Patent ID: 8611009

Claim:
An optical device that has an antireflection function, the optical device comprising: a base; and a plurality of structural bodies, which are formed by convex portions or concave portions, arranged on a surface of the base with a fine pitch that is equal to or smaller than a wavelength of visible light, wherein the plurality of structural bodies are arranged so as to form tracks of a plurality of rows on the surface of the base and form a quasi-hexagonal lattice pattern, a tetragonal lattice pattern, or a quasi-tetragonal lattice pattern, wherein a packing ratio of the structural bodies to the surface of the base is equal to or higher than 65%, and wherein: (i) the plurality of structural bodies form a hexagonal lattice pattern or a quasi-hexagonal lattice pattern on the surface of the base, and wherein, when an arrangement pitch of the plurality of structural bodies within a same track is P 1 and an arrangement pitch of the plurality of structural bodies between two adjacent tracks is P 2 , a ratio of P 1 /P 2 satisfies relationship of 1.00≦P 1 /P 2 ≦1.1 or 1.00<P 1 /P 2 ≦1.1, or (ii) the plurality of structural bodies form a tetragonal lattice pattern or a quasi-tetragonal lattice pattern on the surface of the base, and wherein, when an arrangement pitch of the plurality of structural bodies within a same track is P 1 and an arrangement pitch of the plurality of structural bodies between two adjacent tracks is P 2 , a ratio of P 1 /P 2 satisfies relationship of 1.4<P 1 /P 2 ≦1.5.