Design and Characterization of the Los Alamos Fourier Transform Spectrometer

The Los Alamos Fourier transform spectrometer (FTS) was designed using the same principles as those of the Kitt Peak FTS.1 The Los Alamos FTS has two 8-in. cat's-eye reflectors moving on oil bearings with a travel of 1 meter for each reflector (Fig. 1). The optical path is folded to conserve space through the use of two 8-in. flat mirrors. The beam splitter is composed of two partially reflecting plates mounted one over the other. In this optical arrangement, the upper plate acts as a beam splitter and the bottom plate a beam recombiner. These plates are mounted in a turret that holds two more beam splitters and this turret can be easily rotated to select a different beam splitter. The optical arrangement allows for two light inputs and two light outputs. The two inputs are located at the end of the instrument and at the side. The two outputs are located at the front of the instrument. All important optical elements can be adjusted externally.