Interferometer, noise-equivalent

In recent years, detectors with better noise characteristics (i.e., approaching the shot-noise limit) have been developed for FT-Raman systems. In these systems multiplexing can become a disadvantage because each spectral element contains shot noise from the sum of the entire spectrum. However, even under these conditions, an interferometer still provides the luminosity (etendue), or Jacquinot advantage, over a dispersive system. [Jac-quinot had shown that because of the absence of an entrance slit in an interferometer, for equivalent spectral resolution, the luminosity of an interferometer is greater than a dispersive spectrometer.]... 

Griffiths et al. (9) have compared the signal to noise ratios of interferometers and monochrometers under the assumption that the source temperature and resolution for both types of instrument are equivalent. Their analysis involves a comparison of the factors appearing in equation 8 and a representation of the advantage of an interferometer over a monochrometer as the ratio of the factors associated with each instrument. A summary of Griffith et al. s (9) analysis is presented in the balance of this section. 

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