Compressible boundary-layer density cross sections by UV Rayleigh scattering

Rayleigh scattering has been used to image density cross sections of a compressible boundary layer for the first time to our knowledge. These cross sections were made from a Mach 2.5 boundary layer by illuminating it with a UV laser sheet from an argon-fluoride laser (193 nm). Since Rayleigh scattering is linearly proportional to density, quantitative values are measured, which leads to new instantaneous and statistical information about the structure of this turbulent field.