Outdoor target-in-the-loop coherent beam combination using a stochastic parallel gradient descent algorithm

Matts Björck; Markus Henriksson; Lars Sjöqvist

doi:10.1117/12.2599744

12 September 2021 Outdoor target-in-the-loop coherent beam combination using a stochastic parallel gradient descent algorithm

Matts Björck, Markus Henriksson, Lars Sjöqvist

Author Affiliations +

Proceedings Volume 11867, Technologies for Optical Countermeasures XVIII and High-Power Lasers: Technology and Systems, Platforms, Effects V; 118670E (2021) https://doi.org/10.1117/12.2599744
Event: SPIE Security + Defence, 2021, Online Only

Abstract

This work presents a coherent beam combination (CBC) setup that consists of a four square tiled-aperture system with phase and tip-tilt control for each sub-beam. The system works at a wavelength of 1550 nm. Phase locking was performed with the stochastic parallel gradient descent (SPGD) algorithm, using the power reflected by a remote retro reflecting corner cube to a feedback detector located at the laser head. Experiments were performed for targets located at distances of 470 and 870 m during calm and partly cloudy conditions. The SPGD beam combining results are discussed and compared to optical wave propagation simulations. The optical wave propagation models that have previously been validated in a laboratory setting were extended to include atmospheric turbulence. In order to reproduce the experimental results it was important to include the propagation of the feedback signal from the retroreflector to the detector.

Conference Presentation

Citation Download Citation

Matts Björck, Markus Henriksson, and Lars Sjöqvist "Outdoor target-in-the-loop coherent beam combination using a stochastic parallel gradient descent algorithm", Proc. SPIE 11867, Technologies for Optical Countermeasures XVIII and High-Power Lasers: Technology and Systems, Platforms, Effects V, 118670E (12 September 2021); https://doi.org/10.1117/12.2599744

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