Patent ID: 7539117

Claim:
An optical pickup, comprising: a semiconductor laser; a diffractive optical element operable to diffract a beam emitted by the semiconductor laser; an objective lens operable to focus the diffracted beam on an optical disc; and a detection unit operable to receive the diffracted beam that has been reflected by the optical disc, to detect a tracking error signal, wherein the diffractive optical element has a plurality of first diffraction regions and second diffraction regions, the first and second diffraction regions are configured such that, when a zero order diffraction beam is being focused on a surface of the optical disc, the first diffraction regions diffract a first order diffraction beam such that the first order diffraction beam is focused at a position that is between the objective lens and the optical disc, and the second diffraction regions diffract the first order diffraction beam such that the first order diffraction beam is focused at a position that, with respect to the objective lens, is beyond the optical disc, and the first regions and the second regions are configured such that the first order diffraction beam has a beam width that, on the optical disc in a radial direction thereof, is two times or greater a track pitch of the optical disc.