Optical pickup apparatus and objective lens

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|≦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 ti 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.