Patent ID: 7161891

Claim:
An optical head for use in scanning 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, wherein 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 controlled by varying the configuration of the movable optical element ( 16 ) during scanning by said optical head of different information layers ( 3 , 4 ) of the record carrier simultaneously using the first and second beams ( 12 , 14 ).