Abstract: It is an object of the present invention to record to and reproduce different types of optical disks using light beams with different wavelengths. In an optical head device for recording to and reproducing high-density optical disks using an objective lens with a large NA, a sawtooth-shaped hologram is used for recording to and reproducing conventional optical disks such as DVDs. For blue light, a sawtooth height is the light path length 2?, and second-order diffraction light is used. Red light generates first-order diffraction. The hologram is blazed and has convex lens function, and corrects chromatic aberration of the refractive lens.

Abstract: An objective optical element for use in an optical pickup apparatus comprises a first optical surface including a first diffractive structure which comprises a plurality of concentric ring-shaped diffractive zones having a center on the optical axis and stepped surfaces arranged to be almost parallel to the optical axis and connecting respective neighboring ring-shaped diffractive zones; and a second optical surface including a second diffractive structure which comprises a plurality of concentric ring-shaped diffractive zones having a center on the optical axis and stepped surfaces arranged to be almost parallel to the optical axis and connecting respective neighboring ring-shaped diffractive zones. The stepped surfaces of the first diffractive structure are arranged to face an optical axis side, and the stepped surfaces of the second diffractive structure are arranged to face an opposite side of the optical axis side.

Abstract: An objective lens used for recording data to and/or reproducing data from a plurality of types of optical discs having different thicknesses of cover layers. The objective lens satisfies a condition 0.02<M2?M1<0.15, where M1 represents a magnification of the objective lens when recording/reproducing for a first optical disc is performed using the first light beam, and M2 represents a magnification of the objective lens when the recording/reproducing for a second optical disc is performed using the second light beam. Further, at least one of lens surfaces of the objective lens is provided with a diffracting structure having a plurality of annular zones configured to correct spherical aberrations for both of the first and second optical discs.

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: There is provided an optical pick-up used for recording data to and/or reproducing data from at least three types of optical discs having at least two different thicknesses of cover layers. The optical pick-up includes light sources and an objective lens. A thickness t1 of a first optical disc, a thickness t2 of a second optical disc, and a thickness t3 of a third optical disc satisfy a relationship t1?t2<t3. A numerical aperture NA1 for the first optical disc, a numerical aperture NA2 for the second optical disc and a numerical aperture NA3 for the third optical disc satisfy a relationship NA1?NA2>NA3. Further, a first light beam for the first optical disc is incident on the objective lens as a converging light beam, and the second and third light beams for the second and third optical discs are incident on the objective lens as diverging light beams, respectively.

Abstract: A disk reproducing apparatus for reproducing a disk that is any one of three kinds of disks, BD, DVD and CD, employing a BD objective lens, correct only aberration occurring inside the effective diameter of DVD, and leaves aberration outside the effective diameter, when reproducing DVD. Likewise, the disk reproducing apparatus corrects only aberration occurring inside the effective diameter of CD, and leaves aberration outside the effective diameter, when reproducing CD.

Abstract: An objective lens according to the present invention is provided for use in an optical pickup apparatus at least reproducing and/or recording information using a light flux with a wavelength ?1 emitted by a first light source for a first optical disc and reproducing and/or recording information using a light flux with a wavelength ?2 emitted by a second light source for a second optical disc. The objective lens includes a diffractive structure formed on the at least one optical surface of the objective lens. The light fluxes with the wavelengths ?1 and ?2 enter the objective lens, an optical system magnifications m1 and m2 of the objective lens respectively for the light fluxes with wavelengths ?1 and ?2 have different signs and values from each other, and the diffractive structure has a positive diffractive action.

Abstract: An optical system for use in an optical pickup device for recording and/or reproducing information on an optical recording media, the optical system having an optical axis and comprising: an objective system for converging a light beam emitted from a light source on the optical recording media; an optical aberration correcting element comprising two lenses arranged on an optical path between the light source and the objective system and having an adjustable distance in the direction of the optical axis, the optical aberration correcting element comprising a ring-shaped phase structure formed in at least one lens surface of the optical aberration correcting element, and wherein the ring shaped phase structure is non-periodic and comprises a plurality of concentric ring surfaces k (k=1 . . . N), and each of the ring surfaces has a step in the direction of the optical axis between the adjacent ring surface.

