Patent ID: 7283434

Claim:
An optical pickup device allowing a laser beam of light emitted from a source of a laser beam of light to be reflected by a mirror to provide a reflection of light in turn focused by an objective lens on an optical storage medium, comprising: a circular mirror reflecting said laser beam of light; and a mirror actuator including a piezoelectric element having a thickness in a direction perpendicular to a surface of said mirror, and a circular surface bonded to a circular rear surface of said mirror such that a center of said circular surface of said piezoelectric element and that of said circular rear surface of said mirror match, said piezoelectric element receiving a potential to cause said circular surface bonded to said mirror to expand/contract radially around 360 degrees by a uniform ratio to allow said mirror to have a surface modified in geometry, said piezoelectric element being adjusted in thickness so that as said piezoelectric element expands/contracts, said piezoelectric element allows said mirror to have a surface with a ratio of a radius of curvature in a radial direction of said mirror to that of curvature in a tangential direction of said mirror of (cos(2θ)+1)/2, where θ represents an angle of incidence on said surface of said mirror.