Abstract: An optical pickup apparatus according to the present invention includes: a first light source for emitting a first light flux; a second light source for emitting a second light flux; a third light source for emitting a third light flux; and an objective optical element. The objective optical element has an optical surface including at least two areas provided with optical path difference providing structures. The objective optical element converges the first to third light fluxes each passing through the predetermined areas on the objective optical element onto respective information recording surfaces of the first to third optical disks. The optical pickup apparatus provides a wavelength dependency of a spherical aberration so as to correct a change in a spherical aberration due to a refractive index change with a temperature change of the objective optical element.

Abstract: An optical disk drive for recording information on a recording surface of an optical disk and reading information recorded in the optical disk is provided. The optical disk drive includes a spindle to rotate the optical disk and a carriage movable in parallel with a tracking direction of the optical disk. The carriage includes a laser light source to emit laser light, a collimator lens to convert divergent light into parallel light and is arranged with an optical center thereof being in a farther and offset position with respect to an optical axis of the laser light, a reflecting mirror to receive and deflect the laser light transmitted through the collimator lens in a direction perpendicular to the recording surface of the optical disk, and an objective lens to converge the laser light deflected by the reflecting mirror on a position corresponding to the recording surface of the optical disk.

Abstract: An optical head apparatus is made to be downsized while obtaining an sufficient driving force of an objective lens actuator. The optical head apparatus includes a first optical system including a first objective lens for focusing a light beam upon an optical disc; a second optical system including a second objective lens for focusing a light beam upon an optical disc having an information recording density smaller than the optical disc which the first optical system irradiates upon, the second objective lens having a numerical aperture smaller than the first objective lens; and an up-orienting prism including a first reflecting surface for deflecting a light beam to an optical axis of the first objective lens in the first optical system, and a second reflecting surface for deflecting a light beam to an optical axis of the second objective lens in the second optical system.

Abstract: An optical pickup device, which reduces the size of an optical spot formed on an optical disk, and prevents the degradation of a tracking error signal due to coherent light from a layer adjacent a target recording/reproducing layer of the optical disk. The optical pickup device includes a light source emitting light at a designated wavelength; an object lens concentrating the light incident from the light source thereupon and forming an optical spot on an optical disk having multiple recording layers; and an optical detector receiving the light reflected by the optical disk and detecting a data signal and an error signal, wherein at least one diffraction pattern region partially diffracting or intercepting the light, emitted from the light source and being incident upon the object lens, and the light, reflected by optical disk and being incident upon the object lens, is formed on the object lens.

Abstract: In a three-wavelength-compliant optical disk apparatus, the present invention enables to shorten time required for starting the apparatus such as discrimination of an optical disk and adjustment of a beam-expander. At the time of starting the apparatus, the operation of a tray driver which pulls a loaded optical disk within the apparatus is conducted in parallel with the operation of a beam-expander driver which allows a movable lens of the beam-expander to move to a predetermined position in accordance with the kind of optical disk. Further, at the time of discriminating the disk, the number of times an optical disk of a specific kind has continuously been loaded into the apparatus to date is stored in a memory, and a sequence of discriminating the kind of optical disk that is newly discriminated is switched by referring to the history information.

Abstract: A complex objective lens composed of a hologram and an objective lens, capable of realizing stable and high-precision compatible reproducing/recording of a BD with a base thickness of about 0.1 mm for a blue light beam (wavelength ?1) and a DVD with a base thickness of about 0.6 mm for a red light beam (wavelength ?2). In an inner circumferential portion of the hologram, a grating is formed, which has a cross-sectional shape including as one period a step of heights in the order of 0 time, twice, once, and three times a unit level difference that gives a difference in optical path of about one wavelength with respect to a blue light beam, from an outer peripheral side to an optical axis side. The hologram transmits a blue light beam as 0th-order diffracted light without diffracting it, and disperses a red light beam passing through an inner circumferential portion as +1st-order diffracted light and allows it to be condensed by an objective lens.

