无衍射光束聚焦后的重建与矫正

基于衍射理论分析了无衍射光束聚焦后重建现象.导出重建后的光场分布表达式,数值模拟了重建光束的光强分布.结果表明,重建光束中心光斑较聚焦前的无衍射光束中心光斑大,而且重建后的光束有较大的发散角,光束随着传输很快扩散,光强迅速衰减.此类光束的应用受到限制.利用另一正透镜对重建后的光束加以矫正.并且由几何光学知识,得到了改变重建光束参量的方法,研究结果拓宽了无衍射光束的应用.用体视显微镜和CCD照相机组成的系统拍摄光束强度分布,实验结果与理论计算相吻合.

Reconstruction and Rectification of Non-Diffracting Beam after Focusing

Based on Huygens-Fresnel diffraction integral theory, the reconstruction phenomenon of non-diffracting beam after focusing was demonstrated. The propagation expression of the reconstruction beam was deduced. Using the expression, the intensity distribution of the reconstruction beam was simulated. The results show that the intense central spot size of the reconstruction beam is larger than that of the non-diffracting beam before focusing. The reconstruction beam has a divergent angle, so the intensity of the beam attenuates with the propagation distance. It limits the applications of the reconstruction beam. To rectify the divergence of the reconstruction beam, a second lens was introduced. According to the geometrical optics, the method to change the reconstruction beam parameters was given. In the experiment, the profiles of the transverse intensity of the reconstruction beam in different propagation distances were captured using the optical system of microscope and CCD-camera, the results confirmed by numerical calculation.