Patent ID: 8045427
Filing Date: 2011-10-25
Classification: G11B

Abstract:
1. An optical pickup comprising: a light source configured to emit light; a beam splitter configured to transmit or reflect light; an object lens configured to condense the light transmitted by the beam splitter onto an optical storage; a diffraction grating having a first grating pattern and a second grating pattern, the first grating pattern configured to diffract and divide said light reflected by the optical storage into a main beam and two sub beams, and the second grating pattern configured to diffract said light along a different diffracting direction than the first grating pattern so that the diffracted light by the second grating pattern is excluded from an error detecting process; a condensing lens configured to generate astigmatism to the light diffracted by the first grating pattern; and a light sensor configured to receive the light via the condensing lens and detect a tracking error signal; wherein the first grating pattern has an hour glass shape and is disposed in a central portion of the diffraction grating; and the second grating pattern covers a remainder of the diffraction grating.