| 摘要 |
An optical scanning device ( 1 ) is for scanning an information layer ( 2 ) by means of a radiation beam ( 4 ). The device includes a radiation source ( 7 ) for supplying said radiation beam, an objective lens ( 10 ) for transforming said radiation beam into a scanning spot ( 19 ) at the position of the information layer, and a beam intensity modifier ( 8 ) for redistributing the intensity (I<SUB>2</SUB>) over the cross-section of said radiation beam in order to change the size of said scanning spot. The beam intensity modifier has an entrance pupil ( 8 a) and an exit pupil ( 8 b). Furthermore, it is arranged so that any ray of said radiation beam entering said beam intensity modifier at a distance r<SUB>1 </SUB>from the central ray of that beam reflects at least twice between said entrance and exit pupils that the transverse magnification M of said modifier is defined by a decreasing function of the distance r<SUB>1</SUB>.
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