A spectroradiometric pyrometer was developed to measure temperatures of shock-heated gases with time resolution of about 10 µsec. Gas temperatures in shock-heated CO2–N2 mixtures and in self-sustaining detonations were determined by simultaneously measuring infrared spectral radiance and absorptance at selected wavelengths in CO2 and H2O band spectra. By Kirchhoff’s law, the ratio (radiance/absorptance) equals the Planck blackbody radiance, from which the temperature is easily found. The measured temperatures agreed with values calculated from the measured shock velocities.
Gunter J. Penzias, Stanley A. Dolin, and Herman A. Kruegle, "Spectroradiometric Pyrometry of Shock-Heated Gases by Infrared Emission and Absorption Measurements," Appl. Opt. 5, 225-230 (1966)