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Proceedings Paper

Other Infrared (IR) Transform Spectroscopies
Author(s): T. Hirschfeld
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Paper Abstract

Profiting from the example of Fourier transform spectroscopy, a number of possible other transform spectroscopies, such as Hadamard, Walsh, and Laplace transforms, have been investigated. A number of other transforms show spectroscopic promise in the IR. (1) CHIRP. Here a tunable laser is coupled via a beamsplitter to a spatially extended sample and a heterodyne detector. The audio frequency output of the latter after chirp transformation yields a range resolved signal useful for remote measurements or nonuniform sample measurements. (2) KRAMERS-KRONIG. This transform, for which a simplified fast calculating procedure has evolved in the Fourier domain, interconverts refraction and absorption spectra. Refractive index spectra offer advantages for tunable laser work, can be used for absorption spectrum correction, and can be conveniently obtained by asymmetric FT-IR. (3) ABSORBANCE NONLINEARITY. Particle size or shape, thickness, or concentration distributions within an inhomogeneous sample can be calculated from line shape distortions produced by the energy nonlinearity of the absorption process. Other transforms of potential ability, such as the Hankel, the equiabsorbance, and two dimensional Fourier transforms, will be briefly mentioned.

Paper Details

Date Published: 29 October 1981
PDF: 1 pages
Proc. SPIE 0289, 1981 Intl Conf on Fourier Transform Infrared Spectroscopy, (29 October 1981); doi: 10.1117/12.932196
Show Author Affiliations
T. Hirschfeld, Lawrence Livermore National Laboratory (United States)

Published in SPIE Proceedings Vol. 0289:
1981 Intl Conf on Fourier Transform Infrared Spectroscopy
Hajime Sakai, Editor(s)

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