trifid

Based on Kirchhoff s theory,the approximate formulas of a filament diffraction of Gaussian beam is derived under paraxial approximation,And the characteristics that the middle spot divided into three parts is emerged by the numerical calculated and computer simulate.

依据基尔霍夫衍射理论,利用幂级数展开的方法推导出旁轴条件下高斯光束的单丝衍射的近似计算公式,并通过计算机模拟的方法再现了单丝衍射主极大区的三分裂特性,得出一些与其他文献〔1〕及实验结果相一致的结论。