Electromagnetic effects for the resonance-domain IR diffractive optics

Binary optics technology enables the manufacture of arrays of diffractive m icro-optical elements which are used in many optoelectronic devices, e.g. t he focal plane collection optics. The first-order diffraction grating effic iency decreases in the best part of the resonance-domain region of diffract ion, i.e. when the grating period is close to the optical wavelength in the substrate material. A large fraction of the fast binary lens surface relie f is built of staircase annular structures whose width is of wavelength sca le. Therefore, the rigorous electromagnetic theory of gratings has been app lied in this paper to calculate and analyze the diffraction effects for the resonance-domain longwave (8-12 mu m) infrared (LWIR) binary optics. It is shown that electromagnetic effects limit the speed of the LWIR first-order diffractive lenses and the optical gain achievable with the diffractive le nses used as the focal plane collection optics in the IR detection systems. (C) 2000 Elsevier Science B.V. All rights reserved.