Optical pick-up head, optical information apparatus, and optical information reproducing method

Abstract

An optical information apparatus of the present invention includes: an optical pick-up head including: a light source; a diffraction unit; a condensing unit; a beam splitter; a photodetector; and a tracking error signal generator. An optical recording medium has tracks arranged substantially at a constant pitch. An average of a pitch is tp. When a main beam is placed on the track, a first sub-beam and a second sub-beam are placed between the tracks. The tracking error signal generator performs a differential arithmetic operation with respect to signals output from a light-receiving portion receiving the main beam to generate a first push-pull signal, performs a differential arithmetic operation with respect to signals output from the light-receiving portions receiving the first sub-beam and the second sub-beam to generate a second push-pull signal, and performs a differential arithmetic operation with respect to the first push-pull signal and the second push-pull signal to generate a tracking error signal, in a case where an amplitude of the first push-pull signal obtained at the pitch tp is fluctuated when the light beam is scanned in a direction orthogonal to the tracks of the optical recording medium.