Patent ID: 6671237
Filing Date: 2003-12-30
Classification: G11B

Abstract:
In an optical storage system, an apparatus for focusing a light beam onto a recording medium, the apparatus comprising:a modulator for modulating the light beam to produce a modulated light beam, the modulator modulated responsive to an electric field, the electric field varied between a half-wave retardation level and a predetermined minimal retardation level, the predetermined minimal retardation level approximately one-half of the half-wave retardation level; an objective lens for focusing the modulated light beam onto the recording medium; a focus detector for generating an electrical signal corresponding to a degree of focus of the modulated light beam in reference to the recording medium; a beamsplitter for directing the modulated light beam to the objective lens and directing a reflected light beam from the recording medium to the focus detector; and a focus actuator placed in close proximity to the modulator, the actuator having a mirrored surface for reflecting the modulated light beam to the beamsplitter, wherein the focus actuator is moved in an optical axis responsive to the electrical signal generated by the focus detector.