A high-resolution grating spectrometer has been designed and built for use in the infrared region between 0.8 and 6 µ. A Littrow optical system is employed and a 3-m focal length spherical mirror is utilized as the collimator. By the use of a four-pass optical system and a 17.5-cm grating with 400 lines/mm, a spectral slitwidth of 0.013 cm−1 is obtained in the region of 3.4 µ. Details of the design and operation of the instrument are given and the precision which can be obtained with the mechanical drive system is discussed.