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 optical system for an optical disc drive includes a light source, an objective lens and a collimator lens. The light source emits first and second light beams. The first light beam is for reproducing data from a digital versatile disc while the second light beam is for a compact disc. The objective lens is provided with a diffraction structure which is designed to focus the first light beam on a recording layer of the digital versatile disc and the second light beam on a recording layer of the compact disc. The collimator lens is disposed between the light source and the objective lens. The collimator lens adjusts the diverging/converging angle of the first and second light beams entering the objective lens. The change in spherical aberration of the first light beam caused by wavelength deviation from a design wavelength due to individual specificity of the light source is corrected by adjusting the diverging/converging angle of the first light beam emerging from the collimator lens.

Abstract: An objective lens, comprises a first diffractive structure having plural concentric ring-shaped zones. A n1-th order diffracted ray is converged on an information recording surface of first optical information recording medium through first protective substrate in such a way that when a wavefront aberration is measured within a first numerical aperture NA1, the RMS value of the wavefront aberration becomes 0.07?1 or less, and a n2-th order diffracted ray (n2<n1) is converged on a information recording surface of second optical information recording medium through second protective substrate in such a way that when a wavefront aberration is measured within a second numerical aperture NA2 (NA2<NA1), the RMS value of the wavefront aberration becomes 0.07?2 or less.

Abstract: The present invention provides an objective lens system for forming a spot of a laser beam of ? wavelength on a first information recording surface through a disc protective layer having a first thickness and a second information recording surface through a disc protective layer having a second thickness greater than the first thickness, the objective lens system including: an objective lens having at least one diffraction structure for deflecting incident light by diffraction and at least two refractive surfaces for deflecting the incident light by refraction, wherein the diffraction structure divides the incident light into m1th order diffracted light (m1 is an integer) corresponding to the first information recording surface and m2th order diffracted light (m2 is an integer different from m1) corresponding to the second information recording surface and has negative power to diverge the m2th order diffracted light.

Abstract: An optical head with excellent optical characteristics even when using a light source that substantially has a wavelength broadening is provided. The optical head includes a light source, an objective lens for focusing a light beam emitted from the light source on an information recording medium and a photodetector for detecting the light beam reflected from the information recording medium, wherein defocusing correction means and spherical aberration correction means are provided in an optical path between the light source and the information recording medium. Since both the defocusing correction means and the spherical aberration correction means are provided, while defocusing of a focused spot on the information recording medium caused by a wavelength broadening of the light source and chromatic aberration of the optical system can be corrected, the spherical aberration of the optical system caused by wavelength difference between a design wavelength and an incident wavelength also can be corrected.

Abstract: An optical pickup device includes a light source emitting a light beam having a wavelength within a range of 390 nm to 420 nm and an optical element to perform recording and/or reproducing of information of an optical disk having a protective substrate thickness d1 mm using the first light beam from the first light source, wherein the optical element is made of a mixed material produced by dispersing particles into a resin, a sign of a refractive index change ?n2/?t of the particles owing to a temperature change is opposite to a sign of a refractive index change ?n1/?t of the resin owing to a temperature change, or an absolute value of the refractive index change ?n2/?t is smaller than an absolute value of the refractive index change ?n1/?t.

Abstract: An optical pickup device includes a light source unit an optical system which leads a return light beam to a predetermined light-receiving location and includes an object lens focusing each light beam from the light source unit to a recording surface of a corresponding storage medium and a photodetector arranged at the light-receiving location. The light source unit includes a plurality of light sources outputting light beams respectively, the plurality of light sources being arranged in proximity to each other, and a divergence-angle changing unit changing an angle of divergence of a light beam output from at least one of the plurality of light sources.

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.

Abstract: An optical system including a light source that generates light, a mirror changing an optical path of the light generated by the light source and an aberration correcting element that corrects aberrations generated in the light reflected from the mirror due to an error in the surface shape of the mirror.

Abstract: An optical pickup apparatus includes: first-third light sources; a packaged multiple light source unit for packaging emitting points of at least two of the first-third light sources in one housing; an objective optical system for converging light fluxes emitted by light sources onto information recording surfaces of at least three kinds of optical disks; and a magnification adjusting optical unit having an actuator and a movable lens group and being arranged in an optical path between the packaged multiple light source unit and the objective optical system, wherein the movable lens group is driven by the actuator along the optical axis so as to change a magnification of the objective optical system according to a wavelength of a light flux emitted by the packaged multiple light source unit.

