Abstract

The utility of periodic metal screens or mesh filters for spectral and polarization selectivity from microwave to far-infrared wavelengths is well documented in current literature. Ordinary diffraction is avoided by making the period of the screen less than the wavelength of incident radiation. Under this geometrical constraint, only a single directional mode will propagate; all other diffractive orders are evanescent. Most recently, electron-beam microlithography has made possible the fabrication of periodic metal arrays operating in the middle-infrared spectral region.^1,2 We describe the measured optical properties of selected infrared mesh filters and compare these data with theoretical predictions. Determining the induced current on the screen is a fundamental element of the scattering problem. Here the finite conductivity of the metal plays an important role.

© 1986 Optical Society of America