Optical Filters Based on Dense Arrays of Microscopic Pillars

A proposal for development of a class of high-transmission and antireflection optical filters is derived from the observation that the eyes of moths reflect almost no light, regardless of the wavelength or the angle of incidence of illumination. The low-reflection property of moth eyes is attributable to dense arrays of microscopic pillars that exhibit little or no diffraction or scattering. This is because (1) the dimensions and pitches of the pillars are smaller than the shortest wavelength of incident light in the wavelength range of interest and (2) a dense array of pillars provides a gradual transition in density from open space to a bulk solid material, so that an abrupt density change, which would generate reflections, is not present.