Autonomous holographic imaging system for long term in situ studies of marine particle dynamics.

无数形状和大小千差万别的颗粒，从悬浮的有机/无机物质到单细胞、殖民地和多细胞浮游生物，密集地分布在世界海洋中。它们是沉积物运输、遥感/海洋光学、海洋食物网生态研究和碳封存等领域的主要驱动力。因此，能够直接量化颗粒特征、分布和浓度的仪器对许多科学学科至关重要。数字全息术是研究粒子的理想工具，它在自由流动采样体积内提供三维信息，远远超过传统成像仪器采样的二维截面。未受扰动的颗粒及其相关流场的全息图像可以提供对需要了解颗粒运动和相互作用、颗粒大小、形状、精细尺度分布和时空动力学的科学问题至关重要的数据。通过该项目开发的仪器可以鼓励海洋光学、海洋生物学、生物地球化学循环和小规模流体动力学等交叉学科的研究，并在这些领域取得重大进展。该项目的目标是设计、制造和严格测试/验证一种能够量化约1微米到2厘米大小范围内原位颗粒特征的自主数字全息相机系统。该仪器将被设计用于对未受扰动的体积的水进行采样，并量化颗粒的数量、大小和形状(如横截面面积、表面积、纵横比、球形度)、粒子场的三维空间结构(如最近邻距离)以及在颗粒尺度上的局部流体流动(通过成像体积的全息PIV)。将能够识别具有独特形状特征的颗粒(例如气泡、油滴、浮游植物和浮游动物)和颗粒取向。该仪器将是紧凑型、潜水式、抗生物污垢、完全自主的，具有独立的数据记录和功率，具有可调的分辨率和采样量，并将适用于垂直剖面仪、AUV、拖体和长期部署在系泊设备上。该设备的设计目标是实现科学多功能性和未来的商业化，供科学界日常使用。

A myriad of particles with vastly varying shapes and sizes, ranging from suspended organic/inorganic material to single celled, colonial, and multi-cellular plankton, densely populate the world's oceans. They are major drivers in fields as diverse as sediment transport, remote sensing/ocean optics, ecological studies of marine food webs, and carbon sequestration. Thus, instruments that can directly quantify particle characteristics, distribution, and concentration are critical to numerous science disciplines. Digital holography is an ideal tool to study particles, providing 3-D information within free stream sampling volumes that vastly exceed the 2-D cross sections sampled by conventional imaging instruments. Holographic images of undisturbed particles and their related flow fields can provide data critical to science questions requiring an understanding of particle motions and interactions, particle size, shape, fine-scale distribution, and spatial-temporal dynamics. The instrument being developed through this project could encourage interdisciplinary studies at the intersection of ocean optics, marine biology, biogeochemical cycles, and small-scale fluid dynamics, and lead to significant advancements in each of these areas.The objective of this project is to design, fabricate and rigorously test/validate an autonomous digital holographic camera system capable of quantifying the characteristics of in situ particles within a size range of ~ 1 micron to 2 cm. The instrument will be designed to sample an undisturbed volume of water and quantify particle number, size and shape (e.g. cross-sectional area, surface area, aspect ratio, sphericity), the 3-D spatial structure of the particle field (e.g. nearest neighbor distances), and the local fluid flows at the scale of the particles (via holographic PIV of the imaged volume). Identification of particles with unique shape characteristics (e.g. bubbles, oil droplets, phytoplankton and zooplankton) and particle orientation will be achievable. The instrument will be compact, submersible, biofouling resistant, fully autonomous with self-contained data logging and power, with adjustable resolution and sampling volume, and will be adaptable for use on vertical profilers, AUVs, tow-bodies, and long-term deployment on moorings. The device will be designed with the goal of science versatility and future commercialization for routine use by the scientific community.