High-speed nano-polarimetry for real-time plasmonic bio-imaging
High-speed nano-polarimetry for real-time plasmonic bio-imaging
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DOI：
10.1117/12.2289144
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发表时间：
2018-02
期刊：
影响因子：
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通讯作者：
Yipei Wang;Yunbo Liu;Xintao Zhao;S. Lee
中科院分区：
文献类型：
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作者：
Yipei Wang;Yunbo Liu;Xintao Zhao;S. Lee
等离子体纳米粒子是用于生物成像的极好的非漂白探针。由于它们的各向异性特性，对单个纳米粒子的极化分析可以揭示取向信息、等离子体模式分配和局部微环境。以前的实现利用传统偏振器的机械旋转来使偏振角与纳米粒子的特定轴对齐。然而，偏振片的制造缺陷（例如，不平行）限制了偏振成像中的测量稳定性（例如，光束摆动），而机械旋转限制了测量速度，从而阻碍了准确、实时地获取单个纳米颗粒。在这里，我们展示了一个高速的纳米偏振系统稳定等离子体生物成像通过集成我们的电压可调偏振器（VTP）到显微镜。通过在VTP上施加电压，可以实现极化的角旋转（0 ~ π）。我们证明，我们的电压可调系统在大输入功率范围内（输入功率从50 μW到20 mW的偏差<5%）具有高消光比（~高达250）和均匀传输（~ 55%）。同时，透射偏振可快速调谐，响应时间可达50 ms。与传统的偏振器相比，我们的系统能够以亚像素的空间精度提供单个纳米颗粒的可重复和高速偏振图像。这种极化纳米成像系统可以作为实时单纳米粒子生物成像的有用工具，具有高稳定性和时间分辨率。
Plasmonic nanoparticles are excellent nonbleaching probes for bio-imaging. Due to their anisotropic properties, polarization analysis of individual nanoparticles allows for revealing orientational information, plasmon mode assignment, and the local microenvironment. Previous implementations utilize mechanical rotation of conventional polarizers to align the polarization angles with specific axes of nanoparticles. However, the manufacturing defects of the polarizer (e.g., non-parallelism) limit the measurement stability (e.g., beam wobbling) in polarimetric imaging, while the mechanical rotation limits the measurement speed, and thus hinders accurate, real-time acquisition of individual nanoparticles. Here, we demonstrate a high-speed nano-polarimetric system for stable plasmonic bio-imaging by integrating our voltage-tunable polarizer (VTP) into a microscope. The angular rotation of the polarization (0∼π) can be realized by applying voltage on the VTP. We show that our voltage-tunable system offers high extinction ratio (∼up to 250), and uniform transmission (∼55%) over a large input power range (<5% deviation for input power from 50 μW to ∼20 mW). Meanwhile, the transmission polarization can be rapidly tuned with a response time up to 50 ms. Compared to conventional polarizers, our system is able to provide reproducible and high-speed polarimetric images of individual nanoparticles with sub-pixel spatial precision. Such a polarimetric nanoimaging system could be a useful tool for real-time single nanoparticle bio-imaging with both high stability and time resolution.