Interferometer spectrometer having tiltable reflector assembly and

Abstract

A twin-arm interferometer spectrometer having a tiltable reflector assembly, which includes a pair of mutually facing parallel reflective elements, varies the path length of both interferometer arms simultaneously to achieve high resolution in a small, low maintenance design. Collimated electromagnetic radiation is split by a beamsplitter into first and second arm beams. Both arm beams impinge on the tiltable reflector assembly, to retroreflectors, and back to the beamsplitter wherein they recombine to form an exit beam. The exit beam is directed to a sample and then to a suitable detector. Modulation of the exit beam is produced by tilting the reflector assembly about an axis parallel to the reflective elements in the reflector assembly. This tilting causes a simultaneous variation in the path length of both interferometer arms, and thereby yields a large total path difference with a relatively small movement. Symmetry between the paths of the reference beam and test beam results in greater stability and greater immunity to thermal expansion.