Abstract: An optical pickup apparatus comprises a first light source for emitting a first light flux having first wavelength ?1 (430 nm>?1>380 nm), a second light source for emitting a second light flux having second wavelength ?2 (?2>?1), an objective optical system having phase structure thereon, and at least one moving optical element for guiding the light flux into the objective optical system, the moving optical element being moved in a direction parallel to an optical axis corresponding to the first light wavelength ?1 and the second light wavelength ?2, wherein the objective optical system has phase structure and satisfies M1=M2=0, where, M1 and M2 denote a first and second magnifications of the objective optical system for recording and/or reproducing the information on or from the first and second optical information media.

Abstract: An optical pickup apparatus for reproducing information from an optical information recording medium or for recording information onto an optical information recording medium, is provided with a first light source for emitting first light flux having a first wavelength; a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength; a converging optical system having an optical axis and a diffractive portion, and a photo detector; wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted

Abstract: A complex optical element includes a first optical portion and a second optical portion which are made of materials different from each other. The second optical portion is bonded to an optical functional face of the first optical portion. A concavoconvex face part is formed at the central part of the bond area between the first optical portion and the second optical portion.

Abstract: A first phase structure corrects at least one of a spherical aberration due to a difference between a protective substrate thickness t1 and a protective substrate thickness t2 and a spherical aberration due to a difference between a first wavelength ?1 and a second wavelength ?2, and a second phase structure corrects at least one of a spherical aberration generated when the first wavelength ?1 is changed in a range of ±10 nm, a best image point movement generated when the first wavelength ?1 is changed in a range of ±10 nm, and a spherical aberration generated when environmental temperature is changed.

Abstract: An optical element includes: an element body including a resin containing a polymer having an alicyclic structure. The optical element is treated by one of heat treatment and wet-heat treatment for 15 hours or longer at a temperature lower by 10° C. to 30° C. than a glass transition temperature of the resin after being formed by injecting the resin in a mold. The optical element body has a length along an optical axis of the optical element in a range of 0.5 to 3 mm, and a length in a perpendicular direction to the optical axis in a range of 3 to 5 mm.

Abstract: The present invention provides a first light source (21) that emits light of a first wavelength, that at least either records onto or reproduces information from an information recording medium (30), a light source (22) that emits light of a second wavelength that records onto or reproduces information from an information recording medium (33), a light source (23) that emits light of a third wavelength that records onto or reproduces information from an information recording medium (23), focusing means, an optical element (28) that passes light of the first wavelength and diffracts light of the second and third wavelengths, wherein the optical element (28) is an optical element in which grooves are formed in a substrate, wherein the expression: 380 nm?(n?1)×d?420 nm is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves, and wherein the grooves are formed in two steps of depth d and depth 2d.

Abstract: An optical head device is provided with a semiconductor laser, an aberration correcting element for transmitting a beam from the semiconductor laser, a light guiding portion for introducing the beam from the semiconductor laser to the aberration correcting element, and an objective lens for focusing the beam having passed through the aberration correcting element on an optical disc. The aberration correcting element corrects a longitudinal chromatic aberration occurring in the objective lens and a longitudinal chromatic aberration occurring in the light guiding portion excluding the objective lens and the aberration correcting element based on a longitudinal chromatic aberration occurring in the aberration correcting element when the semiconductor laser emits a beam having a wavelength different by a specified wavelength difference.

Abstract: There is provided an objective lens including a first optical member and a second optical member which are made of materials different from each other and are cemented together at a cementing surface. The cementing surface includes a first phase shift structure having a plurality of refractive surface zones concentrically formed about an optical axis of the objective lens. The first phase shift structure satisfies conditions (1) and (2): 0.85<?2/?1<1.15??(1) 0.10<|(?3??2)/?1|<0.50??(2) where ?1=m(?1)×(?1/(n2(?1)?n1(?1))), ?2=m(?2)×(?2/(n2(?2)?n1(?2))), ?3=m(?3)×(?3/(n2(?3)?n1(?3))), m(?1), m(?2), and m(?3) are diffraction orders at which diffraction efficiencies of the first through third light beams are maximized, respectively, n1 (?1), n1 (?2), and n1 (?3) are refractive indexes of the first optical member, respectively, and n2 (?1), n2 (?2), and n2 (?3) are refractive indexes of the second optical member, respectively.

