We propose a novel instrument for automobile exhaust analysis based on a Hadamard-transform spectrometer, which would be able to make accurate measurements of the concentration of several pollutants simultaneously, would be operated by unskilled personnel, and would complete a measurement scan in less than 1 sec.
J. A. Decker, Jr, "Hadamard-Transform Exhaust-Analysis Spectrometer," Appl. Opt. 10, 24-27 (1971)