A high-resolution infrared spectroscopic system consisting of a large Littrow-type grating monochromator followed by a prism order-sorting system is described. The system has been designed to provide sufficient radiant energy per spectral pass band so that a spectral resolution of about 0.08 cm-1 can be achieved at wavelengths beyond 7 µ. An order-sorting system permits simultaneous recording of the spectrum being measured and a higher-order calibration spectrum. Wavelengths of the lines in absorption spectra can be measured to within 0.005 cm-1.
T. K. McCubbin, Jr., R. P. Grosso, and J. D. Mangus, "A High-Resolution Grating-Prism Spectrometer for the Infrared," Appl. Opt. 1, 431-436 (1962)