| 摘要 |
<P>PROBLEM TO BE SOLVED: To minimize a change in the quantity of light in an optical axis of a laser beam on the surface of an objective lens and around the optical axis even if spherical aberration is corrected. <P>SOLUTION: An optical pickup 1 comprises a light source 2; a group of collimate lenses 3 for parallelizing the laser beam emitted from the light source 2; a group of objective lenses 5 for condensing the laser beam entering via an aperture onto the signal recording surface of an optical disk 11; and a refractive power variable element 6 that is provided between the light source 2 and the group for collimate lenses 3 and corrects the spherical aberration. When the interval between the refractive power variable element and the main plane of the group of collimate lenses, the interval between the main plane of the group of collimate lenses and the aperture of the group of objective lenses, and the refractive power of the group of collimate lenses are set to d<SB>1</SB>', d<SB>2</SB>', and ϕ<SB>2</SB>, respectively, the conditions of a numerical expression 1 are satisfied. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
