Multiple aperture approach to wavefront prediction for adaptive-optic applications

Matthew R. Kemnetz, Stanislav Gordeyev
2017 55th AIAA Aerospace Sciences Meeting   unpublished
A multiple aperture approach for the correction of aero-optical distortions is presented. Measurements were conducted in Notre Dame's Tri-Sonic facility at M = 0.2 at 40kHz with an Ap/δ ≈ 6. In this work we investigated the convective nature of the wavefront in order to verify previous work as well as test the limits of a simply convective assumption. We present two models for wavefront correction, a simply convective model and a linear convolution approach. We found that for a separation of
more » ... a separation of ∆/δ ≈ 3 − 4 a simply convective model of wavefront propagation was not sufficient to characterize the downstream wavefront from upstream data. POD analysis showed that although the large scale structure of the wavefront primarily convects, the small scale structure of the wavefront quickly loses correlation as the separation increases. The convecting-only assumption was then replaced with the time-delayed linear convolution, where information over several sequential time points in the upstream location were used to predict the downstream wavefront. If the first 40 POD modes were used in predicting the downstream wavefront, the reduction of the overall wavefront error was found to be -8 dB for the small separation of ∆/δ = 1 and nearly -5 dB for the largest separation of ∆/δ = 4.
doi:10.2514/6.2017-1344 fatcat:xyypym2oz5hm3hoihc4ezjniue