Design and calibration of a planar imaging system for OH and O2 measurements in high-temperature, large-scale facilities

Abstract

A planar laser-induced fluorescence (FLIP) imaging system for measurements of OH concentration and qualitative imaging of high-temperature O2 in large-scale combustion facilities has been developed. A tunable KrF laser is used to excite rotational transitions in the OH A£V = 3)-Xn(j< = 0) and O2 P?TU (v' = G)~X E~ (v = 6) bands. Excitation and emission transition selections were guided by considerations of the expected thermodynamic conditions, beam attenuation, fluorescence trapping, temperature insensitivity, and mutual fluorescence interference. Absolute OH concentration is derived from the fluorescence signal by a separate calibration. The system was optimized for off-axis imaging with high collection efficiency. The ability of the imaging system to reject thermal luminosity was also assessed.