Polarization properties of far infrared beamsplitters

The energy throughput of an interferometer is calculated for the case where an unsupported thin film is used as a beamsplitter. The polarization of the beam toward the detector is calculated, and it is shown that by setting the beamsplitter at the Brewster angle rather than at the usual 45 degrees, a completely polarized output beam can be produced with very little loss of energy. The theoretical and experimental results are in good agreement. (Author).