推导出部分相干涡旋平顶光束的传输解析公式,并用以研究了聚焦场和自由空间中部分相干涡旋光束形成相干涡旋的特性.结果表明,相干涡旋与光束阶数N,空间相干参数α和参考点位置(x1,y1)有关.依赖于参考点的选择,光谱相干度可能存在零值点,也可能没有零值点.特别是,若选取x1=y1=0,光谱相干度零值点处的位相可以是确定的,因而不存在相干涡旋.
The analytical expression for the propagation of partially coherent flat-topped vortex beams through a paraxial optical ABCD system is derived and used to study the coherence vortex properties of partially coherent vortex beams in the focal region and free space. It is shown that the coherence vortex depends on the beam order N, spatial coherence parameter a and position ( x1, y1 ) of the reference point. Depending on the choice of the reference point, the zero point of the spectral degree of coherence may be present or absent. In particular,if x1= y1 = 0 is chosen,the phase at the zero point of the spectral degree of coherence may be determinate, thus the coherence vortex does not exist.