Measurement of gas-phase temperatures in flames with a point-diffraction interferometer

Experiments were performed to evaluate the performance of a point-diffracti on interferometry (PDI) system to measure gas-phase temperatures in flames. PDI is an interferometric technique that creates the reference beam after the laser beam passes through the test section and directly provides the in dex of refraction in two dimensions. PDI-based temperature measurements wer e compared with thermocouple measurements of two-dimensional and axisymmetr ic thermal boundary layers, as well as two-dimensional and axisymmetric dif fusion flames. The PDI system provided excellent agreement in the measureme nt of thermal profiles in the boundary layers and was within the uncertaint ies that are due to the radiation corrections for the thermocouple-based fl ame temperature measurements. (C) 2001 Optical Society of America.