Turbulence Profiling Using AAOL-BC

Kalensky, Matthew; Jumper, Eric J.; Whiteley, Matthew R.; Diskin, Yakov; Gordeyev, Stanislav; Drye, Richard; Archibald, Aaron; Grose, Mitchell

doi:10.2514/6.2020-0682

Cited by 10 publications

(3 citation statements)

References 21 publications

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“…As such, it is desirable to quantify the atmospheric-optical-turbulence environments in which these systems operate in order to 1) predict system performance and 2) make system design decisions which appropriately account for the degradation to performance imposed by the atmosphere. [1][2][3] However, turbulence strength is variable and depends on location, weather, and diurnal changes, to name a few. Therefore, it is desirable to develop approaches which can easily and robustly characterize optical-turbulence strength.…”

Section: Introductionmentioning

confidence: 99%

Optical-turbulence characterization of a littoral test environment using a Shack-Hartmann wavefront sensor

Bukowski,

O'Sullivan,

Kalensky

et al. 2023

Unconventional Imaging, Sensing, and Adaptive Optics 2023

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Beam propagation systems are often used in a wide range of atmospheric environments. Therefore, it is important to be able to characterize those environments in order to appropriately assess performance and inform design decisions. In this paper, a variety of methods for measuring atmospheric coherence length, r0, were analyzed including a Shack–Hartmann-based differential image motion monitor (DIMM), gradient-tilt variance, slope discrepancy variance, and phase variance methods, as well as using the modulation transfer function (MTF). These methods were tested on varying turbulence strength environments with known atmospheric coherence lengths, first using a single modified von Kármán phase screen, then using full wave-optics simulations with 20 phase screens. The Shack–Hartmann based approaches were shown to greatly increase in error for d/r0> 1 due to discrepancies between gradient tilt and the centroid tilt measured from the SHWFS’ image-plane irradiance patterns. An atmospheric data collection system was built and experimental results were taken for a beam propagating 2.4 km through a littoral environment over a 24 hour period.

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Section: Introductionmentioning

confidence: 99%

Optical-turbulence characterization of a littoral test environment using a Shack-Hartmann wavefront sensor

Bukowski,

O'Sullivan,

Kalensky

et al. 2023

Unconventional Imaging, Sensing, and Adaptive Optics 2023

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“…In order to better understand the underlying physics associated with these aero-optical aberrations, extensive lab-based 2-5, 7, 8, 14-17 and aircraft-based 6,[18][19][20][21][22][23][24][25][26] testing has been conducted in recent years. While many foundational aero-optical experiments and analyses have been conducted, there is still much to learn about the coupling of fluidic properties and optical aberrations.…”

Section: Introductionmentioning

confidence: 99%

Experimental and computational investigation of laser beam propagation through a free shear layer

Wells,

Kalensky,

Rennie

et al. 2023

Unconventional Imaging, Sensing, and Adaptive Optics 2023

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Experimental Shack–Hartmann Wavefront Sensor (SHWFS) measurements were collected and examined to further understand image-plane irradiance pattern behavior in the presence of potentially sharp thermodynamic gradients. An analysis of path-integrated phase and image-plane irradiance pattern spreading discovered regions within a weakly compressible shear layer where sharp gradients were previously not observed. This paper describes the analysis process and shows results which suggest that Shack-Hartmann wavefront sensors are not adequately resolving sharp thermodynamic gradients in aberrating flows.

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“…4 In a recent publication, a double-sided PROPS was used to profile turbulence between an airborne platform and a ground station. 5 Phase-based techniques have the potential to be used over long ranges since they do not suffer from saturation.…”

Section: Introductionmentioning

confidence: 99%

Profiling atmospheric turbulence using a non-cooperative target and a camera bank and validating with sonic anemometers

Wilson

Imeri

Bose‐Pillai³

et al. 2022

Unconventional Imaging and Adaptive Optics 2022

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Knowledge of turbulence distribution along a path can be useful for effective compensation in a highly anisoplanatic situation. In an earlier work, a method to profile turbulence using time-lapse imagery of a distant building from two spatially separated cameras was demonstrated. By using multiple cameras instead of just a pair, the profiling resolution as well as the fraction of the path that can be reasonably profiled can be improved. This idea is demonstrated by using 5 spatially separated cameras capturing images of a distant target with features on it. Extended features on the target are tracked and by measuring the variances of the difference in wavefront tilts sensed between cameras due to all pairs of target features, turbulence information along the imaging path can be extracted. The mathematical framework is discussed and the profiling results are compared against point measurements from a 3D sonic anemometer placed onboard an unmanned aerial system which is driven along the imaging path. The method is relatively low cost and does not require sophisticated instrumentation. Turbulence can be sensed remotely from a single site without deployment of sources or sensors at the target location. Additionally, the method is phase-based, and hence has an advantage over irradiance-based techniques which suffer from saturation issues at long ranges. By imaging elevated targets in the future, turbulence changes with altitude can be investigated as well.

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Turbulence Profiling Using AAOL-BC

Cited by 10 publications

References 21 publications

Optical-turbulence characterization of a littoral test environment using a Shack-Hartmann wavefront sensor

Optical-turbulence characterization of a littoral test environment using a Shack-Hartmann wavefront sensor

Experimental and computational investigation of laser beam propagation through a free shear layer

Profiling atmospheric turbulence using a non-cooperative target and a camera bank and validating with sonic anemometers

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