光学表面冗余粒子在离轴及斜入射高斯波束作用下的辐射力

Radiation forces exerted on redundant particles on optical surface by oblique incident and off-axis Gaussian laser beams

针对光学表面冗余粒子的清除问题,通过离轴高斯波束的球矢量波束展开方法,研究了介质球对离轴及斜入射高斯波束的散射特性;基于得到的结果结合连带勒让德函数的正交递推关系推导了离轴高斯波束对介质球的横向和轴向辐射力的解析表达式,并重点分析了离轴距离和高斯波束斜入射角度分别对轴向辐射力和横向辐射力的影响。结果表明,离轴入射时,在束腰负半轴2μm处出现一个总力极大值,过束腰零点后5μm处出现一个反向次大值点;高斯波束斜入射时,辐射力在束腰中心前后各出现一个极大值,随着入射角的增大,曲线整体下移减小,辐射力极大值所对应的Z0位置固定。得到的结论可用于无损检测工程中,即通过调节高斯波束束腰位置可提高对冗余粒子驱逐和控制的效率。

On the basis of spherical vector wave functions and their coordinate rotation theory,the scattering properties of dielectric particles by oblique incident and off-axis Gaussian laser beams were discussed to clean the redundant particles on the optical surface.By utilizing the results of electromagnetic scattering of the sphere,the analytical expressions of the radiation forces exerted on a sphere was derived by an incident Gaussian beam with arbitrary directions of propagation and polarization.The influence of the off axial position r0 and incident angle of Gaussian beam on the axial and traverse radiation forces were discussed in detail.The results show that the maximum radiation force appears on the-2 μm and the second maximum radiation force appears on the 5 μm by an off axis Gaussian beam.The maximum radiation force appears two round the girdling center position.The larger the incident angle,the smaller the radiation force.The position of maximum radiation force is fixed to the on-axis position Z0.According to the conclusions above,it suggests that adjusting the position of Gaussian beam waist can clear and control the redundant particles more efficiently in the nondestructive examination project.