Thermal-Blooming Laboratory Experiments

• We conducted a multiphase series of laboratory experiments to explore the adaptive optics compensation of a laser beam distorted by strong thermal blooming. Our experimental approach was to create on a small, low-power beam the same phase distortion that would be experienced by a large, high-power beam propagating through the atmosphere and to apply phase compensation via deformable mirrors. We performed the investigations to lay the foundation for future ground-based laser experiments and their corresponding atmosphericpropagation computer models. The experiments had three primary objectives: to provide a controllable, repeatable means of obtaining data for the verification and benchmarking of computer codes, to investigate the different phase-compensation instability (PCI) mechanisms th~t were predicted by theQry and computer code, and to gain information relevant to the design of adaptive optics systems for groundbased laser propagation. The experiments were successful in realizing all tluee objectives: we observed the first experimental evidence of PCI and achieved excellent agreement between experimental results and computer-code . predictions. In addition, the work provided valuable insight to the role of adaptive optics hardware in influencing high-energy beam propagation and to the importance of incorporating realistic hardware models into propagation codes.