Patent ID: 8531930

Claim:
An optical pickup device, comprising: a laser diode, which emits a laser light therefrom; an objective lens, which is configured to irradiate the light beam emitting from said laser diode upon an optical disc; an actuator, which is configured to drive said objective lens; at least two (2) diffraction gratings, including first and second diffraction gratings for dividing the light beam reflecting on an information recording layer of said optical disc; and a photo detector including plural numbers of light receiving parts, which are configured to detect the light beams dividing from said first diffraction grating and said second diffraction grating, wherein said first diffraction grating is mounted on a movable portion of said actuator, said first diffraction grating is divided into at least a first region including an optical axis of the light beam incident upon said diffraction grating, and a second region other than that, the light beam incident upon said first region of said first diffraction grating is diffracted, and said light beam diffracted passes through said second diffraction grating, so that said light beam passing therethrough is detected by said photo detector, said second diffraction grating is divided into at least two (2) regions, including at least a first and second region having characteristics different from each other, the first region of said second diffraction grating transmits through the light beam entering thereon or emits a 0 th dimensional diffraction light therefrom, and the second region of said second diffraction grating diffracts the light beam entering thereon; the second region of said second diffraction grating has three (3) regions, including a diffraction grating region A, a diffraction grating region B and a diffraction grating region C, and among disc diffraction lights diffracted by a track on said optical discs, the 0th dimensional diffraction light enters into said diffraction grating region A and said diffraction grating region C, at least ±1st dimensional diffraction light enters into said diffraction grating region B, and said diffraction grating region B is put between said diffraction grating region A and said diffraction grating region C.