Digital In-Line Holography for Large-Volume Analysis of Vertical Motion of Microscale Marine Plankton and Other Particles
Digital In-Line Holography for Large-Volume Analysis of Vertical Motion of Microscale Marine Plankton and Other Particles
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DOI：
10.1109/joe.2021.3066788
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发表时间：
2021-10-01
影响因子：
4.1
通讯作者：
Thornton, Blair
中科院分区：
文献类型：
--
作者：
Liu, Zonghua;Takahashi, Tomoko;Thornton, Blair
测量海洋微型浮游生物和其他颗粒物质的分布、特征和动态，对于了解海洋环境中元素的垂直通量至关重要。数字全息显微镜是一种强大的方法来测量这些和研究他们的3-D轨迹在一个相对较大的观察体积。本文展示了一种紧凑的在线数字全息显微镜，通过将连续波激光器和短曝光CMOS相机与高效的全局快门相结合，可以大容量和高分辨率地记录海洋颗粒。在空气中的分辨率优于10 μ m，在水中记录的目标的最小可分辨尺寸约为20 μ m。该装置的最大体积通量为1904 mL/s。该显微镜理论上可以拍摄运动速度高达490 mm/s的粒子的无运动模糊全息图，并已在类似于200 mm/s的流水中进行了测试。测量体积的定向提高了数字全息术在剖面下沉速率和主动垂直偏移方面的能力。该系统在一艘研究船上进行了测试，以记录一系列活浮游生物和其他颗粒。使用定制开发的图像处理软件分析一些样品的运动，包括下沉运动和游泳运动。实验结果表明，高分辨率和大体积的组合，可以跟踪稀疏分布的颗粒的运动，可以提高区分不同类型的海洋颗粒和识别浮游生物的行为的能力。
Measuring the distribution, characteristics and dynamics of marine microscale plankton and other particulate matter is essential to understand the vertical flux of elements in the marine environment. Digital holographic microscopy is a powerful approach for measuring these and studying their 3-D trajectories in a relatively large observation volume. This article demonstrates a compact, in-line digital holographic microscope that allows large-volume and high-resolution recording of marine particles through combining a continuous wave laser and a short exposure CMOS camera with efficient global shutters. A resolution of better than 10 mu m is demonstrated in air and the minimum distinguishable size of targets recorded in water is approximately 20 mu m. The maximum volumetric throughput of the setup is 1904 mL/s. The microscope can take motion blur free holograms of particles moving at up to 490 mm/s in theory, and has been tested in the similar to 200-mm/s flowing water. The orientation of the measured volume improves the ability of digital holography in profiling sinking rates and active vertical migration. The system was tested onboard a research vessel to record a range of live plankton and other particles. The motion of some samples, including the sinking motion and swimming motion, was analyzed using custom developed image processing software. The experimental results show that the combination of high resolution and a large volume over which motion of sparse-distribution particles can be tracked, can improve the ability to differentiate between different types of marine particle and identify behaviors of live plankton.