Planar Imaging of Shock Waves at Low Pressure using Filtered Rayleigh Scattering

Spatially resolved two-dimensional density distributions have been obtained of a subatmospheric shock wave using filtered Rayleigh scattering (FRS) of laser light, in which an iodine vapor cell filter is used to block elastic light scattering from windows, walls, and dust particles. Filtered and unfiltered Rayleigh scattering images of the shock at a pressure of 14 Torr are compared, revealing that the filtered approach greatly reduces interference from scattering of laser light off dust particles and nearby surfaces. These findings demonstrate the feasibility of using FRS in an onboard instrument for hypersonic and high altitude flow fields.