余弦平方-高斯光束的双焦开关和焦平面  

Double focal switch and focal plane of cosine-squared Gaussian beams

作　　者：郝中骐[1] 文伟[2] 

机构地区：[1]宜春学院物理科学与工程技术学院,宜春336000 [2]怀化学院物理与电子信息科学系,怀化418008

出　　处：《激光技术》2008年第6期663-666,共4页Laser Technology

摘　　要：为了研究余弦平方-高斯光束通过无光阑透镜后的聚焦特性,采用Collins公式推导了聚焦余弦平方-高斯光束轴上光强分布公式,并利用空间2阶矩法求得光束束腰宽度的解析表达式。通过数值方法研究了轴上光强的双焦开关现象和由束腰所在焦平面的焦移现象,得到了这两种现象随光束参量b、相对入射距离s′及菲涅耳数NF的变化关系。结果表明,只有b>1时才出现双焦开关现象,而实际焦平面在s′≠1时存在焦移。In order to study the focusing properties of cosine-squared Gaussian beams （CsSGB） through a lens without aperture,the equation for the axial irradiance distribution of focused CsSGB are derived based on the Collins formula, and the analytical expression of beams waist width is presented using the second-order moment method. The double focal switch of axial intensity and the focal shift of focal plane where the real position of beams waist located are studied with numerical method. The dependence of both effects discussed above on the beams parameter b,relative incident separation s＇ and beams Fresnel number Nr are analyzed. Results show that double focal switch can take place only for b 〉 1,and the real focal plane has a shift if s＇ ≠ 1.

关 键 词：激光光学 双焦开关 焦平面 COLLINS公式 2阶矩法 余弦平方-高斯光束 

分 类 号：O435[机械工程—光学工程]