WO2006095583A1 - 光ピックアップ装置及び、対物光学ユニット及び対物光学系の設計方法 - Google Patents
光ピックアップ装置及び、対物光学ユニット及び対物光学系の設計方法 Download PDFInfo
- Publication number
- WO2006095583A1 WO2006095583A1 PCT/JP2006/303414 JP2006303414W WO2006095583A1 WO 2006095583 A1 WO2006095583 A1 WO 2006095583A1 JP 2006303414 W JP2006303414 W JP 2006303414W WO 2006095583 A1 WO2006095583 A1 WO 2006095583A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- optical
- path difference
- information recording
- optical path
- difference providing
- Prior art date
Links
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
- G11B7/1365—Separate or integrated refractive elements, e.g. wave plates
- G11B7/1367—Stepped phase plates
-
- 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
- G11B7/1374—Objective lenses
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
-
- 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
- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/127—Lasers; Multiple laser arrays
- G11B7/1275—Two or more lasers having different wavelengths
-
- 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
- G11B7/1353—Diffractive elements, e.g. holograms or gratings
-
- 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
- G11B7/1392—Means for controlling the beam wavefront, e.g. for correction of aberration
- G11B7/13922—Means for controlling the beam wavefront, e.g. for correction of aberration passive
-
- 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
- G11B2007/0006—Recording, reproducing or erasing systems characterised by the structure or type of the carrier adapted for scanning different types of carrier, e.g. CD & DVD
Definitions
- the present invention relates to an optical pickup device and an objective optical unit, and more particularly to an optical pickup device capable of appropriately recording and / or reproducing information on / from different optical information recording media using light sources having different wavelengths.
- the present invention relates to an objective optical unit to be used.
- HD DVD An optical disc for recording and Z or playback, so-called HD DVD (hereinafter referred to as HD), can record 15 to 20 GB of information per layer on an optical disc with a diameter of 12 cm.
- BD coma aberration caused by the tilt (skew) of the optical disk increases, so the protective layer is designed thinner than in DVD (0.1 mm for 0.6 mm of DVD). The amount of coma due to skew is reduced.
- high density optical disc such an optical disc is referred to as a “high density optical disc” in the present specification.
- Optical systems for high-density optical disks and optical systems for DVDs are used as a method for appropriately recording and Z-reproducing information while maintaining compatibility with both high-density optical disks and DVDs.
- an optical system for high-density optical discs and an optical system for DVDs can be used even with compatible optical pickup devices! It is preferable to reduce the number of optical parts constituting the optical pickup device as much as possible. It is most advantageous for simplifying the configuration of the optical pickup device and reducing the cost to make the objective lens arranged opposite to the optical disk in common and further to make this objective lens a single lens configuration.
- a common objective lens for multiple types of optical discs with different recording and Z or reproducing wavelengths a diffraction structure having the wavelength dependence of spherical aberration is formed on the surface, and the wavelength dependence of the diffraction structure is used. Objective lenses that correct spherical aberrations due to differences in the recording and Z or reproduction wavelengths and the protective layer thickness are known.
- Patent Document 1 discloses an objective lens having a single-lens configuration capable of recording and / or reproducing or recording information in a manner compatible with a high-density optical disc and a DVD.
- the objective lens disclosed in Patent Document 1 generates a second-order diffracted light with respect to a blue-violet laser beam, and generates a first-order diffracted light with respect to a red laser beam for DVD.
- the spherical aberration due to the difference in the protective layer thickness between the high-density optical disc and the DVD is corrected by the diffractive action of the diffractive structure.
- this objective lens since this objective lens has a single lens configuration, it can be produced at a low cost, but has the following problems.
- a specific problem is that the wavelength dependence of spherical aberration generated by a diffractive structure is large. In such a case, it is impossible to use a laser light source whose oscillation wavelength is deviated from the design wavelength power, and it is necessary to select the laser light source, which increases the manufacturing cost of the optical pickup device. .
- the diffraction angle of the diffracted light is expressed by “diffraction order X wavelength Z diffraction pitch”. In order to realize compatibility between optical information recording media having different use wavelengths by using the diffraction action, it is necessary to provide a predetermined difference in the diffraction angle between the use wavelengths.
- the above-mentioned “laser light source selection problem” is caused by using a diffraction structure in which the value of “diffraction order X wavelength” is almost the same between wavelengths used for high-density optical discs and DVDs.
- the diffraction pitch must be reduced. .
- the wavelength dependence of the spherical aberration of the diffractive structure increases, and the “laser light source selection problem” as described above becomes apparent.
- Patent Document 1 JP 2004-79146 A
- the present invention has been made in view of the above problems, and is an optical pickup device that can perform recording and Z or reproduction of information with respect to different types of optical information recording media while being compact. And an objective optical unit used therefor.
- the configuration according to the present invention includes:
- a first light source that emits a first light beam having a wavelength ⁇ 1 for forming a condensed spot on the information recording surface of the first optical information recording medium having a protective layer having a thickness of tl;
- a second light source that emits a second light beam having a wavelength ⁇ 2 for forming a condensed spot on the information recording surface of the second optical information recording medium having a protective layer having a thickness t2.
- a third light source that emits a third light beam having a wavelength ⁇ 3 for forming a condensed spot on the information recording surface of the third optical information recording medium having a protective layer having a thickness t3;
- An optical pickup device comprising an objective optical unit having a first optical path difference providing structure having a ring-shaped structure and a second optical path difference providing structure having a ring-shaped structure,
- the respective magnifications of the objective optical unit when the first light flux, the second light flux, and the third light flux are incident on the objective optical unit are substantially the same,
- the first optical path difference providing structure provides a predetermined optical path difference to the first light flux that has passed through the adjacent annular zone, and also provides spherical aberration for all of the first light flux, the second light flux, and the third light flux.
- the second optical path difference providing structure is changed to either under or over, and the second optical path difference providing structure provides a predetermined optical path difference with respect to the first light flux that has passed through the adjacent annular zone, and the first light flux and the first light flux.
- the spherical aberration is changed only to the second light beam among the two light beams and the third light beam.
- FIG. 1 is a diagram schematically showing a configuration of an optical pickup device of an embodiment.
- FIG. 2 is a cross-sectional view of an example of an objective lens OBJ in which a diffractive structure as a first optical path difference providing structure and a phase structure as a second optical path difference providing structure are formed on the optical surface on the light source side.
- FIG. 3 is a cross-sectional view of another objective lens OBJ in which a diffractive structure as a first optical path difference providing structure and a phase structure as a second optical path difference providing structure are formed on the optical surface on the light source side.
- FIG. 4 (a) is a diagram showing the relationship between the height of the optical axis force and the amount of default force when using HD DVD in Example 1
- FIG. 4 (b) is the diagram in Example 1.
- Fig. 4 (c) shows the relationship between the height from the optical axis when using a DVD and the defocus amount
- Fig. 4 (c) shows the relationship between the height of the optical axis force when using a CD and the defocus amount in Example 1.
- FIG. 4 (c) shows the relationship between the height of the optical axis force when using a CD and the defocus amount in Example 1.
- FIG. 5 (a) is a diagram showing the relationship between the height of the optical axis force and the amount of default force when using HD DVD in Example 2
- FIG. 5 (b) is the diagram in Example 2.
- Fig. 5 (c) shows the relationship between the height from the optical axis when using a DVD and the defocus amount
- Fig. 5 (c) shows the relationship between the height of the optical axis force when using a CD and the defocus amount in Example 2.
- Fig. 6 is a diagram showing the relationship between the height of the optical axis force and the amount of default force when using HD DVD in Example 3, and Fig. 6 (b) is the diagram in Example 3.
- Fig. 6 (c) shows the relationship between the height from the optical axis when using a DVD and the defocus amount.
- Figure 6 (c) shows the relationship between the height of the optical axis force when using a CD and the defocus amount in Example 3.
- FIG. 6 is a diagram showing the relationship between the height of the optical axis force and the amount of default force when using HD DVD in Example 3
- Fig. 6 (b) is the diagram in Example 3.
- Fig. 6 (c) shows the relationship between the height from the optical axis when using a DVD and the defocus amount.
- Figure 6 (c) shows the relationship between the height of the optical axis force when using a CD and the defocus amount in Example 3.
- a first light source that emits a first light beam having a wavelength ⁇ 1 for forming a condensed spot on the information recording surface of the first optical information recording medium having a protective layer having a thickness of tl;
- a second light beam having a wavelength ⁇ 2 ( ⁇ 1 ⁇ 2) is emitted to form a light collecting spot on the information recording surface of the second optical information recording medium having a protective layer having a thickness t2 (tl ⁇ t2).
