Abstract: The objective optical system of the present invention includes a first diffraction structure that applies diffraction to the light fluxes of wavelength ?1, wavelength ?2 and wavelength ?3 so that the diffracted lights of the L-th order (L: odd number), M-th order (M: integer) and N-th order (N: integer) each will have the maximum diffraction efficiency, and a first optical path difference-generating structure that substantially provides a phase difference to or two of the light fluxes of wavelength ?1, wavelength ?2 and wavelength ?3.

Abstract: An optical pickup apparatus, includes: first-third light sources emitting first-third light fluxes respectively; a diffractive optical and; an objective optical system having a light converging element, wherein the diffractive optical element includes a first area whose center is on an optical axis; a second area formed in a ring-shape and arranged outside of the first area; a third area formed in a ring-shape and arranged outside of the second area; and the first-third areas have different optical properties each other for the first-third light fluxes, the third area does not form two light fluxes among the first-third light fluxes passing the third area and the light converging element into a converged spot on the information recording surfaces of corresponding disks.

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: This invention is directed to an optical pickup apparatus, condensing optical system, and optical element which can at least reproduce and/or record information from/on a first optical information recording medium having a protective substrate thickness t1 by using a light beam of a first wavelength &lgr;1 emitted from a first light source, and reproduce and/or record information from/on a second optical information recording medium having a protective substrate thickness t2 (t2≧t1) by using a light beam of a second wavelength &lgr;2 (&lgr;2>&lgr;1) emitted from a second light source.

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: First and second light sources, an objective optical element, a photo-detector, first and second coupling elements and a beam splitter are arranged such that a first light flux emitted from the first light source comes into the objective optical element through the first coupling element and the beam splitter and forms a converged light spot on an information recording plane of a first optical information recording medium, a second light flux emitted from the second light source comes into the objective optical element through the second coupling element and the beam splitter and forms a converged light spot on an information recording plane of a second optical information recording medium, and the first and second light fluxes forming the respective converged light spots are reflected from the respective information recording planes and thereafter pass through the objective optical element, the beam splitter and the second coupling element and come into the photo-detector.

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 &lgr;1: −1/7≦m1≦−1/25 and |m1|<|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 &lgr;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 &lgr;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: 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 arrranged 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 &lgr;1 to a maximum diffraction efficiency and for setting M-th (M≠0) order diffracted light of the light beam having the second wavelength &lgr;2 to a maximum diffraction efficiency in case of an assumption of no existence of the optical path difference giving structure.

Abstract: An objective light converging element for use in an optical pickup device and used to converge a light flux having a reference wavelength &lgr; (380 nm≦&lgr;0≦450 nm) emitted from a light source onto an information recording plane of an optical information recording medium equipped with a protective substrate having a thickness of 0.6 mm, has a lens structural section to refract a light flux emitted from the light source; and a ring-shaped diffractive structural section having an optical axis on a center and to diffract a light flux emitted from the light source.

Abstract: An objective lens to converge a light flux having a working reference wavelength &lgr;0(380 nm≦&lgr;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 &dgr;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 &dgr;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 &dgr;SA2 of the third-order spherical aberration component of wavefront aberration caused by a change of a refractive index of the lens body.

Abstract: An optical pickup device, comprises light sources to emit a first light flux having a wavelength &lgr;1 (380 nm<&lgr;1<450 nm); a second light flux having a wavelength &lgr;2 (600 nm<&lgr;2<700 nm); and a light-converging optical system. The light-converging optical system converges the first light flux on a first optical information recording medium through a protective layer having a thickness t1 and the light-converging optical system converges the second light flux on a second optical information recording medium through a protective layer having a thickness t2. The light-converging optical system forms a first spot on the information recording surface of the first optical information recording medium by using N-th order diffracted light ray generated, and the light-converging optical system forms a second spot on the information recording surface of the second optical information recording medium by using M-th order (M≠N) diffracted light ray generated.