Objective lens for optical pick-up apparatus and optical pick-up apparatus

An optical pickup apparatus, comprising:

• a first light source to emit a light flux having a wavelength λ1 for conducting recording or reproducing information by irradiating the light flux onto a first optical information recording medium with a transparent substrate having a thickness t1;
• a second light source to emit a light flux having a wavelength λ2 (λ1<λ2) for conducting recording or reproducing information by irradiating the light flux onto a second optical information recording medium with a transparent substrate having a thickness t2 (t1<t2);
• and
• a light converging optical system including an objective lens to converge each of the light fluxes from the first and second light sources onto a respective information recording plane through each of the transparent substrates of the first and second optical information recording mediums,
• wherein the first and second light sources are provided on a same flat surface, and
• the objective lens has a coma aberration of 0.015 λ1 rms or less when recording or reproducing information is conducted for the first optical information recording medium, and a coma aberration of 0.015 λ2 rms or less when recording or reproducing information is conducted for the second optical information recording medium.

An objective lens for use in an optical pickup apparatus which has a first light source to emit a light flux having a wavelength λ1 for conducting recording or reproducing information by irradiating the light flux onto a first optical information recording medium with a transparent substrate having a thickness t1, a second light source to emit a light flux having a wavelength λ2 (λ1<λ2) for conducting recording or reproducing information by irradiating the light flux onto a second optical information recording medium with a transparent substrate having a thickness t2 (t1<t2), and a light converging optical system including an objective lens to converge each of the light fluxes from the first and second light sources onto a respective information recording plane through each of the transparent substrates of the first and second optical information recording mediums, the objective lens comprising:

• an optical surface including a central optical functional region including an optical axis and an outside optical functional region distant from the optical axis, wherein a light flux having passed through the central optical functional region is used for conducting recording or reproducing information for both of the first and second optical information recording mediums and a light flux having passed through the outside optical functional region is used for conducting recording or reproducing information for only the first optical information recording medium;
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount in the central optical functional region is a positive value, and when recording or reproducing information is conducted for the second optical information recording medium with a light flux from the second light source, the sine condition offense amount in the central optical functional region is a negative value, and
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount at a portion of the outside optical functional region positioned closest to the central optical functional region is smaller than that at a portion of the central optical functional region positioned closest to the outside optical functional region.

An optical pickup apparatus, comprising:

• a first light source to emit a light flux having a wavelength λ1 for conducting recording or reproducing information by irradiating the light flux onto a first optical information recording medium with a transparent substrate having a thickness t1;
• a second light source to emit a light flux having a wavelength λ2 (λ1<λ2) for conducting recording or reproducing information by irradiating the light flux onto a second optical information recording medium with a transparent substrate having a thickness t2 (t1<t2);
• and
• a light converging optical system including an objective lens to converge each of the light fluxes from the first and second light sources onto a respective information recording plane through each of the transparent substrates of the first and second optical information recording mediums,
• wherein the objective lens comprises an optical surface including a central optical functional region including an optical axis and an outside optical functional region distant from the optical axis, and a light flux having passed through the central optical functional region is used for conducting recording or reproducing information for both of the first and second optical information recording mediums and a light flux having passed through the outside optical functional region is used for conducting recording or reproducing information for only the first optical information recording medium;
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount in the central optical functional region is a positive value, and when recording or reproducing information is conducted for the second optical information recording medium with a light flux from the second light source, the sine condition offense amount in the central optical functional region is a negative value, and
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount at a portion of the outside optical functional region positioned closest to the central optical functional region is smaller than that at a portion of the central optical functional region positioned closest to the outside optical functional region.

An objective lens for use in an optical pickup apparatus which has a first light source to emit a light flux having a wavelength λ1 for conducting recording or reproducing information by irradiating the light flux onto a first optical information recording medium with a transparent substrate having a thickness t1, a second light source to emit a light flux having a wavelength λ2 (λ1<λ2) for conducting recording or reproducing information by irradiating the light flux onto a second optical information recording medium with a transparent substrate having a thickness t2 (t1<t2), and a light converging optical system including an objective lens to converge each of the light fluxes from the first and second light sources onto a respective information recording plane through each of the transparent substrates of the first and second optical information recording mediums, wherein the first and second light sources are provided on a same flat surface, the first light source is located substantially on an optical axis and the second light source is located distant by a predetermined distance from the optical axis, the objective lens comprising:

