椭圆高斯光束产生近似无衍射Bessel-Gauss光

研究了轴棱锥聚焦像散椭圆高斯光束的光场分布特性,根据菲涅耳衍射积分理论导出了椭圆高斯光束经轴棱锥衍射后的光场分布,通过数值积分给出椭圆高斯光束经轴棱锥聚焦后的近轴光场强度分布情况,将其与圆高斯光束产生的近似Bessel-Gauss场进行比较,发现椭圆高斯光束经轴棱锥聚焦后的光束在一定的传播距离内也具有无衍射特性,且轴上光强分布与圆高斯光束产生的Bessel-Gauss光束的轴上光强分布具有相似的形式,而这种无衍射光场的强度在垂直于光轴的平面上不再是柱对称分布。根据近轴球面波产生近似Bessel光束的最大无衍射距离公式计算了椭圆Bessel-Gauss光束在子午面和弧矢面上的最大无衍射距离,整个光束的无衍射距离由入射到轴棱锥上的椭圆光斑短轴方向的尺寸决定。

Generation of non-diffracting Bessel-Gauss like beam by elliptical Gauss beam

The distribution of the optical field generated by focusing an astigmatic elliptical Gauss beam using an axicon is studied and the formula of the optical field diffracted by the axicon is derived from Fresnel diffraction integral theory. The intensity of the optical field distribution is calculated by numerical integration. Comparing the field intensity generated by elliptical Gauss beam with the field intensity generated by impinging circular Gauss beam on an axicon, we find that the beam generated by an astigmatic elliptical Gauss beam also has the interesting property of non-diffraction in a certain propagation distance and the similar distribution of on-axis intensity of Bessel-Gauss beam generated by circular Gauss beam, however, the intensity of the optical field perpendicular to optical axis is not cylindrically symmetrical. The maximum non-diffracting lengths of elliptical Bessel-Gauss beam on meridional and sagittal planes are also calculated according to the maximum non-diffractive length formula of spherical wave generating quasi-Bessel beam, and the non-diffracting length of the whole beam is limited by the size of minor axis of incident elliptical spot on the axicon.