根据传统轴棱锥法产生Bessel光束的原理和凹透镜的几何光学效应, 设计并模拟了一套提高Bessel光无衍射距离的光学系统。利用凹透镜的发散特性, 将其分别放置在轴棱锥的前方与后方, 使用Math CAD软件进行模拟并与传统轴棱锥法进行比较, 得出结论: 在轴棱锥前方放置凹透镜使Bessel光的无衍射距离从244 mm增大至638 mm, 同时增大中心光斑半径。在轴棱锥后方放置凹透镜使Bessel光的无衍射距离从244 mm增大至406 mm。使用He-Ne激光作为光源进行实验验证, 实验结果与理论分析及仿真模拟基本一致。可根据实际要求选择凹透镜的曲率半径和位置, 得到无衍射距离较大、质量较高的Bessel光束。

A new optical system to increase the Bessel beam′s diffraction-free distance was designed and simulated based on traditional axicon method and geometric optical effects of concave lens. In the system, the concave lens was placed in front or in rear of the axicon. By simulating this program with Math CAD and comparing with traditional axicon method, some results were obtained that the diffraction free distance was increased from 244 to 638 mm, with central spot magnified when the concave was placed in front, and was increased to 406 mm when the concave was placed in rear. He-Ne laser was used as light source, the experimental results are consistent with the theoretical analysis and numerical simulation. Therefore, a certain curvature radius of the concave lens and the position according to actual requirements can be chosen to obatin the Bessel beam with a longer diffraction free distance and higher quality.