Abstract: There is provided an optical disc drive for recordation/reproduction for three types of optical discs by selectively using one of three types of light beams. The optical disc drive comprises an objective lens. The objective lens has a step structure which gives an optical path length difference to an incident beam at each step. When the third laser beam passes through the objective lens, the objective lens produces normal diffraction order light converging to a recording surface of the third optical disc and undesired diffraction order light converging to a point deviating from the recording surface of the third optical disc. A distance from a point to which the normal diffraction order light converges to a point to which the undesired diffraction order light converges is larger than or equal to twice a pull-in range of a focus error signal obtained when the third optical disc is used.

Abstract: An optical system of an optical pick-up is provided. The optical system includes an optical element including at least a phase shift surface among the surfaces thereof, and located closer to a light source than the objective lens. In this configuration, t1?t2 is satisfied, where t1 represents a thickness of a cover layer of a first optical disc for which a first laser beam is employed, and t2 a thickness of a cover layer of a second optical disc for which a second laser beam, having a longer wavelength than the first laser beam, is employed. NA1?NA2 is satisfied, where NA1 represents a numerical aperture for the first optical disc, and NA2 the numerical aperture for the second optical disc. The phase shift surface includes a first region that converges the first laser beam on a recording surface of the first optical disc, and the second laser beam on a recording surface of the second optical disc.

Abstract: There is provided an optical pick-up including first to third light sources respectively emitting first to third light beams, a first coupling lens, and an objective lens formed to converge each of the first, second and third light beams onto the first, second and third optical discs, respectively. The objective lens has a step structure including a plurality of concentrically formed refractive surface zones divided by steps, the step structure having a function of giving, at each step, an optical path length difference of approximately 2?1 to the first light beam. The first coupling lens causes the first light beam to be incident on the objective lens as a converging beam. The objective lens is positioned to satisfy a condition: ?0.35<f2×M2?f1×M1<?0.07??(1).

Abstract: An optical pickup apparatus comprising: a collimating lens configured to convert laser light having Gaussian distribution property emitted from a laser diode from divergent light to parallel light; an objective lens configured to focus the laser light from the collimating lens onto a signal recording layer of an optical disc; and an adjustment film formed on a surface of an incident face of the collimating lens on which the laser light is incident, and configured to adjust transmittance of the laser light passing through the collimating lens, the adjustment film being formed on the surface of the incident face so that the transmittance is lower on the inner side of the incident face than on the outer side of the incident face.

Abstract: An optical pickup lens focuses laser beams having different wavelengths ?1, ?2 and ?3 on at least three kinds of optical discs. At least one side of the optical pickup lens has a concentric loop zonal structure for compensating wavefront aberration occurring when recording or reproducing an optical disc having a substrate thickness t1 by the laser beam having the wavelength ?1 and wavefront aberration occurring when recording or reproducing an optical disc having a substrate thickness t2 by the laser beam having the wavelength ?2. When recording or reproducing an optical disc having a substrate thickness t3 by the laser beam having the wavelength ?3, a phase difference given to the laser beam having the wavelength ?3 due to the concentric loop zonal structure is about 0.15? or smaller.

Abstract: There is provided an objective lens used for an optical information recording/reproducing device for recording information to and/or reproducing information from two types of optical discs, by selectively using one of two types of substantially collimated light beams including first and second light beams. When wavelengths of the first and second light beams are respectively represented by ?1 (nm) and ?2 (nm), ?1<?2 is satisfied. The objective lens includes a first optical element, and a second optical element made of material different from that of the first optical element. The first and second optical elements are cemented via a cementing surface. Further, the objective lens is configured to satisfy a condition: 0.006 < { ( nR ? ? 2 - nR ? ? 1 ) - ( nB ? ? 2 - nB ? ? 1 ) } × ? [ { ( k ? ? 2 r ? ? 2 3 ) + 8 × A ? ? 42 } × f ? ? 1 3 + 2.29 ] < 0.038 ? .

Abstract: A liquid crystal element for correcting wave aberration included in an optical disc apparatus, is controlled by a liquid crystal element control unit which has a memory portion that stores information about a variation with time of orientation direction of liquid crystal in the case where a voltage is applied to the liquid crystal, with respect to at least one type of voltage value. The liquid crystal element control unit has a drive voltage deciding portion that obtains time period after a predetermined drive voltage is applied to the liquid crystal element until a reproduced signal obtained by processing an electric signal converted by the light detecting unit becomes optimal, and decides a drive voltage to be applied to the liquid crystal element based on the obtained time period, the information stored in the memory portion, and the predetermined drive voltage.