- 2 Wavelength for forming a collecting spot on the information recording surface of the third optical information recording medium having a light source and a protective layer with thickness t3 (t2 ⁇ t3) 3 (1.9 X ⁇ ⁇ ⁇ 3 ⁇ 2
- An objective optical unit having a first optical path difference providing structure having an annular structure and a second optical path difference providing structure having an annular structure
- magnification of the objective optical unit when the first light beam, the second light beam, and the third light beam are incident on the objective optical unit is set to ml, m2, and m3, ml, m2, and m3 are substantially the same.
- the first optical path difference providing structure provides an optical path difference equivalent to an odd multiple of the wavelength ⁇ 1 to the first light flux that has passed through the adjacent annular zone, and includes the first light flux, the second light flux, and the third light flux.
- Spherical aberration is changed to either under or over for all, and the second optical path difference providing structure is equivalent to an even multiple of the wavelength ⁇ 1 for the first light flux that has passed through the adjacent annular zone.
- the spherical aberration of only the second light flux among the first light flux, the second light flux, and the third light flux is changed to the other of the under and over conditions different from the one.
- the objective optical unit may be configured with a plurality of optical element forces, or may be an objective optical element having a single lens force.
- the first optical path difference providing structure provides an optical path difference equivalent to an odd multiple of the wavelength ⁇ 1 to the first light flux that has passed through the adjacent annular zone. Further, the spherical aberration is changed in the under direction for all of the first light flux, the second light flux, and the third light flux, and the second optical path difference providing structure is applied to the first light flux that has passed through the adjacent annular zone. It is preferable to provide an optical path difference corresponding to an even multiple of the wavelength ⁇ 1 and to change the spherical aberration in the over direction only for the second light beam among the first light beam, the second light beam, and the third light beam.
- the configuration according to the present invention appropriately records and Z or reproduces information on three different optical information recording media by a new combination of diffraction and magnification.
- optical path difference providing structures such as diffractive structures that have been used in the past
- the first optical path difference providing structure is designed to appropriately correct aberrations for the first light beam and the third light beam refracted by a base aspheric surface. Further, when the third wavelength is close to an even multiple of the first wavelength, the odd number of times is equivalent to the first luminous flux in order to make the action different for the first luminous flux and the third luminous flux. The optical path difference is given. Then, based on the wavelength difference, the third light flux is given an optical path difference that is shifted by a half wavelength, and the optical action on the first light flux and the third light flux can be made different. Appropriate spherical aberration due to different thickness Can be corrected.
- the second optical path difference providing structure when the first optical path difference providing structure is designed in this way, the second light flux is excessively subjected to the action of making the spherical aberration under, and the objective optical unit itself In combination with the refractive power possessed, there is a risk that a good condensing spot cannot be formed. Therefore, by allowing the second optical path difference providing structure to carry out the action of canceling out the excessive excess, it is possible to appropriately record and / or reproduce information on any optical information recording medium. RU
- the second optical path difference providing structure is bad for the first light flux and the third light flux in which a good wavefront is formed by a combination of the first optical path difference providing structure and refractive power. It is necessary to avoid the influence. Therefore, with respect to the second optical path difference providing structure, an optical path difference that is an even multiple of the wavelength ⁇ 1 is applied to the first light flux, thereby preventing the first light flux from changing in the phase of the wavefront. . Further, when the third light beam has a wavelength that is almost an even multiple of the first light beam, an optical path difference that is an integral multiple of the wavelength ⁇ 1 is given, and similarly the phase of the wave front does not change. It becomes.
- the annular zone pitch so that the light beam having the wavelength ⁇ 1 and the wavelength ⁇ 3 is not bent.
- the first light flux and the third light flux are not influenced by the second optical path difference providing structure.
- even multiples mean a range of (2 ⁇ -0. 1) ⁇ ⁇ 1 or more and (2 ⁇ + 0.1) ⁇ ⁇ 1 or less when ⁇ is a natural number.
- the odd-number equivalent means a range of ⁇ (2 ⁇ -D -0.1 ⁇ ⁇ ⁇ ⁇ or more and ⁇ (2 ⁇ 1) +0.1 ⁇ ⁇ ⁇ or less, where ⁇ is a natural number.
- the second optical path difference structure can be designed so as to give a desired action to the second light flux.
- the second optical path difference providing structure in order to cancel the spherical aberration that has been excessively changed in the under direction by the first optical path difference providing structure, the second optical path difference providing structure is designed to give an action of changing the spherical aberration in the over direction. be able to. In this way, the second light flux is reflected by the refractive action of the objective optical unit.
- the incident light magnifications ml, m2, and m3 of the first light beam, the second light beam, and the third light beam to the objective optical unit satisfy the relational expressions (1), (2), and (3), respectively.
- infinite parallel light is incident on the objective optical unit, and the occurrence of coma aberration can be suppressed during the tracking operation of the objective optical unit. It can be preferably used for a high-speed type information recording / reproducing apparatus.
- the optical pickup device in the configuration according to any one of Items 1 to 4, has a refractive action of the objective optical unit when the first light beam is incident on the objective optical unit. And a condensing spot formed on the information recording surface of the first optical information recording medium in combination with the optical action provided by the first optical path difference providing structure, and the second light flux is incident on the objective optical unit.
- the second optical information recording medium is a combination of the refractive action of the objective optical unit, the optical action provided by the first optical path difference providing structure, and the optical action provided by the second optical path difference providing structure.
- a focused spot is formed on the information recording surface of
- the third optical information recording medium When the third light beam is incident on the objective optical unit, the third optical information recording medium has a combination of a refractive action of the objective optical unit and an optical action provided by the first optical path difference providing structure. A focused spot is formed on the information recording surface.
- optical pickup device in the configuration according to any one of Items 1 to 5, the first optical path difference providing structure and the second optical path difference providing structure are overlapped, Exists on the same optical surface.
- the optical pickup device according to Item 7 in the configuration according to Item 6, has both optical path difference providing structures provided! Since parallel light is incident, vignetting can be suppressed.
- the optical pickup device in the configuration according to any one of Items 1 to 7, the optical function surface of the objective optical unit surrounds a central region including an optical axis and the central region. Has a surrounding area,
- the central area includes the first optical path difference providing structure and the second optical path difference providing structure, and the central area includes the first optical information recording medium, the second optical information recording medium, and the third optical information recording medium.
- the peripheral area is the information recording of the first optical information recording medium, the second optical information recording medium, and the third optical information recording medium. Of the surfaces, only the information recording surfaces of the first optical information recording medium and the second optical information recording medium are used for forming a condensed spot.
- FIG. 2 is a cross-sectional view of an objective lens OBJ in which a diffractive structure as a first optical path difference providing structure and a phase structure as a second optical path difference providing structure are formed on the optical surface on the light source side.
- the diffractive structure DS and the phase structure PS are exaggeratedly drawn so that they can be easily understood.
- the first light beam and the second light beam pass in common, and in the peripheral region PR, only the first light beam passes.
- the diffraction structure DS having a blazed cross section centered on the optical axis X indicated by the solid line is locally displaced in the axial direction because it overlaps the phase structure PS.
- FIG. 2 is a cross-sectional view of an objective lens OBJ in which a diffractive structure as a first optical path difference providing structure and a phase structure as a second optical path difference providing structure are formed on the optical surface on the light source side.
- the diffractive structure DS and the phase structure PS are exaggeratedly drawn
- the diffractive structure DS is composed only of a blazed structure with a positive orientation
- the envelope (dotted line shown in FIG. 2) indicating the shape of the phase structure PS is drawn when the blaze vertices are connected.
- FIG. 3 is a cross-sectional view of another objective lens OBJ that has a diffractive structure as the first optical path difference providing structure and a phase structure as the second optical path difference providing structure formed on the optical surface on the light source side.
- the force is an illustration The surface shape is exaggerated for easy understanding.
- the central region CR includes a first region R1 including the optical axis X, a second region R2 around the first region R1, and a third region R3 that is in the periphery and in contact with the peripheral region PR. It consists of and.
- an envelope shown in the first region R1, since the blazed structure and the phase structure in the negative direction are superimposed, an envelope (shown in FIG.
- the second region R2 is a transition region necessary for switching between a negatively-oriented blazed structure and a positively-oriented blazed structure. This transition region is transparent due to the diffractive structure.
- the optical path difference added to the overwave front is expressed by an optical path difference function, this is an area corresponding to the inflection point of the optical path difference function. If the optical path difference function has an inflection point, the inclination of the optical path difference function becomes small, so that it becomes possible to widen the annular zone pitch and to suppress the decrease in transmittance due to the shape error of the diffractive structure.
