Recent Advances in High Resolution Fourier Transform Spectroscopy

Fourier Transform Spectroscopy is now widely used in many routine measurement applications. In principle, very high resolution can be achieved in FT Spectroscopy rivaling the resolution of infrared laser spectroscopy. In practice however, as resolution is increased, a number of operating parameters must be controlled with rapidly increasing care. Refinements of instrumentation over the last few years based on a fuller understanding of these parameters has led not only to excellent realizations of resolution but also to greater precision in observed line shapes, line intensities and frequency calibration. In FT Spectroscopy, higher resolution is achieved by recording the interferogram over increasingly greater mirror displacement or optical path difference. While the optical path difference is increased, it is necessary to maintain a high level of consistency of interferometer alignment, path difference measurement and path difference consistency for all optical rays going through the interferometer.