| abstract |
One or more light sources (108, 110) emit light within first, second and third wavelength ranges through exhaust (102). The first and second wavelength ranges are characterized by first and second different absorption wavelength ranges of a background gas. The third wavelength range is characterized by an absorption wavelength range of a gas of interest. At least a portion of the light within the first, second and third wavelength ranges is absorbed by the exhaust gas, thereby providing modified light characterized by first, second and third absorption wavelength ranges. One or more detectors (120, 122) receive the modified light. A processing subsystem determines a temperature of the exhaust gas based on the modified light characterized by the first and second absorption wavelength regions and a concentration of the gas of interest based on the modified light characterized by the third absorption wavelength region and the temperature of the exhaust gas. |