一种获得平顶激光光强分布的方法

An approach for achieving flattened laser intensity profile

从ＨｕｙｇｅｎｓＦｒｅｓｎｅｌ衍射积分出发，计算高斯光束经过初级球差透镜聚焦之后的衍射光场。数值结果表明，当透镜的球差系数为负时，在聚焦光场的两个位置，得到了平顶激光光强分布。还讨论了透镜的菲涅耳数对平顶激光光强分布及其出现位置的影响。结果表明，透镜的菲涅耳数愈小，出现平顶激光光强分布的位置愈往聚焦透镜移动。并且，当透镜的菲涅耳数较小时，平顶激光光强分布的顶部呈现光强调制。计算结果表明，负球差透镜可作为获得平顶激光光强分布的简单方法。

Focusing of Gaussian beam by an apertured lens with spherical aberration is calculated,based on Huygens Fresnel diffraction integral.The numerical results show that,when the coefficient of the spherical aberration is negative,one can obtain flattened laser intensity profile in two positions along the focused field.The effect of the limited aperture of the lens on the flattened laser intensity profile is investigated.It is shown that when Fresnel number of the lens become small,the positions where flattened laser intensity profile occur shift towards the focusing lens,and the lens with negative spherical aberration may be a simple approach for achieving flattened laser irradiance.