Optical properties of metallic mesh and Fabry-Pérot interference filters for the far infrared

Abstract

The optical properties of electroformed metallic grids will be studied as a fonction of the wavelength and of the grid constants. The high coefficient of reflection of such grids between 40 and 1 000 microns suggests their use as semi-transparent plates in the construction of far infrared and submillimeter Fabry-Perot interference filters. The possibility of combining three or more grids to obtain filters of wider band-pass will also be presented. We shall discuss construction techniques for Fabry-Perot type filters of both fixed and variable separation. In comparing experimental results with theory we evaluate the effect of surface defects of the grids on the finesse of the Fabry-Perot etalons.