Quantitative Schlieren imaging based on fringe projection

An effective yet simple quantitative synthetic Schlieren imaging technique is presented in this paper. A multiplexed fringe pattern displayed on a common laptop screen is observed through a disturbed medium resulting in a change of the fringe pattern. Fourier analysis of such pattern provides high-resolution and almost real time measurement of rays' deflection due to the medium refractive index variation. The developed technique was applied for measurement of a compressible fluid discharge from a narrow channel in a wind tunnel.