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 optical head device includes a focusing optical system for focusing a laser beam emitted from a semiconductor laser light source on an optical information medium with an objective lens. A chromatic aberration correction element for correcting chromatic aberration occurring in the objective lens is provided between the semiconductor laser light source and the optical information medium. A light distribution correction element in which the transmittance increases with the distance from the center of the aperture surface of the objective lens is provided so as to correct a reduction of the intensity of the light incident on the aperture surface of the objective lens with the distance from the center of the aperture surface.

Abstract: A recording reproducing optical system for an optical information recording medium is provided with a light source; an objective lens; and an aberration correcting optical element provided on an optical path between the light source and the objective lens. The objective lens includes an aspherical surface and one diffractive surface on which a diffractive structure structured by a plurality of concentric ring-shaped zonal steps is formed and the objective lens is a plastic lens structured in one element in one group. The aberration correcting optical element comprises at least one plastic lens on which a diffractive structure structured by a plurality of concentric ring-shaped zonal steps is formed. The following formulas are satisfied: PD1>0 (PD1 is a diffractive power (mm?1)), PD2<0 (PD2 is a diffractive power (mm?1)) and PR2>0 (PR2 is a refractive power (mm?1) as a refractive lens).

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: An optical pickup has a first compatible objective and a second compatible objective, the first objective having a diffractive lens structure capable of recording and playback to and from CD and HD DVD, the second objective having a diffractive lens structure capable of recording and playback to and from both DVD and BD. The first objective has the diffractive lens structure that meets the condition of 0.75?(?1×m1)/(?3×m3)?0.99, where m1 and m3 are diffraction orders of diffracted lights used to read and write CD and HD DVD. The second objective has the diffractive lens structure that meets the condition of 0.75?(?4×m4)/(?2×m2)?0.99, where m2 and m4 are diffraction orders of diffracted lights used to read and write DVD and BD.

Abstract: An optical pickup device wherein at least a high density disc such as HD-DVD is compatible with DVD, and securing an amount of light is compatible with correction of chromatic aberration. An a correcting element representing an optical system used for the aforementioned optical pickup device.

Abstract: A common objective lens typically used in reading data from different optical data storage media that are responsive to laser beams of different wavelengths, such as CD and DVD is provided. The lens has a refracting surface with inner and outer refracting surface regions. Diffraction gratings are provided in both the inner and outer refracting surface regions with each having a differential optical path function. The inner diffraction grating and at least a part of the outer diffraction grating emit an order of diffracted beams which have different polarities to cancel out any spherical aberrations caused by a change in temperature.

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 optical pickup apparatus comprising: a first light source emitting first light flux having wavelength ?1 (380 nm??1?450 nm); a second light source emitting second light flux having wavelength ?2 (600 nm??2?700 nm); a third light source emitting third light flux having wavelength ?3 (750 nm??3?800 nm); a first divergent angle-converting element through which the first light flux passes; a second divergent angle-converting element through which the second light flux and the third light flux pass; and an objective optical element through which the first, second, and third light fluxes pass. Optical magnification m2 of the second divergent angle-converting element for the second light flux and optical magnification m3 of the second divergent angle-converting element for the third light flux are different from each other.

Abstract: An objective lens is formed as an objective lens element with a diffractive surface on one side. The objective lens focuses a collimated light beam of a first wavelength diffracted by the objective lens onto a first recording medium, a collimated light beam of a second wavelength diffracted by the objective lens onto a second recording medium, and a diverging light beam of a third wavelength diffracted by the objective lens onto a third recording medium. The three light beams are focused at three different working distances from the objective lens and the diffraction orders of the diffracted light of two of the light beams is the same. The objective lens satisfies certain conditions related to the shortest of the three different working distances, the focal length of the objective lens element at the shortest of the three wavelengths, and the thickness of the objective lens.

Abstract: An objective lens for converging a light beam emitted from a first light source on a recording surface (17a) of a first optical information recording medium covered with a transparent substrate (7a) and converging a light beam emitted from a second light source on a recording surface (17b) of a second optical information recording medium covered with a transparent substrate (7b) having a thickness greater than the transparent substrate (7a). On an incident plane for the light beam, there are formed a center region (A1), an intermediate region (A2) surrounding the center region (A1), and a peripheral region (A3) surrounding the intermediate region (A2). A diffraction grating (11) is provided on the lens surface of the intermediate region (A2).

