Patent ID: 8493824

Claim:
An optical head comprising: a light source; an objective lens for converging a light beam, which has been emitted from the light source, onto an optical disc; a photodetector section, which receives the light beam, reflected from the optical disc, at multiple divided areas and which outputs a plurality of light detection signals representing the intensities of the light that has been received at the respective areas; and a tilt detecting section for detecting a relative tilt between the objective lens and the optical disc based on the light detection signals, wherein the tilt detecting section generates a first push-pull signal PP 1 based on the light detection signals that have been supplied from a first group of the areas, which are arranged symmetrically with respect to a virtual reference line that is drawn parallel to a tracking direction on the optical disc and that crosses an optical axis, also generates a second push-pull signal PP 2 based on the light detection signals that have been supplied from a second group of the areas, which is different from the first group and which are also arranged symmetrically with respect to the reference line, changes coefficients k according to the magnitude of displacement of the objective lens from a predetermined reference location in a radial direction of the optical disc, and generates a tilt detection signal TLT by the equation: TLT=PP 1− k×PP 2.