为进一步完善多级无衍射光束的传输与变换理论, 拓展双级无衍射光束的应用范围, 根据轴锥镜法和菲涅耳衍射理论对双级无衍射光束的光场分布做了详细理论分析; 基于轴锥镜法搭建生成双级无衍射光束的实验平台, 获取了沿光轴传输至不同距离处的截面光斑及其光强分布, 探究了平行光束不同入射倾角对无衍射光束传输变换的影响.实验结果表明: 双极无衍射出射光场由四个区域组成, 在干涉重合区其光强为一、二级轴棱锥出射场的耦合叠加, 其余区域仍保持单级无衍射光束的传播特性, 其光强大小受轴棱锥透镜的入射光阑与透镜底角影响, 光斑破裂程度与平行光束的入射倾角呈正相关.本文对双极无衍射光束的空间传播特性、光强分布特性、光强影响因素等做了详细分析, 对拓展多级无衍射光束的应用具有指导意义.

In order to complete the transmission and transformation theory of multilevel non-diffracting beam and to expend the application range of two stage non-diffracting beam, the light field distribution of two stage non-diffracting beam was analyzed in detail on the basis of the axicon method and Fresnel diffraction theory. Based on the axicon method, an experimental platform for generating two stage non-diffraction beams is constructed. The cross section spots and their light intensity distributions transmitted along the optical axis at different distances are obtained. The influence of different incidence angles of parallel beams on the propagation and transformation of non-diffracting beams is investigated. Experimental results show that the two stage non-diffracting diffraction light field is composed of four regions, in the interference overlap region, the light intensity is the superposition coupling of the diffraction fields of the first and second axicons, the rest of the region remain the propagation characteristics of the single stage non-diffracting beam. The light intensity is influenced by the incident aperture and the bottom angle of the axicon lens. The rupture degree of the spot is positively correlated with the inclination of parallel beam. In this paper, the spatial propagation characteristics, the intensity distribution characteristics and the influence factors of the light intensity are analyzed in detail, which has an important directive significance to extend the application field of multilevel non-diffracting beams.