| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a binary type diffraction grating optical element which consists of SiO2 and prevents the degradation in diffraction efficiency by an error in mask alignment. SOLUTION: The thin film 12 of the same SiO2 as a SiO2 substrate 11 inscribed with the binary type diffraction gratings is deposited on the substrate by an RR sputtering method and the surface of the substrate 11 is coated with the fine rugged shapes produced by the error in the alignment of a mask, etc., at a minimum thickness, by which the surface is planarized and the degradation in the diffraction gratings is prevented. The effective diffraction efficiency may thus be greatly improved by forming the film for restoring the shape error or the film of the member having the same refractive index as the refractive index of the substrate on the optical element structure in the manner described above. |
