| 摘要 |
PURPOSE: A diffraction grating and an optical pickup device using the same are provided to freely design the size, variation range and pattern of a tracking error signal. CONSTITUTION: A diffraction grating(22) forming main beam and sub beam by diffracting incident beam is divided into a central region(22C) and right and left regions(22L,22R). The right and left regions have a spot symmetry relation. The central region is narrower than the right and left regions of the same width. The central region is divided into at least three sub regions. |
