Konica Minolta Opto, Inc.

Konica Corporation

Konica-minolta Holdings, Inc.

Mitsuru Mimori

Kiyono Ikenaka

Kohei Ota

Junji Hashimura

Tohru Kimura

Yuichi Atarashi

Shinichiro Saito

Katsuya Sakamoto

Hidekazu Totsuka

Kouhei Ohta

Provided are an optical pickup apparatus and an objective lens which can appropriately record and/or reproduce information on three types of discs with different recording densities and improve the light-utilization efficiency using a simple structure. A first optical path difference providing structure is formed on an optical surface of the objective lens. The first optical path difference providing structure is a step structure in which plural ring-shaped step units each including the same number of steps are arranged concentrically about the optical axis as the center. The width win the direction perpendicular to the optical axis of the highest step or the lowest step in at least one step unit in the step structure is approximately half of the average value wof two steps at both sides of the highest step or the lowest step in the direction perpendicular to the optical axis.

Objective lens and optical pickup apparatus

Provided is an optical pickup device which can properly record and/or reproduce information on and/or from three types of discs having different recording densities and is simple in configuration and low cost. An objective lens is also provided. On the optical surface of the objective lens, an optical path difference giving structure is formed. Out of diffracted light generated when a first luminous flux enters the structure, second order diffracted light has the maximum diffraction volume. Out of diffracted light generated when a second luminous flux enters the structure, zero order diffracted light has the maximum diffraction volume. Out of diffracted light generated when a third luminous flux enters the structure, the minus first order diffracted light has the maximum diffraction volume.

An optical pickup apparatus comprises a first light source for emitting a first light flux having first wavelength &#x3bb;1 (430 nm&#x3e;&#x3bb;1&#x3e;380 nm), a second light source for emitting a second light flux having second wavelength &#x3bb;2 (&#x3bb;2&#x3e;&#x3bb;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 &#x3bb;1 and the second light wavelength &#x3bb;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.

Optical pickup apparatus with objective optical system and guiding optical system

The objective optical system of the present invention includes a first diffraction structure that applies diffraction to the light fluxes of wavelength &#x3bb;, wavelength &#x3bb;and wavelength &#x3bb;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 &#x3bb;, wavelength &#x3bb;and wavelength &#x3bb;

Objective optical system, optical pickup apparatus and optical information recording/reproducing apparatus with diffraction structure and optical path difference-generating structure

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 arranged 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&#x2260;0) order diffracted light of the light beam having the first wavelength &#x3bb;to a maximum diffraction efficiency and for setting M-th (M&#x2260;0) order diffracted light of the light beam having the second wavelength &#x3bb;to a maximum diffraction efficiency in case of an assumption of no existence of the optical path difference giving structure.

Optical element, optical objective element, and optical pickup apparatus having diffractive structure and optical difference giving structure

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.

Objective optical element and optical pickup apparatus

An objective optical element of an optical pickup apparatus has a magnification m1 satisfying the following formula for a light flux of the wavelength &#x3bb;:&#x2212;1/7&#x2266;m&#x2266;&#x2212;1/25 and |m|&#x3c;|Mwhere Mis an optical system magnification from the first light source to the first optical information recording medium for a light flux of the wavelength &#x3bb;. 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 &#x3bb;. 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.

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.

Objective optical element with multiple diffractive surfaces and optical pickup device

An optical pickup device, comprises light sources to emit a first light flux having a wavelength &#x3bb;(380 nm&#x3c;&#x3bb;&#x3c;450 nm); a second light flux having a wavelength &#x3bb;(600 nm&#x3c;&#x3bb;&#x3c;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 tand the light-converging optical system converges the second light flux on a second optical information recording medium through a protective layer having a thickness t. 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&#x2260;N) diffracted light ray generated.

Optical pickup device and optical element used for the same

An objective lens to converge a light flux having a working reference wavelength &#x3bb;(380 nm&#x2266;&#x3bb;&#x2266;450 nm) under a working reference temperature Tonto 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 &#x3b4;SAof 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 &#x3b4;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 &#x3b4;SAof the third-order spherical aberration component of wavefront aberration caused by a change of a refractive index of the lens body.

Objective lens and optical pickup device

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 tby using a light beam of a first wavelength &#x3bb;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 t(t&#x2267;t) by using a light beam of a second wavelength &#x3bb;(&#x3bb;) emitted from a second light source. The optical pickup apparatus of the invention includes a first phase modulator which gives a diffraction effect to only the light beam of the wavelength &#x3bb;on at least one optical surface, of a plurality of optical surfaces of a plurality of optical elements arranged on a common optical path through which the light beam of the first wavelength &#x3bb;and the light beam of the second wavelength &#x3bb;pass, and a second phase modulator which gives a diffraction effect to only the light beam of the wavelength &#x3bb;on at least one of the remaining optical surfaces. Each of the first phase modulator and second phase modulator has staircase-like discontinuous parts, each formed from a predetermined number of stepped portions, formed concentrically around an optical axis at the pitch defined by an optical path difference function.

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Kokubunji, Japan

Mitsuru Mimori