Toward Adaptive Optic Mitigation of Aero-Optic Effects

Abstract

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instrut maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate c suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be £ information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRL (From -To) 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 briefly reviews the mechanisms responsible for these aberrations in free-shear-layer flows. The report begins with describing an historic demonstration performed under this effort that combined the 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; this historic demonstration included a man in the loop. The report then describes the development of an automated control system that removes the man in the loop. Also described is some additional work performed under this grant that examined a spatial-filter approach to analyzing the effect of apertures on several aspects of laserbeam control. REPORT DATE (DD-MM-YYYY) 15-02-2009 REPORT TYPE FINAL REPORT DATES COVERED15 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services. Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204. Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENT UL SUPPLEMENTARY NOTES14. ABSTRACT This report describes aero-optic research at the University of Notre Dame. When a laser beam propagates through a variable-index-of-refraction, turbul...