Optical pickup head device, information recording/reproducing apparatus, and method for recording information

摘要

An optical pickup head device includes a diffraction grating for generating zero-order diffracted light and at least first-order diffracted light and provides a tracking error signal with a DPP method. The diffraction grating includes grating patterns with a nonuniform period or phase. The size of the first-order diffracted light converged on an optical recording medium is larger in the direction parallel to a tangent to the track than in the direction perpendicular to the tangent. P 1 /P 0 >PW 2 /PW 1 is established, where PW 1 represents the power that is required to record information on the optical recording medium, PW 2 represents the maximum power that allows information recorded on the optical recording medium to be reproduced without being erased, P 0 represents the light amount of the zero-order diffracted light converged on the optical recording medium, and P 1 represents the light amount of the at least first-order diffracted light converged on the optical recording medium. This configuration makes it possible to detect a tracking error signal with reduced offset, even if a recordable optical recording medium having two information recording planes is used.