- the shape of the phase structure has a predetermined height in the central region as shown in FIG. Until the distance from the optical axis is longer, the optical path length is longer, and outside the specified height, the optical path length is shortened as the optical axis force is further away (dotted line shown in Fig. 3). Is preferred. At this time, it is more preferable that the ring zone having the longest optical path length among the ring zones of the phase structure includes the position of 70% height in the central region.
- the objective optical unit has an outermost region surrounding the peripheral region, and the first light flux that has passed through the outermost region is information on the first optical information recording medium. This may be used for forming a condensing spot on the recording surface, and thus can cope with the high numerical aperture of the first optical information recording medium.
- the outermost area may have an optical path difference providing structure, and the second light flux and the third light flux that have passed through the outermost area may be flared.
- An aperture stop effect can be given to the base.
- the first optical path difference providing structure is a sawtooth diffractive structure.
- a “sawtooth diffractive structure” means, for example, that at least one optical function surface is divided into a plurality of optical function areas centered on the optical axis, and at least one of the plurality of optical function areas has an optical axis. This is a structure in which a ring-shaped region is divided into a center, and a predetermined number of discontinuous steps are provided in each ring zone, and the cross section in the optical axis direction is a saw-tooth shape.
- the annular zone average step amount dl in the direction parallel to the optical axis of the diffractive structure satisfies the following.
- ⁇ 1 Refractive index of the material forming the first optical path difference providing structure for light of ⁇ 1
- ⁇ 2 Refractive index of the material forming the first optical path difference providing structure for light of ⁇ 2
- the objective optical unit is configured by setting the diffraction order of the diffracted light of the first light beam that is generated by the diffractive structure to form the focused spot as Kl and the diffraction order of the diffracted light of the second light beam as ⁇ 2.
- the refractive index for the wavelength 1 of the material is nl and the refractive index for the wavelength ⁇ 2 is ⁇ 2, the following equation is satisfied.
- an annular average step amount d2 in a direction parallel to the optical axis in the first optical path difference providing structure satisfies the following.
- the first light beam that has passed through the first optical path difference providing structure has the highest light amount of the first-order diffracted light
- the second light beam that has passed through the first optical path difference providing structure has the highest light amount of the first-order diffracted light.
- the third light flux that has become higher and has passed through the first optical path difference providing structure has the highest amount of first-order diffracted light.
- the ring zone average step amount d2 in the direction parallel to the optical axis in the first optical path difference providing structure is the following in the structure described in any of items 9 to L1: Meet.
- the first light beam that has passed through the first optical path difference providing structure has the highest amount of third-order diffracted light
- the second light beam that has passed through the first optical path difference providing structure has the highest light quantity of second-order diffracted light.
- the third light flux that has become higher and has passed through the first optical path difference providing structure has the highest amount of second-order diffracted light.
- the first light beam that has passed through the first optical path difference providing structure has the highest amount of third-order diffracted light
- the second light beam that has passed through the first optical path difference providing structure has a second-order diffracted light intensity.
- the third light flux having the highest light amount and having passed through the first optical path difference providing structure has the highest light amount of the first-order diffracted light.
- the first optical path difference providing structure is NPS (Non-Periodic Phase Structure).
- the optical pickup device according to Item 14 is the configuration according to any one of Items 1 to 13.
- the second optical path difference providing structure is a sawtooth diffractive structure.
- the annular zone average step amount d3 in the direction parallel to the optical axis in the second optical path difference providing structure satisfies the following.
- ⁇ 1 ' Refractive index of the material forming the second optical path difference providing structure for light of ⁇ 1
- the first light beam that has passed through the second optical path difference providing structure has the highest amount of second-order diffracted light
- the second light beam that has passed through the second optical path difference providing structure has the highest light amount of first-order diffracted light.
- the third light flux that has become higher and has passed through the second optical path difference providing structure has the highest amount of first-order diffracted light.
- the second optical path difference providing structure has the same pattern in which the cross-sectional shape including the optical axis is stepped.
- This is a superposition type diffractive structure that is arranged in a concentric shape, and the steps are shifted by a height corresponding to the number of level surfaces for each predetermined number of level surfaces.
- the “superimposition type diffractive structure” means that the optical functional surface is composed of a plurality of diffraction periods centered on the optical axis, and the plurality of diffraction periods are composed of a predetermined number of discontinuous steps in the optical axis direction and the optical axis.
- a structure composed of an annular zone force centered on The superposition type diffractive structure is also called a multi-level structure or a DOE structure.
- the diffractive structure has an optical functional surface of an optical element divided into a plurality of annular zones centered on the optical axis, and each annular zone is sawtooth-shaped In this structure, a predetermined number of staircase shapes are further provided in this one sawtooth portion. As a result, it is possible to select light that gives a diffractive action according to wavelength.
- the second optical path difference providing structure so-called wavelength selective diffraction in which a stepped shape is repeated can be used.
- a diffraction action is given only to a specific wavelength, and the other wavelengths can be transmitted as they are.
- the wavelength ⁇ 3 is almost twice the wavelength ⁇ 1, if the third light flux with the wavelength ⁇ 3 can be transmitted as it is, the first light flux with the wavelength ⁇ 1 can also be transmitted as it is. Only the second light flux of 2 can be diffracted.
- the ring zone average step amount d4 parallel to the optical axis of the stepped pattern in the second optical path difference providing structure in the configuration described in item 16 is: Meet.
- ⁇ 1 ' Refractive index of the material forming the second optical path difference providing structure for light of ⁇ 1
- the first light flux that has passed through the second optical path difference providing structure has the highest light amount of the 0th-order diffracted light
- the second light flux that has passed through the second optical path difference providing structure has the highest light quantity of the first-order diffracted light.
- the third light flux that has passed through the second optical path difference providing structure becomes higher, and the amount of 0th-order diffracted light is the highest. Get higher.
- the optical pickup device according to Item 18, in the configuration according to Item 16, has a level surface force formed on each pattern of the second optical path difference providing structure on a base aspherical surface of the objective optical unit element. It is formed along
- the first light beam that has passed through the second optical path difference providing structure has the highest amount of second-order diffracted light
- the second light beam that has passed through the second optical path difference providing structure has the first-order diffracted light
- the third light flux that has passed through the second optical path difference providing structure has the highest light quantity of the first-order diffracted light
- the first light flux that has passed through the second optical path difference providing structure has the highest amount of 0th-order diffracted light
- the second light flux that has passed through the second optical path difference providing structure is It is preferable that the light quantity of the first-order diffracted light is the highest
- the third light flux that has passed through the second optical path difference providing structure has the highest light quantity of the zero-order diffracted light.
- the second optical path difference providing structure is NPS (Non-Periodic Phase Structure)
- NPS may be used as the second optical path difference providing structure.
- NPS refers to a structure in which the wavefront is aligned and the applied force is as-aberrated by giving a phase difference to the light beam passing through the structure. At this time, correction of spherical aberration is not necessarily performed.
- an annular zone having a step is provided around the optical axis, and the step gives an optical path difference that is an even multiple of ⁇ 1 to the light beam having the wavelength ⁇ 1. Thereby, the wavefront of the first light flux is not affected.
- the step that gives an optical path difference that is an even multiple of the wavelength ⁇ 1 gives an optical path difference that is an integral multiple of the wavelength ⁇ 3 for the light flux of the wavelength ⁇ 3, and also affects the wavefront of the third light flux. Absent.
- the wavefront of the second light flux changes as it passes through the NPS. Can be. In the case of NPS as well, it is possible to control how the wavefront changes by adjusting the ring interval.
- the equivalent of an even multiple means a range of (2 ⁇ 0.1) ⁇ ⁇ 1 or more and (2 ⁇ + 0.1) X ⁇ 1 or less when ⁇ is a natural number.
- the wavelength X1 ⁇ is 380nm ⁇ l ⁇ 420nm
- the wavelength ⁇ 2 ⁇ is 630nm ⁇ . 2 and 680
- the wavelength 3 is 760 nm ⁇ 3 830 nm
- the protective layer thickness tl of the first optical information recording medium is 0.0875 mm ⁇ tl ⁇ 0.1125, and the protective layer thickness t2 of the second optical information recording medium is 0.5 mm ⁇ t2 ⁇ 0.
- the protective layer thickness t3 of the third optical information recording medium is 1. Imm ⁇ t3 ⁇ l.3mm.
