| 摘要 |
PROBLEM TO BE SOLVED: To reduce wave-front aberration of an optical element including an optical pickup apparatus utilizing a diffraction grating. SOLUTION: The optical pickup apparatus utilizing the diffraction grating is formed of prisms 101 and 102 and parallel flat plate 103 which is arranged between the sloping surfaces of the prisms 101 and 102 providing the predetermined air layer and the diffraction grating. The diffraction grating is duplicated to the parallel flat plate 103 from a stamper which is produced from an original disc where the predetermined projected area is formed in the area other than the diffraction grating. In this case, the air layer formed by the diffraction grating and the sloping surfaces of the prisms 101 and 102 is set in the predetermined inclination. |
