| 摘要 |
An optical element includes a base and a large number of structures arranged on a surface of the base. The structures are depressions or projections with a conical form. The structures are arranged at a pitch shorter than or equal to a wavelength range of light in a use environment and lower portions of the structures adjacent to one another are connected to one another. An effective refractive index in a depth direction of the structures gradually increases toward the base and draws an S-shaped curved line. |
