Fourier Transform Spectroscopy for atmospheric research and operational use; a historical perspective

Abstract:
I was fortunate to become acquainted with FT Spectroscopy here at University of Toronto in 1962 when the technique was at an early stage of infancy. At that time it took great effort to make a Fourier transform spectrometer (FTS) work both optically and computationally. The first project I was involved in consisted of operating an FTS remotely on a scientific balloon to measure the spectrum of the faint night airglow from a high altitude vantage. Each successive opportunity to work with FTS from which I would learn how to implement it better will be chronicled. The driving force behind this persistent work with FTS was the huge advantages the technique could provide compared with more classical methods of spectroscopy. Initially the sensitivity advantage obtained with the high optical throughput and the efficiency achieved with multiplexing were of greatest interest. With time and the development of array detectors the emphasis of FTS advantages changed to accuracy and precision of spectral measurements achievable with FTS. The presentation will be illustrated with multiple examples of FTS implementations and applications. The evolution of various technologies over the past 50 years also play an important role in the advancement of FTS. In particular Moore’s law pertaining to the growth in computing capability has played a pivotal role in advancing the state of the art of FTS.