Propagation of High-Energy Laser Beams through the Earth's Atmosphere

摘要

This paper surveys work in analysis and computer modeling of adaptive opticshardware, especially in the context of compensation for thermal blooming. Discussed is an analytical theory of thermal blooming phase-compensation instability (PCI) incorporating the actuator geometry of real deformable mirrors and wavefront sensors; we also discuss novel algorithms for computer simulation of adaptive optics hardware. This analytical formalism makes possible a quantitative analysis of the effects of the adaptive-optics control system on PCI, and also leads to a universality theorem for PCI growth rates under certain control-system assumptions. It also leads to the recognition that wind has a stronger effect on PCI growth rates than previously thought. Simulation algorithms discussed here include models of a Hartmann wavefront sensor, multidither adaptive optics, and a null-seeking servo. Analysis and algorithms are illustrated with output from MOLLY, a computer simulation of time-dependent adaptively-compensated laser propagation through turbulence and thermal blooming, optimized for the Cray-2 supercomputer. Of particular note is a comparison between MOLLY output and data from a laboratory study of phase-compensation instability. Reprints. (jhd)