Image blurring due to turbulent wakes for airborne systems: flight tests
Stanislav V. Gordeyev, Nicholas G. De Lucca, Eric J. Jumper, Yakov Diskin, Matthew R. Whiteley · 2017
Image blurring and resolution degradation due to aero-optical effects around a hemispherical turret were studied experimentally in-flight using AAOL-T program at subsonic and transonic speeds. A target board consisted of spoke patterns and three-bar groups with various sizes was used to quantify the image blurring. Aero-optical effects and related image blurring were measured simultaneously using synchronized high-speed cameras. Instantaneous wavefronts were used to compute point-spread functions and modulation transfer functions. It was demonstrated that point-spread functions were mostly axisymmetric over a wide range of viewing angles and could be faithfully approximated by the Gaussian ones. Image degradation was found to primarily dependent on the overall level of aero-optical distortions, expressed in waves, and less on spatial statistical properties of the wavefronts. Simulations of image resolution degradation using realistic aero-optical wavefront spectrum were shown to agree with experimentally-obtained results. Presented results and analysis provide means of estimating the image resolution degradation from statistics of the nearfield aero-optical distortions.