Single-molecule-sensitive microscopy and spectroscopy are transforming biophysics and materials science laboratories. Techniques such as fluorescence correlation spectroscopy (FCS) and single-molecule sensitive fluorescence resonance energy transfer (FRET) are now commonly available in research laboratories but are as yet infrequently available in teaching laboratories. We describe inexpensive electronics and open-source software that bridges this gap, making state-of-the-art research capabilities accessible to undergraduates interested in biophysics. We include a discussion of the intensity correlation function relevant to FCS and how it can be determined from photon arrival times. We demonstrate the system with a measurement of the hydrodynamic radius of a protein using FCS that is suitable for the undergraduate teaching laboratory. The FPGA-based electronics, which are easy to construct, are suitable for more advanced measurements as well, and several applications are described. As implemented, the system has 8 ns timing resolution, can control up to four laser sources, and can collect information from as many as four photon-counting detectors.

中文翻译：

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用于光子统计和相关光谱的廉价电子设备和软件


单分子敏感显微镜和光谱学正在改变生物物理学和材料科学实验室。荧光相关光谱 (FCS) 和单分子敏感荧光共振能量转移 (FRET) 等技术目前在研究实验室中已普遍使用，但在教学实验室中还很少使用。我们描述了弥补这一差距的廉价电子产品和开源软件，使对生物物理学感兴趣的本科生能够获得最先进的研究能力。我们讨论了与 FCS 相关的强度相关函数以及如何从光子到达时间确定它。我们通过使用适用于本科教学实验室的 FCS 测量蛋白质的流体动力学半径来演示该系统。基于 FPGA 的电子器件易于构建，也适用于更高级的测量，并且描述了几种应用。实施后，该系统具有 8 ns 定时分辨率，可以控制多达四个激光源，并可以从多达四个光子计数探测器收集信息。