Abstract: An objective lens, for an optical information read/write device that performs read/write operations on each of a plurality of optical discs using a corresponding one of three laser beams having first, second, and third wavelengths ?1, ?2, and ?3 (nm) satisfying a relationship ?1<?2<?3, respectively, includes a phase shift structure having a plurality of ring-shaped refractive surface zones into which at least one surface of the objective lens is concentrically divided. The objective lens is made of material with an Abbe number ?d satisfying a condition 40??d?80. The phase shift structure has a step between each couple of the adjacent refractive surface zones that gives an optical path difference to an incident laser beam, so that a condition 2N+1.00<|?OPD/?1|<2N+1.30 is satisfied, where ?OPD represents the optical path difference (nm) that the step gives to the laser beam with the first wavelength, and N represents a non-negative integer.

Abstract: There is provided an objective lens used for three types of optical discs including by selectively using one of three types of light beams. At least one of surfaces of the objective lens is provided with a first region converging the third light beam on a recoding surface of the third optical disc. The first region has a step structure configured to have concentric refractive surface zones and to give an optical path length difference to an incident beam at each step formed between adjacent refractive surface zones. The step structure is configured such that the optical path length difference given by each step is substantially equal to an odd multiple of a wavelength of a first light beam, and a value of differentiation of an optical path difference function defining the step structure crosses zero in a height ranging from 30% to 70% of an effective diameter of the first region.

Abstract: An optical pickup apparatus comprising at least: a diffraction grating configured to split first wavelength light into at least a first main beam and first sub-beam, and to split second wavelength light into at least a second main beam and second sub-beam, the diffraction grating including a diffraction surface portion corresponding to the second wavelength light; and a photodetector including a first main light-receiving unit configured to be applied with the first main beam, a first sub-light-receiving unit configured to be applied with the first sub-beam, a second main light-receiving unit configured to be applied with the second main beam, and a second sub-light-receiving unit configured to be applied with the second sub-beam, a distance between the first main light-receiving unit and first sub-light-receiving unit being changed relative to a standardized distance between the first main light-receiving unit and first sub-light-receiving unit.

Abstract: A method of making a plurality of micro-optical systems includes providing a plurality of diffractive optical elements and aligning each diffractive optical element with a refractive optical element. Each micro-optical system includes a refractive optical element and a diffractive optical element. The diffractive optical element provides different focal lengths at three different wavelengths for each micro-optical system and includes adjacent steps within a cycle having a difference of more the 2? for at least one of the three different wavelengths.

Abstract: An optical pickup apparatus for recording and/or reproducing information for an optical information recording medium, comprising a light converging optical system including a coupling lens and an objective lens, wherein a first diffraction structure is installed on the objective lens, and a second diffraction structure is arranged on the coupling lens, whereby the spherical aberration and chromatic aberration caused by the difference in the thickness of the protective layer are corrected in the light converging optical system as a whole.

Abstract: An objective lens is provided for an optical pickup apparatus at least reproducing information for a first optical disc, and recording and/or reproducing information for second and a third optical discs. The objective lens includes an optical surface including a common area including a diffractive structure having a cross section in a serrated shape and divided into a plurality of ring-shaped zones. Refractive index differences between media arranged at both side of the optical surface for a light flux with one and the other wavelength satisfy a predetermined condition, and the objective lens satisfies a predetermined conditions defined by using an approximate coefficient which makes a Pearson's correlation coefficient R satisfy 0.99998?R when a depth parallel to the optical axis of step differences between the ring-shaped zones at a vertical distance from the optical axis is approximated by a least squares method.

Abstract: An optical pickup apparatus which conducts reproducing and/or recording information for a first optical information recording medium by using a light flux having a wavelength ?1 (350??1 (nm)?480) and a second optical information recording medium. The optical pickup apparatus comprises an output angle conversion element which is a fixedly arranged single lens which can convert an output angle of the first light flux and the second light flux. The optical detector equipped in the optical pickup apparatus can receive both of the first light flux and the second light flux. And, both optical surfaces of the output angle conversion element are refractive surfaces.

