This instrument attaches to a grating monochromator and measures absorption spectra with a SNR of 2000 or more over the 270–850-nm wavelength range, with a resolution of at least 0.1 nm. Over the 300–700-nm range a resolution of 0.03 nm is attainable with the same SNR. Thus good absorption spectra can be measured with scale expansions of 30 times. The maximum SNR is 4800, permitting 100 times scale expansion.
John Rolfe and H. J. Labbe, "Spectrophotometer for measuring small sharp absorption bands in solids at low temperatures," Appl. Opt. 19, 1937-1940 (1980)