WO2011093231A1 - Tête optique et dispositif d'enregistrement/reproduction d'informations optiques - Google Patents

Tête optique et dispositif d'enregistrement/reproduction d'informations optiques Download PDF

Info

Publication number
WO2011093231A1
WO2011093231A1 PCT/JP2011/051180 JP2011051180W WO2011093231A1 WO 2011093231 A1 WO2011093231 A1 WO 2011093231A1 JP 2011051180 W JP2011051180 W JP 2011051180W WO 2011093231 A1 WO2011093231 A1 WO 2011093231A1
Authority
WO
WIPO (PCT)
Prior art keywords
lens
objective lens
information recording
optical
pickup device
Prior art date
Application number
PCT/JP2011/051180
Other languages
English (en)
Japanese (ja)
Inventor
寿志 井上
Original Assignee
コニカミノルタオプト株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by コニカミノルタオプト株式会社 filed Critical コニカミノルタオプト株式会社
Priority to CN201180006796.6A priority Critical patent/CN102714045B/zh
Priority to JP2011551837A priority patent/JP5582421B2/ja
Publication of WO2011093231A1 publication Critical patent/WO2011093231A1/fr

Links

Images

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1372—Lenses
    • G11B7/1378—Separate aberration correction lenses; Cylindrical lenses to generate astigmatism; Beam expanders
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
    • G11B2007/0009—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage
    • G11B2007/0013—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage for carriers having multiple discrete layers

