Optical pickup apparatus and objective lens

An optical pickup apparatus, comprising:

• a first light source to emit a light flux having a wavelength λ1;
• a second light source to emit a light flux having a wavelength λ2;
• a light converging optical system including an objective lens and for converging a light flux emitted from the first and second light sources onto a information recording surface of an optical information recording medium;
• wherein the optical pickup apparatus record and/or reproduce information for a first recording medium including a first transparent base board having a thickness ti by using the first light source and the light converging optical system;
• and the optical pickup apparatus record and/or reproduce information for a second recording medium including a second transparent base board having a thickness t2 (t1<t2) by using the second light source and the light converging optical system;
• wherein the objective lens is a plastic lens,
• wherein when the information is recorded for or reproduced from the first optical information recording medium, the objective lens converges a divergent light flux emitted from the first light source onto the first optical information recording medium and the following conditional formula is satisfied:
• |δSA3/δU|·|δU|+|δ|SA4/δT|·|δT|≦0.07 λ1rms
• where δSA3/δU represents a change of spherical aberration for object-to-image distance change δU(|δU|≦0.5 mm) and δSA4/δT represents a change of spherical aberration for temperature change δT(|δT|≦30° C.) when the information is recorded for or reproduced from the first optical information recording medium;
• and
• wherein when the information is recorded for or reproduced from the second optical information recording medium, the objective lens converges a divergent light flux emitted from the second light source onto the second optical information recording medium and the following conditional formula is satisfied:
• |δSA5/δU|·|U|+|δSA6/δT|·|δT|≦0.07 λ2rms
• where δSA5/δU represents a change of spherical aberration for object-to-image distance change 6U(|δU|≦0.5 mm) and δSA6/δT represents a change of spherical aberration for temperature change δT(|δT|≦30° C.) when the information is recorded for or reproduced from the second optical information recording medium.

An objective lens for use in an optical pickup apparatus having a light source and a light converging optical system, wherein the optical pickup apparatus can record and/or reproduce information for a first recording medium including a first transparent base board having a thickness t1 and a second recording medium including a second transparent base board having a thickness t2 (t1<t2);

• comprising:
• a diffractive structure on at least a peripheral region within an effective diameter of at least one surface;
• wherein the objective lens is a plastic lens,
• wherein the objective lens converges a divergent light flux emitted from the light source onto an information recording surface of the first or second optical information recording medium;
• and
• wherein the following conditional formula is satisfied when δSA1/δT represents a change in spherical aberration for temperature change δT in a light flux passing through the diffractive structure on the peripheral region among light fluxes emitted from the light source, and λ represents a wavelength of the light source.
• |δSA1/δT|≦0.002 λrms/° C.

An objective lens for use in an optical pickup apparatus having first and second light sources to emit a light flux having a different wavelength from each other and a light converging optical system including the objective lens, wherein the optical pickup apparatus record and/or reproduce information for a first recording medium including a first transparent base board having a thickness t1 by using the first light source and the light converging optical system;

• and the optical pickup apparatus record and/or reproduce information for a second recording medium including a second transparent base board having a thickness t2 (t1<t2) by using the second light source and the light converging optical system, comprising:
• a diffractive structure on a peripheral region within an effective diameter of at least one surface;
• wherein the objective lens is a plastic lens,
• wherein the objective lens converges a divergent light flux emitted from the first and second light sources onto an information recording surface of the first or second optical information recording medium;
• and
• wherein the following conditional formula is satisfied when δSA1/δT represents a change in spherical aberration for temperature change δT in a light flux passing through the diffractive structure on the peripheral region among light fluxes emitted from the light source, and λ1 represents a wavelength of the first light source.
• |δSA1/δT|≦0.002 λ1rms/° C.

