| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical element having good anti-reflection performance not only at a central part of an optical surface having a small curvature radius but also at the periphery thereof.SOLUTION: An optical element comprises: a base member 11 having an optical surface; a concave-convex structure 13 having an average pitch smaller than the shortest wavelength of a used wavelength range; and at least one intermediate layer 12 formed between the optical surface and the concave-convex structure, made of material different from that of the concave-convex structure, and having a refractive index between that of the base member and that of the material forming the concave-convex structure. The optical surface has a rotational symmetry axis. Thickness of the intermediate layer or each of thicknesses of the intermediate layer and the concave-convex structure varies to increase as distance from the rotational symmetry axis increases. |
