Fizeau Interferometers: Extracting Sub-band Information

Abstract

Measurements of the 2.7 K CMB radiation provide the most stringent constraints on cosmological models. The power spectra of the temperature anisotropies and the E-mode polarization of the CMB are explained well by the inflationary paradigm. The next generation of CMB experiments aim at providing the most direct evidence for inflation through the detection of B-modes in the CMB polarization, presumed to have been caused by gravitational waves generated during inflation. B-mode polarization signals are very small (~10–8 K) compared with the temperature anisotropies (~10–4 K). Systematic effects in CMB telescopes can cause leakage from temperature anisotropy into polarization. Bolometric interferometry is a novel approach to measuring this small signal with lower leakage. Subdividing the frequency passband of a Fizeau interferometer would mitigate the problem of “fringe smearing.” The sub-band splitting method described here is general and can be applied to broadband Fizeau interferometers across the electromagnetic spectrum. © 2021, Springer Nature Singapore Pte Ltd.