An objective lens for use in an optical pickup apparatus having a light source and a light converging optical system including the objective lens, wherein the optical pickup apparatus can record and/or reproduce information for a first recording medium including a first transparent base board having a thickness t1 and a second recording medium including a second transparent base board having a thickness t2 (t1<t2), comprising:

• two kinds of regions toward a peripheral region from an optical axis within an effective diameter of at least one surface;
• and
• a diffractive structure on at least the peripheral region within the effective diameter;
• wherein the objective lens is a plastic lens,
• wherein the objective lens converges a divergent light flux emitted from the light source onto the first or second optical information recording medium;
• and
• wherein the following conditional formula is satisfied when δSA1/δT represents a change in spherical aberration for temperature change δT in a light flux passing through the diffractive structure on the peripheral region among light fluxes emitted from the light source, and λ represents a wavelength of the light source;
• |δSA1/δT|≦0.002 λrms/° C., and
• wherein an inner side region for the peripheral region has a function to correct a spherical aberration when recording or reproducing information for the second optical information recording medium.

An objective lens for use in an optical pickup apparatus having first and second light sources to emit a light flux having a different wavelength from each other and a light converging optical system including the objective lens, wherein the optical pickup apparatus record and/or reproduce information for a first recording medium including a first transparent base board having a thickness t1 by using the first light source and the light converging optical system;

• and the optical pickup apparatus record and/or reproduce information for a second recording medium including a second transparent base board having a thickness t2 (t1<t2) by using the second light source and the light converging optical system, comprising:
• at least two kinds of regions toward a peripheral region from an optical axis within an effective diameter of at least one surface;
• and
• a diffractive structure on at least the peripheral region within the effective diameter;
• wherein the objective lens is a plastic lens,
• wherein the objective lens converges a divergent light flux emitted from each light source onto an information recording surface of the first or second optical information recording medium;
• and
• wherein the following conditional formula is satisfied when δSA1/δT represents a change in spherical aberration for temperature change δT in a light flux passing through the diffractive structure on the peripheral region among light fluxes emitted from the first light source, and λ1 represents a wavelength of the first light source;
• |δSA1/δT≦0.002 λ1rms/° C., and
• wherein an inner side region for the peripheral region has a function to correct a spherical aberration when recording or reproducing information for the second optical information recording medium.

An objective lens for use in an optical pickup apparatus having a light source and a light converging optical system, wherein the optical pickup apparatus can record and/or reproduce information for a recording medium including a transparent base board having a thickness t1;

• comprising:
• a diffractive structure on at least a peripheral region within an effective diameter of at least one surface;
• wherein the objective lens is a plastic lens,
• wherein the objective lens converges a divergent light flux emitted from the light source onto an information recording surface of the optical information recording medium;
• and
• wherein the following conditional formula is satisfied when δSA1/δT represents a change in spherical aberration for temperature change δT in a light flux passing through the diffractive structure on the peripheral region among light fluxes emitted from the light source, and λ represents a wavelength of the light source.
• |δSA1/δT|≦0.002 λrms/° C.

An objective lens for conducting recording and/or reproducing of information for an optical information recording medium by converging light emitted from a light source on an information recording surface of the optical information recording medium through a transparent base board, comprising:

• at least two or more kinds of optical surface regions provided in an effective diameter on at least one side surface;
• a diffractive section formed on an outermost optical surface on the one side surface or on an outermost optical surface on the other side surface at which a light flux having passed through the outermost optical surface on the one side surface further passes, wherein ring-shaped diffractive zones to utilize nth order light ray are formed on the diffractive section;
• wherein average pitch Pout of the ring-shaped diffractive zones satisfies the following conditional formula when a focal length of the objective lens is represented by f.
• 2.00×10−4≦Pout/(|n|·f)≦3.50×10−3

An objective lens for use in an optical pickup apparatus having a light source and a light converging optical system including the objective lens, wherein the optical pickup apparatus record and/or reproduce information for a first recording medium including a first transparent base board having a thickness t1 and a second recording medium including a second transparent base board having a thickness t2 (t1<t2) by using the light source and the light converging optical system, comprising:

