title: Speckle-metric-optimization-based adaptive optics for laser beam projection and coherent beam combining.
abstract: Maximization of a projected laser beam's power density at a remotely located extended object (speckle target) can be achieved by using an adaptive optics (AO) technique based on sensing and optimization of the target-return speckle field's statistical characteristics, referred to here as speckle metrics (SM). SM AO was demonstrated in a target-in-the-loop coherent beam combining experiment using a bistatic laser beam projection system composed of a coherent fiber-array transmitter and a power-in-the-bucket receiver. SM sensing utilized a 50 MHz rate dithering of the projected beam that provided a stair-mode approximation of the outgoing combined beam's wavefront tip and tilt with subaperture piston phases. Fiber-integrated phase shifters were used for both the dithering and SM optimization with stochastic parallel gradient descent control.
authors: Intelligent Optics Laboratory, School of Engineering, University of Dayton, 300 College Park, Dayton, Ohio 45469-2951, USA. mikhail.vorontsov@udayton.edu
authors: Mikhail
authors: M
authors: Vorontsov
authors: Thomas
authors: T
authors: Weyrauch
authors: Svetlana
authors: S
authors: Lachinova
authors: Micah
authors: M
authors: Gatz
authors: Gary
authors: G
authors: Carhart