Patent ID: 7489448

Claim:
An optical scanning device for scanning an information layer ( 101 ) by means of a radiation beam ( 3 , 5 , 30 , 30 ′), the device comprising a radiation source ( 2 , 200 ) for emitting said radiation beam, an objective ( 7 , 90 ) for converting said radiation beam to a scanning spot at the position of said information layer, and mounting means ( 9 ) to adjust the distance between the radiation source and the objective, characterized in that an optical component ( 6 ) is provided by means of which the rim intensity of the radiation beam ( 5 , 30 ′) at the entrance pupil of the objective ( 7 , 90 ) is substantially independent of the distance between the radiation source ( 2 , 200 ) and the objective for constant marginal beam angle of said radiation beam at the entrance pupil of the objective.