Optical scanning unit, optical write and/or read apparatus comprising said unit and a method of manufacturing the scanning unit and the write and/or read apparatus

摘要

The invention relates to an optical scanning unit for scanning an information track in an optically readable record carrier (13). The scanning unit comprises a frame (1) and an optical system for focusing a radiation beam produced by a radiation source (3) so as to form a scanning spot (V) on the record carrier and to image the scanning spot on a radiation-sensitive detection system (15). The optical system comprises a holder (7) which is movable relative to the frame and which has a central longitudinal axis (7a) and an objective lens (9), which is secured to a supporting surface (31) of the holder and which has an optical axis which extends at least substantially parallel to the beam axis (10) of the radiation beam. The supporting surface of the holder which faces the objective lens is spherically curved, the centre of curvature (Z) being situated at that side of the supporting surface which is remote from the objective lens and being situated at least substantially on said longitudinal axis of the holder.