A Fourier transform spectrometer (abbreviated FTS) is a Michelson interferometer with a movable mirror. By scanning the movable mirror over some distance, an interference pattern is produced that encodes the spectrum of the source (in fact, it turns out to be its Fourier transform Eric Weisstein's World of Math). Fourier transform spectrometers have a multiplex advantage over dispersive spectral detection techniques for signal, but a multiplex disadvantage for noise.
In its simplest form, a Fourier transform spectrometer consists of two mirrors located at a right angle to each other and oriented perpendicularly, with a beamsplitter placed at the vertex of the right angle and oriented at a 45° angle relative to the two mirrors. Radiation incident on the beamsplitter from one of the two "ports" is then divided into two parts, each of which propagates down one of the two arms and is reflected off one of the mirrors. The two beams are then recombined and transmitted out the other port. When the position of one mirror is continuously varied along the axis of the corresponding arm, an interference pattern is swept out as the two phase-shifted beams interfere with each other.
Beamsplitter, Fabry-Perot Interferometer, Michelson Interferometer, Multiplex Advantage
References
Bell, R. J. Introductory Fourier Transform Spectroscopy. New York: Academic Press, 1972.
Connes, P. "Lasers and Light." In How Light is Analyzed (Ed. Schawlow).
Cooley, J. W. and Tukey, O. W. "An Algorithm for the Machine Calculation of Complex Fourier Series." Math. Comput. 19, 297-301, 1965.
Ferraro, J. R. and Krishnan, K. K. (Eds.). Practical Fourier Transform Infrared Spectroscopy: Industrial and Laboratory Chemical Analysis. San Diego, CA: Academic Press, 1990.
Forman, M. L.; Steel, W. H.; and Vanesse, G. A. "Correction of Asymmetric Interferograms Obtained from Fourier Spectroscopy." J. Opt. Soc. Amer. 56, 59-63, 1966.
Griffiths, P. R. Chemical Infrared Fourier Transform Spectroscopy. New York: Wiley, 1975.
Griffiths, P. R. and De Haseth, J. A. Fourier Transform Infrared Spectrometry. New York: Wiley, 1986.
Hunten, D. M. "Fourier Transform Spectroscopy of the Planets." Science 162, 313-318, 1968.
Loewenstein, E. V. "The History and Current Status of Fourier Transform Spectroscopy." Appl. Opt. 5, 845-854, 1966.
Mertz, L. Transformations in Optics. New York: Wiley, 1965.
Mertz, L. "Auxiliary Computation for Fourier Spectroscopy." Infrared Phys. 7, 17-23, 1967.
Michelson, A. A. "Visibility of Interference-Fringes in the Focus of a Telescope." Phil. Mag. 31, 256-259, 1891.
Michelson, A. A. "On the Application of Interference Methods to Spectroscopic Measurements." Phil. Mag. 34, 280, 1892.
Michelson, A. A. Light Waves and their Uses. Chicago, IL: University of Chicago Press, 1961.
Robinson, D. W. and Reid, G. T. Interferogram Analysis: Digital Fringe Pattern Measurement Techniques. 1993.
Rubens, H. and Wood, R. W. "Focal Isolation of Long Heat-Waves." Phil. Mag. 21, 249-261, 1911.
Sakai, H.; Vanasse, G. A.; and Forman, M. L. "Spectral Recovery in Fourier Spectroscopy." J. Opt. Soc. Amer. 58, 84-90, 1968.
Strang, G. "Wavelet Transforms Versus Fourier Transforms." Bull. Amer. Math. Soc. 28, 288-305, 1993.
Vanasse, G. A.; and Sakai, H. "Fourier Spectroscopy." Ch. 7 in Progress in Optics, Volume VI (Ed. E. Wolf). Amsterdam, Netherlands: North-Holland, pp. 260-330, 1967.
Weisstein, E. W. "Books about Fourier Transform Spectroscopy." http://www.ericweisstein.com/encyclopedias/books/FourierTransformSpectroscopy.html.
