Abstract: An optical pickup apparatus for reproducing and/or recording information on an optical information recording medium, includes a light source to emit a light flux with a wavelength in the range of 200-700 nm, the emitted light flux having a light intensity distribution in nearly Gaussian distribution; a light intensity distribution converting element to transform the light intensity distribution of the light flux emitted by the light source into a desired light intensity distribution wherein a light intensity of an outgoing light passing through an outermost periphery of an effective aperture becomes 45%-95% of a light intensity of an outgoing light passing through an optical axis position; and an objective optical element to converge a light flux emitted by the light intensity distribution converting element onto an information recording surface on the optical information recording medium.

Abstract: An objective lens comprises at least inner and outer optically functional regions arranged in a direction perpendicular to an optical axis and each of the inner and outer optically functional regions has a diffractive structure. The objective lens comprises a light amount reducing structure to reduce an amount of the light flux passing through a region of the objective lens other than the inner optically functional region when recording or reproducing is conducted for CD.

Abstract: An objective lens has a first meniscus-shape lens including a first object-side surface having a positive reflective power; and a second meniscus-shape lens having a positive reflective power. The first meniscus-shape lens and the second meniscus-shape are arranged in that order from an object side.

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 objective lens is provided with plural optical functional regions including an inside optical functional region, an outside optical functional region and an intermediate optical functional region provided between the inside and outside optical functional regions. The absolute value of an amount of a spherical aberration of a light flux coming to the second optical information recording medium after having passed through the intermediate optical functional region is made larger than that of an amount of a spherical aberration of a light flux coming to the second optical information recording medium after having passed through the inside optical functional region when recording and/or reproducing information is conducted for the second optical information recording medium.

Abstract: An optical pickup apparatus for first and second optical information recording medium, comprises first and second light sources to emit first and second light flux; a single objective lens made and a diaphragm having an aperture. The pitch of a plurality of ring-shaped diffractive zones provided on the objective lens, becomes gradually small from the optical axis to a point h and the pitch increases at the point h. At the time of conducting recording or reproducing information of the second optical information recording medium, the second light flux has a spherical aberration discontinuous portion at the point h where a spherical aberration-stepped amount is 7 &mgr;m to 40 &mgr;m, and a spherical aberration of a light ray of the second light flux having passed through the outermost portion of the aperture of the diaphragm is 7 &mgr;m to 40 &mgr;m.

Abstract: An objective lens is provided with plural optical functional regions including an inside optical functional region, an outside optical functional region and an intermediate optical functional region provided between the inside and outside optical functional regions. The absolute value of an amount of a spherical aberration of a light flux coming to the second optical information recording medium after having passed through the intermediate optical functional region is made larger than that of an amount of a spherical aberration of a light flux coming to the second optical information recording medium after having passed through the inside optical functional region when recording and/or reproducing information is conducted for the second optical information recording medium.

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 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.

Abstract: An objective optical element for use in an optical pickup apparatus, includes an objective lens to converge the light flux emitted from the first and second light sources; and an optical functional surface including a common region and an exclusive region. When a first optical information medium is used, a sine condition unsatisfied-amount whose value is maximum exists on the common region.

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 comprises at least inner and outer optically functional regions arranged in a direction perpendicular to an optical axis and each of the inner and outer optically functional regions has a diffractive structure. The objective lens comprises a light amount reducing structure to reduce an amount of the light flux passing through a region of the objective lens other than the inner optically functional region when recording or reproducing is conducted for CD.

Abstract: An objective lens of an optical pickup apparatus converges a divergent light flux onto an information recording surface.

Abstract: An optical pickup apparatus for first and second optical information recording medium, comprises first and second light sources to emit first and second light flux; a single objective lens made and a diaphragm having an aperture. The pitch of a plurality of ring-shaped diffractive zones provided on the objective lens, becomes gradually small from the optical axis to a point h and the pitch increases at the point h. At the time of conducting recording or reproducing information of the second optical information recording medium, the second light flux has a spherical aberration discontinuous portion at the point h where a spherical aberration-stepped amount is 7 &mgr;m to 40 &mgr;m, and a spherical aberration of a light ray of the second light flux having passed through the outermost portion of the aperture of the diaphragm is 7 &mgr;m to 40 &mgr;m.