• at least two kinds of optical surface regions comprising, in a direction perpendicular to the optical axis in the order from an optical axis, an optical surface region including the optical axis and an outermost optical surface region within an effective diameter of at least one surface;
• and
• a diffractive section formed on the outermost optical surface on the one side surface or on an outermost optical surface on the other side surface at which a light flux having passed through the outermost optical surface on the one side surface further passes, wherein ring-shaped diffractive zones to utilize nth order light ray are formed on the diffractive section;
• wherein average pitch Pout of the ring-shaped diffractive zones satisfies the following conditional formula when a focal length of the objective lens is represented by f.
• 2.00×10−4≦Pout/(|n|·f)≦3.50×10−3

An optical pickup apparatus, comprising:

• a light source;
• and
• a light converging optical system including the objective lens,
• wherein the optical pickup apparatus records and/or reproduces information for a first recording medium including a first transparent base board having a thickness t1 and a second recording medium including a second transparent base board having a thickness t2 (t1<t2) by using the light source and the light converging optical system;
• the objective comprising
• at least two kinds of optical surface regions comprising, in a direction perpendicular to the optical axis in the order from an optical axis, an optical surface region including the optical axis and an outermost optical surface region within an effective diameter of at least one surface;
• and
• a diffractive section formed on the outermost optical surface on the one side surface or on an outermost optical surface on the other side surface at which a light flux having passed through the outermost optical surface on the one side surface further passes, wherein ring-shaped diffractive zones to utilize nth order light ray are formed on the diffractive section;
• wherein average pitch Pout of the ring-shaped diffractive zones satisfies the following conditional formula when a focal length of the objective lens is represented by f.
• 2.00×10−≦Pout/(|n|·f)≦3.50×10−3

An objective lens for use in an optical pickup apparatus having a light source and a light converging optical system including the objective lens, wherein the optical pickup apparatus record and/or reproduce information for a first recording medium including a first transparent base board having a thickness ti and a second recording medium including a second transparent base board having a thickness t2 (t1<t2) by using the light source and the light converging optical system, comprising:

• at least two kinds of optical surface regions comprising in a direction perpendicular to the optical axis in the order from an optical axis within an effective diameter of at least one surface, wherein the light source emits a divergent light flux and the emitted divergent light flux enters to be incident on the objective lens;
• and
• a ring-shaped diffractive zone formed on an outermost optical surface on the one side surface or on an outermost optical surface on the other side surface at which a light flux having passed through the outermost optical surface on the one side surface further passes so that a temperature characteristic of the light flux having passed through the outermost optical surface is corrected;
• wherein the objective lens comprises an optical surface region at an inside of the outermost optical surface region and the optical surface is applied with a spherical aberration design proper for recording or reproducing information for the second optical information recording medium.

An objective lens for use in an optical pickup apparatus having a first light source to emit a light flux having a wavelength λ1, a second light source to emit a light flux having a wavelength λ2 (λ1<λ2), and a light converging optical system including the objective lens, the optical pickup apparatus record and/or reproduce information for a first recording medium including a first transparent base board having a thickness t1 by using the first light source and the light converging optical system;

• and the optical pickup apparatus record and/or reproduce information for a second recording medium including a second transparent base board having a thickness t2 by using the second light source and the light converging optical system;
• the objective lens comprising:
• at least two kinds of optical surface regions comprising in a direction perpendicular to the optical axis in the order from an optical axis within an effective diameter of at least one surface;
• and
• a ring-shaped diffractive zone formed on an outermost optical surface on the one side surface or on an outermost optical surface on the other side surface at which a light flux having passed through the outermost optical surface on the one side surface further passes so that a temperature characteristic of the light flux having passed through the outermost optical surface is corrected when recording or reproducing information for the first optical information recording medium;
• wherein the objective lens comprises an optical surface region at an inside of the outermost optical surface region and the optical surface is applied with a spherical aberration design proper for recording or reproducing information for the second optical information recording medium.