• an optical surface including a central optical functional region including an optical axis and an outside optical functional region distant from the optical axis, wherein a light flux having passed through the central optical functional region is used for conducting recording or reproducing information for both of the first and second optical information recording mediums and a light flux having passed through the outside optical functional region is used for conducting recording or reproducing information for only the first optical information recording medium;
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount in the central optical functional region is a positive value, and when recording or reproducing information is conducted for the second optical information recording medium with a light flux from the second light source, the sine condition offense amount in the central optical functional region is a negative value,
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount at a portion of the outside optical functional region positioned closest to the central optical functional region is smaller than that at a portion of the central optical functional region positioned closest to the outside optical functional region, and
• wherein the objective lens has a coma aberration of 0.015 λ1 rms or less when recording or reproducing information is conducted for the first optical information recording medium, and a coma aberration of 0.015 λ2 rms or less when recording or reproducing information is conducted 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 for conducting recording or reproducing information by irradiating the light flux onto a first optical information recording medium with a transparent substrate having a thickness t1;
• a second light source to emit a light flux having a wavelength λ2 (λ1<λ2) for conducting recording or reproducing information by irradiating the light flux onto a second optical information recording medium with a transparent substrate having a thickness t2 (t1<t2);
• and
• a light converging optical system including an objective lens to converge each of the light fluxes from the first and second light sources onto a respective information recording plane through each of the transparent substrates of the first and second optical information recording mediums,
• wherein the first and second light sources are provided on a same flat surface, the first light source is located substantially on an optical axis and the second light source is located distant by a predetermined distance from the optical axis,
• wherein the objective lens comprises an optical surface including a central optical functional region including an optical axis and an outside optical functional region distant from the optical axis, and a light flux having passed through the central optical functional region is used for conducting recording or reproducing information for both of the first and second optical information recording mediums and a light flux having passed through the outside optical functional region is used for conducting recording or reproducing information for only the first optical information recording medium;
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount in the central optical functional region is a positive value, and when recording or reproducing information is conducted for the second optical information recording medium with a light flux from the second light source, the sine condition offense amount in the central optical functional region is a negative value,
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount at a portion of the outside optical functional region positioned closest to the central optical functional region is smaller than that at a portion of the central optical functional region positioned closest to the outside optical functional region, and
• wherein the objective lens has a coma aberration of 0.015 λ1 rms or less when recording or reproducing information is conducted for the first optical information recording medium, and a coma aberration of 0.015 λ2 rms or less when recording or reproducing information is conducted for the second optical information recording medium.

An objective lens for use in an optical pickup apparatus which has a first light source to emit a light flux having a wavelength λ1 for conducting recording or reproducing information by irradiating the light flux onto a first optical information recording medium with a transparent substrate having a thickness t1, a second light source to emit a light flux having a wavelength λ2 (λ1<λ2) for conducting recording or reproducing information by irradiating the light flux onto a second optical information recording medium with a transparent substrate having a thickness t2 (t1<t2), and a light converging optical system including an objective lens to converge each of the light fluxes from the first and second light sources onto a respective information recording plane through the transparent substrate of the first and second optical information recording mediums, wherein the objective lens converges a light flux from the first and second light sources onto the first and second optical information recording mediums, and the optical pickup apparatus further comprises an inclination providing optical element dividing at least one of a light flux from the first light source and a light flux from the second light source among light fluxes incident in the objective lens into a central light flux converging along the optical axis onto a corresponding optical information recording medium and a peripheral light flux converging with an inclination toward to the outside of the optical axis onto the corresponding optical information recording medium, a central light receiving member to receive the central light flux and a peripheral light receiving member to receive the peripheral light flux, the objective lens comprising:

• an optical surface including a central optical functional region including an optical axis and an outside optical functional region distant from the optical axis, wherein a light flux having passed through the central optical functional region is used for conducting recording or reproducing information for both of the first and second optical information recording mediums and a light flux having passed through the outside optical functional region is used for conducting recording or reproducing information for only the first optical information recording medium;
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount in the central optical functional region is a positive value, and when recording or reproducing information is conducted for the second optical information recording medium with a light flux from the second light source, the sine condition offense amount in the central optical functional region is a negative value, and
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount at a portion of the outside optical functional region positioned closest to the central optical functional region is smaller than that at a portion of the central optical functional region positioned closest to the outside optical functional region.

