MRI:ID - Development of an Imaging Nonlinear Optical Ellipsometer

有了这项来自主要研究仪器计划（MRI）的奖项，普渡大学的Garth Simpson及其同事将开发一种具有全偏振能力的SHG显微镜，以增强非线性光学斯托克斯椭圆偏振术（NOSE）。该仪器将包括一个倒置的光学显微镜修改，以允许在光束扫描配置共焦成像。显微镜将配备一个用于快速偏振调制的光弹性调制器，一对用于偏振相关SHG检测的光电倍增管（PMT），以及一对用于偏振相关双光子激发荧光（TPEF）检测的PMT。该仪器将产生详细的偏振信息和纳米结构信息，从分子张量和理论建模获得。该仪器最初将用于研究细胞壁构建（通过细胞骨架肌动蛋白-肌球蛋白网络动力学）和解构（纤维素材料的酶促降解，用于可再生能源）机制。这些努力将利用二次谐波产生（SHG）的手性特异性活动，其允许确定绝对极性取向和纤维组装内的共平行与反平行对齐的程度。该仪器将影响涉及表面和界面的广泛研究领域。

With this award from the Major Research Instrumentation program (MRI), Garth Simpson and colleagues of Purdue University will develop a SHG microscope with full polarization capability to enhance nonlinear optical Stokes ellipsometry (NOSE). The instrument will consist of an inverted optical microscope modified to allow confocal imaging in a beam-scanning configuration. The microscope will be equipped with a photoelastic modulator for rapid polarization modulation, a pair of photomultiplier tubes (PMTs) for polarization-dependent SHG detection, and a pair of PMTs for polarization dependent two photon excited fluorescence (TPEF) detection. This instrument will yield detailed polarization information and nanoscale structural information, obtained from molecular tensors and theoretical modeling. This instrument will be utilized initially to study cell wall construction (through cytoskeletal actin-myosin network dynamics) and deconstruction (enzymatic degradation of cellulosic materials for renewable energy) mechanisms. These efforts will capitalize on the chiral-specific activities of second harmonic generation (SHG), which allow for determination of absolute polar orientation and the degree of coparallel versus anti-parallel alignment within fibrous assemblies. This instrument will affect a broad range of research areas involving surfaces and interfaces.