- the wavelength X1 ⁇ is 380nm ⁇ l ⁇ 420nm
- the wavelength ⁇ 2 ⁇ is 630nm ⁇ . 2 and 680
- the wavelength 3 is 760 nm ⁇ 3 830 nm
- the protective layer thickness tl of the first optical information recording medium is 0.5 mm ⁇ tl ⁇ 0.7 mm
- the protective layer thickness t2 of the second optical information recording medium is 0.5 mm ⁇ t2 ⁇ 0. 7 mm
- the protective layer thickness t3 of the third optical information recording medium is 1. Imm ⁇ t3 ⁇ l.3mm.
- the wavelengths ⁇ 1, 2 and ⁇ 3 of the first optical information recording medium, the second optical information recording medium are designed so as to satisfy the above conditional expression.
- Item 22 is the optical pickup device according to Item 1, wherein the objective optical unit is made of glass.
- the objective optical unit is made of plastic.
- the objective optical unit may be made of glass and plastic as material! /.
- the objective optical unit according to Item 24 has a first optical path difference providing structure having an annular structure and a second optical path difference providing structure having an annular structure,
- the first light beam having a wavelength of 1 incident on the objective optical unit is focused on the information recording surface of the first optical information recording medium having a protective layer with a magnification ⁇ and a thickness of tl, and is incident on the objective optical unit.
- 2 2 ( ⁇ ⁇ ⁇ 2) second light beam converges on the information recording surface of the second optical information recording medium with a magnification ⁇ and a protective layer of thickness t2 (tl ⁇ t2) and enters the objective optical unit Of a third optical information recording medium having a protective layer with a thickness of t3 (t2 ⁇ t3) at a third luminous flux power factor of ⁇ 3 (1.9 X ⁇ 1 ⁇ ⁇ 2.
- the first optical path difference providing structure provides an optical path difference equivalent to an odd multiple of the wavelength ⁇ 1 to the first light flux that has passed through the adjacent annular zone, and the first light flux, the second light flux, and the third light flux. For all of the above, the spherical aberration is changed to either under or over,
- the second optical path difference providing structure provides an optical path difference equivalent to an even multiple of the wavelength ⁇ 1 to the first light flux that has passed through the adjacent annular zone, and the first light flux, the second light flux, and the third light flux. Among these, only the second light flux changes the spherical aberration to the other of the under and over, which is different from the one.
- the magnification ⁇ of the objective optical unit is approximately zero.
- Item 27 is the objective optical unit according to any one of Items 24 to 26, wherein when the first light beam is incident on the objective optical unit, the objective optical unit has a refracting action and the first optical unit.
- a condensing spot is formed on the information recording surface of the first optical information recording medium in combination with the optical action provided by the optical path difference providing structure, and the objective beam is incident on the objective optical unit when the second light flux is incident on the objective optical unit.
- the information recording surface of the second optical information recording medium is combined with the refractive action of the optical unit, the optical action provided by the first optical path difference providing structure, and the optical action provided by the second optical path difference providing structure.
- a focused spot is formed,
- the objective optical unit according to Item 28 in the configuration according to any one of Items 24 to 27, the first optical path difference providing structure and the second optical path difference providing structure are overlapped, and the same Present on the optical surface.
- the optical surface provided with both optical path difference providing structures is the light source side.
- the objective optical unit according to Item 30 is the configuration according to any one of Items 24 to 29, wherein the optical function surface of the objective optical unit includes a central region including an optical axis and a peripheral region surrounding the central region.
- the central region includes the first optical path difference providing structure and the second optical path difference providing structure, and the first optical path difference providing structure is incident on an objective optical unit and passes through the central region and the peripheral region.
- the first light beam of the light beam is focused on the information recording surface of the first optical information recording medium having a protective layer with a magnification ⁇ and a thickness of tl, and is incident on the objective optical unit and passes through the central region and the peripheral region.
- a second light beam of ⁇ 2 ( ⁇ 1 ⁇ 2) is focused on the information recording surface of the second optical information recording medium having a protective layer with a magnification of ⁇ and a thickness of t2 (tl ⁇ t2), and is focused on the objective optical unit.
- the third light flux of wavelength 3 (1.9 ⁇ ⁇ 1 ⁇ 3 ⁇ 2.
- IX ⁇ ⁇ ) that has entered and passed through the central region passes through a protective layer with a magnification ⁇ and a thickness t3 (t2 ⁇ t3).
- the second optical path difference providing structure is a first optical information in which a first light beam having a wavelength ⁇ 1 incident on an objective optical unit and passed through the central region and the peripheral region has a protective layer having a magnification ⁇ and a thickness tl.
- the third light flux of wavelength ⁇ 3 that has passed through is condensed on the information recording surface of the third optical information recording medium having a protective layer with a thickness of t3 and a magnification of ⁇ , it passes through the adjacent annular zone.
- An optical path difference equivalent to an even multiple of the wavelength ⁇ 1 is given to the first luminous flux, and spherical aberration is underperformed only for the second luminous flux among the first luminous flux, the second luminous flux, and the third luminous flux. Change over to the other one of the above.
- the first optical path difference providing structure is a sawtooth diffractive structure.
- the objective optical unit according to Item 32 is the configuration according to Item 31,
- the annular zone average step amount dl in the direction parallel to the optical axis of the diffractive structure satisfies the following.
- ⁇ 1 Refractive index of the material forming the first optical path difference providing structure for light of ⁇ 1
- ⁇ 2 refractive index of the material forming the first optical path difference providing structure for light of ⁇ 2
- the objective optical unit described in Item 33 is configured as described in Item 31.
- the annular zone step difference d2 in the direction parallel to the optical axis satisfies the following.
- the objective optical unit described in Item 34 has the configuration described in Items 31-33,
- the annular zone step difference d2 in the direction parallel to the optical axis satisfies the following.
- ⁇ 1 Refractive index of the material forming the first optical path difference providing structure for light of ⁇ 1
- Item 35 is the objective optical unit according to any one of Items 24 to 30, wherein the first optical path difference providing structure is NPS (Non-Periodic Phase Structure)
- the second optical path difference providing structure is a sawtooth diffractive structure.
- the objective optical unit according to Item 37 is the configuration according to Item 36,
- the annular zone step difference d3 in the direction parallel to the optical axis satisfies the following.
- ⁇ 1 ' Refractive index of the material forming the second optical path difference providing structure for light of ⁇ 1
- the objective optical unit according to Item 38 is the configuration according to any one of Items 24 to 35, wherein the second optical path difference providing structure has a concentric pattern in which the cross-sectional shape including the optical axis is stepped.
- This is a superposition type diffractive structure in which the steps are shifted by a height corresponding to the number of steps corresponding to the number of level surfaces for each predetermined number of level surfaces.
- the annular zone average step amount d4 parallel to the optical axis of the stepped pattern satisfies the following.
- the objective optical unit described in Item 40 has the configuration described in Item 38.
- Level surfaces formed in each pattern of the second optical path difference providing structure are formed along the base aspherical surface of the objective optical unit.
- the second optical path difference providing structure is NPS (Non-Periodic Phase Structure)
- the wavelength ⁇ 1 is 380 nm ⁇ 1 and 420 nm
- the wavelength ⁇ 2 is 630 nm ⁇ 2 680
- the wavelength 3 is 760 nm ⁇ 3 830 nm
- the protective layer thickness tl of the first optical information recording medium is 0.0875 mm ⁇ tl ⁇ 0.1125, and the protective layer thickness t2 of the second optical information recording medium is 0.5 mm ⁇ t2 ⁇ 0.
- the protective layer thickness t3 of the third optical information recording medium is 1. Imm ⁇ t3 ⁇ l.3mm.
- the wavelength ⁇ 1 is 380 nm ⁇ 1 and 420 nm
- the wavelength ⁇ 2 is 630 nm ⁇ 2 680
- the wavelength 3 is 760 nm ⁇ 3 830 nm
- the protective layer thickness tl of the first optical information recording medium is 0.5 mm ⁇ tl ⁇ 0.75 mm
- the protective layer thickness t2 of the second optical information recording medium is 0.5 mm ⁇ t2 ⁇ 0. 7 mm
- the protective layer thickness t3 of the third optical information recording medium is 1. Imm ⁇ t3 ⁇ l.3mm.
- the objective optical unit according to Item 44 in the configuration according to any one of Items 24 to 43, the objective optical unit is made of glass. [0082] In the objective optical unit described in Item 45, in the configuration described in any one of Items 24 to 43, the objective optical unit is made of plastic.
- a focused spot is formed on the information recording surface of the first optical information recording medium having a protective layer with a thickness of tl using the first light beam having the wavelength ⁇ 1 emitted, and the second light source power Condensed spot formation on the information recording surface of the second optical information recording medium having a protective layer with a thickness of t2 (tl ⁇ t2) using the emitted second light beam of wavelength ⁇ 2 ( ⁇ 1 ⁇ 2)
- a protective layer with a thickness of t3 (t2 ⁇ t3) is applied using a third light beam of wavelength 3 (1.9.9 X ⁇ 1 ⁇ 3 ⁇ 2. IX ⁇ ⁇ ) emitted from the third light source.