Abstract: An objective optical system according to the present invention is provided for use in an optical pickup apparatus for recording or reproducing information on an information recording surface of a first optical information recording medium using a first light flux emitted from a first light source. The objective optical system is provided with: a first lens with a positive refractive power including plastic; a second lens with a positive refractive power including plastic; and a first phase structure. A wavefront aberration change amount of the objective optical system when a wavelength of the first light flux changes, and a wavefront aberration change amount of the objective optical system when an ambient temperature of the objective optical system satisfy the predefined condition.

Abstract: An objective lens according to the present invention is an objective lens used for an optical pickup apparatus, and the objective lens includes a superimposed structure on a surface of a lens with a power in which a first optical path difference providing structure changing spherical aberration in under-corrected direction when a wavelength of an incident light flux becomes longer, and a second optical path difference providing structure changing spherical aberration in over-corrected direction when a wavelength of an incident light flux becomes longer are superimposed.

Abstract: An objective optical element for use in an optical pickup apparatus, includes two or more optical elements having a first surface having a first phase difference providing structure and a second surface having a second phase difference providing structure, wherein each of the first and second phase difference providing structures emit a diffracted light flux corresponding to each of the entering first-third light fluxes, or emit a transmitting light flux which is not applied a diffractive action corresponding to each of the entering first-third light fluxes, and the first-third light fluxes enter into the objective optical element as an almost infinite parallel light flux for information reproducing and/or recording on the first-third optical information recording media respectively.

Abstract: An objective lens of an optical pickup apparatus converges a divergent light flux onto an information recording surface. The following conditional formula is satisfied: |?SA1/?U|·|?U|+|?SA2/?T|·|?T|?0.07 ?rms where ? represents a wavelength of a light source, ?SA1/?U represents a change of a spherical aberration for an object-to-image distance change ?U (|?U|?0.5 mm) and ?SA2/?T represents a change of spherical aberration for a temperature change ?T (|?T|?30° C.), the object-to-image distance is a distance between the light source (a light emitting point) and the information recording surface.

Abstract: An objective lens according to the present invention is an objective lens used for an optical pickup apparatus, and the objective lens includes a superimposed structure on a surface of a lens with a power in which a first optical path difference providing structure changing spherical aberration in under-corrected direction when a wavelength of an incident light flux becomes longer, and a second optical path difference providing structure changing spherical aberration in over-corrected direction when a wavelength of an incident light flux becomes longer are superimposed.

Abstract: An optical element comprises: a diffractive structure having a plurality of diffracting ring-shaped zones arranged around an optical axis on at least one optical surface; and an optical path difference giving structure arranged on an optical surface of at least one of the plurality of diffracting ring-shaped zones, for giving a prescribed optical path difference to a prescribed light beam passing through the diffracting ring-shaped zone, wherein the optical surface of the diffractive structure is a structure having a diffracting function for setting L-th (L?0) order diffracted light of the light beam having the first wavelength ?1 to a maximum diffraction efficiency and for setting M-th (M?0) order diffracted light of the light beam having the second wavelength ?2 to a maximum diffraction efficiency in case of an assumption of no existence of the optical path difference giving structure.

Abstract: The present invention provides an optical pickup apparatus including a first light source, a second light source, a third light source, and a light-converging optical system including an objective lens. The objective lens includes at least one optical surface with a diffractive structure. The diffractive structure includes a plurality of ring shaped zones. Each of the ring shaped zones is concentrically arranged around an optical axis and includes a step difference extending along the optical axis. In the objective lens, the predetermined conditions according to the offence against a sine condition, an average of step differences of the plurality of ring shaped zones, a focal length, and a magnification, are satisfied.

