Fleit, Jacobson, Cohn, Price, Holman & Stern
Optical head apparatus for writing and reading data on an optical disk having a lens with an inclined optical axis
 An optical head apparatus is adapted to write and read data onto and from an optical disk using an optical beam emitted from a light-emitting element. Such an optical head apparatus includes: a lens actuator having a lens casing for retaining an objective, magnetic circuits provided on two sides of the lens casing, a coil having a part placed in the gaps formed by the magnetic circuits; a focus detector having a detection lens assembly consisting of a plurality of lenses for correcting aberration, a divided photodetector for receiving a light beam which has been converged by being passed through the detection lens assembly, and a differential amplifier for taking out a differential output from the divided photodetector, the detection lens assembly, the divided photodetector, and the differential amplifier being disposed in the optical path of light reflecting from the optical disk. The detection lens assembly has a lens which is the closest lens to the focal point thereof, the center line of at least a focal point side interface of the lens is inclined with respect to the optical axes of the other lenses. 
Fuji Electrochemical Co., Ltd.
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Takayuki
Nakano