Effects of shock-related discontinuities on SHWFS measurements: modeling and simulation
Matthew Kalensky, Matthew R. Kemnetz, Mark F. Spencer
Abstract
Shock waves result from turning supersonic or locally supersonic flow and result in a large change in gas properties downstream of the shock. This change in gas properties, namely, the large increase in freestream density can affect the wavefront of a laser beam propagating through the shock. In this paper, analytic expressions are developed to describe the effects of these shock waves on the wavefront a laser beam propagating through the shock both parallel and on an angle relative to the shock direction. Furthermore, these near-field disturbances are then brought to a focus at the image-plane using a thin lens transmittance function with the Fresnel diffraction integral. The effects of the near-field disturbances imposed by the shock on the image-plane irradiance patterns are investigated and the implications of these image-plane irradiance patterns on Shack-Hartmann wavefront sensor measurements are also discussed.