A thermometry technique based on atomic lineshapes using diode laser LIF in flames

We report on the development of a novel diode laser thermometry technique permitting temperature measurements in flames based on the fluorescence lineshapes of an atomic tracer species. The technique, which we term OLAF (one-line atomic fluorescence) requires only a single diode laser source for excitation, is simple to implement, and has excellent spatial resolution. Temperatures are deduced from the 5²P_1/2 → 6²S_1/2 transition of atomic indium, the lineshape of which is highly sensitive to temperature changes at typical flame conditions. A rigorous validation is performed in a reference flame with comparisons to measurements by CARS and by Na-line reversal, and to numerical simulations.