| 摘要 |
Part of reflected light from an optical disc enters a diffraction element ( 10 ). The ±first-order diffracted light and zero-order diffracted light from the diffraction device ( 10 ) travel via a cylindrical lens ( 11 ) and a spot lens ( 12 ) and enter a photodetector ( 13 ). If an objective lens shifts, a beam on the diffraction element ( 10 ) also shifts. Therefore, the intensity distribution of a spot of the zero-order diffracted light falling on light-receiving areas (A, B, C, D) of a four-part light-receiving element ( 13 a) becomes bright as a whole, while the intensity distributions of spots of the ±first-order diffracted light falling on light-receiving areas (E, F) of light-receiving elements ( 13 b, 13 c) become dark as a whole. Thus, an optical pickup tracking error detecting method and an optical pickup device enabling good tracking control are provided. |
