本文介绍了非均匀部分相干光束的概念,并用数值模拟的方法详细研究了其在自由空间传输后的变化.研究结果表明,经过自由空间传输后非均匀部分相干光束会发生不同于传统相干模型光束的显著变化.这种变化和光束传输距离、光源空间相干度分布、光源光强分布密切相关.经过传输后,源平面自相干附近点的空间相干度发生突变,在短距离传输过程中源平面高相干区域的空间相干度会降低,接收面各点的空间相干曲线不再相同,随着传输距离增加,非均匀空间相干度会逐渐趋于均匀.
This paper introduces the concept of non-uniform partially coherent beams and investigates the spatial coherence change during beam propagation. Results show that non-uniform spatial coherence would make significantly changes during propagation, which is completely different from the classical beams. These changes have relationships with propagation distance, spatial coherence, and intensity distribution of the source. The points adjoining self-coherence area would mutate when beams propagate from the source; the high coherence area in the source may decrease after the beams propagate a short distance. Curves of spatial coherence would not overlap after propagation, while the spatial coherence tends to be uniform with increasing propagation distance.