Holographic interferometer for aerodynamic flow analysis

A holographic interferometer with a circular, 140 mm diameter field developed by the ONERA Fluid Mechanics Laboratory is presented, emphasizing the instrument's construction and its implementation in a wind tunnel. Some advantages of the interferometer include a wind tunnel passage which can vary from 645 mm to 1140 mm, the location of the laser head on top of the beam which ensures an easy replacement, and the protection of light paths from the air's refraction index gradients and surrounding light. The optical design, which features the possible adjustment of the R/T ratio by acting on the polarization direction of the rectilinear radiation emitted from the laser is discussed.