Abstract: The present invention has a beam shaping element for converting the light source 11 into a light flux whose emitting angle is almost equal and for projecting it, and a generation amount of the astigmatism generated by the temperature change is suppressed by a linear expansion of the beam shaping element.

Abstract: An optical pickup device, including: first, second and third light sources performing recording and/or reproduction of information for information recording surfaces of first, second and third optical information recording medium each having a protective substrate with a thickness t1, t2 and t3, respectively; a first objective optical system for guiding at least the first beam to the information recording surface of first optical information recording medium; second objective optical system provided separately from the first objective optical system, for guiding at least the third beam to information recording surface of the third optical information recording medium; and at least one light receiving element for detecting light reflected on the information recording surfaces of the first to third optical information recording media.

Abstract: An optical pickup apparatus for recording/reproducing information onto/from a first and a second optical information recording media respectively having a first and second protective layers with a thickness of t1 and t2, using first light beams having a wavelength ?1, the optical pickup apparatus comprises, a first light source having the wavelength of ?1, a first and a second objective optical elements, wherein when recording/reproducing the information onto/from the first optical information recording media, one of the first and the second objective optical lenses is used to condense the first light beams onto a first information recording surface and when recording/reproducing the information onto/from the second optical information recording medium, the other objective optical lens is used to condense the first light beams onto a second information recording surface, wherein the thickness of t1 and the thickness of t2 satisfy a following formula, 2.5<t2/t1.

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 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: An optical pickup apparatus comprises a first, second and third light beam sources for emitting first light beams having wavelengths ?1, ?2 and ?3 (?1<?2<?3) for a first, second and third recording medium respectively having a first, a second and a third protective layers of thickness t1, t2 and t3, an objective optical lens for converging the first, the second and the third light beams onto respective recording surfaces of the first, second and the third recording media, a tracking device for moving the objective optical lens, a first divergent angle changing element for changing a divergent angle of light beams, which is capable of moving in the optical axis direction and placed in an optical path, and a coma aberration correction element for correcting coma aberration caused when the tracking device moves the objective optical element.

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: In a beam shaping device for converting the laser light emitted from a semiconductor laser light source from an elliptic beam to a circular beam, the light-entrance-side and light-exit-side surfaces of the beam shaping device both have a curvature only in the minor-axis direction of the cross section of the elliptic beam. Of the light-entrance-side and light-exit-side surfaces, one is a circular-arc cylindrical surface and the other is a non-circular-arc cylindrical surface. The beam shaping device fulfills prescribed conditions with respect to the center thickness, surface shapes, and/or other features.

Abstract: In a beam shaping device for converting the laser light emitted from a semiconductor laser light source from an elliptic beam to a circular beam, the light-entrance-side and light-exit-side surfaces of the beam shaping device both have a curvature only in the major-axis direction of the cross section of the elliptic beam. Of the light-entrance-side and light-exit-side surfaces, one is a circular-arc cylindrical surface and the other is a non-circular-arc cylindrical surface.

Abstract: This invention provides an optical element which has an optical surface in which a first light beam having a wavelength ?x and a second light beam having a wavelength ?y, which are emitted from light sources, become incident, including a diffraction structure in which a plurality of zone portions are formed, the zone portions being arranged in a radial direction about an optical axis and forming one period by a plurality of zones formed into a staircase shape divided by steps in a section including the optical axis, wherein the plurality of zone portions of said diffraction structure include a first zone portion and a second zone portion whose numbers of zones in one period are different, and of the plurality of zones which form one period, the zones except the zone which gives a largest optical path length to the passing second light beam have at least two different widths in a direction perpendicular to the optical axis, and of the plurality of zones which form the zone portion, two zones which are adjacent

Abstract: An objective optical system for use in an optical pickup apparatus, comprises an aberration correcting element having at least two phase structures of a first and second phase structures; and a light converging element to converge the first light flux emitted from the aberration correcting element onto an information recording plane of the first optical disk and to converge the second light flux emitted from the aberration correcting element onto an information recording plane of the second optical disk; wherein the second phase structure refrains at least one of a change in the light converging characteristic of the objective optical system due to a change in the wavelength of the first light flux and a change in the light converging characteristic of the objective optical system due to a change in environmental temperature.

