Two-photon digital imaging of CO in combustion flows using planar laser-induced fluorescence.

Two-dimensional imaging of CO distributions in combustion gases is demonstrated using planar laser-induced fluorescence. The illumination technique is based on the combination of a nonlinear absorption scheme, in which two photons at 230.1 nm excite several rotational transitions of the B (1)Sigma(+) ? X(1)Sigma(+) system, and the use of an ultraviolet multipass cell for producing the laser sheet. The subsequent visible fluorescence (B(1)Sigma(+) ? A (1)Pi) is imaged onto an intensified two-dimensional photodiode array. Experimental results are presented for carbon monoxide-air and methane-air flames.