厄米-余弦-高斯光束通过像散透镜的焦开关

应用惠更斯-菲涅耳衍射积分公式,研究了厄米-余弦-高斯光束通过像散透镜后的焦开关现象.数值计算结果表明,厄米-余弦-高斯光束通过有像散透镜的光学系统,在像散参数和光束菲涅耳数一定时,改变光学系统几何参数δ(即光束入射面到透镜的距离与透镜焦距之比),不仅在δ=1.O时发生通常所说的焦开关现象,而且在δ≠1.O时的其他位置也可以产生焦开关现象,即焦开关现象不仅可以在几何焦点处产生,也可以在几何焦点右侧或左侧产生.讨论了光束参数对焦开关的产生及其位置的影响;分析研究了在给定光束参数和光束菲涅耳数条件下,光学系统几何参数δ取不同值时,厄米-余弦-高斯光束通过像散透镜后的相对焦移随像散参数的变化规律.结果表明,可以通过改变光束参数和像散参数来控制焦开关发生的位置和产生焦开关的次数.

Focal Switch Of Herlnite-C0sine-Gaussian Beams Passing through an Astigmatic Lens

Based on the general Huygens-Fresnel diffraction integral formula, the focal switch effect of Hermite-cosine-Gaussian beams passing through an astigmatic lens is investigated in detail. The results of numerical calculations show that this kind of focal switch is dependent of the geometric parameter of the optical system δ, and the focal switch effect occurs regardless of whether the δ is 1.0 or not, i.e. the focal switches could occur not only at geometric focus but also at the right or the left of the geometric focus. The influence of beam parameter on the occurrence and the position of focal switches is discussed. The dependence of the relative focal shift on the astigmatic parameter is examined at different geometric parameters of the optical system δ for a particular beam parameter and Fresnel number. The result shows that the occurrence and the position of focal switches can be controlled by changing the beam parameter and astigmatic parameter.