An optical pickup apparatus, comprising:

• a light source;
• and
• a light converging optical system including the objective lens, wherein the optical pickup apparatus record and/or reproduce information for a first recording medium including a first transparent base board having a thickness t1 and a second recording medium including a second transparent base board having a thickness t2 (t1<t2) by using the light source and the light converging optical system,
• the objective lens comprising
• at least two kinds of optical surface regions comprising in a direction perpendicular to the optical axis in the order from an optical axis within an effective diameter of at least one surface, wherein the light source emits a divergent light flux and the emitted divergent light flux enters to be incident on the objective lens;
• and
• a ring-shaped diffractive zone formed on an outermost optical surface on the one side surface or on an outermost optical surface on the other side surface at which a light flux having passed through the outermost optical surface on the one side surface further passes so that a temperature characteristic of the light flux having passed through the outermost optical surface is corrected;
• wherein the objective lens comprises an optical surface region at an inside of the outermost optical surface region and the optical surface is applied with a spherical aberration design proper for recording or reproducing information for the second optical information recording medium.

An optical pickup apparatus, comprising:

• a first light source to emit a light flux having a wavelength λ1;
• a second light source to emit a light flux having a wavelength λ2 (λ1<λ2);
• and
• a second light source to emit a light flux having a wavelength λ2 (λ1<λ2);
• and
• a light converging optical system including the objective lens,
• wherein the optical pickup apparatus records and/or reproduces information for a first recording medium including a first transparent base board having a thickness t1 and a second recording medium including a second transparent base board having a thickness t2 (t1<t2) by using the first and second light sources and the light converging optical system;
• the objective lens comprising:
• at least two kinds of optical surface regions comprising in a direction perpendicular to the optical axis in the order from an optical axis within an effective diameter of at least one surface;
• and
• a ring-shaped diffractive zone formed on an outermost optical surface on the one side surface or on an outermost optical surface on the other side surface at which a light flux having passed through the outermost optical surface on the one side surface further passes so that a temperature characteristic of the light flux having passed through the outermost optical surface is corrected when recording or reproducing information for the first optical information recording medium;
• wherein the objective lens comprises an optical surface region at an inside of the outermost optical surface region and the optical surface is applied with a spherical aberration design proper for recording or reproducing information for the second optical information recording medium.

An objective lens for an optical pickup device having a first light source to emit a light flux having a wavelength λ1, a second light source to emit a light flux having a wavelength λ2 (λ1<λ2) and a light converging optical system, wherein the optical pickup apparatus conducts recording or reproducing information for a first optical information recording medium including transparent base board having a thickness t1 by using the first light source and the light converging optical system, and the optical pickup apparatus conducts recording or reproducing information for a second optical information recording medium including a transparent base board having a thickness t2 (t1<t2), comprising:

• at least two kinds of optically functional surfaces which regionrranged in a direction perpendicular to an optical axis and have a different optical action from others;
• wherein at least an outermost optically functional surface among the optically functional surfaces is used only when recording or reproducing information for the first optical information recording medium,
• wherein the objective lens is made of a uniform optical material, and
• wherein a value of refractive index change dn/dT for a temperature change of the optical material satisfies the following conditional formula under the conditions of the wavelength of the light source and a room temperature environment.
• |dn/dT|≦100×10−6(/° C.)

An optical pickup device, comprising:

• a first light source to emit a light flux having a wavelength λ1;
• a second light source to emit a light flux having a wavelength λ2 (λ1<λ2);
• and
• a light converging optical system;
• wherein the optical pickup apparatus conducts recording or reproducing information for a first optical information recording medium including transparent base board having a thickness t1 by using the first light source and the light converging optical system, and the optical pickup apparatus conducts recording or reproducing information for a second optical information recording medium including a transparent base board having a thickness t2 (t1<t2) by using the second light source and the light converging optical system,
• wherein the object lens comprises at least two kinds of optically functional surfaces which regionrranged in a direction perpendicular to an optical axis and have a different optical action from others;
• wherein at least an outermost optically functional surface among the optically functional surfaces is used only when recording or reproducing information for the first optical information recording medium,
• wherein the objective lens is made of a uniform optical material, and
• wherein a value of refractive index change dn/dT for a temperature change of the optical material satisfies the following conditional formula under the conditions of the wavelength of the light source and a room temperature environment.
• |dn/dT|≦10.0×10−6(/° C.)

