We introduce two-beam phase correlation spectroscopy (2B-ΦCS$2\mathrm{B}\text{-}\mathrm{\Phi }\mathrm{CS}$) as a label-free technique to measure the dynamics of flowing particles; e.g., in vitro or in vivo blood flow. 2B-ΦCS$2\mathrm{B}\text{-}\mathrm{\Phi }\mathrm{CS}$ combines phase imaging with correlation spectroscopy, using the intrinsic refractive index contrast of particles against the fluid background in correlation analysis. This method starts with the acquisition of a time series of phase images of flowing particles using partially coherent point-diffraction digital holographic microscopy. Then, phase fluctuations from two selected circular regions in the image series are correlated to determine the concentration and flow velocity of the particles by fitting pair correlation curves with a physical model. 2B-ΦCS$2\mathrm{B}\text{-}\mathrm{\Phi }\mathrm{CS}$ is a facile procedure when using a microfluidic channel, as shown by the measurements on flowing yeast microparticles, polymethyl methacrylate microparticles, and diluted rat blood. In the latter experiment, the concentration and average diameter of rat blood cells were determined to be (4.7±1.9)×106 μL−1$(4.7\pm 1.9)\times {10}^6{\mathrm{\mu L}}^{-1}$ and 4.6±0.4 μm$4.6\pm 0.4\mathrm{\mu m}$, respectively. We further analyzed the flow of mainly red blood cells in the tail vessels of live zebrafish embryos. Arterial and venous flow velocities were measured as 290±110 μm s−1$290\pm 110\mathrm{\mu m}{\mathrm{s}}^{-1}$ and 120±50 μm s−1$120\pm 50\mathrm{\mu m}{\mathrm{s}}^{-1}$, respectively. We envision that our technique will find applications in imaging transparent organisms and other areas of the life sciences and biomedicine.

中文翻译：

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双光束相位相关光谱学：一种量化生物流体中粒子流动的无标记全息方法

我们引入双光束相位相关光谱 ( 2 B - Φ CS$2\mathrm{B}\text{-}\mathrm{\Phi }\mathrm{CS}$ ) 作为一种无标记技术来测量流动粒子的动力学；例如，体外或体内血流。2 B - Φ CS$2\mathrm{B}\text{-}\mathrm{\Phi }\mathrm{CS}$将相位成像与相关光谱相结合，在相关分析中使用粒子与流体背景的固有折射率对比。该方法首先使用部分相干点衍射数字全息显微镜获取流动粒子的时间序列相位图像。然后，将图像系列中两个选定圆形区域的相位波动相关联，通过将对相关曲线与物理模型拟合来确定粒子的浓度和流速。2 B - Φ CS$2\mathrm{B}\text{-}\mathrm{\Phi }\mathrm{CS}$当使用微流体通道时，这是一个简单的过程，如流动酵母微粒、聚甲基丙烯酸甲酯微粒和稀释大鼠血液的测量所示。在后面的实验中，大鼠血细胞的浓度和平均直径分别被确定为（4.7 ± 1.9 ）× 10 6 μL - 1 $(4.7\pm 1.9)\times {10}^6{\mathrm{\mu L}}^{-1}$和4.6 ± 0.4μm $4.6\pm 0.4\mathrm{\mu m}$。我们进一步分析了活斑马鱼胚胎尾部血管中主要是红细胞的流动。动脉和静脉流速测量为290 ± 110 μm s - 1 $290\pm 110\mathrm{\mu m}{\mathrm{s}}^{-1}$和分别为120 ± 50 μm s − 1 $120\pm 50\mathrm{\mu m}{\mathrm{s}}^{-1}$。我们设想，我们的技术将在透明生物体成像以及生命科学和生物医学的其他领域得到应用。