Abstract: A light beam splitting element that splits a beam incident on a beam receiving surface into a plurality of beams. The beam receiving surface has at least one predetermined area that directs a portion of the incident beam to proceed in a predetermined direction, the portion of the beam incident on the one predetermined area being insusceptible to spherical aberration. Further, the beam receiving surface has at least another predetermined area that directs another portion of the incident beam to proceed in another predetermined direction, the another portion of the beam incident on the another predetermined area being susceptible to spherical aberration.

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 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: 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 an average of step differences of the plurality of ring shaped zones, a focal length, a magnification, and the Abbe number, are satisfied.

Abstract: The present invention provides an optical pickup apparatus for recording and/or reproducing information for different kinds of optical information recording media. The optical pickup apparatus 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; a light-converging optical system including an objective lens. The objective lens includes at least one optical surface including a diffractive structure which 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 of the optical pickup apparatus, the offence against a sine condition, an average of step differences of the plurality of ring shaped zones, focal length, and magnification satisfy the predetermined conditions.

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 lens includes a hologram, a refractive lens, and a phase level difference. The hologram has a sawtooth shape grating having a sawtooth shape in cross-section, and generates +2nd-order diffracted light most strongly with respect to blue light and +1st-order diffracted light most strongly with respect to red light, by setting a height of the sawtooth shape grating. The +2nd-order diffracted light of blue light is condensed through a substrate with a thickness t1, and the +1st-diffracted light of red light is condensed through a substrate with a thickness t2 (t1<t2). The difference in optical path length occurring when the blue light passes through the phase level difference is five times the wavelength of the blue light.

Abstract: A lens for an optical recording and reproducing system includes: a plane of incidence on which a light generated from a light source is made incident; a first reflection side for reflecting a light passing through a plane of incidence; and a second reflection side for reflecting again the light that has been reflected on the first reflection side, the second reflection side being formed to be an ellipsoid side, and the first reflection side and the second reflection side being coated with a reflection material. A very small optical system in its size and weight is possibly constructed, so that information recording and reproducing can be possible only with one focussing lens without a necessity of an objective lens. Accordingly, an ultra-thin optical recording and reproducing system of which height is remarkably reduced can be provided.

Abstract: A article having a micro-sized shape being formed on the surface of the article by pressing a die onto the surface, wherein the elastic modulus of the article at room temperature is in the range of 1–4 GPa, the thickness of the article after forming is equal to 0.1 mm or more and 20 mm or less and the aspect ratio of the micro-sized shape is equal to 1 or more. A forming method to produce an article comprising the steps of setting the temperature of a die having a micro sized shape to be equal or higher than the glass transitional temperature of material having an elastic modulus of 1 to 4 (GPa) pressing the die to the material to transfer the micro sized shape to the material, and cooling the die having the micro sized shape.

Abstract: An optical pickup having a light-emitting element, an objective lens unit, a reflecting mirror and a light-receiving element, emits a beam onto an optical recording medium and uses a reflected beam to read recorded information. In the objective lens unit, a central part of a surface, facing the light-emitting element, of an objective lens disposed so that an optical axis is substantially aligned with a chief ray of the beam emitted by the light-emitting element, is a transmissive diffraction grating, and a central part of a surface of the objective lens that will face the optical recording medium is a convex mirror which bulges toward the light-emitting element. The reflecting mirror, which is annular and encompasses the optical axis of the objective lens, reflects toward the objective lens the beam from the light-emitting element that has passed through the transmissive diffraction grating and been reflected by the convex mirror.

Abstract: A hybrid objective lens has a refractive lens and a diffractive optical element constructed by plural coaxial ring-shaped zones on at least one optical surface thereof. When n1, n2 and n3 each is a diffraction order of a diffracted ray having a maximum light amount among diffracted rays of each of first, second and third light flux having wavelength ?1, ?2 and ?3 when respective light flux comes to be incident into the diffractive structure respectively, the following formulas are satisfied: |n1|>|n2|, and |n1|>|n3|, and the hybrid objective lens converges a n1-th, n2-th and n3-th order diffracted ray of the first, second and third light flux onto an information recording plane of each of the first, second ant third optical information recording medium respectively so as to form an appropriate wavefront within respective prescribed necessary image side numerical apertures.

