Optical information-processing apparatus

摘要

In an optical information-processing apparatus, retrieving and recording laser beams are focused on an optical disk in a recording mode. The retrieving and recording laser beams are reflected from the optical disk and are transferred by the objective lens. The transferred retrieving laser beam is spatially separated from the transferred recording laser beam and is incident on the photo-sensitive region of a photodetector the edge of photo-sensitive region is so arranged as to be separated at distance d2 from the recording laser beam when the objective lens is in focusing state. The distance d2 satisfies the following inequality:PPd2 m d1PPwherein d1 is a distance between the beam spot on the optical disk in the focusing state and m is a magnification of the optical system between the optical disk and the photodetector.