平顶光束通过像散透镜的传输和光束参量的变化

对平顶光束通过像散透镜的传输和光束参量(包括束宽、束腰宽度和位置、远场发散角和M2因子)的变化做了研究.结果表明,像散使平顶光束在x方向的束腰宽度增加,远场发散角减小,实际焦点的位置远离透镜,而在y方向正相反.平顶光束的M2因子与像散无关.x、y方向束宽和远场发散角的相对误差随光束阶数,瑞利长度,像散系数和透镜焦距变化.当x、y方向的光束阶数和初始束宽相等时,几何焦面上两方向束宽的相对误差相等,但在实际焦面上不同.

Propagation of Flattened Beams Through an Astigmatic Lens and Changes in Their Beam Parameters

The propagation of flattened beams through an astigmatic lens and changes in their beam parameters,such as the beam width,waist width and position,far-field divergence angle and M2 factor were studied.It is found that the astigmatism gives rise to an increase of the waist width and a decrease of the far-field divergence angle in the x direction,and the real focal position shifts far away from the lens.The results in the y direction are in contrary.The M2 factor of flattened beams is independent of the astigmatism.The relative errors of the beam width and far-field divergence angle vary with the beam order,astigmatic coefficient,Raleigh length and focal length of the lens.The relative errors of the beam width in the x and y directions at the geometric focal plane are equal if the beam orders in the two directions and initial beam width are equal,whereas they are different at the real focal plane.