Far Infrared Bandpass Filters and Measurements on a Reciprocal Grid

Abstract

Transmittance and reflectance measurements on wirecloth and electroformed metallic meshes are presented in the region 0.01 <or= lambda/d <or= 5. The results were obtained under equal geometric optical conditions with a vacuum grating spectrometer. The measurements are used for the construction of a transmission bandpass filter in the wavenumber region nu > 18 cm(-1). In order to be able to construct a bandpass filter in the entire far ir, a reciprocal grid is investigated and found to be suitable as a transmission low pass filter characterized only by geometrical parameters.