Definitions

  • the present invention relates to an optical pickup device capable of recording and / or reproducing information with respect to an optical disc having three or more information recording surfaces in the thickness direction, and an optical information recording / reproducing device having the optical pickup device.
  • a high-density optical disk system capable of recording and / or reproducing information (hereinafter, “recording and / or reproduction” is referred to as “recording / reproduction”) using a blue-violet semiconductor laser having a wavelength of about 400 nm.
  • Patent Document 1 the magnification of the objective lens is changed by moving a coupling lens arranged between the light source and the objective lens in the optical axis direction, and the selected information recording surface is tertiary.
  • An optical pickup device capable of condensing a light beam with reduced spherical aberration is disclosed.
  • the operation of changing the information recording surface on which information is to be recorded / reproduced from one information recording surface to another information recording surface may be referred to as “focus jump” in this specification.
  • a relatively thick type called a so-called half height, which is conventionally mounted on a stationary recorder or the like, is coupled.
  • a relatively thin optical pickup device called a so-called slim type mounted on the back of a notebook PC or thin television has sufficient space for moving the coupling lens. There is a problem that it cannot be secured.
  • an optical pickup device when information is recorded / reproduced with respect to an optical disc, the objective lens is tilted along the radial direction and / or the tangential direction of the optical disc (in this specification, The coma generated by the lens tilt) can cancel the coma generated by the warp or tilt of the optical disc (referred to as disc tilt in this specification). Therefore, if the amount of coma generated when the lens is tilted is small, the amount of lens tilt required to correct the coma due to disc tilt increases, so it is necessary to ensure a sufficiently large dynamic range of the lens tilt. As a result, problems such as an increase in the size of the optical pickup device and an increase in power consumption of the actuator occur.
  • the coupling lens is used as the optical axis.
  • the divergent light beam enters the objective lens, so that the coma aberration amount when the lens is tilted is smaller than when the parallel light beam is incident.
  • spherical aberration is generated in a beam spot due to a temperature change (referred to as temperature aberration in this specification).
  • a plastic having a focal length of 1.41 mm The amount of change in spherical aberration due to a 30 ° C. change in the objective lens made of material is about 100 m ⁇ rms, which exceeds the Marshall limit value of 70 m ⁇ rms.
  • the NA is about 0.60 to 0.67, the amount of spherical aberration caused by temperature change is relatively small, and it is not necessary to correct this spherical aberration.
  • the present invention has been made in consideration of the above-mentioned problems, and can reduce the amount of movement of the coupling lens, is compact and low-cost, and is suitable as a slim type optical pickup device, and has a multilayer information recording surface.
  • An object of the present invention is to provide an optical pickup device capable of recording / reproducing information on / from an optical disc.
  • the “transparent substrate thickness” is the distance from the light beam incident surface of the optical disc to the information recording surface.
  • each information recording surface is transparent.
  • the substrate thickness will be different from each other.
  • an objective lens for an optical pickup is combined with a cover glass having a predetermined thickness, and the correction state of the spherical aberration is determined so that the spherical aberration is minimized (the thickness of the cover glass is determined as the design cover glass). Also called thickness).
  • the design cover glass thickness may be the same as or different from the transparent substrate thickness of any information recording surface of the optical disc. When the thickness of the cover glass changes, the characteristics of the objective lens also change.
  • cover glass thickness is used to distinguish it from the “transparent substrate” of the optical disk (note that the term “cover glass” is used).
  • cover glass thickness is not limited to glass, but a resin may be added).
  • the optical pickup apparatus includes an information recording surface having a light source that emits a light beam having a wavelength ⁇ 1 (390 nm ⁇ 1 ⁇ 415 nm), a coupling lens, and an objective lens, and having transparent substrate thicknesses different from each other.
  • the coupling lens has at least one moving lens that is movable in the optical axis direction, and moves the moving lens in the optical axis direction between the light source and the objective lens, so that Select one of the information recording surfaces
  • the objective lens is a single lens
  • the image side numerical aperture (NA) of the objective lens is 0.8 or more and 0.95 or less
  • Spherical aberration is minimal at room temperature (25 ⁇ 3 ° C.) and cover glass thickness T (mm) satisfying formula (1), where T MAX (mm) is the maximum transparent substrate thickness among the transparent substrate thicknesses.
  • the thinner optical pickup device so-called slim type optical pickup device, has relatively severe restrictions on the moving space of the coupling lens compared to the thick optical pickup device, so-called half-height type.
  • a fixed element such as a polarizing beam splitter or a half mirror is generally arranged between the coupling lens and the light source, it is difficult to move the coupling lens greatly to the light source side.
  • the present inventor is directed to the light source side with respect to the origin when the magnification M at which the spherical aberration is minimized satisfies the formula (2) in the cover glass thickness T satisfying the formula (1).
  • the amount of movement of the coupling lens toward can be made smaller than the amount of movement of the coupling lens toward the objective lens with respect to the origin.
  • the total movement amount of the coupling lens is secured, and information recording / reproduction is selected by selecting one of information recording surfaces of three or more layers. It was made possible to do.
  • an objective lens for recording / reproducing information with respect to the information recording surface having a thicker transparent substrate is used as a pickup device corresponding to a BD having an information recording surface of three or more layers. It is necessary that the tilt sensitivity does not become too small. In particular, when a plastic objective lens is used, the lens tilt sensitivity when the environmental temperature becomes high during recording / reproduction of information on the information recording surface with the thicker transparent substrate is high. It is necessary not to become too small. By satisfying the expression (1), it is possible to prevent the tilt sensitivity of the objective lens from becoming too small when recording / reproducing information on the information recording surface having the thicker transparent substrate.
  • the optical pickup device according to the first aspect, wherein a position where a parallel light beam is emitted from the coupling lens to the objective lens side is an origin of the moving lens, and the light source from the origin.
  • the maximum moving distance of the moving lens toward the side is smaller than the maximum moving distance of the moving lens toward the objective lens from the origin.
  • the information recording surface where the moving distance from the origin of the moving lens when the information recording surface farthest from the light beam incident surface of the optical disc is selected and condensed is the closest to the light beam incident surface of the optical disc Is preferably smaller than the moving distance from the origin of the moving lens when the light beam is selected.
  • the optical pickup device wherein a position where a parallel light beam is emitted from the coupling lens to the objective lens side is an origin of the moving lens, and from the origin.
  • the light source side is ( ⁇ ) and the optical disc side is (+) from the origin
  • the movement when the information recording surface farthest from the light beam incident surface of the optical disc is selected and the light beam is condensed is selected.
  • the lens position is A (A ⁇ 0)
  • the position of the moving lens when the information recording surface closest to the light beam incident surface of the optical disc is selected and the light beam is condensed is B (B> 0). If there is, ⁇ 10 ⁇ B / A ⁇ ⁇ 1.5 (3) It is characterized by satisfying.
  • the information recording surface having three or more layers while avoiding interference between the coupling lens and the element fixed on the light source side Information can be recorded / reproduced by selecting either of the above.
  • the optical pickup device wherein a position where a parallel light beam is emitted from the coupling lens toward the objective lens is an origin of the moving lens, and from the origin.
  • the light source side is ( ⁇ ) and the optical disc side is (+) from the origin
  • the movement when the information recording surface farthest from the light beam incident surface of the optical disc is selected and the light beam is condensed is selected.
  • the lens position is A (A> 0)
  • the position of the moving lens when the information recording surface closest to the light beam incident surface of the optical disc is selected and the light beam is condensed is B (B> 0). If there is, 5 ⁇ B / A ⁇ 15 (4) It is characterized by satisfying.
  • the moving lens does not move to the light source side, so that the arrangement of the coupling lens and the element fixed to the light source side is eliminated. Increased freedom.
  • An optical pickup device is the invention according to any one of the first to fourth aspects, wherein a focal length f (mm) of the objective lens at the wavelength ⁇ 1 is expressed by the following equation: 1.0 ⁇ f ⁇ 1.45 (5) It is characterized by satisfying.
  • the optical pickup device is the invention according to any one of claims 1 to 5, wherein the sine condition violation amount is a positive maximum value between 70% and 90% of the effective radius at the magnification M.
  • the sine condition violation amount does not have a negative maximum value within the effective radius.
  • the residual higher-order spherical aberration at the time of focus jump can be made smaller, the amount of movement of the coupling lens at the time of focus jump can be made smaller, and information on the thicker transparent substrate thickness
  • the lens tilt sensitivity can be reduced even during the recording / reproduction of information on the recording surface, and the lens tilt sensitivity can be reduced even if the objective lens is made of plastic and the ambient temperature is high. It is possible to further suppress the reduction of the above.
  • the optical pickup device is the invention according to any one of claims 1 to 5, wherein the sine condition violation amount is a positive maximum value between 70% and 90% of the effective radius at the magnification M. Furthermore, the sine condition violation amount has a negative maximum value at a position closer to the optical axis than the positive maximum value.
  • the residual higher-order spherical aberration at the time of focus jump can be reduced, the amount of movement of the coupling lens at the time of focus jump can be reduced, and the information recording surface with the thicker transparent substrate
  • the lens tilt sensitivity can be reduced even during recording / reproduction of information, and even when the objective lens is made of plastic and the ambient temperature becomes high, the lens tilt sensitivity is reduced.
  • the amount of aberration that occurs when two opposing optical surfaces shift in the direction perpendicular to the optical axis due to manufacturing errors can be suppressed, and a lens on the optical axis can be suppressed. Since it is possible to reduce the amount of aberration that occurs when the thickness shifts in the optical axis direction due to manufacturing errors, it is possible to provide an objective lens that is easier to manufacture. .
  • the objective lens is made of a glass material.
  • An optical pickup device is characterized in that, in the invention according to any one of the first to seventh aspects, the objective lens is made of a plastic material.
