Optical scanning device

An optical head for use in the scanning of a record carrier, the record carrier having data stored on data tracks therein on a plurality of information layers ( 3, 4 ) at a plurality of depths within the record carrier. The optical head comprises: a movable optical element ( 16 ) arranged in an optical path to act upon a first radiation beam ( 12 ) and a second radiation beam ( 14 ) to provide the beams with a different displacement perpendicular to the optical path; and a lens system for focusing said first beam ( 12 ) at a first focal point (A) on a first information layer ( 3 ) of the record carrier and the focusing of the second beam ( 14 ) at a second different focal point (B) on a second information layer ( 4 ), wherein a spacing, transverse to the data tracks, between said first and second focal points (A, B) is controllable by varying the configuration of the movable optical element.