A. Anderson*, D. Naylor, B. Gom, I. Veenendaal, A. Christiansen, W. Jellema, and P. Ade. “Determining the efficiency of a cryogenic far-infrared diffraction grating spectrometer used as a post-dispersing module for a high-resolution spectrometer”. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI, 12190:121902C, 2022. Montréal, Québec, Canada. DOI: 10.1117/12.2628259. Poster
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Recent advances in far-infrared detector technology have led to increases in raw sensitivity of more than an order of magnitude over previous state-of-the-art detectors. With such sensitivity, photon noise becomes the dominant noise component, even when using cryogenically cooled optics, unless a method of restricting the spectral bandpass is employed. The leading instrument concept features reflecting grating spectrometers to post-disperse the light that has been modulated by a polarizing Fourier transform spectrometer (FTS) onto a detector array, thereby reducing the photon noise on each detector. This paper describes the development of a cryogenic (4 K) reflection grating spectrometer which operates over the wavelength range from 285 μm – 500 μm and was used to post-disperse the output from a room-temperature polarizing FTS. Measurements of the grating resolving power and diffraction efficiency are presented as a function of both wavelength and polarization to characterize the instrument performance.