  • An optical pickup device is the invention according to any one of the first to ninth aspects, wherein the coupling lens is a single lens, and the single lens is the moving lens. To do.
  • An optical pickup device is the optical pickup device according to any one of the first to ninth aspects, wherein the coupling lens has a two-group configuration of a positive lens group and a negative lens group, and the positive lens. At least one lens in the group is the moving lens.
  • the present invention it is possible to further reduce the amount of movement of the moving lens, and it is possible to provide a more compact optical pickup device.
  • the optical pickup device has at least one light source (first light source).
  • first light source a plurality of types of light sources may be provided so as to support a plurality of types of optical disks.
  • the optical pickup device of the present invention has a condensing optical system for condensing at least the first light flux from the first light source on the information recording surface of the first optical disc.
  • the condensing optical system condenses the second light beam on the information recording surface of the second optical disk, and the third light beam on the information recording surface of the third optical disk. You may make it condense.
  • the optical pickup device of the present invention includes a light receiving element that receives at least a reflected light beam from the information recording surface of the first optical disc.
  • the light receiving element receives a reflected light beam from the information recording surface of the second optical disk and receives a reflected light beam from the information recording surface of the third optical disk. Also good.
  • object side means the light source side
  • image side means the optical disk side.
  • the first optical disk has a transparent substrate having a thickness t1 and an information recording surface.
  • the second optical disc has a transparent substrate having a thickness t2 (t1 ⁇ t2) and an information recording surface.
  • the third optical disc has a transparent substrate having a thickness of t3 (t2 ⁇ t3) and an information recording surface.
  • the first optical disc is preferably a BD
  • the second optical disc is a DVD
  • the third optical disc is preferably a CD, but is not limited thereto.
  • the first optical disc has three or more information recording surfaces stacked in the thickness direction. That is, the first optical disc has three or more information recording surfaces in the thickness direction that have different distances from the light incident surface of the optical disc to the information recording surface (this is referred to as “transparent substrate thickness” in this specification). It is. Of course, you may have four or more information recording surfaces.
  • the second optical disc and the third optical disc may also have a plurality of information recording surfaces.
  • the “maximum transparent substrate thickness” means the transparent substrate thickness of the information recording surface farthest from the light incident surface of the optical disc among the plurality of information recording surfaces, and the “minimum transparent substrate thickness” means the optical disc. The thickness of the transparent substrate on the information recording surface closest to the incident surface of the light beam in FIG.
  • the amount of movement of the coupling lens when performing a focus jump becomes longer, and the coupling lens
  • the optical pickup device selects one of the plurality of information recording surfaces of the first optical disc, and condenses the light beam emitted from the light source onto the selected information recording surface by the objective lens. By doing so, information is recorded and / or reproduced.
  • BD means that information is recorded / reproduced by a light beam having a wavelength of about 390 to 415 nm and an objective lens having an NA of about 0.8 to 0.95, and the thickness of the transparent substrate is 0.05 to 0.00.
  • the optical pickup device of the present invention has at least three layers. It is possible to deal with a BD having the above information recording surface.
  • DVD is a general term for DVD series optical discs in which information is recorded / reproduced by an objective lens having an NA of about 0.60 to 0.67 and the thickness of the transparent substrate is about 0.6 mm.
  • CD is a general term for CD series optical discs in which information is recorded / reproduced by an objective lens having an NA of about 0.45 to 0.51 and the transparent substrate has a thickness of about 1.2 mm.
  • CD-ROM, CD-Audio, CD-Video, CD-R, CD-RW and the like As for the recording density, the recording density of BD is the highest, followed by the order of DVD and CD.
  • the first light source, the second light source, and the third light source are preferably laser light sources.
  • the laser light source a semiconductor laser, a silicon laser, or the like can be preferably used.
  • the wavelength ⁇ 3 ( ⁇ 3> ⁇ 2) is the following conditional expressions (10), (11), 1.5 ⁇ ⁇ 1 ⁇ 2 ⁇ 1.7 ⁇ ⁇ 1 (10) 1.8 ⁇ ⁇ 1 ⁇ 3 ⁇ 2.0 ⁇ ⁇ 1 (11) It is preferable to satisfy.
  • the first wavelength ⁇ 1 of the first light source is preferably 350 nm or more and 440 nm or less, more preferably 390 nm.
  • the second wavelength ⁇ 2 of the second light source is preferably 570 nm or more and 680 nm or less, more preferably 630 nm or more and 670 nm or less
  • the third wavelength ⁇ 3 of the third light source is preferably 750 nm. As mentioned above, it is 880 nm or less, More preferably, it is 760 nm or more and 820 nm or less.
  • the first light source, the second light source, and the third light source may be unitized.
  • the unitization means that the first light source and the second light source are fixedly housed in one package, for example.
  • a light receiving element to be described later may be packaged.
  • a photodetector such as a photodiode is preferably used.
  • Light reflected on the information recording surface of the optical disc enters the light receiving element, and a read signal of information recorded on each optical disc is obtained using the output signal. Furthermore, it detects the change in the light amount due to the spot shape change and position change on the light receiving element, performs focus detection and track detection, and based on this detection, the objective lens can be moved for focusing and tracking I can do it.
  • the light receiving element may comprise a plurality of photodetectors.
  • the light receiving element may have a main photodetector and a sub photodetector.
  • two sub photodetectors are provided on both sides of a photodetector that receives main light used for recording and reproducing information, and the sub light for tracking adjustment is received by the two sub photodetectors. It is good also as a simple light receiving element.
  • the light receiving element may have a plurality of light receiving elements corresponding to the respective light sources.
  • the condensing optical system has a coupling lens and an objective lens.
  • the coupling lens is a lens group that is disposed between the objective lens and the light source and changes the divergence angle of the light beam.
  • the collimator is a kind of coupling lens, and is a coupling lens that emits an incident light beam as parallel light or substantially parallel light.
  • the coupling lens may be composed of only a positive lens group or may have a positive lens group and a negative lens group.
  • the positive lens group has at least one positive lens.
  • the positive lens group may include only one positive lens or may include a plurality of lenses.
  • the negative lens group includes at least one negative lens.
  • the negative lens group may include only one negative lens or may include a plurality of lenses. Examples of a preferable coupling lens include only a single positive lens or a combination of a single positive lens and a single negative lens.
  • a lens that is movable in the optical axis direction may be referred to as a “moving lens”.
  • the amount of movement of the coupling lens is used in the same meaning as “the amount of movement of the moving lens”.
  • the power of the lens group moved in the optical axis direction is increased (that is, in the optical axis direction). It is conceivable to shorten the focal length of the lens group that is moved to (1). This is because the amount of movement of the lens group moved in the optical axis direction decreases as the power of the lens group increases (that is, as the focal length of the lens group decreases).
  • the coupling lens has a group configuration
  • the focal length of the lens group moved in the optical axis direction that is, equal to the focal length of the coupling lens
  • the spot condensed by the objective lens becomes an ellipse.
  • the recording and / or reproduction of information on the BD may be hindered. The reason for this will be described below.
  • the coupling lens has a two-group configuration including a positive lens group and a negative lens group, and at least one lens in the positive lens group is moved in the optical axis direction, thereby It is preferable to select whether to collect light on the information recording surface.
  • the coupling lens is a two-group thin lens system composed of a positive lens and a negative lens, and the positive lens is moved along the optical axis direction during focus jump.
  • the power of the positive lens is P P
  • the focal length of the positive lens is f P
  • the power of the negative lens is P N
  • the focal length of the negative lens is f N
  • the distance between the positive lens and the negative lens is L
  • the coupling lens The system power P C and the focal length f C of the entire coupling lens system are expressed by the following equation (12):
  • P C P + P N ⁇ L ⁇ P P ⁇ P N
  • P C 1 / f C
  • P C 1 / f P + 1 / f N -L / (f P ⁇ f N)
  • the system magnification M is about -0.1. Further, in consideration of a space in which an optical element such as a polarizing beam splitter disposed between the light source and the coupling lens is considered, the focal length f C of the entire coupling lens system cannot be extremely shortened.
  • the distance between the objective lens and the BD (also referred to as a working distance) is not too short, and in order to reduce the thickness of the optical pickup device, optimal range of the focal length f O of the lens naturally determined.
  • the focal length range of the entire system needs to be a predetermined range, and the movement of the coupling lens necessary at the time of focus jump Considering only the amount, the focal length f C of the entire coupling lens system cannot be reduced unnecessarily.
  • the power P P of the positive lens is increased, and further, the power P of the negative lens is set so that the focal length f C of the entire coupling lens system is not too short. It is preferable to increase the absolute value of N (see equation (12)).
  • the movement amount of the positive lens group required at the time of focus jump is reduced by moving the positive lens group in the optical axis direction.
  • the arrangement of the positive lens group and the negative lens group may be arranged in the order of the negative lens group and the positive lens group from the light source side, or may be arranged in the order of the positive lens group and the negative lens group from the light source side. good.
  • the preferred arrangement is the former.
  • the optimum example of the coupling lens in the optical pickup device is composed of a combination of one positive lens and one negative lens, and the negative lens and the positive lens from the light source side. It is preferable to arrange in this order.
  • the present invention is not limited to this, and from the viewpoint of simplifying the configuration of the coupling lens as much as possible, there can be an option of a single positive lens coupling lens.
  • At least one lens (preferably a positive lens) of the positive lens group is movable in the optical axis direction in order to correct spherical aberration occurring on the selected information recording surface of the first optical disk. It is preferable that For example, when recording and / or reproducing on one information recording surface of the first optical disk and then recording and / or reproducing on another information recording surface of the first optical disk, the positive lens group of the coupling lens group Spherical aberration that occurs at the time of focus jump to a different information recording surface of the first optical disk by moving at least one lens in the optical axis direction, changing the divergence of the light beam, and changing the magnification of the objective lens Correct.
  • FIG. 1 is a diagram showing the results of studies conducted by the present inventors.