Abstract: An optical head according to the present invention includes: a first light source that emits light with a first wavelength; a beam splitter that splits the light emitted from the first light source into a first light beam traveling in a first direction and a second light beam traveling in a second direction different from the first direction; a first collimator lens for changing degrees of divergence of the first light beam; a first mirror that changes the traveling directions of the first light beam, of which the degrees of divergence have been changed; a first objective lens for converging the first light beam, which has had its traveling directions changed, toward a storage layer of a first optical disk; a mover that holds the first objective lens; a first photodetector that receives the first light beam reflected from the storage layer of the first optical disk and converts it into an electrical signal; a condenser lens for condensing the second light beam; and a second photodetector that receives the sec

Abstract: An objective optical lens for use in an optical pickup apparatus, includes: an optical surface divided into at least two areas including: a central area including a first diffractive structure; and a peripheral area including a second diffractive structure, the objective lens is a single lens and is commonly used for the first to third optical information recording media, the objective lens converges diffracted light fluxes with same diffraction order generated in the first diffractive structure onto information recording surfaces of the first to third optical information recording media, respectively, the objective lens converges diffracted light fluxes with different diffraction order generated in the second diffractive structure onto information recording surfaces of the first and second optical information recording media, respectively.

Abstract: A converging optical element for use in an optical pickup apparatus reproducing and/or recording information on a first optical disc using a first light flux with a wavelength ?1 emitted by a first light source, reproducing and/or recording information on a second optical disc using a second light flux with a wavelength ?2 emitted by a second light source, and reproducing and/or recording information on a third optical disc using a third light flux with a wavelength ?3 emitted by a third light source, the converting optical element includes: a phase structure arranged on at least one surface of the converging optical element, wherein when f3 is a focal length of the converging optical element for the third light flux, the focal length f3 satisfies a predefined condition.

Abstract: An objective lens system for an optical pickup apparatus, includes in order from an object side: a first lens group having negative paraxial power P1 (mm?1); and a second lens group having positive paraxial power P2 (mm?1) for converging a light flux emitted from the first lens group on an information recording surface of an optical information recording medium.

Abstract: In order to prevent a spectrum of a wavelength channel from becoming narrower, a device according to the present invention includes a light dividing section capable of dividing a wavelength spectrum in an input light beam and outputting a plurality of divided light beams, which are spatially separated and have wavelength spectrum portions different from each other, and a wavelength-to-special-position-converter capable of spatially multiplexing the wavelength spectrum portions of the plurality of divided light beams from the light dividing section.

Abstract: An optical pickup which is compatible with at least one high density recording medium that uses a blue-violet beam and at least one lower density recording medium, the optical pickup including: an optical unit to selectively emit one of a plurality of beams with different wavelengths onto one of the at least one high density recording medium and the at least one lower density recording medium, and to receive the respective beam reflected from the respective recording medium; and a holographic objective lens to focus the respective beams emitted by the optical unit on a recording surface of the respective recording medium, the holographic objective lens including a first holographic lens region and a second holographic lens region located inside the first holographic lens region, wherein holographic patterns of the first and second holographic lens regions respectively produce a first effective numerical aperture (NA) for the at least one high density recording medium and at least one additional effective NA s

Abstract: An optical element for use in an optical pickup device to conduct reproducing and/or recording information for a first disk including a protective substrate by the use of a first light flux emitted from a first light source and to conduct reproducing and/or recording information for a second disk including a protective substrate by the use of a second light flux emitted from a first light source, the optical element includes: an optical surface on which a first phase structure is formed to have a function to correct a spherical aberration; an optical surface on which a second phase structure is formed such that when the wavelength of the first light flux changes, the second phase structure generates a spherical aberration in a direction reverse to the direction of a spherical aberration generated by the first phase structure.

Abstract: An objective lens unit, includes: an objective lens for irradiating and converging laser light on an optical disc as an a light information recording medium; and a lens frame for retaining the objective lens, wherein the lens frame is structured so that at least a portion closer to a rotation center of the optical disc is offset to an inner side of the lens frame with regards to a virtual edge section closer to the rotation center of the optical disc, wherein the virtual edge section is in a nodal line of a virtual plane that includes an end face which is closest to the optical disc in the lens frame and the objective lens, and that is perpendicular to an optical axis and a virtual rotation curved surface that is obtained when a virtual straight line passing a portion which is farthest from the optical axis in the lens frame and the objective lens, in parallel with the optical axis, is rotated around the optical axis as a center axis.