An optical pickup apparatus, comprising:

• a first light source to emit a light flux having a wavelength λ1 for conducting recording or reproducing information by irradiating the light flux onto a first optical information recording medium with a transparent substrate having a thickness t1;
• a second light source to emit a light flux having a wavelength λ2 (λ1<λ2) for conducting recording or reproducing information by irradiating the light flux onto a second optical information recording medium with a transparent substrate having a thickness t2 (t1<t2);
• and
• a light converging optical system including an objective lens to converge each of the light fluxes from the first and second light sources onto a respective information recording plane through each of the transparent substrates of the first and second optical information recording mediums,
• wherein the objective lens converges a light flux from the first and second light sources onto the first and second optical information recording mediums,
• wherein the optical pickup apparatus further comprises an inclination providing optical element dividing at least one of a light flux from the first light source and a light flux from the second light source among light fluxes incident in the objective lens into a central light flux converging along the optical axis onto a corresponding optical information recording medium and a peripheral light flux converging with an inclination toward to the outside of the optical axis onto the corresponding optical information recording medium, a central light receiving member to receive the central light flux and a peripheral light receiving member to receive the peripheral light flux,
• wherein the objective lens comprises an optical surface including a central optical functional region including an optical axis and an outside optical functional region distant from the optical axis, and a light flux having passed through the central optical functional region is used for conducting recording or reproducing information for both of the first and second optical information recording mediums and a light flux having passed through the outside optical functional region is used for conducting recording or reproducing information for only the first optical information recording medium;
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount in the central optical functional region is a positive value, and when recording or reproducing information is conducted for the second optical information recording medium with a light flux from the second light source, the sine condition offense amount in the central optical functional region is a negative value, and
• wherein when recording or reproducing information is conducted for the first optical information recording medium with a light flux from the first light source, the sine condition offense amount at a portion of the outside optical functional region positioned closest to the central optical functional region is smaller than that at a portion of the central optical functional region positioned closest to the outside optical functional region.

An objective lens for use in an optical pickup apparatus which has a first light source to emit a light flux having a wavelength λ1 for conducting recording or reproducing information by irradiating the light flux onto a first optical information recording medium with a transparent substrate having a thickness t1, a second light source to emit a light flux having a wavelength λ2 (λ1<λ2) for conducting recording or reproducing information by irradiating the light flux onto a second optical information recording medium with a transparent substrate having a thickness t2 (t1<t2), and a light converging optical system including an objective lens to converge each of the light fluxes from the first and second light sources onto a respective information recording plane through each of the transparent substrates of the first and second optical information recording mediums, the objective lens comprising:

• a light source side optical surface including a central optical functional region including an optical axis and an outside optical functional region distant from the optical axis, wherein diffractive structures are formed on the central and outside optical functional regions and a light flux having passed through the central optical functional region is used for conducting recording or reproducing information for both of the first and second optical information recording mediums and a light flux having passed through the outside optical functional region is used for conducting recording or reproducing information for only the first optical information recording medium, and
• an optical information recording medium side optical surface including a central optical functional region including an optical axis and an outside optical functional region distant from the optical axis, wherein a refractive surface is formed on the central optical functional region and another refractive surface different in aspherical coefficient from that of the refractive surface is formed on the outside optical functional surface, and a light flux having passed through the central optical functional region is used for conducting recording or reproducing information for both of the first and second optical information recording medium and a light flux having passed through the outside optical functional region is used for conducting recording or reproducing information for only the first optical information recording medium.

An optical pickup apparatus, comprising:

• a first light source to emit a light flux having a wavelength λ1 for conducting recording or reproducing information by irradiating the light flux onto a first optical information recording medium with a transparent substrate having a thickness t1;
• a second light source to emit a light flux having a wavelength λ2 (λ1<λ2) for conducting recording or reproducing information by irradiating the light flux onto a second optical information recording medium with a transparent substrate having a thickness t2 (t1<t2);
• and
• a light converging optical system including an objective lens to converge each of the light fluxes from the first and second light sources onto a respective information recording plane through each of the transparent substrates of the first and second optical information recording mediums,
• wherein the objective lens comprises:
• a light source side optical surface including a central optical functional region including an optical axis and an outside optical functional region distant from the optical axis, wherein diffractive structures are formed on the central and outside optical functional regions and a light flux having passed through the central optical functional region is used for conducting recording or reproducing information for both of the first and second optical information recording mediums and a light flux having passed through the outside optical functional region is used for conducting recording or reproducing information for only the first optical information recording medium, and
• an optical information recording medium side optical surface including a central optical functional region including an optical axis and an outside optical functional region distant from the optical axis, wherein a refractive surface is formed on the central optical functional region and another refractive surface different in aspherical coefficient from that of the refractive surface is formed on the outside optical functional surface, and a light flux having passed through the central optical functional region is used for conducting recording or reproducing information for both of the first and second optical information recording mediums and a light flux having passed through the outside optical functional region is used for conducting recording or reproducing information for only the first optical information recording medium.