Turbulence-Aberrated Laser Wavefront Profiling With Shack-Hartmann Microlenses

This study focuses on experimental profiling of turbulence-aberrated laser wavefronts using a Shack-Hartmann (S-H) microlens array as a means of investigating the aero-optical effects that large-scale turbulence properties have on propagated laser wavefronts. Imaging of the phase and intensity of laser sheets propagated through separated turbulent compressible shear layers, which cause the laser wavefront to become aberrated, is performed under the following flow conditions; Re ∼ 6×10⁶ based on visual thickness and M_∞ ∼ 0.9. The data captured by the S-H sensor enables the direct determination of the laser optical wavefront profile. The optical wavefront profile provides path-integrated information regarding the refractive turbulence field and interfaces. The optical wavefronts are compared with laser induced fluorescence images of the refractive fields and interfaces taken simultaneously which allows for verification of computational methods of analyzing the optical wavefront within the flow. The present work validates the use of laser wavefront profiling as a means for detecting information about the refractive turbulence properties.