Abstract: An optical scanning device (1) is for scanning two information layers (2, 2?) with two radiation beams (4) in two operating modes. It comprises a radiation source (7) for emitting the two radiation beams, an objective lens system (8) for converging the two beams on the positions of the two information layers, and a phase structure (24) having an optical axis (19) and including a central part (P1) and at least one marginal part (P2) for forming a non-periodic stepped profile in the radial direction. One (P2) of said central and marginal parts (P1, P2) includes at least two segments (AS2,1, AS2,2) having two different step heights (h2,1, h2,2), respectively, for introducing in said first operating mode two wavefront modifications W2,1,1? and W2,2,1?, respectively, and in said second operating mode two wavefront modifications W2,1,2? and W2,2,2?, respectively, where the difference (w2,1,2+?W2,2,2)?(?W2,1,1+?W2,2,1?) is asymmetric.

Abstract: The present invention relates to an optical pickup, and more particularly to an optical pickup comprising an optical modulator for reflecting and diffracting an incident light beam to generate multiple beams, and the optical pickup simultaneously reads a plurality of data bits using multiple beams at the time of reading optical disc information, thus promptly processing optical disk information, thereby the optical pickup of the present invention can cope with various types of optical disk media using light beams with different wavelengths.

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: 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: 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: An optical pick-up apparatus has a first light source, a second light source, and an optical system including an objective lens. An optical functional surface of the objective lens is divided into at least first and second concentric optical functional regions. The second functional region is provided with a diffractive structure to correct a spherical aberration of a converged light spot on an information recording plane to be regulated in a range where reproduction and/or recording information for a first optical information recording medium can be conducted when the refractive index of the optical element and the wavelength of the first light source vary due to a change of the working temperature of the optical system.

Abstract: A photodetector, includes: a semiconductor chip that converts received light to an electric signal; and a resin body that encapsulates the semiconductor chip. The photodetector further includes a protective unit, and at least a light transmission area, through which the light passes, in a surface of the resin body on an incident side of the light is covered by the protective unit. Covering the light transmission area with the protective unit that is less in reactivity with light than the resin body can suppress deformation of the resin body due to light, thus suppressing deterioration of the optical characteristics of the photodetector.

Abstract: An objective lens for use in an optical pickup apparatus has a diffractive optical surface. A first light flux having a first wavelength of ?1 is converged as a first number diffraction order diffracted-ray other than the zero-th order diffracted-ray onto an information recording plane of the first optical information recording medium having a thinner protective substrate t1 by the diffractive optical surface and a second light flux having a second wavelength of ?2 (?1<?2) is converged as a second number diffraction order diffracted-ray other than the zero-th order diffracted-ray onto the information recording plane of the second optical information recording medium having a thicker protective substrate t2 (t1<t2) by the diffractive optical surface. The second number diffraction order is different from the first number diffraction order.

Abstract: An objective lens to converge a light flux having a working reference wavelength ?0 (380 nm??0?450 nm) under a working reference temperature T0 onto an optical information recording medium equipped with a protective substrate having a thickness of 0.6 mm with almost no aberration. The diffractive structural section of the objective lens has a first compensating function to compensate a change amount ?SA1 of the third-order spherical aberration component of wavefront aberration caused by a fluctuation of a working wavelength, a second compensating function to compensate a deviation ?WD of a converged-light spot in an optical axis direction caused by a fluctuation of a working wavelength, and a third compensating function to compensate a change amount ?SA2 of the third-order spherical aberration component of wavefront aberration caused by a change of a refractive index of the lens body.

Abstract: The present invention relates to an optical pickup apparatus enabling to reproduce/record data of different kinds of disks in different thicknesses, using one single optical pickup. The optical pickup apparatus includes two objective lens, in which one objective lens has an incident plane and an outgoing plant formed of a flat plane at a designated radius domain from an optical axis, thereby preventing spherical aberration caused by the difference of the thickness between different kinds of disks.

Abstract: An optical head with excellent optical characteristics even when using a light source that substantially has a wavelength broadening is provided. The optical head includes a light source, an objective lens for focusing a light beam emitted from the light source on an information recording medium and a photodetector for detecting the light beam reflected from the information recording medium, wherein defocusing correction means and spherical aberration correction means are provided in an optical path between the light source and the information recording medium. Since both the defocusing correction means and the spherical aberration correction means are provided, while defocusing of a focused spot on the information recording medium caused by a wavelength broadening of the light source and chromatic aberration of the optical system can be corrected, the spherical aberration of the optical system caused by wavelength difference between a design wavelength and an incident wavelength also can be corrected.