Patent ID: 8702302

Claim:
A combustion gas measurement apparatus mounted in a gas turbine, the measurement apparatus comprising: a tunable laser generating a radiation beam passing through a combustion gas path in the gas turbine; a controller for the tunable laser and tuning the laser to emit radiation having at least a first selected wavelength and a second selected wavelength which both correspond to temperature-dependent transitions of a combustion species of the gas, wherein the first selected wavelength and the second selected wavelength lack neighboring wavelengths corresponding to lines of absorption strength; a detector sensing the radiation beam passing through the combustion gas and generating absorption signals indicative of an absorption of the beam by the combustion gas at each of the first wavelength and the second wavelength, and a processor executing a program stored on a non-transitory storage medium determining a combustion gas temperature based on a ratio of the absorption signals for the first wavelength and the second wavelength.