Common-mode rejection in Martin-Puplett spectrometers for astronomical observations at mm-wavelengths

TL;DR

This paper investigates the ability of Martin-Puplett interferometers to reject common-mode signals at millimeter wavelengths, demonstrating their potential for precise measurements of cosmic microwave background anisotropy.

Contribution

It provides experimental analysis of common-mode rejection in MPI and explores its application in measuring CMB anisotropy.

Findings

MPI achieves high common-mode rejection at mm wavelengths

Effective for detecting small brightness gradients in large backgrounds

Potential for precise CMB anisotropy measurements

Abstract

The Martin-Puplett interferometer (MPI) is a differential Fourier transform spectrometer (FTS), measuring the difference between spectral brightness at two input ports. This unique feature makes the MPI an optimal zero instrument, able to detect small brightness gradients embeddend in a large common background. In this paper we investigate experimentally the common-mode rejection achievable in the MPI at mm wavelengths, and discuss the use of the instrument to measure the spectrum of cosmic microwave background (CMB) anisotropy.