  • a first optical disc (BD) having a surface, when the optimum spherical aberration difference AS generated when each optimum focusing spot is formed on the information recording surface that is farthest away, and when the environmental temperature changes by ⁇ 30 ° C.
  • the maximum spherical aberration BS that occurs and the maximum spherical aberration CS that occurs when the wavelength of the light source changes by ⁇ 5 nm were determined.
  • Such spherical aberration can be corrected by moving the coupling lens in the optical axis direction and changing the magnification of the objective lens. However, if the same coupling lens is used, the total amount of spherical aberration is the amount of movement of the coupling lens. It is equivalent to.
  • the amount of spherical aberration is obtained regardless of whether the optical surface is an aspherical refractive surface or a diffractive surface. Is about 410 to 430 m ⁇ rms, and it can be said that the amount of movement of the coupling lens is relatively small.
  • the total amount of spherical aberration is 680 m ⁇ rms in an objective lens having an aspherical refractive surface. The amount of movement is required to be about 1.5 times that required when an optical disc having two information recording surfaces is used. Furthermore, as shown in FIG.
  • the objective lens is made of glass and the optical surface is a diffractive surface that corrects spherical aberration that occurs when the wavelength fluctuates, in addition to spherical aberration BS due to environmental temperature changes, spherical aberration CS due to wavelength fluctuations of the light source due to the function of the diffractive surface Therefore, the amount of movement of the coupling lens is smaller (corresponding to the correction amount of the spherical aberration of 500 m ⁇ rms in FIG. 1C). That is, in order to reduce the amount of movement of the coupling lens, the objective lens is preferably made of a glass material.
  • the amount of movement of the coupling lens when the optical disk having two information recording surfaces is used is smaller than that of the coupling lens when the optical disk having four information recording surfaces is used. Since the amount of movement is still about twice, it is preferable to further devise in order to suppress the amount of movement of the coupling lens. The same applies to the amount of movement of the coupling lens when using an optical disc having three information recording surfaces or five or more information recording surfaces. Therefore, in the present invention, it is possible to further reduce the amount of movement of the coupling lens by breaking the sine condition of the objective lens.
  • an optical disc having two information recording surfaces an information recording surface having a smaller distance from the light beam incident surface of the optical disc is RL1, an information recording surface having a larger distance from the light beam incident surface of the optical disc is RL2
  • optical disk having four information recording surfaces (assuming that the information recording surface having the smallest distance from the light beam incident surface of the optical disk is RL1, and the information recording surface having the largest distance from the light beam incident surface of the optical disk is RL4), An optical disk was assumed in which the distance from the light beam incident surface of the optical disk to RL1 was 50 ⁇ m and the distance from the light beam incident surface of the optical disk to RL4 was 100 ⁇ m.
  • the objective lens refers to an optical system that is disposed at a position facing the optical disk in the optical pickup device and has a function of condensing a light beam emitted from the light source onto the information recording surface of the optical disk.
  • the objective lens is a single plastic lens or glass lens.
  • the objective lens may be composed of only a refractive surface or may have an optical path difference providing structure.
  • the hybrid lens which provided the optical path difference providing structure with the photocurable resin, UV curable resin, or thermosetting resin etc. on the glass lens may be sufficient.
  • the objective lens preferably has a refractive surface that is aspheric.
  • the base surface on which the optical path difference providing structure is provided is preferably an aspherical surface.
  • the optical surface on the light source side of the objective lens may be referred to as the optical surface on the object side, and the optical surface on the optical disk side may be referred to as the optical surface on the image side.
  • the absolute value of the radius of curvature of the optical surface on the light source side is preferably smaller than the absolute value of the radius of curvature of the optical surface on the image side.
  • the objective lens is a glass lens, as described with reference to FIG. 1, it is not necessary to move the coupling lens in order to correct the spherical aberration caused by the temperature change. This is preferable because it can be reduced and the optical pickup device can be downsized.
  • the objective lens is a glass lens
  • a glass material having a glass transition point Tg of 500 ° C. or lower more preferably 400 ° C. or lower.
  • a glass material having a glass transition point Tg of 500 ° C. or lower molding at a relatively low temperature is possible, so that the life of the mold can be extended.
  • Examples of such a glass material having a low glass transition point Tg include K-PG325 and K-PG375 (both product names) manufactured by Sumita Optical Glass Co., Ltd.
  • a physical property value which is important when molding and manufacturing a glass lens is a linear expansion coefficient ⁇ . Even if a material having a Tg of 400 ° C. or lower is selected, the temperature difference from room temperature is still large compared to the resin material. When lens molding is performed using a glass material having a large linear expansion coefficient ⁇ , cracks are likely to occur when the temperature is lowered.
  • the linear expansion coefficient ⁇ of the glass material is preferably 200 ( ⁇ 10 ⁇ 7 / K) or less, more preferably 120 ( ⁇ 10 ⁇ 7 / K) or less.
  • the specific gravity of a glass lens is generally larger than that of a plastic lens, if the objective lens is a glass lens, the mass becomes large and a load is imposed on the actuator that drives the objective lens. Therefore, when the objective lens is a glass lens, it is preferable to use a glass material having a small specific gravity.
  • the specific gravity is preferably 4.0 or less, more preferably the specific gravity is 3.0 or less.
  • the objective lens is a plastic lens
  • an alicyclic hydrocarbon polymer material such as a cyclic olefin resin material.
  • the resin material has a refractive index of 1.54 to 1.60 at a temperature of 25 ° C. with respect to a wavelength of 405 nm, and a wavelength of 405 nm according to a temperature change within a temperature range of ⁇ 5 ° C. to 70 ° C.
  • the coupling lens is preferably a plastic lens.
  • a first preferred example is a polymer block [A] containing a repeating unit [1] represented by the following formula (1), a repeating unit [1] represented by the following formula (1) and the following formula ( 2) and / or polymer block [B] containing the repeating unit [3] represented by the following formula (3), and the repeating unit in the block [A] It consists of a block copolymer in which the relationship between the molar fraction a (mol%) of [1] and the molar fraction b (mol%) of the repeating unit [1] in the block [B] is a> b. It is a resin composition.
  • R 1 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms
  • R 2 to R 12 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a hydroxyl group, a carbon number of 1 ⁇ 20 alkoxy groups or halogen groups.
  • R 13 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.
  • each of R 14 and R 15 independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.
  • the second preferred example is obtained by addition polymerization of a monomer composition comprising at least an ⁇ -olefin having 2 to 20 carbon atoms and a cyclic olefin represented by the following general formula (4).
  • Polymer (B) obtained by addition polymerization of polymer (A) and a monomer composition comprising an ⁇ -olefin having 2 to 20 carbon atoms and a cyclic olefin represented by the following general formula (5) ).
  • R 1 to R 18 , R a and R b are each independently a hydrogen atom, A halogen atom or a hydrocarbon group, R 15 to R 18 may be bonded to each other to form a monocycle or polycycle, and the monocycle or polycycle in parentheses may have a double bond Alternatively, R 15 and R 16 , or R 17 and R 18 may form an alkylidene group. ]
  • R 19 to R 26 each independently represents a hydrogen atom, a halogen atom or a hydrocarbon group.
  • the following additives may be added.
  • Stabilizer It is preferable to add at least one stabilizer selected from a phenol stabilizer, a hindered amine stabilizer, a phosphorus stabilizer, and a sulfur stabilizer. By suitably selecting and adding these stabilizers, for example, it is possible to more highly suppress the white turbidity and the optical characteristic fluctuations such as the refractive index fluctuations when continuously irradiated with light having a short wavelength of 405 nm. .
  • phenol-based stabilizer conventionally known ones can be used.
  • 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate
  • 2 4-di-t-amyl-6- (1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate and the like
  • JP-A Nos. 63-179953 and 1-168643 JP-A Nos. 63-179953 and 1-168643.
  • Preferred hindered amine stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis ( 1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (N-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-benzyloxy-2, 2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-cyclohexyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6) -Pentamethyl-4-piperidyl) 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1-acryloyl-2,2, , 6-Tetramethyl-4-piperidyl) 2,2-bis (3,5-di-t-but
  • the preferable phosphorus stabilizer is not particularly limited as long as it is a substance usually used in the general resin industry.
  • triphenyl phosphite diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonyl).
  • Phenyl) phosphite tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9 Monophosphite compounds such as 1,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) Phosphite), 4,4 'isopropylidene-bis (phenyl-di-alkyl (C12-C15)) Fight) and the like diphosphite compounds such as.
  • monophosphite compounds are preferable, and tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite and the like are particularly preferable.
  • Preferred sulfur stabilizers include, for example, dilauryl 3,3-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3- Thiodipropionate, pentaerythritol-tetrakis- ( ⁇ -lauryl-thio) -propionate, 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane Etc.
  • each of these stabilizers is appropriately selected within a range not to impair the purpose of the present invention, but is usually 0.01 to 2 parts by mass with respect to 100 parts by mass of the alicyclic hydrocarbon-based copolymer, The amount is preferably 0.01 to 1 part by mass.
  • a surfactant is a compound having a hydrophilic group and a hydrophobic group in the same molecule.
  • the surfactant can prevent white turbidity of the resin composition by adjusting the rate of moisture adhesion to the resin surface and the rate of moisture evaporation from the surface.
  • hydrophilic group of the surfactant examples include a hydroxy group, a hydroxyalkyl group having 1 or more carbon atoms, a hydroxyl group, a carbonyl group, an ester group, an amino group, an amide group, an ammonium salt, a thiol, a sulfonate, A phosphate, a polyalkylene glycol group, etc. are mentioned.
  • the amino group may be primary, secondary, or tertiary.
  • the hydrophobic group of the surfactant include an alkyl group having 6 or more carbon atoms, a silyl group having an alkyl group having 6 or more carbon atoms, and a fluoroalkyl group having 6 or more carbon atoms.
  • the alkyl group having 6 or more carbon atoms may have an aromatic ring as a substituent.
  • Specific examples of the alkyl group include hexyl, heptyl, octyl, nonyl, decyl, undecenyl, dodecyl, tridecyl, tetradecyl, myristyl, stearyl, lauryl, palmityl, cyclohexyl and the like.
  • the aromatic ring include a phenyl group.
  • the surfactant only needs to have at least one hydrophilic group and hydrophobic group as described above in the same molecule, and may have two or more groups.
