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从Collins公式出发 ,研究了平顶高斯光束通过光阑透镜的焦移 ,并用大量数值计算例予以说明。研究表明 ,截断平顶高斯光束的焦移不但由光束的阶数N、光束菲涅耳Fw 决定 ,还与孔径菲涅耳数Fa 有关。与无光阑情形比较 ,对于光阑透镜 ,即使在Fw 很大的情况下 ,仍然存在焦移。
Based on the Collins formula, the focal shift of a flat-topped Gaussian beam passing through the aperture lens is studied and a large number of numerical examples are given to illustrate this. The results show that the truncation of the flat-topped Gaussian beam is not only determined by the order N of the beam but also by the Fresnel Fw beam, which is also related to the aperture Fresnel number Fa. Compared with the case without diaphragm, for the diaphragm lens, even in the case of Fw is very large, there is still a focal shift.