Patent ID: 8125875

Claim:
An optical pickup capable of correcting spherical aberration, comprising: an objective lens for condensing a light beam emitted from a light source onto a recording surface of an information recording medium; a plurality of aberration correction lenses for correcting spherical aberration of the light beam condensed onto the recording surface by the objective lens; a movable portion for supporting at least one of the aberration correction lenses; a fixed portion for supporting the aberration correction lens other than the one supported by the movable portion, the movable portion being disposed in the fixed portion in a slidable manner; a shaft disposed in parallel with the optical axis of the aberration correction lens in the fixed portion for supporting the movable portion in a rotatable manner about the axis and in a slidable manner in the direction of the axis of the shaft; a feed screw having a helical groove, disposed in parallel with the optical axis of the plurality of aberration correction lenses; an engaging portion disposed in the movable portion, having an engaging groove like a male thread engaging with the helical groove of the feed screw; and a coil spring engaging with the outer surface of the shaft, for pressing the movable portion in the direction of the axis of the shaft, wherein each end portion of the feed screw is provided with a cylindrical portion having an outer diameter smaller than an inner diameter of the feed screw, and a resetting elastic portion supported by the fixed portion or the movable portion is provided for pressing the movable portion in the direction opposite to the pressing direction of the coil spring.