高数值孔径物镜下CARS显微成像光场分布计算

Calculations of Optical Field Distributions of Coherent Anti-Stokes Raman Scattering Microscopy Using a High Numerical Aperture Objective

为了更好地解释相干反斯托克斯拉曼散射(CARS)显微成像的基本原理,方便对CARS显微图像进行处理,使用角频谱的方法对物镜后的CARS显微成像光场分布进行了研究,计算了横向和轴向的光场分布随着物镜数值孔径以及入射光斑大小的变化情况。计算结果表明,光场分布的半峰全宽基本随着数值孔径的增大而减小,并且入射光束腰斑半径越大,CARS显微成像的分辨率也相对越高。理论计算工作为即将开展的实验奠定了基础。

In order to better explain the basic principle of coherent anti-Stokes Raman scattering （CARS） microscopy and facilitate image processing of CARS micrograph, the method of angular spectrum is proposed to study the optical field distributions of CARS microscopy. Based on this method, lateral and axial optical field distributions as a function of the numerical aperture of objective and the spot size of incident beam are calculated, respectively. Calculations indicate that the full-width at half-maximum （FWHM） of the optical field decreases as the numerical aperture increases, and the bigger the waist radius of incident beam is, the higher the resolution of CARS imaging is. Theoretical calculations lay a solid foundation for the future experiments.