- a design method of an objective optical system used in an optical pickup device that forms a focused spot on an information recording surface of a third optical information recording medium having:
- a plurality of refractive optical surfaces of the objective optical system A plurality of refractive optical surfaces of the objective optical system
- a first step of designing a first optical path difference providing structure that provides an optical path difference equivalent to an odd multiple of the wavelength ⁇ 1 with respect to the first luminous flux that has passed through the adjacent annular zone, Spherical aberration when the second light flux is incident so that the magnification of the objective optical system designed in the first step is ⁇ and a focused spot is formed on the information recording surface of the second information recording medium
- the “objective optical unit” is light that is arranged at a position facing the optical information recording medium in the optical pickup device and has different wavelengths emitted from the light source.
- An optical element including at least a condensing element having a function of condensing a bundle on each information recording surface of an optical information recording medium (both optical disks) having different recording densities.
- the objective optical unit is made of a glass lens
- a glass material having a glass transition point Tg of 400 ° C or lower is used, molding at a relatively low temperature is possible. Can be extended.
- 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.
- glass glass generally has a specific gravity greater than that of a resin lens. Therefore, if the objective optical unit is a glass lens, the weight increases and a burden is imposed on the actuator that drives the objective optical system. Therefore, when the objective optical unit is a glass lens, it is preferable to use a glass material having a small specific gravity. Specifically, the specific gravity is preferably 3.0 or less, more preferably 2.8 or less.
- the refractive index at a temperature of 25 ° C with respect to a wavelength of 405 nm is preferable among the cyclic olefin systems preferably using a cyclic olefin-based resin material.
- the refractive index change rate dNZdT (° C _1 ) for a wavelength of 405 nm with a temperature change within the range of 54 to 1.60 and in the temperature range of 5 ° C to 70 ° C is 10 X 10 _ It is more preferable to use a resin material in the range of 5 to ⁇ 8 ⁇ 10 ⁇ 5.
- As the resin material suitable for the objective optical unit according to the present invention there is “Asamal resin” other than the above-mentioned cyclic polyolefin.
- Assumal resin is a resin material in which particles with a diameter of 30 nm or less having a refractive index change rate with the opposite sign to the temperature change of the resin as a base material are dispersed. .
- Assumal resin is a resin material in which particles with a diameter of 30 nm or less having a refractive index change rate with the opposite sign to the temperature change of the resin as a base material are dispersed. .
- Assumal resin is a resin material in which particles with a diameter of 30 nm or less having a refractive index change rate with the opposite sign to the temperature change of the resin as a base material are dispersed.
- Assumal resin is a resin material in which particles with a diameter of 30 nm or less having a refractive index change rate with the opposite sign to the temperature change of
- the refractive index of the resin material decreases as the temperature increases, but the refractive index of inorganic particles increases as the temperature increases. Therefore, it is also known to prevent a change in refractive index by causing these properties to work together to cancel each other.
- inorganic particles having a size of 30 nanometers or less, preferably 20 nanometers or less, and more preferably 10 to 15 nanometers are dispersed in the base resin. By using scattered materials, it is possible to provide an objective optical unit that has no or very low temperature dependence of the refractive index.
- niobium oxide (Nb 2 O 3) fine particles are dispersed in acrylic resin.
- Base material niobium oxide (Nb 2 O 3) fine particles are dispersed in acrylic resin.
- the ratio of the coconut oil is 80, and the ratio of niobium oxide is about 20, and these are uniformly mixed.
- the fine particles have a problem that they tend to aggregate, but the necessary dispersion state can be generated by a technique such as applying a charge to the particle surface and dispersing.
- the mixing and dispersion of the base resin and particles is preferably performed in-line at the time of injection molding of the objective optical unit.
- the material is not cooled and solidified until it is formed into an objective optical unit.
- the volume ratio can be appropriately increased or decreased in order to control the rate of change of the refractive index with respect to the temperature, and a plurality of types of nano-sized inorganic particles can be blended and dispersed.
- the ratio is 80:20, ie 4: 1 in the above example, but from 90:10 (9: 1) to 60:40
- the fine particles are preferably inorganic, and more preferably acidic. And it is preferable that the acid state is saturated and the acid is not oxidized any more.
- the base resin which is a high molecular weight organic compound, and is preferably an acid so as to prevent deterioration due to use.
- the base resin which is a high molecular weight organic compound, and is preferably an acid so as to prevent deterioration due to use.
- oxidation tends to be accelerated under severe conditions such as high temperatures and laser irradiation.
- inorganic oxide fine particles can prevent deterioration due to oxidation.
- the base resin it is preferable to appropriately use a resin as described in JP-A-2004-144951, JP-A-2004-144953, JP-A-2004-144954, and the like. Can do.
- thermoplastic resin inorganic fine particles dispersed in thermoplastic resin are specially used as plastic resin.
- the rate of change in refractive index with temperature of the obtained thermoplastic resin composition is not limited to
- I dn / dT I can be arbitrarily selected from inorganic fine particles that can achieve the object of the present invention.
- oxide fine particles, metal salt fine particles, semiconductor fine particles, and the like are preferably used.
- those that do not generate absorption, light emission, fluorescence, etc. in the wavelength region used as an optical element are appropriately selected and used. Is preferable
- the oxide fine particles used in the configuration according to the present invention include metal forces constituting metal oxides Li, Na, Mg, Al, Si, K :, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, Nb, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ta, Hf, W, Ir, Tl,
- a metal oxide that is one or more metals selected from the group consisting of Pb, Bi, and rare earth metal force can be used.
- silicon oxide, titanium oxide, zinc oxide, and the like can be used.
- Rare earth oxides can also be used as the element. Specifically, scandium oxide, yttrium oxide, lanthanum oxide, cerium oxide, acid praseodymium, acid nickel neodymium, samarium oxide, and acid oxide pium. Also included are acid gadolinium, acid terbium, acid dysprosium, acid holmium, acid erbium, yttrium oxide, ytterbium oxide, and lutetium oxide.
- the metal salt fine particles include carbonates, phosphates, sulfates and the like, and specifically, calcium carbonate, aluminum phosphate and the like.
- the semiconductor fine particles in the configuration according to the present invention mean fine particles having a semiconductor crystal composition, and specific examples of the semiconductor crystal composition include carbon, silicon, and germanium.
- Periodic table Group 14 elements such as tin, phosphorus (black phosphorus) periodic table Group 15 elements, selenium, tellurium and other Group 16 elements, carbide (SiC), etc.
- Ga S gallium sulfide
- Ga Se gallium selenide
- Ga T gallium telluride
- periodic group 13 elements with periodic group 16 elements such as indium telluride (In Te)
- Group compound semiconductor arsenic sulfide (III) (As S), selenium arsenic (III) (As Se), arsenic telluride (III) (As Te), antimony sulfate
- Compound of Group 11 element and Group 17 element of Periodic Table Compound of Periodic Table Group 10 element such as Nickel Oxide ()) (NiO), Group 16 Element of Periodic Table, Cobalt Oxide ( ⁇ ) (CoO), sulfated cobalt ( ⁇ ) (CoS) periodic table group 9 elements and periodic table group 16 elements, triiron tetroxide (Fe 2 O 3), iron sulfide (2) (FeS ) Etc.
- Periodic table group 7 element such as manganese (II) (MnO), etc.
- Periodic table of hum (II) (VO), acid-vanadium (IV) (VO), acid-tantalum (V) (TaO), etc.
- titanium oxide TiO, Ti O, Ti O, Ti
- MgS selenium-magnesium
- MgSe selenium-magnesium
- other compounds of Group 2 elements of the periodic table and Group 16 elements of the periodic table cadmium oxide ( ⁇ ) chromium ( ⁇ ) (CdCr 2 O 3), cadmium selenide ( ⁇ ) chromium
- Examples include chalcogen spinels such as (HgCr Se), and noble titanate (BaTiO).
- the confirmed semiconductor cluster is exemplified as well.
- dnZdT of thermoplastic resin has a negative value, that is, the refractive index decreases as the temperature increases. Therefore, in order to efficiently reduce I dn / dT I of the thermoplastic resin composition, it is preferable to disperse fine particles having a large dnZdT. When using fine particles having the same sign as dnZ dT of thermoplastic resin, it is preferable that the absolute value of dnZdT of the fine particles is smaller than dnZdT of thermoplastic resin as a base material.