Abstract: An optical system has an optical functional surface including a common region used for conducting information recording and/or reproducing for both of a first optical information recording medium and a second optical information recording medium. The common region comprises a refractive surface of an imaginary basic aspherical surface and a optical path difference providing structure in which plural ring-shapes zones are separated around the center of an optical axis and neighboring ring-shaped zones are displaced to each other in a direction of an optical axis so as to cause an optical path difference obtained by multiplying a predetermined wavelength ?s (?1<?s<?2) with almost an integer. The refractive surface of the imaginary basic aspherical surface is structured such that a spherical aberration becomes under on the first information recording medium and a spherical aberration becomes over on the second information recording medium.

Abstract: An optical pickup apparatus for reproducing information from an optical information recording medium or for recording information onto an optical information recording medium, is provided with a first light source for emitting first light flux having a first wavelength; a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength; a converging optical system having an optical axis and a diffractive portion, and a photo detector; wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted

Abstract: A zone phase correcting lens wherein a change in the third-order spherical aberration or the like is small in the case of a change in temperature and an optical head device having the zone phase correcting lens used as an objective lens. A minus sign is appended to the height measurement of a step formed so as to make the lens thickness in the optical axis thinner toward the outer region and a plus sign is appended to a step formed so as to make the lens thickness thicker toward the outer region. Supposing that D is an absolute value of the sum of the height measurements of the steps having the minus sign on the first surface and the second surface and E is an absolute value of the sum of the height measurements of the steps having the plus sign on the first surface and the second surface, a wavelength ?1 and a refractive index N1 of the lens for a first laser beam satisfy the following conditions: 10×?1<{D×(N1?1)}<30×?1 2×E<D.

Abstract: The present invention provides a first light source (21) that emits light of a first wavelength, that at least either records onto or reproduces information from an information recording medium (30), a light source (22) that emits light of a second wavelength that records onto or reproduces information from an information recording medium (33), a light source (23) that emits light of a third wavelength that records onto or reproduces information from an information recording medium (23), focusing means, an optical element (28) that passes light of the first wavelength and diffracts light of the second and third wavelengths, wherein the optical element (28) is an optical element in which grooves are formed in a substrate, wherein the expression: 380 nm?(n?1)×d?420 nm is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves, and wherein the grooves are formed in two steps of depth d and depth 2d.

Abstract: An objective optical element of an optical pickup apparatus has a magnification m1 satisfying the following formula for a light flux of the wavelength ?1:?1/7?m1??1/25 and |m1 |<|M1, where M1 is an optical system magnification from the first light source to the first optical information recording medium for a light flux of the wavelength ?1. The objective optical element comprises a common region and an exclusive region. The exclusive region includes an exclusive diffractive structure having a function to suppress an increase of spherical aberration due to a raise of atmospheric temperature. A light flux of a wavelength ?2. having passed through the exclusive diffractive structure intersects with the optical axis at a position different from the position of the converged light spot formed on the information recording plane of the second optical information recording medium.

Abstract: A multi-focal objective lens for use in an optical pickup apparatus for recording and/or reproducing information using a first light flux with a wavelength ?1 on a first and second optical discs, includes a first optical surface including a first diffractive structure. The multi-focal objective lens converges a diffracted light flux with one of the m-th diffraction order and the n-th diffraction order on an information recording surface of the first optical disc for recording and/or reproducing information of the first optical disc, and converges a diffracted light flux with another of the m-th diffraction order and the n-th diffraction order on an information recording surface of the second optical disc for recording and/or reproducing information of the second optical disc.

Abstract: An objective lens consists of two lens elements of different materials that are cemented. The lens surfaces that are cemented includes a phase function so that the cemented surface forms a optical diffractive surface that enables the objective lens to focus incident light of three different wavelengths with different numerical apertures onto different optical recording media. Three conditions are satisfied so as to achieve optimum imaging. The optical diffractive surface is shaped so that the order of the diffracted light of the shortest wavelength ?1 having the largest diffracted intensity is zero and different from the order of the diffracted light of the second wavelength ?2 having the largest diffracted intensity, and the order of the diffracted light of the first wavelength ?1 having the largest diffracted intensity is also different from the order of the diffracted light of the third wavelength ?3 having the largest diffracted intensity.