, the light is shielded by closing each through-hole 23. That is, if the through hole 23 is left as it is after assembly, there is a possibility that an adverse optical effect may be a problem. Therefore, the through hole 23 is blocked using a material that is opaque to the light source wavelength of the light emitting unit 9. Is preferred.

  Next, the configuration form (II) will be described.

  FIG. 3 shows a main part of a configuration example 24 of the optical system of the optical head device 3, and illustrates a configuration in which a liquid crystal element is used as the aberration correction element 6.

  In this example, the bottom surface of the receiving recess 7a of the holding member 7 is the mounting surface 7b, and the portion of the objective lens 5 near the periphery is bonded and fixed. Further, the surface opposite to the receiving recess 7a is an attachment surface 7c for the aberration correction element.

  The central hole 7d formed in the holding member 7 has a cylindrical inner surface. The objective lens 5 is fixed to the mounting surface 7b in a state where the convex curved surface 5b of the objective lens 5 is positioned in the center hole 7d (the outer peripheral edge of the convex curved surface 5b is visible from the aberration correction element 6 side).

  When the aperture is provided in the holding member as described above, the center on the optical axis is sufficiently considered in consideration of the mounting error between the objective lens and the aperture and the mounting error between the aberration correction element and the aperture. It is necessary to align, and it is difficult to guarantee the accuracy of work. Thus, by providing the aperture not in the holding member but in the aberration correction element, it is possible to eliminate the adverse effects caused by the relative positioning between the three members.

  About an aperture, the structural form shown below is mentioned, for example.

(II-1) Form using electrode pattern (II-2) Form using wavelength selective member (filter such as dichroic mirror).

  First, in (II-1), when the electrode pattern is formed in the manufacturing process of the aberration correction element, the aperture can be formed together.

  For example, in the case of a liquid crystal element, a circular or annular electrode pattern is formed on a glass substrate using a transparent conductive material. An electrode pattern 26 for forming an aperture 25 at the outer peripheral edge portion is formed on a semiconductor substrate. It can be attached with high positional accuracy by process technology (such as photolithography). Therefore, there is an advantage that the center position of the aperture 25 can be accurately defined in the aberration correction element 6.

  Further, when a liquid crystal element is used as the aberration correction element, the electrode pattern 26 that defines the aperture in the liquid crystal element is assumed to be light transmissive during assembly (not energized), and is energized and shielded when the apparatus is used. It is preferable to configure so as to have an action. That is, in the step of positioning the center of the aberration correction element 6 with respect to the center of the objective lens 5, the electrode portion that defines the aperture 25 is made transparent so that the presence of the aperture does not interfere with the work. When the optical head device assembled after positioning is used, the light transmittance is reduced by energizing the electrode portion that defines the aperture 25, thereby realizing the function as an aperture.

  With regard to the form (II-2), for example, the light is transmitted with respect to the wavelength of light (natural light, light from an illumination light source, etc.) used in the step of positioning the center of the aberration correction element 6 with respect to the center of the objective lens 5. Aberration correction element using a wavelength-selective member (such as a dichroic filter or an interference filter) that has a light-shielding property with respect to the wavelength of a light source (such as the laser light source of the light emitting unit 9) used in the apparatus 6 may be provided (the electrode pattern 26 in FIG. 3 is replaced with a filter). That is, when the center position of the objective lens 5 and the aberration correction element 6 is aligned, the presence of the filter is not optically disturbed when viewed from the aberration correction element 6 side, and the objective lens side can be seen through the filter. Like that. When the optical head device 3 assembled after positioning is used, the filter has a high reflectance or a low transmittance with respect to the wavelength of the light emitting unit 9, and thus the light shielding property is exhibited. Function is realized.

  As described above, in the form (II), by providing the aperture 25 inside the aberration correction element 6, it is only necessary to consider the relative mounting accuracy of the objective lens 5 and the aberration correction element 6. It becomes possible to easily and accurately align the center of the aberration correction element 6 with respect to the objective lens 5 attached to the holding member 7.

