Fourier transform phase difference method optimization for supersonic gas flow characterization

摘要

In this work we propose a complete characterization method for supersonic gas flow. The optical phase of fringe patterns acquired in a simple Mach Zehnder interferometer is extracted with a differential phase evaluation method based on Fourier Transform (without translation to the frequency origin); reducing the computation steps and decreasing the errors due to the unwrapping process. Optical phase, gradient and Laplacian maps obtained allow detailed analysis of the pressure distribution, and shock wave patterns. We optimize phase evaluation process by studying and comparing effects of four different bandpass filters on phase maps by using quality maps as estimator.