| 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 focal distance is changed. <P>SOLUTION: An optical pickup 1 comprises a light source 2 for emitting the laser beam; a group of at least one collimate lens 3 for parallelizing the laser beam emitted from the light source 2; a group of at least one objective lens 5 for condensing the laser beam parallelized by the group of collimate lenses 3 that enter via an aperture onto the signal recording surface of an optical disk 11; and a refractive power variable element 6 that is provided at the same position as or close to the aperture provided directly before the group of objective lenses 5 between the group for collimate lenses 3 and the group of objective lenses 5, and changes the focal distance of the group of objective lenses 5 by varying refractive power. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