  For example, the center position can be detected from the outer peripheral shape of the convex curved surface 5 b of the objective lens 5 as viewed from the aberration correction element 6 side. In order to position the aberration correction element 6 with respect to the objective lens 5 with high accuracy, for example. In the objective lens 5, it is preferable to mark the center of the surface on the aberration correction element 6 side. For example, by forming a concave portion, a convex portion or the like as the alignment mark 27 in the objective lens 5 in advance, optical recognition of the lens center position can be accurately performed. Since such marks (marks) can be formed simultaneously with the lens surface during the mold processing of the objective lens, the center position of the objective lens can be accurately displayed. Further, since this method can be applied to the aberration correction element 6, it is possible to sufficiently guarantee the positioning accuracy between the two by marking the element and aligning the marks of the objective lens and the aberration correction element. Is possible.

  Next, a method for manufacturing an optical head device according to the present invention will be described with reference to FIG.

  The holding member 7 shown in this example is different from the configuration example shown in FIG. 2 in that the through hole 23 is not formed at all, and other matters (the objective lens 5 and the aberration correcting element). There is no fundamental difference in the shape of 6). That is, the objective lens 5 is attached to one attachment surface 7 b of the holding member 7, and the aberration correction element 6 is attached to the other attachment surface 7 c of the holding member 7. An aperture 21 positioned between the objective lens 5 and the aberration correction element 6 is defined by a minimum diameter portion on the inner peripheral surface of the central hole 7d of the holding member 7.

  In the apparatus 28 used in the center alignment process of the objective lens 5 and the aberration correction element 6, a coherent light source (laser light source or the like) 29 is disposed on the optical recording medium side with respect to the objective lens 5, and from the light source Light that is converted into a parallel light beam through an optical element such as a collimator lens 30 is irradiated perpendicularly to the surface 5 a of the objective lens 5.

  The work procedure is as follows.

(1) Attach the objective lens 5 to the holding member 7 and fix it by bonding or the like. (2) When attaching the aberration correction element 6 to the holding member 7, the coherent light source 29 emits light. (3) The objective lens 5 is focused. The center of the light spot and the center of the aberration correction element 6 are aligned. (4) The aberration correction element 6 is positioned and fixed to the holding member 7 by bonding or the like.

  In step (3), the center of the imaging spot transmitted through the objective lens 5 attached to the holding member 7 and the center of the aberration correction element 6 coincide with each other on the common optical axis with accuracy within an allowable range. As described above, adjustment and setting are performed using an effector (such as a robot hand) based on an image recognition process using an imaging device (not shown).

  As described above, the objective lens 5 is irradiated with coherent light from the side facing the optical recording medium, passes through the objective lens 5 and forms an image at the focal point, and the aberration correction element 6. , The aberration correction element 6 can be accurately positioned with respect to the objective lens 5 without being directly affected by the aperture 21 provided between the objective lens 5 and the aberration correction element 6. it can.

  According to each configuration described above, since the center of the aberration correction element can be accurately aligned with respect to the center of the objective lens and attached to the holding member, the center position between the objective lens and the aberration correction element Occurrence of aberration due to deviation can be suppressed. Therefore, as a result of the aberration correction being reliably performed, information reading and recording performance by the optical head device can be improved, and the reliability of the device can be improved.

It is explanatory drawing which shows the apparatus structural example which concerns on this invention. It is a figure which shows the structural example which formed the through-hole in the holding member. It is a figure which shows the structural example which provided the aperture in the aberration correction element, (A) The figure is a schematic diagram which shows a cross-sectional structure, (B) The figure is a schematic diagram of the aberration correction element seen from the optical axis direction. It is explanatory drawing of the manufacturing method of the optical head apparatus based on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Information processing apparatus, 2 ... Optical recording medium, 3 ... Optical head apparatus, 5 ... Objective lens, 6 ... Aberration correction element, 7 ... Holding member, 7b, 7c ... Mounting surface, 21 ... Aperture, 23 ... Through Hole, 25 ... Aperture, 27 ... Mark for alignment

Claims (16)

