【摘要】 贝塞尔光束由于具有无衍射传输特性和自恢复特性而被广泛应用于粒子捕获和生物光子学等领域.采用柯林斯衍射积分公式研究了贝塞尔光束经过小直径圆孔障碍物后在无衍射传输区域以外的衍射特性,并利用直径为100μm和150μm的圆孔障碍物进行了实验验证.结果表明,在圆孔所确定的无衍射传输区域以外,衍射光斑不再符合贝塞尔结构分布,而是外环较亮、中心较弱,同时存在多个更弱中间圆环的多环结构,环数与圆孔允许通过的贝塞尔光束环数一致,各环尺寸随传播距离线性发散.另外,根据模拟结果,在衍射区域以外的"中空"演化现象随着圆孔障碍物孔径的增大逐渐明显,且各环的光强维持恒定比值,不随传输距离改变.通过对贝塞尔光束过小孔径圆孔障碍物后的衍射特性研究,进一步丰富了当前的贝塞尔光束衍射传输理论,对贝塞尔光束的应用研究具有指导意义.更多还原

【Abstract】 Bessel beams are widely applied in such fields as particle trapping and biophotoics for their diffraction-free transmission and self-reconstructing properties. In this paper,the Collins diffraction integral formula is adopted to study the diffraction properties of a Bessel beam beyond the diffraction-free zone when it passes through aperture obstacles with small diameters,and apertures with diameters of 100 μm and 150 μm are applied respectively for experimental verification. According to simulation and experimental results,the beam profile does not fit a Bessel function any longer after it passes through the diffraction-free zone. Instead,the beam has a bright outer ring,a weak central spot and several weaker rings between them. The number of the rings is equal to that of the Bessel beam allowed by the aperture,and the diameters of the rings diverge linearly with propagation distance. In addition,according to simulation,a hollow beam becomes more obvious outside the diffraction-free zone with an increase of the aperture diameter,and the intensity ratio of the rings remains the same when the propagation distance changes. The results of the study on the diffraction properties of the Bessel beam after small apertures can fur-ther enrich the current knowledge on Bessel beam diffraction,and are valuable for further applications of the Bessel beam as well.更多还原