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

从悬浮的有机/无机物质到单细胞、群体和多细胞浮游生物，无数形状和大小各异的颗粒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多种领域的主要推动力。因此，能够直接量化粒子特性、分布和浓度的仪器对许多科学学科至关重要。数字全息是研究粒子的理想工具，在自由流采样体积内提供3-D信息，远远超过传统成像仪器采样的2-D横截面。未受干扰粒子及其相关流场的全息图像可以为需要理解粒子运动和相互作用、粒子大小、形状、精细尺度分布和时空动力学的科学问题提供关键数据。通过该项目开发的仪器可以鼓励在海洋光学、海洋生物学、生物地球化学循环和小规模流体动力学交叉领域进行跨学科研究，并在这些领域取得重大进展。该项目的目标是设计、制造并严格测试/验证一个自主数字全息相机系统，该系统能够量化1微米至2厘米尺寸范围内的原位颗粒的特性。该仪器将被设计用于对未受干扰的水体积进行采样，并量化颗粒数量、大小和形状（例如横截面积、表面积、纵横比、球形度）、颗粒场的三维空间结构（例如最近邻距离）以及颗粒尺度下的局部流体流动（通过成像体积的全息PIV）。可以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）和颗粒方向。该仪器结构紧凑，可潜水，抗生物污染，完全自主，具有独立的数据记录和电源，可调节分辨率和采样量，适用于垂直剖面仪，auv，拖体，以及在系泊上的长期部署。该装置的设计目标是科学的多功能性和未来的商业化，以供科学界日常使用。

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.