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Activity title

Modelling, Measuring and Mitigating Optical Turbulence: M3T

Activity Reference

SET-ET-118

Panel

Sensors & Electronics Technology

Security Classification

NATO UNCLASSIFIED

Status

Planning

Activity type

ET

Start date

2019

End date

2020

Keywords

Adaptive Optics, Image, Laser Beam, Modeling, Optical Turbulence Propagation, Performance Improvement, Quality Metric, Target in the Loop

Background

Increasing range and/or resolution of Electro-optics (EO) systems (including laser systems) is more and more challenging. Turbulence in the path between target and EO systems degrades the performance of imaging systems, laser communications, beam delivery systems, and directed energy weapons. This can include turbulence in air and in underwater scenarios. To overcome turbulence-induced limitations, mitigation techniques can be applied. Adaptive Optics (AO) systems are more efficient for laser beam delivery systems, while data processing is more suitable for visible/IR imaging sensors. However, the higher the turbulence between target and EO systems, the lower the effectiveness of these techniques. Better understanding of turbulence-induced effects ènables improved military capabilities by development of equipment with extended range and knowledge of the limitations of EO systems in operational conditions. Previous SET RTG (165 and 226) investigated the effects of turbulence on imaging and laser systems performance over long ranges, including, via a multi-national field trial in Quebec, Canada, collecting and processing data for verification of models and simulations. Preliminary methods were proposed and successfully tested to characterize the propagation channel. Operation at extended ranges and for a wider variability of weather conditions will require novel modeling approaches. An extension of the methods for profiling the turbulence along the path in both air and underwater EO systems application will provide a better knowledge of its effects on system performance. To evaluate turbulence effects and mitigation techniques effectiveness, relevant performance metrics must be defined and assessed. Finally, the results of this research need to be implemented in guidelines for new EO systems.

Objectives

To design a concurrent modelling, simulation and measurement trial which will be conducted in a follow-on TG, whose purpose is to collect experimental data and compare with modeling and simulation results. The TG will focus on: 1) laser beam and image propagation in deep turbulence conditions, 2) turbulence characterization for both air and underwater applications; 3) system performance metrics evaluation; and 4) mitigation techniques development and assessment thereof. This ET will also define an IEEE Signal Processing Cup Challenge for evaluating emerging image restoration algorithms that will exploit field trial data.

Topics

• Turbulence characterization: Turbulence profiling in 3D (example: non-homogenous turbulence in coastal regions; interface marine-land environment) • Performance metrics for atmospheric turbulence effects and mitigation techniques evaluation • Mitigation techniques evaluation in case of 1) laser beam delivery : New sensors, Adaptive Optics concepts, Innovative Optical designs, Effect of the target structure and surfaces on Target in the Loop beam delivery and directed energy beams 2) image processing : participation to IEEE SP Cup Challenge to evaluate emerging algorithm performance, Reflection on real-time image processing and robustness

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