基于汉克尔波理论和衍射积分理论详细分析了轴棱锥对无衍射光束的线聚焦特性,提出了一种产生周期性局域空心光束的新方法,即无衍射贝塞尔光束经过轴棱锥聚焦后产生具有塔尔博特效应的局域空心光束.数值模拟了无衍射贝塞尔光束照射轴棱锥后,沿传输距离变化的光强分布及一个周期内光强的演变和局域空心光束的形成过程.设计实验系统,由He-Ne激光经过一套光学系统后透过轴棱锥,产生近似无衍射贝塞尔光束,再由第二个轴棱锥对产生的无衍射贝塞尔光束进行线聚焦,在第二个轴棱锥后面由显微镜观测到周期性局域空心光束,并用CCD照相机拍摄了两个周期内的光斑图,实验结果和理论分析相符合.研究结果可用于多层面微粒的操控,对周期性局域空心光束在光学微操控领域的应用具有重要的指导意义.
The line focusing characteristics of axicon illuminated by non-diffracting Bessel beam was analyzed in terms of Hankel theory and diffraction integral theory, and a new kind of method to generate periodic bottle beam was put forward, i.e. Talbot effect bottle beam was generated by axicon illuminated by non-diffracting Bessel beam. Intensity distributions along the propagation path and the intensity evolution of the bottle beams in a complete period after the axicon illuminated by non-diffracting Bessel beam were simulated numerically. An optical system was designed and Bessel-like beam was obtained by light wave emitted from He-Ne laser passing through axicon after the optical system, and then an axicon was used to focus the Bessel-like beam. Periodic bottle beam was then observed after the axicon, and the spot diagram of two periodics were taken by a CCD camera. Experimental results agree well with the theoretical analysis. This result has a practical significance in multi-plane micro-manipulation and may serve as a guideline in optical micro-control by periodic bottle beam.