Adaptive Optics for Turbulent Shear Layers
Abstract
This report describes aero-optic research at the University of Notre Dame. When a laser beam propagates through a variable-index-of-refraction, turbulent fluid, its wavefront becomes aberrated, reducing associated optical-system performance. For flight Mach numbers as low as 0.3 Mach, turbulence in the flow past the aircraft become important in aberrating wavefronts (aero-optics). This report reviews the mechanisms responsible for these aberrations in free-shear-layer flows, the so-called Weakly-Compressible Model, which identifies the coherent structures in the flow as the major contributor to the flow's aberrating character. The report describes the use of flow control to regularize these coherent structures so as to reduce the bandwidth required by an adaptive-optic system to mitigate their effects. The report describes two historic demonstrations of the combined use of flow control and feed-forward adaptive optics to correct the aberrations imposed on an otherwise collimated laser beam projected through a heated jet and a Mach 0.8 free shear layer, respectively.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 20, 2006
- Accession Number
- ADA469562
Entities
People
- Eric J. Jumper
Organizations
- University of Notre Dame