ABSTRACT
Mach–Zehnder shearing holographic interferometry was successfully applied for studying shock flows over different aerodynamic models in a supersonic wind tunnel. The proposed optical scheme of a diffraction shear interferometer demonstrates a high tolerance to acoustical disturbances of powerful aerodynamic facilities. A high level of stability allows recording of signal holograms during the run of a facility using CW helium–neon and argon ion lasers. The holographic shearing interferometer was designed in the Supersonic Wind Tunnel Laboratory (the Technion) to perform real-time interference measurements. This chapter discusses preliminary results on optical diagnostics of bow shocks in a supersonic wind tunnel by applying a dual hologram shearing interferometry technique. A strong refraction effect of the probing beam penetrating the region in the vicinity of a bow shock over a blunt nose cone model has been discovered. Microscopy made it possible to accurately study the structure of a shock flow and measure spatial frequencies of signal holograms.