Abstract: An objective optical element for use in an optical pickup apparatus first-third light sources emitting first-third light fluxes and a light converging optical system, includes a first optical path difference providing structure for providing an optical path difference which provides a substantial phase change to the third light flux and does not provide a substantial phase change to the first and second light fluxes; and a second optical path difference providing structure for providing an optical path difference to the first light flux, the second light flux and the third light flux, wherein the objective optical element converges the first-third light fluxes through the protective layers with the thicknesses t1-t3 onto an information recording surface of the first-third optical information media respectively.

Abstract: An optical pickup apparatus comprising: a first, second and third light sources emitting first, second and third light flux having first wavelength of ?1, second wavelength of ?2 and third wavelength of ?3, respectively; and an objective optical system converging the first, second and third light fluxes onto an information recording surface of a first, second and third optical disk, respectively, wherein the objective optical system has a phase structure, and wherein when a first, second and third magnifications of the objective optical system for conducting reproducing information from and/or recording information on the first, second and third optical disks are represented by M1, M2, and M3, respectively, |dM1?M2|, which represents an absolute value of a difference between M1 and M2, satisfies the following relation. |dM1?M2|<0.

Abstract: An objective lens system for optical pickups reading and/or writing information by condensing a luminous flux from a light source onto an optical information recording medium, consists of, a single lens having, from a light source side, a first surface convex to the light source side and a second surface convex to an image side. A medium of the single lens is a homogeneous medium. At least one of the two surfaces is aspherical. The system satisfies the predetermined conditions.

Abstract: This invention provides an optical pickup apparatus which includes a plurality of light sources, a beam shaping element which is arranged in an optical path through which a light beam emitted from at least one of the light sources passes, and an optical system which includes a divergence angle conversion element and an objective lens and is arranged in an optical path through which the light beams emitted from the plurality of light sources pass, and records and/or reproduces information by condensing, through the objective lens, the light beam emitted from each light source on the information recording surface of a corresponding optical information recording medium. An almost elliptical cross-sectional shape of the light beam which enters the beam shaping element is shaped into a cross-sectional shape closer to an almost circular shape or a circular shape, and the light beam emerges from the beam shaping element.

Abstract: An optical pickup apparatus includes a diffractive optical element, and an objective lens that focuses a light beam of a first wavelength ?1, a light beam of a second wavelength ?2 and a light beam of a third wavelength ?3 on a first recording medium, a second recording medium, and a third recording medium, respectively, the wavelengths ?1, ?2, and ?3 being different from each other.

Abstract: An optical pickup apparatus has a diffractive optical element and an objective lens that focuses light beams of different wavelengths, namely a first wavelength &lgr;1, a second wavelength &lgr;2, and a third wavelength &lgr;3, on an information recording surface formed on different types of recording medium, namely a first recording medium, a second recording medium, and a third recording medium, respectively. The diffractive optical element has a first diffractive surface that does not diffract the light beams of the first and third wavelengths &lgr;1 and &lgr;3 but that diffracts the light beam of the second wavelength &lgr;2 and a second diffractive surface that does not diffract the light beams of the first and second wavelengths &lgr;1 and &lgr;2 but that diffracts the light beam of the third wavelength &lgr;3.

Abstract: A zoom optical system has a focus adjusting unit that performs focusing for an object by moving along an optical axis thereof and a magnification adjusting unit that corrects a change in optical magnification caused by the focusing by moving along an optical axis thereof.

Abstract: A scanning optical system has an object side lens unit for condensing light from an object, a mirror for performing a main scan to read the image of the object by deflecting the light transmitted through the object side lens and an image side lens unit for forming an image on the image sensing surface using both the extra-axial light and axial light in a subscan direction deflected by the mirror. The scanning optical system satisfies the predetermined condition defined by lenses of Abbe number.

Abstract: An objective lens system for optical pickups reading and/or writing information by condensing a luminous flux from a light source onto an optical information recording medium, consists of, a single lens having, from a light source side, a first surface convex to the light source side and a second surface convex to an image side. A medium of the single lens is a homogeneous medium. At least one of the two surfaces is aspherical. The system satisfies the predetermined conditions.