The recording system employs a contact-modulated amplifier and self-balancing potentiometer in an electrical null circuit including variable response speed and gain. The control system automatically adjusts the slits and zero at preselected prism positions. Familiar spectra illustrate the effects of variables such as slit width, recording speed, and response speed.
GERALD M. RASSWEILER, MAX D. LISTON, J. F. LASH, and D. L. FRY, "Recording and Control System for Infra-Red Spectrophotometer," J. Opt. Soc. Am. 37, 963-963 (1947)