Patent ID: 7297386

Claim:
An antireflection structure, comprising: a base having a shape of a flat plate; and a finely roughened antireflection part formed integrally with the base; wherein: (1) the finely roughened antireflection part includes a plurality of projections and a plurality of depressions defined by the projections, no other layer covering the plurality of projections and the plurality of depressions such that the surface of the plurality of projections and the plurality of depressions is exposed to the air; (2) the projections are distributed such that P MAX ≦λ MIN , where P MAX is a greatest distance between tips of adjacent projections and λ MIN is a shortest wavelength of visible light in a vacuum; (3) a horizontal cross-sectional area of the projections increases continuously from the tips of the projections to bottoms of the depressions so that a ratio of the horizontal cross-sectional area of the projections to a cross-sectional area of the finely roughened antireflection part in a plane including the bottoms of the depressions increases continuously from 0% to 100% from the tips of the projections to the bottoms of the depressions; (4) a vertical cross-sectional shape of each projection is sharper at a tip part of each projection than at a bottom part of each depression; (5) a vertical cross-sectional shape of the finely roughened antireflection part includes only curved edges; and (6) the base and the finely roughened part are formed of a same material.