Abstract

Absorption and complete multipath interference have been included in the calculation of the modulation efficiency of a far i.r. Michelson interferometer with 25-μm and 100-μm Mylar beam splitters over the range of wavenumbers between 20 cm⁻¹ and 125 cm⁻¹ for angles of incidence between 45° and 80°. These results show that optimum performance of an interferometer in terms of highest and most uniform modulation efficiency for unpolarized radiation will be obtained by selecting the beam-splitter thickness to cover the wavenumber range of interest within the first interference lobe and by utilizing higher angles of incidence than the mechanically convenient 45°. Practical constraints will usually limit this angle to a value somewhat less than the optimum of about 75° for Mylar beam splitters.

© 1978 Optical Society of America

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