Optical pickup apparatus

摘要

An optical pickup apparatus for reproducing information from an optical recording medium such as a compact disc comprising: a laser device; one or more diffraction devices; and a photodetector receiving a laser beam diffracted by the diffraction device. The surfaces of the diffraction device are provided with an antireflection coating. When the apparatus is used for the three-beam method, the two photodetecting areas in the photodetector for producing the tracking error signal are different in size and in positional relation to the laser device.