In an optical head device that includes an objective lens and an aberration correction element and a holding member thereof, and an aperture is provided between the objective lens and the aberration correction element.
In order to position the center of the aberration correction element with respect to the center of the objective lens as viewed from the optical axis direction, there are three or more through-holes communicating the attachment surface of the objective lens and the attachment surface of the aberration correction element. The optical head device is formed on the holding member so that a part of the outer shape of the objective lens can be seen from the aberration correction element side through the through hole. The optical head device according to claim 1,
An optical head device characterized in that the through hole is closed after positioning the center of the aberration correction element with respect to the center of the objective lens. In an optical head device that includes an objective lens and an aberration correction element and a holding member thereof, and an aperture is provided between the objective lens and the aberration correction element.
An optical head device characterized in that the aperture is formed in the aberration correction element. In the optical head device according to claim 3,
The optical head device, wherein the aberration correction element is a liquid crystal element, and the aperture is formed using an electrode. The optical head device according to claim 4,
When the center of the aberration correction element is positioned with respect to the center of the objective lens viewed from the optical axis direction, the electrode that defines the aperture is in a transparent state, and the electrode that defines the aperture is used when used after the positioning. An optical head device characterized in that the transmittance decreases when energized. In the optical head device according to claim 3,
An optical head device characterized in that the aperture is formed using a wavelength selective member. In the optical head device according to claim 3,
An optical head device, wherein an alignment mark for aligning the center of the aberration correction element with the center of the objective lens viewed from the optical axis direction is formed on the objective lens or the aberration correction element. An optical head device comprising an objective lens for irradiating a light spot onto an optical recording medium, an aberration correction element, and a holding member thereof, and an aperture provided between the objective lens and the aberration correction element In the manufacturing method,
In the step of aligning the center of the aberration correction element with the center of the objective lens attached to the holding member, the objective lens is irradiated with coherent light from the optical recording medium side,
A method of manufacturing an optical head device, comprising: aligning a center of a light spot that has passed through the objective lens and formed an image at a focal point thereof with a center of the aberration correction element. An objective lens for irradiating the optical recording medium with a light spot is attached to a holding member, and an aberration correction element is attached to an attachment surface of the holding member opposite to the attachment surface of the objective lens, and the In the optical head device in which an aperture is provided between the objective lens and the aberration correction element,
Among the objective lenses, when the coherent light is irradiated from the optical recording medium side, the center of the imaging spot transmitted through the objective lens and the center of the aberration correction element coincide on the common optical axis. An optical head device, characterized in that In an information processing apparatus for reproducing or recording information on an optical recording medium using an optical component in which an objective lens and an aberration correction element are attached to a holding member and an aperture is provided between the objective lens and the aberration correction element.
In order to position the center of the aberration correction element with respect to the center of the objective lens as viewed from the optical axis direction, there are three or more through-holes communicating the attachment surface of the objective lens and the attachment surface of the aberration correction element. The information processing apparatus is configured to be formed on the holding member so that a part of the outer shape of the objective lens can be seen from the aberration correction element side through the through hole. The information processing apparatus according to claim 10,
An information processing apparatus, wherein the through hole is closed after the center of the aberration correction element is positioned with respect to the center of the objective lens. In an information processing apparatus that performs information reproduction or recording on an optical recording medium using an optical component in which an objective lens and an aberration correction element are attached to a holding member, and an aperture is provided between the objective lens and the aberration correction element.
An information processing apparatus, wherein the aperture is formed in the aberration correction element. The information processing apparatus according to claim 12,
The information processing apparatus, wherein the aberration correction element is a liquid crystal element, and the aperture is formed using an electrode. The information processing apparatus according to claim 13,
When the center of the aberration correction element is positioned with respect to the center of the objective lens viewed from the optical axis direction, the electrode that defines the aperture is in a transparent state, and the electrode that defines the aperture when the apparatus is used after the positioning An information processing apparatus characterized in that the transmittance is reduced by energizing the power. The information processing apparatus according to claim 12,
An information processing apparatus, wherein the aperture is formed using a wavelength selective member. The information processing apparatus according to claim 12,
An information processing apparatus, wherein an alignment mark for aligning the center of the aberration correction element with the center of the objective lens viewed from the optical axis direction is formed on the objective lens or the aberration correction element.

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