A Triple Fabry-Perot Spectrometer for the Far Infrared

Abstract

A Far Infrared Limb Observing Spectrometer (FILOS) is being developed for observations of OH and other upper atmospheric species. It uses three Fabry-Perot etalons in series to obtain resolution of 1 part in 100,000 at a wavelength of 100 microns. The largest of the three etalons is placed between the telescope and the atmosphere and has dimensions of 10 cm. The smaller two etalons are cooled to 4 K and function to filter out a single order of the large Fabry-Perot resonator. A Triple Fabry-Perot spectrometer is a very simple and effective way of obtaining high resolution spectra of atmospheric emission. Versions are being developed for balloon observations and are being proposed as part of the Earth Observing System for the Polar Orbiting Platform or for the Manned Space Station. Current methods of fabrication and testing the etalons will be described, along with measured and projected performance.