  • examples of such a surfactant include myristyl diethanolamine, 2-hydroxyethyl-2-hydroxydodecylamine, 2-hydroxyethyl-2-hydroxytridecylamine, 2-hydroxyethyl-2- Hydroxytetradecylamine, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, di-2-hydroxyethyl-2-hydroxydodecylamine, alkyl (8-18 carbon atoms) benzyldimethylammonium chloride, ethylene
  • examples thereof include bisalkyl (carbon number 8 to 18) amide, stearyl diethanolamide, lauryl diethanolamide, myristyl diethanolamide, palmityl diethanolamide, and the like.
  • amine compounds or amide compounds having a hydroxyalkyl group are preferably used. In the present invention, two or more of these compounds may be used in combination.
  • the surfactant is based on 100 parts by mass of the alicyclic hydrocarbon-based polymer. It is preferable to add 0.01 to 10 parts by mass.
  • the addition amount of the surfactant is more preferably 0.05 to 5 parts by mass, still more preferably 0.3 to 3 parts by mass with respect to 100 parts by mass of the alicyclic hydrocarbon-based polymer.
  • Plasticizer The plasticizer is added as necessary to adjust the melt index of the copolymer.
  • Plasticizers include bis (2-ethylhexyl) adipate, bis (2-butoxyethyl) adipate, bis (2-ethylhexyl) azelate, dipropylene glycol dibenzoate, tri-n-butyl citrate, tricitrate citrate -N-butylacetyl, epoxidized soybean oil, 2-ethylhexyl epoxidized tall oil, chlorinated paraffin, tri-2-ethylhexyl phosphate, tricresyl phosphate, t-butylphenyl phosphate, tri-2-ethylhexyl phosphate Diphenyl, dibutyl phthalate, diisohexyl phthalate, diheptyl phthalate, dinonyl phthalate, diundecyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, diisode
  • cycloolefin resins are preferably used.
  • ZEONEX manufactured by Nippon Zeon, APEL manufactured by Mitsui Chemicals, TOPAS ADVANCED, TOPAS manufactured by POLYMERS, and ARTON manufactured by JSR are preferable. Take as an example.
  • the Abbe number of the material constituting the objective lens is preferably 50 or more.
  • the maximum transparent substrate thickness (information recording surface at the deepest position) of the transparent substrate thickness of the optical disc Spherical distance is minimum at room temperature (25 ⁇ 3 ° C.) and cover glass thickness T (mm) satisfying the following expression (1)
  • T MAX (mm) is the distance between the surface of the optical disk and the surface of the optical disk:
  • the target value to be satisfied by the objective lens for BD of three or more layers is examined, and the information recording surface (that is, the transparent substrate thickness is the farthest from the light incident surface).
  • the third-order coma aberration (DT) that occurs when the optical disk is tilted when the environmental temperature becomes high during recording / reproducing information on the thickest information recording surface) and the objective lens is tilted
  • the ratio with the third-order coma aberration CM (LT) generated at the time is set to about 0.36.
  • the value of this ratio is the same as the information recording surface L0 (100 ⁇ m) on the thicker transparent substrate in the optical pickup device equipped with an objective lens that records / reproduces information with respect to the two-layer BD. ),
  • the environmental temperature becomes high during the recording / reproduction of information
  • the cover glass thickness T satisfies the upper limit of the expression (1 ′)
  • the degree of convergence of the light beam incident on the objective lens becomes too large when information is recorded / reproduced on the information recording surface having the thinnest transparent substrate thickness.
  • the lens shift characteristics can be further improved, and the residual higher-order spherical aberration when the focus jump is made to the information recording surface having the thinnest transparent substrate can be further reduced.
  • the position where the parallel light beam is emitted from the coupling lens to the objective lens side is defined as the origin of the moving lens.
  • the maximum moving distance of the moving lens from the origin toward the light source can be made smaller than the maximum moving distance of the coupling lens from the origin toward the objective lens.
  • the position of the moving lens when focusing the light beam by selecting the information recording surface farthest from the light beam incident surface of the optical disk is
  • a (A ⁇ 0) and the position of the moving lens when focusing the light beam by selecting the information recording surface closest to the light beam incident surface of the optical disk is B (B> 0)
  • conditional expression (1) it is also possible to move the moving lens only from the origin to the objective lens side without moving the moving lens from the origin to the light source side.
  • any one of the information recording surfaces of three or more layers can be used while further avoiding interference between the coupling lens and the element fixed on the light source side. Select and record / playback information.
  • the position of the moving lens when focusing the light beam by selecting the information recording surface farthest from the light beam incident surface of the optical disk is
  • a (A> 0) and the position of the moving lens when focusing the light beam by selecting the information recording surface closest to the light beam incident surface of the optical disk is B (B> 0)
  • the sine condition is h when a light beam having a height h 1 from the optical axis is incident on the lens parallel to the optical axis, and when the light beam is emitted from the lens at an emission angle U. 1 / sinU satisfies a certain value.
  • U. 1 / sinU a constant value regardless of the height from the height h 1 from the optical axis
  • the sine condition is satisfied and the lateral magnification of each light ray within the effective diameter can be regarded as constant.
  • This sine condition is a calculated value on the axis, but is effective in correcting off-axis lateral magnification error (ie off-axis coma).
  • FIG. 3 is a graph showing the sine condition violation amount in the objective lens on the horizontal axis and the height from the optical axis on the vertical axis.
  • the graph matches the vertical axis, but in the case of an objective lens that does not satisfy the sine condition, the graph moves away from the vertical axis to the positive side and / or the negative side as shown in FIG. It becomes.
  • the sine condition violation amount For an objective lens that does not satisfy the sine condition, if the sine condition is satisfied near the optical axis and effective diameter, the sine condition violation amount always has a maximum value.
  • SCmax the maximum value on the positive side of the sine condition violation amount
  • SCmin the maximum value on the negative side
  • the objective lens having the characteristics shown in FIG. 3A is an example in which the violating sine condition has one negative maximum value SCmin and no positive maximum value SCmax. According to such an objective lens, since the surface shift sensitivity is small and the on-axis thickness error sensitivity is small, it is easy to manufacture. On the other hand, as the coupling lens moves, the higher-order spherical aberration increases and the magnification changes. It has the characteristic that the change in spherical aberration due to is small. Therefore, when the coupling lens is moved to select an information recording surface in an optical disc having three or more layers, there is a possibility that the necessary movement amount increases.
  • the objective lens having the characteristics shown in FIGS. 3B and 3C has a sine condition violation amount on the positive side between 70% and 90% of the effective radius of the objective lens at the magnification M described above. At least one local maximum value SCmax (preferably only one). According to the objective lens as shown in FIGS. 3B and 3C, the sine condition violation amount has a positive maximum value SCmax between 70% and 90% of the effective radius of the objective lens. Since the higher-order spherical aberration that occurs with the movement of the ring lens is reduced and the change in spherical aberration due to the change in magnification is large, the coupling lens is moved to select the information recording surface in an optical disc with three or more layers. In this case, the necessary movement amount can be reduced.
  • the sine condition violation amount has one negative maximum value on the optical axis side than the positive maximum value. Further, in the example of FIG. 3C, the sine condition violation amount has only a positive maximum value and does not have a negative maximum value. In both the example of FIG. 3B and the example of FIG. 3C, the sine condition violation amount monotonously decreases in the peripheral portion from the maximum value.
  • the sine condition violation amount has a positive maximum value and the sine condition violation amount has a negative maximum value between 70% and 90% of the effective radius.
  • the residual higher-order spherical aberration at the time of focus jump can be reduced, the amount of movement of the coupling lens at the time of focus jump can be reduced, and information can be recorded on the information recording surface with the thicker transparent substrate.
  • the two opposing optical surfaces shift in the direction perpendicular to the optical axis due to manufacturing errors.
  • the amount of aberration that occurs when the lens thickness on the optical axis shifts in the direction of the optical axis due to manufacturing errors can also be suppressed. Easy-to-use objective It is possible to provide a lens.
  • the sine condition violation amount has a positive maximum value and the sine condition violation amount has a negative maximum value between 70% and 90% of the effective radius. If not, the residual higher-order spherical aberration at the time of focus jump can be further reduced, the amount of movement of the coupling lens at the time of focus jump can be further reduced, and the information recording surface with the thicker transparent substrate can be used. On the other hand, even when the environmental temperature becomes high during the recording / reproducing of information, it is possible to further suppress the reduction of the lens tilt sensitivity.
  • the third-order spherical aberration generated in the objective lens due to the change in the divergence / convergence of incident light and the third-order spherical aberration generated during the focus jump are generated. It is preferable to set the positive maximum value of the sine condition so as to be almost similar to the change of the spherical aberration and the higher order spherical aberration.
  • the objective lens may be set in a shape that violates the sine condition, giving priority to reducing the amount of movement of the coupling lens, or giving priority to minimizing residual aberration during focus jump.
  • the shape of the condition violation amount may be set.
  • the cover glass thickness when the spherical aberration is minimized at the normal temperature (25 ⁇ 3 ° C.) and the magnification M satisfying the above-mentioned expression (2) is T (mm), and the normal temperature (25 ⁇ 3 ° C.).
  • the focal length of the wavelength ⁇ 1 is f (mm)
  • the change rate ⁇ SA3 / ( ⁇ M ⁇ f) of the third-order spherical aberration with respect to the magnification change of the objective lens at normal temperature (25 ⁇ 3 ° C.) and the cover glass thickness T ( ⁇ rms / mm) is the formula (14), 21 ⁇
  • both the suppression of the residual higher-order spherical aberration during the focus jump and the movement amount of the coupling lens are compatible. It becomes possible to do.
  • conditional expression (14 ′) 21.5 ⁇
  • the third-order spherical aberration ⁇ SA3 and the fifth-order spherical aberration ⁇ SA5 that occur when the magnification of the objective lens is changed at room temperature (25 ⁇ 3 ° C.) and the cover glass thickness T are expressed by the following equation (15): 4.2 ⁇ SA3 / ⁇ SA5 ⁇ 5.2 (15) It is preferable to satisfy.
  • the ratio of the change of the third-order spherical aberration and the fifth-order spherical aberration when the magnification is changed is the ratio of the third-order spherical aberration and the fifth-order spherical aberration when the cover glass thickness is changed. Therefore, it is possible to achieve both the suppression of the residual higher-order spherical aberration during the focus jump and the suppression of the movement amount of the coupling lens.
  • conditional expression (15 ′) 4.3 ⁇ SA3 / ⁇ SA5 ⁇ 4.9 (15 ′) Is to satisfy.
  • the fifth-order coma aberration CM5 (occurred when an oblique light beam having a half angle of view of 1 degree is incident on the objective lens at normal temperature (25 ⁇ 3 ° C.), the above-mentioned transparent substrate thickness T, and magnification M. ⁇ rms) is the equation (16), 0.02 ⁇
