14 March 2013 Large-aperture approximation for not-so-large apertures
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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.
© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)
Christopher Porter, Christopher Porter, Stanislav V. Gordeyev, Stanislav V. Gordeyev, Eric J. Jumper, Eric J. Jumper, } "Large-aperture approximation for not-so-large apertures," Optical Engineering 52(7), 071417 (14 March 2013). https://doi.org/10.1117/1.OE.52.7.071417 . Submission:


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