Measurement of concentrations of components of a gaseous mixture

Claim 1

A process for measuring the concentration of each of a first plurality of known gases in a mixture comprising the steps of passing individually through a known concentration of each of the gases monochromatic radiation, which is modulated in intensity at a predetermined rate, at each of a second plurality of wavelengths; measuring the fraction of the radiation absorbed at each wavelength by each gas in passing therethrough and deriving the absorption coefficient for each gas at each wavelength; passing monochromatic radiation which is modulated in intensity at a predetermined rate at each of said wavelengths through the mixture of gases whose concentrations are to be measured; measuring the fraction of the radiation absorbed at each wavelength in passing through the mixture by developing a first signal output at each wavelength from a pressure-sensitive element responsive to the pressure changes in the mixture, said pressure changes caused by the resulting time-varying absorption of portions of the radiation at the predetermined rate, a second signal output from a light-sensitive element responsive to the level of the monochromatic radiation at each wavelength incident on the mixture, and a third signal proportional to the ratio of the first signal to the second signal; and deriving the concentrations of each of the gases in the mixtures from said third signal measurements and the previously derived absorption coefficients.