| 摘要 |
<p>The invention relates to an optical scanning device for scanning an optically readable record carrier (1). The scanning device includes a radiation source (5), a radiation-sensitive detection system (7), and an optical scanning unit for focusing a scanning beam (3) produced by the radiation source to a scanning spot (9) on the record carrier. The scanning unit inlcuding a lens system having an optical axis (13), which lens system comprises a first lens unit having a main lens (15) and a second lens unit having an auxiliary lens (17). The scanning device further includes a first detection means involved in detection of the main lens with respect to the record carrier, and a second detection means involved in detection of the auxiliary lens. The scanning unit further includes a first electrical drive unit for moving the first lens unit in dependence upon a signal supplied by the first detection means, and a second electrical drive unit for moving the second lens unit with respect to the main lens in dependence upon a signal supplied by the second detection means. The second drive unit comprises a first part and a second part which cooperates with the first part via an air gap (51). The first part is secured to the first lens unit and the second part is secured to the second lens unit. In order to counteract spherical aberration and/or coma and/or astigmatism during scanning the second detection means includes a position and orientation detector system for detecting the position and orientation of the auxiliary lens with respect to the record carrier during scanning.</p> |
