部分相干修正贝塞尔高斯光束通过球差透镜的聚焦特性

Focusing Properties of Partially Coherent Modified Bessel-Gauss Beams Passing Through a Lens with Spherical Aberration

由部分相干光的传输理论出发,对部分相干修正贝塞尔高斯光束通过球差透镜聚焦后轴上光强分布进行了研究.数值计算表明:当光谱相干度较小时,正、负球差对应的最佳聚焦点位于无球差时对应的最佳聚焦点的两侧;当光谱相干度较大时,正、负球差对应的最佳聚焦点将位于无球差时对应的最佳聚焦点的左侧.研究进一步表明,最佳聚焦点随着透镜菲涅耳数的增大向几何焦点方向靠近,并趋于一个定值.当光束菲涅耳数为1时,无球差时对应的最佳聚焦点逐渐趋于0.908,该值与光谱相干度无关,当透镜具有球差时,该值与光谱相干度有关.

Starting from the propagation law of partially coherent light, the focusing of partially coherent modified Bessel Gauss beam （MBGB） passing through a spherically aberrated lens was studied. It shows that, when the parameter ξ related to the spectral degree of coherence is small, the best focal positions corresponding to positive and negative spherical aberrations are at the both sides of the focus for the aberration free case. When the parameter ξ is large, the best focal positions corresponding to positive and negative spherical aberrations are at the left of the focus for the aberration-free ease. It is also found that as the Fresnel number of the lens increases, the best focal points move towards the geometrical focus and approaches a constant. When the Fresnel number of Gaussian beams equals to 1, the best focal position for the aberration-free ease gradually approach 0. 908 and is independent of the parameter ξ. While the best focal positions corresponding to positive and negative spherical aberrations are dependent upon the spectral degree of coherence.