DIFFRACTION GRATING, OPTICAL PICKUP DEVICE, AND OPTICAL DISK DEVICE

PROBLEM TO BE SOLVED: To enable stage tracking control.SOLUTION: A diffraction grating includes: first and second lattice areas formed by dividing a lattice surface into two pieces at a division line parallel with a first direction; a third lattice area formed in the first lattice area; and a fourth lattice formed in the second lattice area. Near a center of the lattice surface, the third lattice area, the first lattice area, the second lattice area, and the forth lattice area are successively aligned in a second direction orthogonal to the first direction, and the first lattice area and the second lattice area are successively aligned in the second direction orthogonal to the first direction in the lattice surface except near the center of the lattice surface. Groove directions and groove periods of the first to the forth lattice areas are the same each other. A lattice pattern of the first lattice area has a phase difference of 180° to a lattice pattern of the second lattice area, and a lattice pattern of the third lattice area has a phase difference of 180° to a lattice pattern of the fourth lattice area.