Lin Jian, Wang Haifeng, Zheng Wei, Lu Fake, Sheppard Colin, Huang Zhiwei
Bioimaging Laboratory, Department of Bioengineering, Faculty of Engineering, National University of Singapore, Singapore 117576.
Opt Express. 2009 Feb 16;17(4):2423-34. doi: 10.1364/oe.17.002423.
We employ the finite-difference time-domain (FDTD) technique as a numerical approach to studying the effects of polarization, scatterers' sizes and orientations on near-field coherent anti-Stokes Raman scattering (CARS) microscopy imaging. The results show that to acquire better image contrast and larger near-field CARS signals, the scatterers with diameters of less than three-eighths of the pump field wavelength (lambda(p)) are preferable to be oriented along the polarization direction of the excitation light fields. It is also found that when the scatterers' sizes are smaller than half a wavelength of the pump field, the perpendicular polarization component of the induced near-field CARS radiations is strictly confined within the regions at the scatterer-water interface or the subsurface of scatterers, yielding a high image contrast (up to 200) with a spatial resolution of lambda(p)/16. This study indicates that perpendicular polarization components of near-field CARS microscopy could be used to uncover very fine structures of intra- and/or inter- cellular organelles in cells with nanoscale resolutions.
我们采用时域有限差分（FDTD）技术作为一种数值方法，来研究偏振、散射体尺寸和取向对近场相干反斯托克斯拉曼散射（CARS）显微镜成像的影响。结果表明，为了获得更好的图像对比度和更大的近场CARS信号，直径小于泵浦场波长（λp）八分之三的散射体最好沿激发光场的偏振方向取向。还发现，当散射体尺寸小于泵浦场波长的一半时，感应近场CARS辐射的垂直偏振分量严格限制在散射体 - 水界面或散射体亚表面区域内，从而产生高达200的高图像对比度，空间分辨率为λp/16。这项研究表明，近场CARS显微镜的垂直偏振分量可用于以纳米级分辨率揭示细胞内和/或细胞间细胞器的非常精细的结构。