An objective lens for use in an optical pickup device having a first light source to emit a light flux having a wavelength λ1;

• a second light source to emit a light flux having a wavelength λ2 (λ1λ2);
• and a light converging optical system;
• wherein the optical pickup apparatus conducts recording or reproducing information for a first optical information recording medium including transparent base board having a thickness t1 by using the first light source and the light converging optical system, and the optical pickup apparatus conducts recording or reproducing information for a second optical information recording medium including a transparent base board having a thickness t2 (t1<t2) by using the second light source and the light converging optical system, the object lens comprising:
• at least two kinds of optically functional surfaces which regionrranged in a direction perpendicular to an optical axis and have a different optical action from others;
• wherein at least an outermost optically functional surface among the optically functional surfaces is used only when recording or reproducing information for the first optical information recording medium,
• wherein the objective lens is a pasted lens in which at least two kinds of optical elements each made of a different optical material from other, and
• wherein a value of refractive index change dn/dT for a temperature change of an optical material used for an optical element having a power component stronger than that of other satisfies the following conditional formula under the conditions of the wavelength of the light source and a room temperature environment.
• |dn/dT|≦10.0×10−6(/° C.)

An optical pickup device, comprising:

• a first light source to emit a light flux having a wavelength λ1;
• a second light source to emit a light flux having a wavelength λ2 (λ1<λ1);
• and
• a light converging optical system;
• wherein the optical pickup apparatus conducts recording or reproducing information for a first optical information recording medium including transparent base board having a thickness t1 by using the first light source and the light converging optical system, and the optical pickup apparatus conducts recording or reproducing information for a second optical information recording medium including a transparent base board having a thickness t2 (t1<t2) by using the second light source and the light converging optical system,
• wherein the object lens comprises at least two kinds of optically functional surfaces which regionrranged in a direction perpendicular to an optical axis and have a different optical action from others;
• wherein at least an outermost optically functional surface among the optically functional surfaces is used only when recording or reproducing information for the first optical information recording medium,
• wherein the objective lens is a pasted lens in which at least two kinds of optical elements each made of a different optical material from other, and
• wherein a value of refractive index change dn/dT for a temperature change of an optical material used for an optical element having a power component stronger than that of other satisfies the following conditional formula under the conditions of the wavelength of the light source and a room temperature environment.
• |dn/dT|≦10.0×10−6(/° C.)

An optical pickup device, comprising:

• a first light source to emit a light flux having a wavelength λ1;
• a second light source to emit a light flux having a wavelength λ2 (λ1<λ2);
• and
• a light converging optical system;
• wherein the optical pickup apparatus conducts recording or reproducing information for a first optical information recording medium including transparent base board having a thickness t1 by using the first light source and the light converging optical system, and the optical pickup apparatus conducts recording or reproducing information for a second optical information recording medium including a transparent base board having a thickness t2 (t1<t2) by using the second light source and the light converging optical system,
• wherein the objective lens is a pasted lens in which at least two kinds of optical elements each made of a different optical material from other or is made of a uniform optical material, and
• wherein a value of refractive index change dn/dT for a temperature change of an optical material used for an optical element having a strongest power component in the objective lens satisfies the following conditional formula under the conditions of the wavelength of the light source and a room temperature environment,
• |dn/dT|≦10.0×10−6(/° C.)
• wherein the object lens comprises a limiting member at a peripheral section for an optical axis in order to reduce a transmittance for a light ray or in order to intercept the light ray when recording or reproducing information for the second optical information recording medium, and
• wherein the objective lens has a function to correct a spherical aberration for a light ray transmitting a portion near to an optical axis when recording or reproducing information for the first optical information recording medium or the second optical information recording medium.