Research Starter Grant: Three-Dimensional Polarization Second-Harmonic Generation Microscopy

伊利诺伊大学厄巴纳-香槟分校的杜桑博士获得一笔赠款，用于开发三维偏振二次谐波发生显微镜。 这种方法是一种替代传统的荧光显微镜使用非线性光学散射，以完全消除任何依赖外源性探针，而是使用的化学性质的研究中的样本作为造影剂，从而允许真正的非侵入性成像。这里需要说明的是，SHG显微镜适用于一种特殊的，但极其相关的生物系统？那些表现出有序的分子空间排列（非中心对称性）。在这种情况下，这种系统在与强激光脉冲相互作用时自然地产生频率为原始激光脉冲的两倍的光。这种SHG光是用来成像标本的，其方式与双光子荧光显微镜中使用荧光的方式大致相同。然而，这种技术的利用仅限于利用产生SHG的原始光的电场矢量（偏振）的两个自由度。在这种情况下，偏振被用来产生关于样品的分子对称性的信息。所提出的技术将利用光的全3D偏振状态，以便首次产生三维偏振SHG。三维偏振SHG显微镜将创建集成矢量光束与标准偏振光学。具体来说，径向偏振矢量光束产生增强偏振在显微镜？的焦点，而横向偏振分量是从商业偏振光学操作获得。这种新的仪器将允许在生物发现的进步，以及提供独特的培训和教育机会，本科生和研究生在生物科学以及工程。 通过跨学科的研究和开发，这些学科的学生将深入了解设计和开发以及细胞生物学的基本原理。

A grant is awarded to Dr. Toussaint of the University of Illinois at Urbana-Champaign to develop a three-dimensional polarization second harmonic generation microscope. This approach is an alternative approach to traditional fluorescence microscopy using nonlinear optical scattering to completely obviate any reliance on exogenous probes, and rather uses the chemical properties of the specimen under study as the contrast agent, thereby allowing for truly noninvasive imaging. The caveat here is that SHG microscopy works for a special, but extremely relevant, class of biological systems?those that exhibit an ordered spatial arrangement of molecules (noncentrosymmetry). In this case, such systems upon interacting with an intense laser pulse naturally produce light at twice the frequency of the original laser pulse. This SHG light is what is used to image specimens in much the same way as fluorescence is used in two-photon fluorescence microscopy. However, utilization of this technique has been limited to exploiting only two degrees-of-freedom of the electric field vector (polarization) of the original light generating the SHG. In this case, the polarization is used to yield information on the molecular symmetries of specimens. The proposed technique will utilize the full 3D state of polarization of the light in order to generate, for the first time, three-dimensional polarization SHG. Three-dimensional polarization SHG microscopy will be created by integrating vector beams with standard polarization optics. Specifically, a radially polarized vector beam produces an enhanced polarization at a microscope?s focus, while the transverse polarization components are obtained from manipulation of commercial polarization optics. This new instrument will allow for advances in biological discovery as well as provide unique training and educational opportunities to undergraduate and graduate students in the biological sciences as well as engineering. Through interdisciplinary research and development students across these disciplines will gain insights into the fundamentals of design and development as well as cell biology.