Photon-noise-limited Fourier spectroscopy

Abstract

A simple, approximate calculation is made of the effect of photon noise on Fourier spectroscopy when detector noise is small. The usual comment that there is no advantage due to multiplexing in these circumstances is true only for dense spectra, such as line-absorption spectra, whereas for line-emission spectra, especially with narrow lines and high resolution, there is a gain of signal-to-noise ratio over an equivalent scanning spectrometer. For weak spectra there may also be a gain, instead of the usual loss, in the range of observable line intensities.