Development and validation of a cryogenic far-infrared diffraction grating spectrometer used to post-disperse the output from a Fourier transform spectrometer

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 diffraction gratings which 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 discusses the development of a cryogenic (4 K) diffraction grating spectrometer which operates over the wavelength range from 285 - 500 $\mu$m 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.

arXiv comment9 pages, 14 figures. The following article has been accepted by Review of Scientific Instruments. It can be found at https://doi.org/10.1063/5.0177603

References in corpus (5)

• Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy
• The Infrared Astronomical Mission AKARI
• SPICA - a large cryogenic infrared space telescope Unveiling the obscured Universe
• Mid-IR cosmological spectrophotometric surveys from space: Measuring AGN and star formation at the Cosmic Noon with a SPICA-like mission
• Astronomical imaging Fourier spectroscopy at far-infrared wavelengths