SOME PROPERTIES OF ABSORBING BEAM-SPLITTERS

The equality of the reflected and transmitted irradiances by an unsupp orted metallic beam splitter is considered. An approximate analytical expression for the film thickness which ensures this condition for the parallel and perpendicular polarizations is given. The phase differen ce between the two output fields is expressed as a function of the opt ical parameters of the film. This phase difference departs substantial ly from pi/2, which is obtained from energy conservation in a lossless beam splitter.