One of the best Fourier transform spectrometers in the world, known for high stability of the interferometer and state of the art scanning mechanism. Capable of operation both in continuous and step scanning regimes. This instrument is equipped with a complete set of optics and detectors for broad band operation throughout IR and THz ranges. Cryogenic detectors with record high sensitivity enable measurements of weak signals, including of samples at low temperatures mounted in the optical cryostat. Very flexible design makes possible a broad range of experimental setups, including spectral characterization of external sources of radiation.