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 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 pickup apparatus comprises two light sources having two wavelengths (&lgr;1<&lgr;2) and a converging optical system having an objective lens. The objective lens comprises a central region; a peripheral region provided at an outside of the central region on at least one optical surface of the objective lens; a diffractive ring-shaped zones which is blazed on a basis of a wavelength &lgr;0 (&lgr;1<&lgr;0<&lgr;2) and is formed on each of the central region and the peripheral region; and a phase difference suppressing structure to suppress a phase difference between a wavefront of a light flux passing the central region and a wavefront of a light flux passing the peripheral region when recording or reproducing information is conducted for the first optical information recording medium.

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 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 at least two kinds of optical information recording media, comprises a first light source; a second light source; an optical converging system; and a photo detector. An optical element of the optical converging system comprises a first region including an optical axis and a second region adjoining the first region and locating at the outside of the first region, the first region is a refractive surface and the second region is a diffractive surface. When a first light flux passes through the second region, the light amount of n-th order diffracted ray of the first light flux is larger than that of any other order diffracted ray of the first light flux, and when a second light flux passes through the second region of the optical element, the light amount of n-th order diffracted ray of the second light flux is larger than that of any other order diffracted ray of the second light flux, where n is an integer except 0.

Abstract: An optical pickup apparatus for a first optical medium including a first transparent base plate having a thickness of t1 and a second optical medium including a second transparent base plate having a thickness of t2 (t2>t1), comprises a first light source to emit a first light flux having a wavelength of &lgr;1; a second light source to emit a second light flux having a wavelength of &lgr;2 (&lgr;1<&lgr;2); a converging optical system having an objective lens and a diffracting section and to converge the first light flux or the second light flux onto the first optical medium or the second optical medium; and an optical detector. When the converging optical system converges the second light flux onto the second information recording surface so as to conduct reproducing and/or recording the information of the second optical information recording medium, a spherical aberration has at least one discontinuous portion or at least one substantially discontinuous portion.

Abstract: An optical pickup apparatus conducts recording or reproducing information for an information recording plane of a first or second optical information recording medium and comprises a first light source and a second light source mounted on a same base board; a converging optical system; and a coupling lens. The converging optical system comprises an objective lens to converge a first or second light flux having passed through the coupling lens on a first or second optical information recording medium; and a diffractive structure to change a focal length in accordance with a wavelength of a light flux emitted from the first light source or the second light source.

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 &lgr;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 &lgr;2 (&lgr;1<&lgr;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 for use in an optical pickup apparatus in which first and second light sources are provided on a same flat surface, converges each of the light fluxes from the first and second light sources onto an information recording plane through each of transparent substrates of a first and second optical information recording mediums and has a coma aberration of 0.015 &lgr;1 rms or less when recording or reproducing information is conducted for the first optical information recording medium, and a coma aberration of 0.015 &lgr;2 rms or less when recording or reproducing information is conducted for the second optical information recording medium.

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 &lgr;s (&lgr;1<&lgr;s<&lgr;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 comprises two light sources having two wavelengths (&lgr;1<&lgr;2) and a converging optical system having an objective lens. The objective lens comprises a central region; a peripheral region provided at an outside of the central region on at least one optical surface of the objective lens; a diffractive ring-shaped zones which is blazed on a basis of a wavelength &lgr;0 (&lgr;1<&lgr;0<&lgr;2) and is formed on each of the central region and the peripheral region; and a phase difference suppressing structure to suppress a phase difference between a wavefront of a light flux passing the central region and a wavefront of a light flux passing the peripheral region when recording or reproducing information is conducted for the first optical information recording medium.

Abstract: An objective lens for use in an optical pickup apparatus to record or reproduce information in an optical information recording medium, comprises an aspheric surface, wherein the following conditional formula is satisfied: 1.1≦d1/f≦3 where d1 represents axial lens thickness and f represents a focal length.

Abstract: An objective lens for us in an optical pickup apparatus to record or reproduce information in an optical information recording medium, comprises an aspheric surface, wherein the following conditional formula is satisfied: 1.1≦d1/f≦3 where d1 represents axial lens thickness and f represents a focal length.

Abstract: A diffractive lens, comprises an optical axis; a lens surface having a peripheral portion, and a diffractive relief provided on the lens surface, wherein the diffractive relief is shaped in annular zones, and wherein following conditional formulas (1) and (2) are satisfied: hi−1≦h<hi  (1) x=f(h−hti)+S  (2) where i is a suffix showing an ordinal number of each of the diffractive annular zones obtained by counting each diffractive annular zone in such a manner that a diffractive annular zone including the optical axis is counted as a first diffractive annular zone and other diffractive annular zones are counted respectively in consecutive order from the optical axis toward the peripheral portion; h is a distance between a point and X axis in which, when the optical axis is deemed as X axis, the distance is from X axis to the point in a direction perpendicular to X axis; hi is a distance from X axis to a border between i-th diffractive annular zone and (i&plus

Abstract: An objective lens for use in an optical pickup apparatus to record or reproduce information in an optical information recording medium, comprises an aspheric surface, wherein the following conditional formula is satisfied: 1.1≦d1/f≦3 where d1 represents axial lens thickness and f represents a focal length.

Abstract: A zoom lens to form an image of an object with variable magnification, is provided with a first lens group having a positive refracting power, and a second lens group positioned closer to the image than the first lens group and having a negative refracting power. When the magnification is changed, a distance between the first lens group and the second lens group is changed. The first lens group comprises a 1-1 lens, a 1-2 lens and a 1-3 lens aligned in this order from the object. The zoom lens comprises at least two plastic lenses.

Abstract: In a near field type optical disk recording and/or reproducing apparatus, provided with a light source; an objective single lens to converse light from the light source to a focusing point; an optical disk; and a rotating device to rotate the optical disk; the objective lens has a first surface at the light source side and a second surface at the focusing point side, and the first surface is a curved surface on which a diffraction surface is provided.

Abstract: An optical pickup apparatus for conducting recording and/or reproducing information of an optical information recording medium, comprises a light source; a converging optical system having an objective lens; and a photo-detector. The converging optical system comprises a plastic lens and a spherical aberration deviation correcting element to correct deviation of a spherical aberration of the converging optical system. A numerical aperture of the objective lens at an image-side is 0.65 or more.