PSEUDO-COHERENCE EFFECT IN ASYMMETRIC FOURIER TRANSFORM SPECTROSCOPY

$^{1}$ E. E. Russell and E. E. Bell, Infrared Physics, (1966). $^{2}$ This was discussed by E. E. Bell at the ``Colloque sur les M\'ethodes Nouvelles de Spectroscopic Instrumentale,'' April 1966, Orsay, France.Author Institution: Laboratory of Molecular Spectroscopy and Infrared Studies, Department of Physics, The Ohio State UniversityThe interferogram which is produced with a Michelson interferometer with a sample in one arm is $asymmetric.^{1}$ This interferogram is the algebraic sum of the interferograms which would be produced in the same instrument by each of the polarization components alone, and by each of the elements of sample area (larger than the Airy disc) alone. This algebraic sum contains none of the information about the coherence of the polarization components or of the coherence of the irradiation of the same area elements. As a result, the Fourier transform of the asymmetric interferogram gives the result which would have been obtained if there were coherence between these radiation components. The effect of this fact will be illustrated by a measurement of the transmittance of a sample of polyethylene in the far infrared and by a measurement of $n_{e} = n_{o}$ for crystal quartz, made without a polarizer, in the far infrared. This work was supported in part by a contract between The Air Force Cambridge Research Laboratories and The Ohio State University Research Foundation