Abstract: A reflector system for Michelson interferometers comprises: a beam splitter arranged in the measurement ray path, which splits the measurement beam path into two split ray paths; a first mirror arrangement in each split ray path reflecting parallel to the incident ray; and at least one second mirror reflecting parallel to the incident ray, which is arranged in the ray path reflected from one of the first mirror arrangements and is coupled to the beam splitter, a partially transparent reflector serving as beam splitter, and the beam splitter and second mirror being arranged on a common carrier.

Abstract: To reduce the data rate of a digitalized measuring signal produced in Fourier spectroscopy, the analog signal representing the interferogram is mixed with a second electrical signal whose frequency is modulated in proportion to the deviation of the instantaneous actual speed of the moving mirror of a double beam interferometer from its constant desired speed. Only the difference frequencies produced as a result of the frequency mixing are digitalized and supplied to an associated computer for analysis of the interferogram. The digital measuring signal thus obtained is distinguished by a substantially reduced data rate without giving rise to additional errors in the frequency transformation. To produce the second frequency modulated electrical signal, a laser source is used which supplies a laser beam into the interferometer parallel to the measuring beam.