相干合成光束在湍流大气中的传输

分析了湍流大气对相干合成光束传输的影响,根据广义惠更斯-菲涅耳原理,对相干合成光束在不同强度湍流大气中传输进行计算,对接收平面处的光强分布的统计特性,如桶中功率(PIB)曲线、局部功率曲线进行比较.研究结果表明,较弱的湍流大气对相干合成光束的传输影响较小,接收平面的光强分布以及PIB曲线基本不变;随着湍流强度的增大,相干合成光束的光强分布和PIB曲线产生显著变化,光斑扩展和能量的弥散速度加快,光束的能量集中度显著降低.计算了湍流大气传输后光束的空间相干度,认为空间相干度下降是降低相干合成效果的原因,对如何降低湍流大气的影响进行讨论.

Propagation of Coherently Combined Laser Beam in Turbulent Atmosphere

The effect of turbulent atmosphere on the propagation of coherently combined laser beam is studied. Propagation of coherently combined laser beam in turbulent atmosphere is numerically calculated by using generalized Huygens-Fresnel principle. The statistical characteristics, i.e. power in the bucket (PIB) curve and fractional power curve are calculated. It is revealed that the propagation of coherently combined beam suffers less in weak turbulence, and the irradiance distribution and PIB curve in the receiving plane are the same as its counterparts in free space. However, the beam spot will spread faster as the effect of turbulence gets stronger, and the energy centrality reduces evidently. The spectral degree of coherence of laser beam after propagation in the turbulent atmosphere is calculated. It is revealed that degrading in beam coherence causes the declining of coherent combinination. The way for eliminating the effect of turbulent atmosphere is discussed.