A new synthesis method for synthesizing on-axis flat-topped beams by using a defocusing telescope system
使用离焦望远镜系统合成轴上平顶光束的一种新方法

A new method for synthesizing on-axis flat-topped beams by using a defocusing telescope system is proposed, where the flat-topped multi-Gaussian beam is chosen as the ideal beam. Within the framework of the paraxial approximation and based on the Collins diffraction integral formula, the analytical expressions for the on-axis field and incident field are derived and analyzed physically. The effect of beam order N, flat-top length parameter L, position of the flat-top centre zc and central longitudinal spatial frequency Sc on the on-axis intensity distribution is illustrated by numerical examples. A comparison of our results with the method for simulating the ideal beam by use of the rectangular function shows the advantages of our method.