- fine particles having dnZdT of the opposite sign to dnZdT of the thermoplastic resin as a base material that is, fine particles having a positive value of dnZdT are preferably used.
- the dnZdT of the fine particles to be dispersed can be appropriately selected depending on the value of the dnZdT of the thermoplastic resin used as the base material.
- DnZdT of particles - 20 X 10_ is larger than the preferred device 10 X 10- 6 greater than 6 further preferred.
- the fine particles having a large dnZdT for example, gallium nitride, zinc sulfide, zinc oxide, lithium niobate, lithium tantalate, or the like is preferably used.
- thermoplastic resin when fine particles are dispersed in thermoplastic resin, it is desirable that the difference in the refractive index of the particles is small. As a result of the study by the inventors, it was found that the difference in refractive index between the thermoplastic resin and the dispersed fine particles is small, and that it is difficult to cause scattering when light is transmitted. When fine particles are dispersed in thermoplastic resin, the larger the particle, the easier it is to cause scattering when light is transmitted. However, if the difference in refractive index between the thermoplastic resin and the dispersed fine particles is small, We discovered that even when large particles are used, the degree of light scattering is small.
- the difference in refractive index between the thermoplastic resin and the dispersed fine particles is preferably in the range of 0 to 0.3, and more preferably in the range of 0 to 0.15.
- the refractive index of a thermoplastic resin preferably used as an optical material is often about 1.4 to 1.6.
- the material dispersed in these thermoplastic resins include silica (oxidized). (Carbon), calcium carbonate, aluminum phosphate, aluminum oxide, magnesium oxide, aluminum / magnesium oxide, etc. are preferably used.
- dnZdT of a thermoplastic resin composition can be effectively reduced by dispersing fine particles having a relatively low refractive index.
- the details of the reason why I dnZdT I of the thermoplastic resin composition in which fine particles with low refractive index are dispersed are small, the temperature change of the volume fraction of inorganic fine particles in the resin composition is not It is thought that the lower the refractive index of the fine particles, the smaller the I dn / dT I of the resin composition will be.
- fine particles having a relatively low refractive index for example, silica (acid silicate), calcium carbonate, and aluminum phosphate are preferably used.
- thermoplastic resin composition It is difficult to simultaneously improve the dnZdT reduction effect, light transmittance, desired refractive index, etc. of the thermoplastic resin composition, and the fine particles dispersed in the thermoplastic resin are thermoplastic resin.
- the size of the dnZdT of the microparticles itself, the difference between the dnZdT of the microparticles and the dnZdT of the thermoplastic resin used as the base material, the refractive index of the microparticles, etc. should be selected appropriately Can do.
- fine particles that are compatible with the thermoplastic resin as a base material that is, dispersibility with respect to the thermoplastic resin, and hardly cause scattering, to maintain light transmittance.
- silica is preferably used as fine particles for reducing I dn / dT I while maintaining light transmittance.
- the fine particles one kind of inorganic fine particles may be used, or a plurality of kinds of inorganic fine particles may be used in combination. By using a plurality of types of fine particles having different properties, the required properties can be improved more efficiently.
- the inorganic fine particles according to the present invention preferably have an average particle size of 1 nm or more and 30 nm or less, more preferably 1 nm or more and 20 nm or less, and further preferably 1 nm or more and lOnm or less. If the average particle size is less than lnm, it is difficult to disperse the inorganic fine particles and the desired performance may not be obtained. Therefore, the average particle size is preferably lnm or more. If it exceeds the upper limit, the resulting thermoplastic material composition may become turbid and the transparency may be lowered, and the light transmittance may be less than 70%. Therefore, the average particle size is preferably 30 ⁇ m or less.
- the average particle diameter here refers to the volume average value of the diameter (sphere equivalent particle diameter) when each particle is converted to a sphere having the same volume.
- the shape of the inorganic fine particles is not particularly limited, but spherical fine particles are preferably used.
- the minimum particle diameter minimum distance between the tangent lines when drawing two tangent lines that touch the outer circumference of the fine particle
- Z maximum diameter the corresponding value when drawing two tangent lines that touch the outer circumference of the fine particle
- the maximum value of the distance between tangents is 0.5 to 1.0. Force S is preferable, and 0.7 to 1.0 is still more preferable.
- the particle size distribution is not particularly limited, but in order to achieve the effects of the present invention more efficiently, it has a relatively narrow distribution than that having a wide distribution. Those are preferably used.
- optical pickup device which is compact and can appropriately record and Z or reproduce information on different types of high-density optical discs.
- FIG. 1 shows an optical pickup according to the present embodiment that can appropriately record and Z or reproduce information on BD (or HD DVD), DVD and CD, which are different optical information recording media (both optical discs).
- FIG. 3 is a diagram schematically showing a configuration of a device PU1.
- the powerful optical pickup device PU1 can be installed in an optical information recording / reproducing device.
- the first optical information recording medium is BD
- the second optical information recording medium is DVD
- the third optical information recording medium is CD.
- information recording and DVD Second semiconductor laser EP1 (second light source) that emits light when emitting Z or reproducing and emits a 680 nm laser beam (second beam), and emits light when recording and Z or reproducing information on a CD Third laser diode EP2 (third light source) that emits a 750-nm laser beam (third beam), first light-receiving unit DS1 that receives the reflected beam from DVD information recording surface RL2, and CD information recording
- the laser module LM includes a second light receiving unit DS2 that receives a reflected light beam from the surface RL3 and a prism PS.
- the central region including the optical axis on the aspheric optical surface on the light source side, the peripheral region disposed around the central region, and the outermost region disposed around the central region
- the first optical path difference providing structure and the second optical path difference providing structure are overlapped with each other in the central area.
- the first optical path difference providing structure is a ring-shaped structure that provides an optical path difference equivalent to an odd multiple of the wavelength ⁇ 1 to the first light flux that has passed through the adjacent annular zone, and the first light flux for BD,
- the spherical aberration is changed in the under direction for all of the second luminous flux for DVD and the third luminous flux for CD.
- the second optical path difference providing structure has a ring-shaped structure, and applies an optical path difference equivalent to an even multiple of the wavelength ⁇ 1 to the light beam that has passed through the adjacent annular zone, and the second light beam for DVD. Only the spherical aberration is changed in the over direction.
- the objective optical element system OBJ is designed by the following procedure.
- the first step when the first light flux, the second light flux, and the third light flux are incident on the objective optical system so that the magnification of the objective optical system in use is the same for BD, DVD, and CD.
- the first light flux difference passing structure formed by forming a first optical path difference providing structure having an annular structure on one optical surface of the plurality of refractive optical surfaces, and passing through the adjacent annular zones.
- the first optical path difference providing structure is designed so that an optical path difference equivalent to an odd multiple of ⁇ 1 is applied.
- the first optical path difference providing structure is designed so that the spherical aberration is changed to either under or over with respect to the first light flux, the second light flux, and the third light flux.
- the second light beam is incident on the objective optical system designed in the first step so as to have the same magnification as the first step, and is condensed on the information recording surface of the DVD.
- the second optical path difference providing structure is designed so as to correct the spherical aberration generated by the action of the refractive optical surface designed in the first step and the first optical path difference providing structure.
- a second optical path difference providing structure having an annular structure is formed, and an optical path difference equivalent to an even multiple of ⁇ ⁇ is applied to the first light flux that has passed through the adjacent annular zone.
- the second optical path difference providing structure is designed.
- the second optical path difference providing structure is designed so that the spherical aberration is changed to the other one of the under and over different from the above only for the second light flux.
- the optimum refractive optical surface, the first optical path difference providing structure, and the second optical path difference providing structure are designed.
- the spherical aberration is corrected to under by passing through the providing structure.
- information recording and recording can be appropriately performed on a DVD having a protective layer thickness t2.
- the light beam having a wavelength of 3 emitted from the infrared semiconductor laser EP2 is incident on the objective optical element OBJ as a parallel light beam
- spherical aberration is corrected in the first case only with the aspheric optical surface. Since the spherical aberration is appropriately corrected by passing through the optical path difference providing structure, and the second optical path difference providing structure does not have an influence, information recording and Z or Playback can be performed.
- the divergent light beam having a first wavelength of 408 nm emitted from the blue-violet semiconductor laser LD1 is transmitted through the polarization dichroic prism PPS and converted into a parallel light beam by the collimator lens CL, and then by a 1Z4 wavelength plate (not shown).
- the reflected light beam modulated by the information pits on the information recording surface RL1 is transmitted again through the objective optical element OBJ and the aperture stop ST, and then converted from circularly polarized light to linearly polarized light by a 1Z4 wavelength plate (not shown).