  • Conditional expression (16) is set from another viewpoint to satisfy both the suppression of the residual higher-order spherical aberration during the focus jump and the suppression of the movement amount of the coupling lens.
  • the expression (16) at the magnification M satisfying the expression (2) it is possible to satisfy both the suppression of the residual higher-order spherical aberration at the time of the focus jump and the suppression of the movement amount of the coupling lens.
  • CM3 Third-order coma aberration CM3 ( ⁇ rms) generated when an oblique light beam having a half angle of view of 1 degree is incident on the objective lens at normal temperature (25 ⁇ 3 ° C.), cover glass thickness, and magnification M. ) Is the formula (17), 0 ⁇
  • conditional expression (17) it is possible to prevent the lens tilt sensitivity from becoming too small even when information is recorded / reproduced on the information recording surface having the larger transparent substrate thickness. Further, even if the objective lens is made of plastic, the lens tilt sensitivity is small even when the environmental temperature becomes high during the recording / reproducing of information on the information recording surface having the thicker transparent substrate. Since it can prevent becoming too much, it is preferable.
  • the objective lens has a positive maximum value of the sine condition violation amount as SC MAX (mm) and the focal length of the wavelength ⁇ 1 at room temperature (25 ⁇ 3 ° C.) as f (mm), the expression (18) , 0.003 ⁇ SC MAX / f ⁇ 0.022 (18) It is preferable to satisfy.
  • the higher-order spherical aberration at the time of focus jump is not undercorrected, and the sine condition violation Setting the coma aberration correction state when the oblique light beam is incident so that the amount is smaller than the upper limit of the equation (18), the higher-order spherical aberration is not overcorrected. Can be suppressed.
  • conditional expression (18 ′) 0.003 ⁇ SC MAX / f ⁇ 0.015 (18 ') Is to satisfy.
  • the amount of lens tilt required to correct the coma generated by the disc tilt will increase.
  • the objective lens collides with the optical disk when the lens is tilted.
  • the coma generated by the lens tilt changes depending on the sine condition violation amount of the objective lens, and the sine condition violation amount depends on the magnification of the objective lens in a state where information is recorded / reproduced with respect to the optical disc. It changes depending on. Specifically, in an objective lens in which the sine condition violation amount is corrected when a parallel light beam is incident on the objective lens, the sine condition violation amount is changed to the negative side when a divergent light beam is incident on the objective lens. Therefore, the amount of coma generated by the lens tilt is reduced. The amount of coma aberration decreases as the divergence of the light beam incident on the objective lens increases.
  • the divergence of the light beam incident on the objective lens is maximized when information is recorded and / or reproduced on the information recording surface having the longest distance from the light beam incident surface. Furthermore, in the case of an objective lens made of a plastic material, the degree of divergence of the light flux is further increased in order to correct the spherical aberration caused by the change in the environmental temperature.
  • the cover glass thickness equal to the maximum transparent substrate thickness T MAX is non-parallel to the objective lens so that the third-order spherical aberration of the focused spot by the objective lens is corrected.
  • conditional expression (19 ′) 0.35 ⁇
  • the absolute value of the spherical aberration of the spot collected through the cover glass thickness equal to the maximum transparent substrate thickness T MAX is: It is preferable to set the correction state of the spherical aberration of the objective lens so that the spherical aberration of the spot collected through the cover glass thickness equal to the minimum transparent substrate thickness T MIN becomes smaller.
  • (20) Is synonymous with
  • a non-parallel light beam is made incident on the objective lens so that the third-order spherical aberration of the focused spot by the objective lens is corrected at normal temperature (25 ⁇ 3 ° C.) and the maximum transparent substrate thickness T MAX .
  • the objective lens so that the third-order spherical aberration of the focused spot by the objective lens is corrected at the magnification M1 in the above state, normal temperature (25 ⁇ 3 ° C.), and the minimum transparent substrate thickness TMIN .
  • the magnification M2 in a state where a parallel light beam is incident is expressed by the equation (21), 0 ⁇ M1 / M2 ⁇ 0.92 (21) It is preferable to satisfy.
  • T is not an intermediate point between T MAX and T MIN.
  • T MAX is not an intermediate point between T MAX and T MIN.
  • Expression (21) defines the preferable range from the viewpoint of magnification.
  • the refractive index N of the objective lens with respect to the wavelength ⁇ 1 at normal temperature (25 ⁇ 3 ° C.) and the inclination angle ⁇ (degree) in the outermost effective diameter of the optical surface on the light source side (object side) are ( 22) Formula, -59.8 ⁇ N + 162 ⁇ ⁇ 59.8 ⁇ N + 166 (22) It is preferable to satisfy.
  • the refractive index of the objective lens with respect to the wavelength ⁇ 1 at normal temperature (25 ⁇ 3 ° C.) is N
  • the first derivative X ′ of the aspherical deformation amount X (h) (mm) of the optical surface on the optical disk side is N
  • the radius height at which (h) is switched from negative to positive is H (mm)
  • equation (23) ⁇ 2.8 ⁇ N + 5.1 ⁇ H ⁇ 2.8 ⁇ N + 5.4 (23) It is characterized by satisfying.
  • the aspherical deformation amount X (h) is defined by the distance in the optical axis direction from the plane contacting the surface vertex of the optical surface on the optical disk side to the aspherical surface, and negative when the plane is deformed from the plane to the light source side.
  • the case of deformation from the plane to the optical disk side is positive, and H is a relative value when the effective radius is 1.
  • the objective lens used in the optical pickup device of the present invention may be an objective lens that substantially satisfies the sine condition.
  • NA1 The numerical aperture on the image side of the objective lens necessary for reproducing / recording information on the first optical disc is NA1, and the numerical aperture on the image side of the objective lens necessary for reproducing / recording information on the second optical disc.
  • NA2 NA1> NA2
  • NA3 NA2> NA3
  • NA1 is 0.8 or more and 0.95 or less, and more preferably 0.8 or more and 0.9 or less.
  • NA1 is preferably 0.85.
  • NA2 is preferably 0.55 or more and 0.7 or less.
  • NA2 is preferably 0.60 or 0.65.
  • NA3 is preferably 0.4 or more and 0.55 or less.
  • NA3 is preferably 0.45 or 0.53.
  • the objective lens is represented by the following formula (24): 0.9 ⁇ d / f ⁇ 1.5 (24) It is preferable to satisfy. However, d represents the thickness (mm) on the optical axis of the objective lens, and f represents the focal length (mm) of the objective lens in the first light flux.
  • the optical pickup device of the present invention can be applied to an objective lens having a focal length f of 1.0 mm or more and 2.4 mm or less, but the effect of the present invention is more remarkable when it is a slim type optical pickup. Since it is an apparatus, the focal length f of the objective lens in which the effect of the present invention becomes more remarkable is 1.0 mm or more and 1.45 mm or less. What becomes more conspicuous is 1.0 mm or more and 1.41 mm or less, and what becomes more conspicuous is 1.0 mm or more and 1.27 mm or less. The most prominent is 1.0 mm or more and 1.2 mm or less.
  • the effective diameter of the light incident surface of the objective lens is 1.7 mm or more and 2.4 mm or less. More preferably, they are 1.7 mm or more and 2.2 mm or less, More preferably, they are 1.7 mm or more and 2.0 mm or less.
  • the focal length of the first light flux is preferably 8.5 mm or more and 14.2 mm or less, more preferably 12 mm or more and 14 mm or less. is there.
  • the working distance of the objective lens when using the first optical disk is preferably 0.15 mm or more and 1.0 mm or less.
  • An optical information recording / reproducing apparatus includes an optical disk drive device having the above-described optical pickup device.
  • the optical disk drive apparatus can hold an optical disk mounted from the optical information recording / reproducing apparatus main body containing the optical pickup apparatus or the like. There are a system in which only the tray is taken out, and a system in which the optical disc drive apparatus main body in which the optical pickup device is stored is taken out to the outside.
  • the optical information recording / reproducing apparatus using each method described above is generally equipped with the following components, but is not limited thereto.
  • An optical pickup device housed in a housing or the like, a drive source of an optical pickup device such as a seek motor that moves the optical pickup device together with the housing toward the inner periphery or outer periphery of the optical disc, and the optical pickup device housing the inner periphery or outer periphery of the optical disc include a transfer means of an optical pickup device having a guide rail or the like that guides toward the head, a spindle motor that rotates the optical disk, and the like.
  • the former method is provided with a tray that can be held in a state in which an optical disk is mounted and a loading mechanism for sliding the tray, and the latter method has no tray and loading mechanism. It is preferable that each component is provided in a drawer corresponding to a chassis that can be pulled out to the outside.
  • an optical pickup device having a thickness of 8 mm or less is defined as a slim type optical pickup device.
  • the thickness of the optical pickup device refers to the distance from the lower surface of the optical pickup body to the surface of the optical disk, and the working distance of the objective lens (the distance from the light beam exit surface of the objective lens to the optical disk surface).
  • the optical disk drive apparatus on which the slim type optical pickup apparatus is mounted preferably has a thickness of 13 mm or less, and examples thereof include an optical disk drive apparatus having a thickness of 12.7 mm or 9.5 mm.
  • an optical pickup device that is compact and low-cost, suitable as a slim type optical pickup device, and capable of recording / reproducing information with respect to an optical disc having a multilayer information recording surface. Can do.
  • FIG. 4 is a graph showing the pupil radius on the vertical axis and the sine condition on the horizontal axis for Example 1.
  • FIG. 10 is a graph showing the pupil radius on the vertical axis and the sine condition on the horizontal axis for Example 4.
  • FIG. 10 is a graph which takes a pupil radius for Example 5 and takes a sine condition on the horizontal axis.
  • FIG. 4 shows that information is appropriately recorded on a BD that is an optical disk having three information recording surfaces RL1 to RL3 (referred to as RL1, RL2, and RL3 in order of increasing distance from the light beam incident surface of the optical disk) in the thickness direction.
  • FIG. 2 is a diagram schematically showing a configuration of an optical pickup device PU1 of the present embodiment that can perform reproduction.
  • the present invention is not limited to the present embodiment. For example, FIG.
  • the objective lens OBJ is made compatible with BD / DVD / CD, or the objective lens for DVD / CD is separately arranged, so that the BD / DVD is used.
  • An optical pickup device compatible with CD can be used.
  • the optical pickup device PU1 moves the objective lens OBJ, the objective lens OBJ in the focusing direction and the tracking direction, and tilts in the radial direction and / or tangential direction of the optical disc, the ⁇ / 4 wavelength plate QWP, Coupling lens CL having a positive mirror group L2 composed of one positive lens having a positive refractive power and a negative lens group L3 comprising one negative lens having a negative refractive power, a positive lens group A reflected light beam from the information recording surfaces RL1 to RL3 of the uniaxial actuator AC1 that moves only L2 in the optical axis direction, a polarization beam splitter PBS, a semiconductor laser LD that emits a laser beam (light beam) of 405 nm, a sensor lens SL, and a BD.
  • a light receiving element PD for receiving light is included.
  • the coupling lens CL is disposed between the polarization beam splitter PBS and the ⁇ / 4 wavelength plate QWP.
