15 May 2012 Aero-optical jitter estimation using higher-order wavefronts
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Abstract
Wavefront measurements from wind tunnel or ight testing of an optical system are aected by jitter sources due to the measurement platform, system vibrations, or aero-mechanical bueting. Depending on the nature of the testing, the wavefront jitter will be a composite of several eects, one of which is the aero-optical jitter; i.e., the wavefront tilt due to random air density uctuations only. To isolate the aero-optical jitter component from recent testing, we have developed an estimation technique which uses only higher-order wavefront measurements to determine the jitter. Because these higher-order measurements are unaected by other jitter sources in the system, they can be used regardless of the additional sources of jitter in the test conguration. By analogy with work done previously with free-stream turbulence, we have developed a minimum mean-square error (MMSE) estimator using higher-order wavefront modes to compute the current-frame tilt components through a linear operation. The estimator is determined from computational uid dynamics (CFD) evaluation of aero-optical disturbances, but does not depend on the strength of such disturbances. Applying this technique to turret ight test data, we found aero-optical jitter to be 25 ± 2 μrad/m and to scale with (p/pSL)M2Dt (~ 1 μrad in the actual test cases examined.) The half-power point of the aero-optical jitter variance was found to be ~2u(see manuscript)Dt and to roll off in temporal frequency with a power law between f-11/3 and f-10/3.
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Matthew R. Whiteley, Matthew R. Whiteley, David J. Goorskey, David J. Goorskey, Richard Drye, Richard Drye, } "Aero-optical jitter estimation using higher-order wavefronts", Proc. SPIE 8395, Acquisition, Tracking, Pointing, and Laser Systems Technologies XXVI, 83950E (15 May 2012); doi: 10.1117/12.921877; https://doi.org/10.1117/12.921877
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