部分相干光束在生物组织中的传输行为

Propagation behavior of the partially coherent beams in the biological tissue

基于广义惠更斯-菲涅尔原理,推导了部分相干拉盖尔-高斯(partially coherent Laguerre-Gaussian,PCLG)光束在生物组织传输中交叉谱密度函数的解析表达式,并研究了光束在小鼠真皮组织传输中归一化光强和相位演化受传输距离z、拓扑荷m和径向指数n、空间相干长度σ变化的影响。结果表明,随传输距离增大,光束光强逐渐减弱的同时,光强分布轮廓也由多峰状逐渐演变为单峰状;初始的m阶相干涡旋和n个圆刃型位错先演化成m+2n个相干涡旋,再新生m+2n个相干涡旋。此外,拓扑荷、径向指数、空间相干长度越大,光束的光强分布变化和相位演化越慢。

Based on the generalized Huygens-Fresnel principle,the analytical expression of the cross-spectral density function for the partially coherent Laguerre-Gaussian(PCLG)beam propagating in biological tissues is derived,and used to study the effect of propagation distance z,topological charge m,radial index n,and spatial coherence lengthσon the normalized intensity and phase evolution of the beam in the dermis of mouse tissue.It is shown that as the propagation distance increases,the intensity gradually decreases,the intensity distribution profile slowly evolves from multi-peak shape to single-peak shape.Initial m-order coherence vortex and n circular edge dislocations evolve into m+2n coherent vortices firstly,and then m+2n coherent vortices are newly created.In addition,the larger the topological charge,radial index,and spatial coherence length,the slower the change in the intensity distribution and phase evolution.