  • the amount of movement of the positive lens group L2 of the coupling lens CL is that the position where the luminous flux from the semiconductor laser LD becomes a parallel luminous flux when passing through the positive lens group L2 is the origin, and the direction from the origin to the semiconductor laser LD side.
  • the maximum moving distance of the positive lens unit L2 is smaller than the maximum moving distance of the positive lens unit L2 from the origin toward the objective lens OBJ.
  • the semiconductor laser LD side from the origin is ( ⁇ ) and the objective lens OBJ side is (+) from the origin
  • the information recording surface RL3 farthest from the light incident surface of the BD is selected to collect the light flux.
  • the position of the positive lens group L2 is A (A ⁇ 0)
  • the position of the positive lens group L2 when the information recording surface RL1 closest to the light beam incident surface of BD is selected to collect the light beam is B ( When B> 0), the following equation (3): ⁇ 10 ⁇ B / A ⁇ ⁇ 1.5 (3) Meet.
  • the position of the positive lens group L2 when the information recording surface RL3 farthest from the light incident surface of the BD is selected to collect the light is A (A> 0)
  • the light incident surface of the BD is
  • the position of the positive lens unit L2 when selecting the closest information recording surface RL1 and condensing the light beam is B (B> 0)
  • the objective lens OBJ is a single lens made of plastic or glass, and the focal length f (mm) at the wavelength ⁇ 1 of the objective lens OBJ is expressed by the following equation (5): 1.0 ⁇ f ⁇ 1.45 (5) Meet.
  • the positive lens group L2 of the coupling lens CL is moved to the position (B) of the solid line by the uniaxial actuator AC1.
  • the positive lens unit L2 After passing through the positive lens unit L2 to be a weak divergent light beam, it is reflected by the rising mirror MR, converted from linearly polarized light to circularly polarized light by the ⁇ / 4 wavelength plate QWP, and the light beam diameter is regulated by a diaphragm (not shown). Then, it becomes a spot formed on the first information recording surface RL1 by the objective lens OBJ through the transparent substrate PL1 having the first thickness as shown by a solid line.
  • the reflected light beam modulated by the information pits on the first information recording surface RL1 is again transmitted through the objective lens OBJ and the diaphragm, and then converted from circularly polarized light to linearly polarized light by the ⁇ / 4 wave plate QWP, and is raised to the rising mirror MR. , And passes through the positive lens group L2 and the negative lens group L3 of the coupling lens CL to be a convergent light beam. After being reflected by the polarization beam splitter PBS, it is reflected on the light receiving surface of the light receiving element PD by the sensor lens SL. Converge. Then, using the output signal of the light receiving element PD, the information recorded on the first information recording surface RL1 can be read by focusing or tracking the objective lens OBJ by the triaxial actuator AC2.
  • the positive lens group L2 of the coupling lens CL is moved to the position of the alternate long and short dash line (between B and A) by the uniaxial actuator AC1.
  • the positive lens unit L2 After passing through the positive lens unit L2 to be a substantially parallel light beam, it is reflected by the rising mirror MR, converted from linearly polarized light to circularly polarized light by the ⁇ / 4 wavelength plate QWP, and the light beam diameter is regulated by a diaphragm (not shown). Then, it becomes a spot formed on the second information recording surface RL2 by the objective lens OBJ through the transparent substrate PL2 having the second thickness (thicker than the first thickness) as indicated by a one-dot chain line.
  • the reflected light beam modulated by the information pits on the second information recording surface RL2 is again transmitted through the objective lens OBJ and the stop, and then converted from circularly polarized light to linearly polarized light by the ⁇ / 4 wavelength plate QWP, and the rising mirror MR , And passes through the positive lens group L2 and the negative lens group L3 of the coupling lens CL to be a convergent light beam.
  • the polarization beam splitter PBS After being reflected by the polarization beam splitter PBS, it is reflected on the light receiving surface of the light receiving element PD by the sensor lens SL. Converge. Then, using the output signal of the light receiving element PD, the information recorded on the second information recording surface RL2 can be read by focusing or tracking the objective lens OBJ by the triaxial actuator AC2.
  • the positive lens group L2 of the coupling lens CL is moved to the dotted line position (A) by the uniaxial actuator AC1.
  • the positive lens unit L2 After passing through the positive lens unit L2 to be a weakly convergent light beam, it is reflected by the rising mirror MR, converted from linearly polarized light to circularly polarized light by the ⁇ / 4 wavelength plate QWP, and the light beam diameter is regulated by a diaphragm (not shown). Then, it becomes a spot formed on the third information recording surface RL3 by the objective lens OBJ through the transparent substrate PL3 having the third thickness (thicker than the second thickness) as indicated by a dotted line.
  • the reflected light beam modulated by the information pits on the third information recording surface RL3 is again transmitted through the objective lens OBJ and the diaphragm, and then converted from circularly polarized light to linearly polarized light by the ⁇ / 4 wavelength plate QWP, and the rising mirror MR , And passes through the positive lens group L2 and the negative lens group L3 of the coupling lens CL to be a convergent light beam.
  • the polarization beam splitter PBS After being reflected by the polarization beam splitter PBS, it is reflected on the light receiving surface of the light receiving element PD by the sensor lens SL. Converge. Then, using the output signal of the light receiving element PD, the information recorded on the third information recording surface RL3 can be read by focusing or tracking the objective lens OBJ by the triaxial actuator AC2.
  • the polarization beam splitter PBS is disposed close to the coupling lens CL on the semiconductor laser LD side, whereas it stands relatively far on the objective lens OBJ side. Since the raising mirror MR is arranged, different information recording surfaces can be obtained by making the maximum distance for moving the coupling lens CL arranged at the origin to the semiconductor laser LD side smaller than the maximum distance for moving to the objective lens OBJ side. It is possible to obtain a compact optical pickup device while ensuring a total movement distance for condensing the spot.
  • the objective lens OBJ is moved in the radial direction of the optical disk and / or by the triaxial actuator AC2. Tilt along the tangential direction. As a result, it is possible to stably record and / or reproduce information on the warped optical disc, and to maintain a good spot quality on the information recording surface even when the optical disc is tilted during rotation.
  • FIG. 5 shows that information is appropriately recorded on a BD that is an optical disc having three information recording surfaces RL1 to RL3 in the thickness direction (referred to as RL1, RL2, and RL3 in order of increasing distance from the light incident surface of the optical disc).
  • the coupling lens CL which is a single positive lens, can be moved in the optical axis direction by the actuator AC1, and therefore the description of the other components is omitted.
  • the coupling lens CL is disposed between the polarization beam splitter PBS and the ⁇ / 4 wavelength plate QWP, and the amount of movement of the coupling lens CL is that the light flux from the semiconductor laser LD is coupled.
  • the maximum moving distance of the coupling lens CL from the origin to the semiconductor laser LD side is the coupling lens CL from the origin to the objective lens OBJ side. It is smaller than the maximum travel distance.
  • the semiconductor laser LD side from the origin is ( ⁇ ) and the objective lens OBJ side is (+) from the origin
  • the information recording surface RL3 farthest from the light incident surface of the BD is selected to collect the light flux.
  • the position of the coupling lens CL is A (A ⁇ 0)
  • the position of the coupling lens CL is B (B> 0)
  • the following equation (3) ⁇ 10 ⁇ B / A ⁇ ⁇ 1.5 (3) Meet.
  • the position of the coupling lens CL when the information recording surface RL3 farthest from the light incident surface of the BD is selected and the light is condensed is A (A> 0)
  • the light incident surface of the BD is If the position of the coupling lens CL when selecting the closest information recording surface RL1 and condensing the light beam is B (B> 0), the following equation (4): 5 ⁇ B / A ⁇ 15 (4) Meet.
  • the design wavelength of the objective lens is 405 nm or 408 nm
  • r in the table below is the radius of curvature
  • d is the position in the optical axis direction from the i-th surface to the i + 1-th surface
  • Nd is the surface of each surface in the d-line (587.6 nm).
  • Refractive index N405 represents the refractive index of each surface at the design wavelength of 405 nm
  • N408 represents the refractive index of each surface at the designed wavelength of 408 nm
  • ⁇ d represents the Abbe number in the d-line.
  • a power of 10 (for example, 2.5 ⁇ 10 ⁇ 3 ) is expressed using E (for example, 2.5E ⁇ 3).
  • the optical surface of the objective lens is formed as an aspherical surface that is axisymmetric about the optical axis, each of which is defined by an equation in which the coefficient shown in Table 1 is substituted into Equation (1).
  • X (h) is an axis in the optical axis direction (the light traveling direction is positive)
  • ⁇ is a conical coefficient
  • a i is an aspherical coefficient
  • h is a height from the optical axis
  • r is a paraxial curvature. Radius.
  • Example 1 Tables 1 and 2 show lens data of Example 1 that is suitable for use in the embodiment of FIG.
  • the coupling lens includes one positive lens and one negative lens.
  • the moving lens moves to the light source side, and when recording / reproducing the frontmost layer, the moving lens moves to the objective lens side (that is, A is a negative value and B is a positive value). value).
  • FIG. 6 shows a sine condition curve of the first embodiment. As shown in FIG. 6, in the objective lens of Example 1, the sine condition violation amount has a positive maximum value at a position that is 80% and 5 minutes of the pupil radius.
  • Example 2 Tables 3 and 4 show the lens data of Example 2 that is suitable for use in the embodiment of FIG.
  • the sine condition violation amount has a positive maximum value at a position of 80% of the pupil radius, and has a negative maximum value at a position of 40% of the pupil radius. ing.
  • Example 3 Tables 5 and 6 show lens data of Example 1 suitable for use in the embodiment of FIG.
  • FIG. 8 shows a sine condition curve of the third embodiment. As shown in FIG. 8, in the objective lens of Example 3, the sine condition violation amount has a positive maximum value at a position that is 80% and 5 minutes of the pupil radius.
  • Example 4 show lens data of Example 4 that is preferable for use in the embodiment of FIG.
  • the sine condition violation amount has a positive maximum value at a position of 80% of the pupil radius, and has a negative maximum value at a position of 30% of the pupil radius. ing.
  • Example 5 Tables 9 and 10 show lens data of Example 5 which is preferable for use in the embodiment of FIG.
  • FIG. 10 shows a sine condition curve of the fifth embodiment. As shown in FIG. 10, in the objective lens of Example 5, the sine condition violation amount is almost zero.
  • Table 11 summarizes the characteristic values of each example. Note that the values of stroke A and stroke B marked with * in the table indicate that the position where the parallel light beam is emitted from the coupling lens is 0 (origin), and the moving lens moves to the light source side ( ⁇ ). The case of moving to the side was defined as (+).
  • OBJ Objective lens PU1, PU2 Optical pickup device Blue-violet semiconductor laser AC1 Single-axis actuator AC2 Three-axis actuator PBS Polarizing beam splitter CL Coupling lens L2 Positive lens group L3 Negative lens group LD Semiconductor laser MR Rising mirror PD Light receiving element SL sensor Lens PL1 First transparent substrate PL2 Second transparent substrate PL3 Third transparent substrate RL1 First information recording surface RL2 Second information recording surface RL3 Third information recording surface QWP ⁇ / 4 wavelength plate

