System and method for determining combustion temperature using infrared emissions

In a system for measuring IR radiation of a flame in a gas turbine having a combustion chamber and a turbine section, the improvement comprising a lens for collecting infrared radiation from a portion of the flame nearest to an inlet to the turbine section, said lens focusing said infrared radiation on one end of an optical fiber, said lens and optical fiber comprising sapphire, a first mounting means for supporting said lens and the one end of the optical fiber in fixed relation to the flame, means for supplying compressed air to said mounting means to shield said mounting means and said lens from combustion gases in said flame, means for positioning a second end of the optical fiber in position to direct said infrared radiation transmitted by the fiber onto a first infrared filter having a first infrared transmission of 2.28 μm (+/−0.005 μm), a second infrared filter having a second infrared transmission of 2.6 μm (+/−0.015 μm), a third infrared filter having a third infrared transmission of 2.7 μm (+/−0.015 μm), and a fourth infrared filter having a fourth infrared transmission of 2.8 μm (+/−0.005 μm), said first infrared filter generating a discrete background infrared radiation wavelength, said second, third and fourth infrared filter each generating a discrete infrared radiation corresponding to CO2 and H2O gas emissions, each said filter directing said discrete infrared radiation wavelength onto an associated detector, and optical chopping means for interrupting the infrared radiation at a predetermined frequency before it reaches said spectral IR filters.