Optical scanning device

An optical scanning device for scanning a track of an information layer of an optical record carrier using a radiation beam, the track being substantially circular with a center of curvature, the optical scanning device comprising;

• a radiation source for providing said radiation beam;
• a lens system for transforming said radiation beam to a scanning spot on said information layer, the lens system including a first objective lens assembly having an optical axis;
• a head rotation unit for supporting said first objective lens assembly, the head rotation unit being rotatable about an axis of rotation, and said center of curvature of said track being substantially coinciding with said axis of rotation;
• and
• a first driving means for rotating said head rotation unit about said axis of rotation,
• characterized in that said first objective lens assembly is movable substantially in a radial direction with respect to and perpendicular to said axis of rotation,
• wherein said head rotation unit further comprises a first positioning means for controlling a position of said first objective lens assembly substantially in said radial direction with respect to said axis of rotation, and
• wherein said first positioning means further includes a second counterbalancing means for reducing the dependence of the centrifugal forces of said head rotation unit on its rotation frequency.

An optical scanning system for scanning an optical record carrier, the optical scanning system including an optical record carrier having an information layer provided with a substantially circular track, and an optical scanning device for scanning a track of an information layer of an optical record carrier using a radiation beam, the track being substantially circular with a center of curvature, the optical scanning device comprising:

• a radiation source for providing said radiation beam;
• a lens system for transforming said radiation beam to a scanning spot on said information layer, the lens system including a first objective lens assembly having an optical axis;
• a head rotation unit for supporting said first objective lens assembly, the head rotation unit being rotatable about an axis of rotation, and said center of curvature of said track being substantially coinciding with said axis of rotation;
• and
• a first driving means for rotating said head rotation unit about said axis of rotation,
• characterized in that said first objective lens assembly is movable substantially in a radial direction with respect to and perpendicular to said axis of rotation, wherein said optical record carrier includes a non-round substrate.