- the light is converged by CL, passes through the polarization dichroic prism PPS, and then converges on the light receiving surface of the first photodetector PD1. Then, the information recorded on the BD can be read by using the output signal of the first photodetector PD1 and tracking the objective optical element OBJ with the two-axis actuator AC.
- the 680-nm divergent light beam emitted from the red semiconductor laser EP1 is reflected by the prism PS, then reflected by the polarization dichroic prism PPS, converted into a parallel light beam by the collimator lens CL, and then a 1Z4 wavelength plate (not shown)
- the linear polarization force is converted into circularly polarized light by, and enters the objective optical element OBJ.
- the light beam condensed by the central region and the peripheral region of the objective optical element OBJ becomes a spot formed on the information recording surface RL2 of the DVD through the protective layer PL2 having a thickness of 0.6 mm.
- the light flux that has passed through other than the central region and the peripheral region is flared.
- the reflected light beam modulated by the information pits on the information recording surface RL2 is again transmitted through the objective optical element OBJ and the aperture stop ST, and then converted from circularly polarized light to linearly polarized light by a 1Z4 wavelength plate (not shown).
- the light is converged by CL and reflected by the polarization dichroic prism PPS, then reflected twice in the prism and then converged on the first light receiving part DS1.
- the information recorded on the DVD can be read using the output signal of the first light receiving unit DS1.
- the 750-nm divergent light beam emitted from the infrared semiconductor laser EP2 is reflected by the prism PS, then reflected by the polarization dichroic prism PPS, converted into a parallel light beam by the collimating lens CL, and then 1Z4 wavelength (not shown) It is converted into circularly polarized light by the plate and is incident on the objective optical element OBJ.
- the light beam collected only by the central region of the objective optical element OBJ becomes a spot formed on the information recording surface RL3 of the CD via the protective layer PL3 having a thickness of 1.2 mm.
- the light beam that has passed through the rest is flared.
- the reflected light beam modulated by the information pits on the information recording surface RL3 is again transmitted through the objective optical element OBJ and the aperture stop ST, and then converted from circularly polarized light to linearly polarized light by a 1Z4 wavelength plate (not shown). It is made into a convergent luminous flux by CL, and it becomes a polarization dichroic prism PPS. After the reflection, the light is reflected twice in the prism, and then converged on the second light receiving unit DS2. The information recorded on the CD can be read using the output signal of the second light receiving unit DS2.
- Example 1 the first optical path difference providing structure and the second optical path difference providing structure are formed in the central region of the optical surface of the single objective optical element.
- Tables 1 to 3 show the lens data.
- ri is the radius of curvature
- di is the i-th surface force
- ni is the refractive index of each surface.
- an exponent of 10 for example, 2. 5 X 10 _3)
- E e.g., 2. 5 XE 3
- * d i represents the displacement from the i-th surface to the i + 1-th surface.
- Optical path difference function (Diffraction order HD DVD: 3rd order DVD: 2nd order)
- Optical path difference function (Diffraction order HD DVD: 3rd order DVD 2nd order CD 2nd order)
- Optical path difference function (Diffraction order HD DVD: 3rd order DVD: 2nd order CD: 2nd order)
- optical surface of the objective optical element is formed as an aspherical surface that is symmetric about the optical axis and is defined by a mathematical formula obtained by substituting the coefficients shown in Table 13 into Formula 1. Same as in examples 2 and 3.)
- the optical path length given to the light flux of each wavelength by the first optical path difference providing structure and the second optical path difference providing structure is a coefficient shown in Tables 1 to 3 in the optical path difference function of Formula 2. (It is the same in the embodiments 2 and 3).
- ⁇ The wavelength of the light beam incident on the diffractive structure
- a B Blaze wavelength
- Fig. 4 (a) is a diagram showing the relationship between the height of the optical axis force and the defocus amount when using HD DVD in Example 1
- Fig. 4 (b) shows the use of DVD in Example 1.
- 4 (c) is a diagram showing the relationship between the height of the optical axis force and the defocus amount when using a CD in Example 1. It is.
- Example 2 the first optical path difference providing structure and the second optical path difference providing structure are formed in the central region of the optical surface of the single objective optical element.
- Tables 4-6 show the lens data.
- Figure 5 (a) shows the height of the optical axis force and the defocus amount when using HD DVD in Example 2.
- Fig. 5 (b) is a diagram showing the relationship between the height of the optical axis force when using a DVD and the defocus amount in Example 2
- FIG. 6 is a diagram showing the relationship between the height of the optical axis force when using a CD in Example 2 and the defocus amount.
- * cM represents the displacement from the i-th surface to the i + 1-th surface.
- ⁇ di ' ⁇ d' is the c representing the displacement from the '' surface to the first surface.
- Optical path difference function (Diffraction order HD DVD: 3rd order DVD: 2nd order)
- Optical path difference function (Diffraction order HD DVD: 3rd order DVD: 2nd order CD: 2nd order)
- Optical path difference function (Diffraction order HD DVD: 3rd order DVD: 2nd order CD: 2nd order)
- Example 3 the first optical path difference providing structure and the second optical path difference providing structure are formed in the central region of the optical surface of the single objective optical element.
- Tables 7 to 9 show the lens data.
- Fig. 6 (a) is a diagram showing the relationship between the height of the optical axis force when using HD DVD and the defocus amount in Example 3, and
- Fig. 6 (b) shows the light when using DVD in Example 3.
- FIG. 6 (c) is a diagram showing the relationship between the height of the axial force and the defocus amount, and FIG.
- Optical path difference function (Diffraction order HD DVD: 1st order DVD: 1st order CD: 1st order)
- Optical path difference function (Diffraction order HD DVD: 1st order DVD: 1st order CD: 1st order)
- Optical path difference function (Diffraction order HD DVD: 1st order DVD: 1st order CD: 1st order)
- Table 10 shows the chromatic aberration for each type of optical disc, the amount of optical path difference imparted by the optical path difference imparting structure, and the diffraction efficiency for each type of optical disc for each example.
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- General Physics & Mathematics (AREA)
- Optical Head (AREA)
- Lenses (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP06714553A EP1858012A4 (en) | 2005-03-08 | 2006-02-24 | OPTICAL DETECTION ELEMENT AND OPTICAL OBJECTIVE UNIT AND METHOD FOR THE DESIGN OF AN OPTICAL LENS SYSTEM |
JP2007507044A JP3957003B2 (ja) | 2005-03-08 | 2006-02-24 | 光ピックアップ装置及び、対物光学ユニット及び対物光学系の設計方法 |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2005064156 | 2005-03-08 | ||
JP2005-064156 | 2005-03-08 | ||
JP2005-262358 | 2005-09-09 | ||
JP2005262358 | 2005-09-09 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2006095583A1 true WO2006095583A1 (ja) | 2006-09-14 |
Family
ID=36953184