Landscapes

  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Head (AREA)
  • Optical Recording Or Reproduction (AREA)

Abstract

Afin d'obtenir une tête optique qui peut réduire la quantité de mouvement d'une lentille de couplage, qui est compacte et à faible coût, qui est efficace dans une forme ultramince et qui peut effectuer un enregistrement de données sur un disque optique, ayant une surface d'enregistrement de données multicouche, et une reproduction de données à partir de celui-ci, l'invention porte sur une tête optique qui présente une source de lumière, une lentille de couplage et une seule lentille de focalisation, dont l'ouverture numérique côté objet est supérieure ou égale à 0,8 et inférieure ou égale à 0,95 ; la lentille de couplage présente une lentille mobile ; au moyen d'un déplacement de la lentille mobile entre la source de lumière et la lentille de focalisation dans la direction de l'axe de lumière, une surface d'enregistrement de données est sélectionnée, et si TMAX est l'épaisseur de substrat transparent maximale, à température ambiante et avec une épaisseur de verre de revêtement T qui satisfait la formule 1, le grossissement (M), lorsqu'une aberration sphérique est réduite à un minimum, satisfait la formule 2 : TMAX × 0,80 ≤ T ≤ TMAX × 1,1 (1) -0,003 ≤ M ≤ 0,003 (2)
PCT/JP2011/051180 2010-01-29 2011-01-24 Tête optique et dispositif d'enregistrement/reproduction d'informations optiques WO2011093231A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN201180006796.6A CN102714045B (zh) 2010-01-29 2011-01-24 光拾取装置以及光信息记录再生装置
JP2011551837A JP5582421B2 (ja) 2010-01-29 2011-01-24 光ピックアップ装置及び光情報記録再生装置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2010018670 2010-01-29
JP2010-018670 2010-07-30

Publications (1)

Publication Number Publication Date
WO2011093231A1 true WO2011093231A1 (fr) 2011-08-04

Family

ID=44319219

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2011/051180 WO2011093231A1 (fr) 2010-01-29 2011-01-24 Tête optique et dispositif d'enregistrement/reproduction d'informations optiques

Country Status (3)

Country Link
JP (1) JP5582421B2 (fr)
CN (1) CN102714045B (fr)
WO (1) WO2011093231A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001296471A (ja) * 2000-04-14 2001-10-26 Asahi Optical Co Ltd 光ヘッド用対物レンズ
JP2003005032A (ja) * 2001-06-20 2003-01-08 Konica Corp 対物レンズ、光ピックアップ装置及び記録・再生装置
JP2004103087A (ja) * 2002-09-06 2004-04-02 Sanyo Electric Co Ltd 光ピックアップ装置
WO2006115046A1 (fr) * 2005-04-21 2006-11-02 Matsushita Electric Industrial Co., Ltd. Tete optique et enregistreur/duplicateur d’informations optiques
JP2009048747A (ja) * 2007-08-22 2009-03-05 Sony Corp 光ピックアップ及びこれを用いた光ディスク装置
WO2010004858A1 (fr) * 2008-07-10 2010-01-14 コニカミノルタオプト株式会社 Lentille de focalisation et tête optique

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004171682A (ja) * 2002-11-20 2004-06-17 Olympus Corp 光学情報記録再生装置
JP4530884B2 (ja) * 2005-03-08 2010-08-25 株式会社リコー 光ピックアップ装置およびこれを用いた光ディスクドライブ装置
JP2007133967A (ja) * 2005-11-10 2007-05-31 Canon Inc 光学式情報記録再生装置
WO2009047907A1 (fr) * 2007-10-10 2009-04-16 Panasonic Corporation Dispositif de capture optique et lentille de collimation
WO2010047093A1 (fr) * 2008-10-24 2010-04-29 パナソニック株式会社 Tête optique, dispositif à disque optique et dispositif de traitement d'informations

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001296471A (ja) * 2000-04-14 2001-10-26 Asahi Optical Co Ltd 光ヘッド用対物レンズ
JP2003005032A (ja) * 2001-06-20 2003-01-08 Konica Corp 対物レンズ、光ピックアップ装置及び記録・再生装置
JP2004103087A (ja) * 2002-09-06 2004-04-02 Sanyo Electric Co Ltd 光ピックアップ装置
WO2006115046A1 (fr) * 2005-04-21 2006-11-02 Matsushita Electric Industrial Co., Ltd. Tete optique et enregistreur/duplicateur d’informations optiques
JP2009048747A (ja) * 2007-08-22 2009-03-05 Sony Corp 光ピックアップ及びこれを用いた光ディスク装置
WO2010004858A1 (fr) * 2008-07-10 2010-01-14 コニカミノルタオプト株式会社 Lentille de focalisation et tête optique

Also Published As

Publication number Publication date
JP5582421B2 (ja) 2014-09-03
CN102714045A (zh) 2012-10-03
CN102714045B (zh) 2015-01-21
JPWO2011093231A1 (ja) 2013-06-06

Similar Documents

Publication Publication Date Title
WO2010044355A1 (fr) Lentille de focalisation et tête optique
WO2013047202A1 (fr) Lentille de focalisation et dispositif capteur optique
WO2011132691A1 (fr) Lentille d'objectif pour dispositif de capture optique, dispositif de capture optique et dispositif optique d'enregistrement/de reproduction d'informations
JP5582421B2 (ja) 光ピックアップ装置及び光情報記録再生装置
JP5713248B2 (ja) 光ピックアップ装置用の対物レンズ及び光ピックアップ装置
JP5152439B2 (ja) 光ピックアップ装置用の対物レンズ及び光ピックアップ装置
JP2011198446A (ja) 光ピックアップ装置
WO2011052469A1 (fr) Dispositif de lecture optique
WO2011099317A1 (fr) Capteur optique
WO2011065276A1 (fr) Objectif pour utilisation d'un dispositif de lecture optique et dispositif de lecture optique
WO2011078022A1 (fr) Lentille d'objectif pour dispositif de capture optique et dispositif de capture optique
JP5835320B2 (ja) 光ピックアップ装置用の対物レンズ、光ピックアップ装置及び光情報記録再生装置
JP5093634B2 (ja) 光ピックアップ装置用の対物レンズ及び光ピックアップ装置
JP5229657B2 (ja) 光ピックアップ装置用の対物レンズ、光ピックアップ装置及び光情報記録再生装置
JP5585879B2 (ja) 光ピックアップ装置及び光情報記録再生装置
JPWO2012036052A1 (ja) 光ピックアップ装置用の対物レンズ、光ピックアップ装置及び光情報記録再生装置
WO2013027622A1 (fr) Lentille d'objectif et dispositif de lecture optique
JP2010097664A (ja) 対物レンズ
WO2011122275A1 (fr) Dispositif de capture optique et lentille de couplage pour le dispositif de capture optique
WO2013121615A1 (fr) Lentille de focalisation pour dispositif de capture optique et dispositif de capture optique
WO2012070438A1 (fr) Lentille de focalisation pour un capteur optique et capteur optique
WO2013084558A1 (fr) Lentille de focalisation pour dispositif de capteur optique, dispositif de capteur optique et dispositif d'enregistrement et de reproduction d'informations optique
WO2012063847A1 (fr) Lentille d'objectif pour dispositif de lecture optique, dispositif de lecture optique, et dispositif d'enregistrement/reproduction d'informations optiques
WO2012133363A1 (fr) Lentille de focalisation pour dispositif de capture optique, dispositif de capture optique et lecteur/enregistreur d'informations optique
JP2013206514A (ja) 光ピックアップ装置用の対物レンズ、光ピックアップ装置及び光情報記録再生装置

Legal Events

Date Code Title Description
WWE Wipo information: entry into national phase

Ref document number: 201180006796.6

Country of ref document: CN

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 11736944

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2011551837

Country of ref document: JP

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 11736944

Country of ref document: EP

Kind code of ref document: A1