Development of the dispersing component for a cryogenic post-dispersed polarizing Fourier transform spectrometer
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Date
2022
Authors
Anderson, Alicia May
University of Lethbridge. Faculty of Arts and Science
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Publisher
Lethbridge, Alta. : University of Lethbridge, Dept. of Physics and Astonomy
Abstract
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 thesis discusses the development of a cryogenic (4 K) reflection grating spectrometer which operates over the wavelength range from 285 - 500 µm and was used to post-disperse the output from a room-temperature polarizing FTS. Measurements of the grating spectral response and diffraction efficiency are presented as a function of both wavelength and polarization to characterize the instrumental performance.
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Keywords
far infrared , Fourier transform spectrometer , diffraction efficiency , diffraction grating , astronomy and astrophysics , cryogenic instrumentation , Fourier transform infrared spectroscopy , Low temperature engineering , Diffraction gratings--Design and construction , Infrared astronomy--Instruments--Design and construction , Submillimeter astronomy--Instruments--Design and construction , Dissertations, Academic