OPTICAL SCANNING DEVICE

摘要

The invention relates to an optical scanning device (1) for scanning an information layer (2) by means of a radiation beam (4). The device includes: a radiation source (6) for providing said radiation beam, a lens system (7) for transforming said radiation beam to a converging beam (16), and a wavefront modifier including a first element (301) and a second element (302) having each an aspheric surface and being mutually movable in a plane perpendicular to an optical axis (12) of said lens system for introducing a wavefront modification (W>1<) in said converging beam. According to the invention, the aspheric surfaces of said first and second elements are shaped so that a mutual rotational displacement of the elements about an axis of rotation (Z>A<) which is parallel to said optical axis (12) generates said wavefront modification (W>1<).