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2006/303414 WO2006095583A1 (ja) | 2005-03-08 | 2006-02-24 | 光ピックアップ装置及び、対物光学ユニット及び対物光学系の設計方法 |
Country Status (7)
Country | Link |
---|---|
US (2) | US20060203692A1 (ja) |
EP (1) | EP1858012A4 (ja) |
JP (1) | JP3957003B2 (ja) |
KR (2) | KR20120003510A (ja) |
CN (1) | CN101685647B (ja) |
TW (1) | TW200643926A (ja) |
WO (1) | WO2006095583A1 (ja) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2008117663A1 (ja) * | 2007-03-28 | 2008-10-02 | Konica Minolta Opto, Inc. | 光ピックアップ装置及び光ピックアップ装置用の対物光学素子 |
CN101882447A (zh) * | 2009-05-07 | 2010-11-10 | 柯尼卡美能达精密光学株式会社 | 物镜、光拾取装置及光信息记录再生装置 |
CN102007538A (zh) * | 2008-04-17 | 2011-04-06 | 柯尼卡美能达精密光学株式会社 | 物镜及光拾取装置 |
WO2012093553A1 (ja) * | 2011-01-07 | 2012-07-12 | 三洋電機株式会社 | 対物レンズおよびそれを用いた光ピックアップ装置 |
US8477583B2 (en) | 2011-06-20 | 2013-07-02 | Panasonic Corporation | Optical pickup and optical disc device including the same |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007317295A (ja) * | 2006-05-25 | 2007-12-06 | Pentax Corp | 光情報記録再生装置用光学素子、光情報記録再生装置および光情報記録再生装置用光学素子の設計方法 |
US8140353B2 (en) * | 2006-06-29 | 2012-03-20 | The Invention Science Fund I, Llc | Compliance data for health-related procedures |
CA2699494A1 (en) * | 2007-09-13 | 2009-03-19 | Cyalume Technologies, Inc. | Infra-red lighting system and device |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2003091764A1 (en) * | 2002-04-18 | 2003-11-06 | Matsushita Electric Industrial Co., Ltd. | Optical element, optical head, optical information recording/reproduction device, computer, video recording device, video reproduction device, server, and car navigation system |
JP2004247025A (ja) * | 2002-12-18 | 2004-09-02 | Konica Minolta Holdings Inc | 光ピックアップ装置及び光学素子 |
JP2005038575A (ja) * | 2003-06-23 | 2005-02-10 | Konica Minolta Opto Inc | 光ピックアップ装置 |
JP2005038585A (ja) * | 2003-06-30 | 2005-02-10 | Konica Minolta Opto Inc | 光ピックアップ装置、集光光学系及び光学素子 |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ATE441183T1 (de) * | 1999-01-22 | 2009-09-15 | Konica Minolta Opto Inc | Optische abtastvorrichtung, mit der optischen abtastvorrichtung versehenes aufnahme/wiedergabegerät, optisches element und verfahren zur datenaufnahme/wiedergabe |
US7035196B2 (en) * | 2000-03-14 | 2006-04-25 | Matsushita Electric Industrial Co., Ltd. | Optical head device and optical recording and reproducing apparatus having lasers aligned in a tangential direction |
JP4465838B2 (ja) * | 2000-09-01 | 2010-05-26 | コニカミノルタホールディングス株式会社 | 光ピックアップ装置及び対物レンズ |
DE60321414D1 (de) * | 2002-02-27 | 2008-07-17 | Ricoh Kk | Optischer Abtastkopf für verschiedene Wellenlängen |
US7577077B2 (en) * | 2002-09-05 | 2009-08-18 | Konica Corporation | Optical pickup apparatus and optical element |
KR101037031B1 (ko) * | 2002-09-30 | 2011-05-25 | 코니카 미노루따 호르딩구스 가부시끼가이샤 | 광학 요소, 대물 광학 요소 및 광학 픽업 장치 |
EP1465170A3 (en) * | 2003-03-31 | 2007-05-16 | Konica Minolta Holdings, Inc. | Converging optical system of optical pickup device |
US7038862B2 (en) * | 2003-06-17 | 2006-05-02 | Pentax Corporation | Objective lens for optical pick-up |
JP5002118B2 (ja) * | 2003-06-18 | 2012-08-15 | コニカミノルタアドバンストレイヤー株式会社 | 光ピックアップ装置用の光学素子、及び光ピックアップ装置 |
WO2005015554A1 (ja) * | 2003-08-12 | 2005-02-17 | Konica Minolta Opto, Inc. | 光ピックアップ装置 |
ATE381097T1 (de) * | 2004-03-24 | 2007-12-15 | Koninkl Philips Electronics Nv | Scanning-einrichtung für einen optischen aufzeichnungsträger |
-
2006
- 2006-02-24 KR KR1020117031147A patent/KR20120003510A/ko not_active Application Discontinuation
- 2006-02-24 KR KR1020077020211A patent/KR20070108226A/ko not_active Application Discontinuation
- 2006-02-24 EP EP06714553A patent/EP1858012A4/en not_active Withdrawn
- 2006-02-24 JP JP2007507044A patent/JP3957003B2/ja not_active Expired - Fee Related
- 2006-02-24 WO PCT/JP2006/303414 patent/WO2006095583A1/ja active Application Filing
- 2006-02-24 CN CN2009101749242A patent/CN101685647B/zh not_active Expired - Fee Related
- 2006-03-03 TW TW095107264A patent/TW200643926A/zh unknown
- 2006-03-03 US US11/366,546 patent/US20060203692A1/en not_active Abandoned
-
2012
- 2012-02-28 US US13/407,405 patent/US20120155241A1/en not_active Abandoned
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2003091764A1 (en) * | 2002-04-18 | 2003-11-06 | Matsushita Electric Industrial Co., Ltd. | Optical element, optical head, optical information recording/reproduction device, computer, video recording device, video reproduction device, server, and car navigation system |
JP2004247025A (ja) * | 2002-12-18 | 2004-09-02 | Konica Minolta Holdings Inc | 光ピックアップ装置及び光学素子 |
JP2005038575A (ja) * | 2003-06-23 | 2005-02-10 | Konica Minolta Opto Inc | 光ピックアップ装置 |
JP2005038585A (ja) * | 2003-06-30 | 2005-02-10 | Konica Minolta Opto Inc | 光ピックアップ装置、集光光学系及び光学素子 |
Non-Patent Citations (1)
Title |
---|
See also references of EP1858012A4 * |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2008117663A1 (ja) * | 2007-03-28 | 2008-10-02 | Konica Minolta Opto, Inc. | 光ピックアップ装置及び光ピックアップ装置用の対物光学素子 |
CN102007538A (zh) * | 2008-04-17 | 2011-04-06 | 柯尼卡美能达精密光学株式会社 | 物镜及光拾取装置 |
CN101882447A (zh) * | 2009-05-07 | 2010-11-10 | 柯尼卡美能达精密光学株式会社 | 物镜、光拾取装置及光信息记录再生装置 |
WO2010128653A1 (ja) * | 2009-05-07 | 2010-11-11 | コニカミノルタオプト株式会社 | 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 |
WO2010128654A1 (ja) * | 2009-05-07 | 2010-11-11 | コニカミノルタオプト株式会社 | 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 |
CN101901607A (zh) * | 2009-05-07 | 2010-12-01 | 柯尼卡美能达精密光学株式会社 | 物镜、光拾取装置及光信息记录再生装置 |
JP4636213B2 (ja) * | 2009-05-07 | 2011-02-23 | コニカミノルタオプト株式会社 | 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 |
JP2012169038A (ja) * | 2009-05-07 | 2012-09-06 | Konica Minolta Advanced Layers Inc | 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 |
JP5062365B2 (ja) * | 2009-05-07 | 2012-10-31 | コニカミノルタアドバンストレイヤー株式会社 | 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 |
CN101901607B (zh) * | 2009-05-07 | 2014-09-10 | 柯尼卡美能达精密光学株式会社 | 物镜、光拾取装置及光信息记录再生装置 |
WO2012093553A1 (ja) * | 2011-01-07 | 2012-07-12 | 三洋電機株式会社 | 対物レンズおよびそれを用いた光ピックアップ装置 |
US8477583B2 (en) | 2011-06-20 | 2013-07-02 | Panasonic Corporation | Optical pickup and optical disc device including the same |
Also Published As
Publication number | Publication date |
---|---|
TW200643926A (en) | 2006-12-16 |
EP1858012A4 (en) | 2008-12-10 |
KR20070108226A (ko) | 2007-11-08 |
CN101685647A (zh) | 2010-03-31 |
US20120155241A1 (en) | 2012-06-21 |
KR20120003510A (ko) | 2012-01-10 |
EP1858012A1 (en) | 2007-11-21 |
JPWO2006095583A1 (ja) | 2008-08-14 |
CN101685647B (zh) | 2012-05-23 |
JP3957003B2 (ja) | 2007-08-08 |
US20060203692A1 (en) | 2006-09-14 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP4187054B2 (ja) | 光ピックアップ装置、対物光学素子及び光情報記録再生装置 | |
JP5013129B2 (ja) | 光ピックアップ装置、対物光学素子及び光情報記録再生装置 | |
US7623434B2 (en) | Objective lens, optical pickup apparatus and optical disc driving apparatus | |
JPWO2005117001A1 (ja) | 対物光学系、光ピックアップ装置、及び光ディスクドライブ装置 | |
US8098564B2 (en) | Objective lens for optical pickup apparatus, objective lens unit for optical pickup apparatus and optical pickup apparatus using the same | |
JP3957003B2 (ja) | 光ピックアップ装置及び、対物光学ユニット及び対物光学系の設計方法 | |
JP5003428B2 (ja) | 光ピックアップ装置及び対物光学素子 | |
JP2007242114A (ja) | 光ピックアップ装置 | |
CN101105956A (zh) | 光拾取装置、对物光学元件和光信息记录重放装置 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 200680007108.7 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
WWE | Wipo information: entry into national phase |
Ref document number: 2007507044 Country of ref document: JP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2006714553 Country of ref document: EP Ref document number: 1020077020211 Country of ref document: KR |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
NENP | Non-entry into the national phase |
Ref country code: RU |
|
WWP | Wipo information: published in national office |
Ref document number: 2006714553 Country of ref document: EP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1020117031147 Country of ref document: KR |