Simulation of deep turbulence compensation for a laser phased array

The performance of a 127 element phased array laser system is simulated for the case of an extended target in the presence of strong atmospheric turbulence. The phases of the individual sub-apertures of a phased array laser system can be controlled to compensate for the beam quality degradation caused by atmospheric turbulence. This is done by setting the phases of the sub-apertures to the conjugate of the phase received from a beacon located at the target. As the level of turbulence increases, the ability of an adaptive optics system to correct for turbulence decreases; the quality of this compensation decreases due to increases in both scintillation and fitting error. In the case where the laser system itself is used to create the beacon on an extended target, the quality of the beacon produced is also degraded by this atmospheric turbulence and this further impacts the quality of the compensation. This study simulates a 10 km tactical engagement to quantify the performance impacts due to turbulence, and the portion of this impact due to the inability of the system to form a perfect beacon in these conditions. Performance is measured by both Strehl ratio and power delivered within a near diffraction limited circle. Results are presented comparing uncompensated, compensated with a perfect beacon, and compensated with simulated beacon cases as the level of turbulence increases.