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 housing for housing and supporting a lens, an optical fiber, an optical chopper, and a plurality of infrared detectors;

• said lens for collecting infrared radiation from that portion of a flame nearest to an inlet to the turbine section and focusing said infrared radiation on a first end of said optical fiber, a second end of said optical fiber being held in a fixed relationship to said detectors so that infrared radiation transmitted by said fiber is projected 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 infrared radiation wavelength onto an associated detector, and an optical chopper for interrupting the infrared beam at a predetermined frequency before it reaches said first end of said optical fiber.