Special Section on Aero-Optics and Adaptive Optics for Aero-Optics

Large-aperture approximation for not-so-large apertures

[+] Author Affiliations
Chris Porter

USAF Academy, Department of Aeronautics, Colorado 80840

Stanislav Gordeyev, Eric Jumper

University of Notre Dame, Department of Mechanical and Aerospace Engineering, Hessert Laboratory for Aerospace Research, Notre Dame, Indiana 46556

Opt. Eng. 52(7), 071417 (Mar 14, 2013). doi:10.1117/1.OE.52.7.071417
History: Received October 5, 2012; Revised February 22, 2013; Accepted February 25, 2013
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Abstract.  In-flight wavefront measurements around a flat-window turret at subsonic Mach numbers are analyzed in instantaneous and time-averaged sense. In addition to the root-mean-squared levels of aero-optical distortions, higher-order spatial statistics are calculated, and their dependence as a function of the viewing angle is discussed. Given the optical data obtained, the applicability of the commonly used large aperture approximation (LAA) is revisited. We show that, for all angles, the LAA consistently underestimates the time-averaged Strehl ratio, so the LAA should be used very cautiously. Some reasons for these discrepancies are traced to non-Gaussian spatial distribution of the optical wavefronts. A different approximation for computing time-averaged Strehl ratios is proposed, and the results are discussed.

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© 2013 Society of Photo-Optical Instrumentation Engineers

Citation

Chris Porter ; Stanislav Gordeyev and Eric Jumper
"Large-aperture approximation for not-so-large apertures", Opt. Eng. 52(7), 071417 (Mar 14, 2013). ; http://dx.doi.org/10.1117/1.OE.52.7.071417


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