聚焦柱面光束的等效菲涅耳数及焦移

Effective Fresnel Number and Focal Shifts of Focused Cylindrical Light Beams

定义了平面波入射柱面透镜的等效菲涅耳数,并基于等效菲涅耳数的含义,利用一种新的简单的方法研究了平面波入射柱面透镜的聚焦光场的聚焦特性。结果显示,聚焦光场的相对焦移可以用一个简单的解析表达式来计算,即表示为等效菲涅耳数的函数。为了说明等效菲涅耳数的定义,将由这种简单的新方法得到的结果与基于衍射积分的数值计算得到的结果进行比较,结果显示,两种方法得到的结果吻合的很好。因此,可以用这种新方法来简单而准确地计算相对焦移。

We define the effective Fresnel number of the cylindrical lens illuminated by plane wave. Based on the concept of the effective Fresnel number, the focusing properties of the cylindrical lens illuminated by the plane wave are investigated in a simple way. It is shown that the relative focal shift can be evaluated by an analytical formulation, which is expressed as a function of the effective Fresnel number. To evaluate our approach, we make the comparison between the results obtained by this new method and the numerical calculation based on the diffraction integral. The results indicate that we can simply and exactly evaluate the focal shifts with this new method.