Applications of Fourier Transform Spectrometry in the Ultraviolet, Visible, and Near-IR

Abstract

Abstract Although Fourier transform spectrometry is now synonymous with infrared spectroscopy, its first applications were in the visible simply because the eye was the only available detector in those early years. Connes [l] has given a particularly readable synopsis of the early history of interferometry in which he traces its beginnings to Fizeau and Foucault and their studies of the solar spectrum in the mid-1800s. Even in those early days using available, optical components, Fizeau built an interferometer capable of reproducibly detecting 1/20th of a fringe of mirror movement in the visible. This system was also used to measure the first infrared interferogram of the sun (using photographic detection). Michelson, in the late 19th century was attempting to improve on Fizeau's measurements when he began his now famous work which resulted in the discovery that the Balmer line of hydrogen was actually a doublet instead of the singlet produced by dispersive spectrometers. He was the first to link spectroscopy with interferometry although he did not realize that the Fourier transform was necessary for the complete reconstruction of the spectrum from the interferogram This was pointed out quickly, however, by Lord Rayleigh.