Tunable Spatial Resolution Focused Laser Differential Interferometer for Density Fluctuation Measurement

We first propose and demonstrate a novel approach for achieving a focused laser differential interferometer (FLDI) system with tunable spatial resolution. The spatial resolution of the FLDI can be adjusted continuously between 83 mu m and 382 mu m. The density fluctuation of a supersonic shear flow is measured using the FLDI system with a spatial resolution of 182 mu m, and the density fluctuations at different locations of the supersonic shear flow are measured and analyzed. The ability to adjust the spatial resolution in this work is of great significance for enhancing the spatial resolution and flexibility of the FLDI system.