Enhancing the Perfomance of a Submersible Holographic Camera and Automating Analysis for Determining Particle Location and Turbulance in the Ocean

增强潜水式全息相机的性能并自动分析以确定海洋中的粒子位置和湍流

• 批准号: 9909170
• 负责人: Joseph Katz
• 金额: $ 48.18万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-01 至 2002-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9909170&HistoricalAwards=false
• 关键词: Enhancing; Perfomance; Submersible; Holographic; Camera

9909170KatzThis ocean sciences technology development project builds on previous work to develop and test a submersible holographic camera system using lasers to produce holograms, from which the motion and distribution of small particles can be studied. A submersible "holocamera" system for recording in-situ holograms in the ocean presently operates in an in-line mode utilizing a ruby laser as its light source. It is powered by onboard batteries and is controlled via two fiber optic cables, which also provide real time data from other onboard environmental sensors. The system is designed to minimize the effect the system has on the sampled water volume. The present effort focuses on enhancing the performance of the holocamera and continuing the development of hologram analysis procedures. Holography is a unique tool that can provide the instantaneous location of microscopic particles over a large sample volume as well as the shape, size and orientation of each particle. A series of holograms can also be used to determine the full 3 -D velocity field of the liquid in that sample volume and the relative velocities of larger particles. The data analysis procedure consists of reconstructing a recorded hologram to create a 3 - D frozen image of the original sample volume. By scanning the reconstructed image at high magnification, one can observe and measure desired details down to less than 10 mm within a sample volume of about 1000 cm3. Work will be undertaken to automate and improve the efficiency of the analysis procedures by incorporating and developing software tools that will perform 1) image enhancement using a variety of histogram-based, non-linear and morphological filters; 2) particle detection involving use of blob analysis subroutines; and 3) particle classification based on size and shape. A further enhancement will provide the capability for Holographic Particle Image Velocimetry by providing the holocamera with a separate, off-axis reference beam, and a spatial, high pass filter inserted between the sample volume and the film. The ability to measure the 3-D liquid velocity distribution in the ocean and the relative motion of selected particles will be developed using methods used for laboratory applications where the liquid flow field is measured using the displacement of small particles. In situ methods will be developed to obtain all three velocity components from a single hologram by determining the axial displacement of particles accurately using their exact location in space (particle tracking); and by using the continuity equation that enables computation of the axial component from the spatial distribution of the other two. Methods to address the overlap problem for in-line holography and for off-axis holography are proposed.Field tests will be performed in conjunction with investigators from Harbor Branch Oceanographic Institute. Their research requires data on the local shear strains (i.e. 3 - D velocity distribution) in the scale of planktonic organisms as well as correlation between copepod abundance and marine snow and/or other resource abundance. Both can be simultaneously provided by the holocamera. This sensor could be applied to other physical and biological oceanographic problems such as small scale turbulence, microscale patchiness of organisms, capture of food particles, and describing the size and motion of bubbles including those smaller than multi-frequency acoustical techniques can measure.

9909170 Katz这一海洋科学技术开发项目是在以前工作的基础上开发和测试一种水下全息照相系统，该系统使用激光产生全息图，从而可以研究小颗粒的运动和分布。 一种用于在海洋中记录现场全息图的潜水“全息照相机”系统目前以在线模式工作，利用红宝石激光器作为其光源。它由机载电池供电，并通过两条光纤电缆进行控制，光纤电缆还提供来自其他机载环境传感器的真实的时间数据。该系统被设计为最小化系统对采样水量的影响。目前的工作重点是提高全息照相机的性能，并继续发展全息图分析程序。全息术是一种独特的工具，可以提供大样品体积上微观颗粒的瞬时位置以及每个颗粒的形状，大小和方向。一系列的全息图也可以用来确定该样品体积中的液体的全三维速度场和较大颗粒的相对速度。数据分析程序包括重建记录的全息图，以创建原始样品体积的3 - D冻结图像。通过以高放大率扫描重建图像，可以在约1000 cm 3的样品体积内观察和测量小于10 mm的所需细节。将开展工作，通过合并和开发软件工具来实现分析程序的自动化并提高分析程序的效率，这些软件工具将执行：1）使用各种基于直方图的非线性和形态学滤波器进行图像增强; 2）使用斑点分析子程序进行颗粒检测; 3）基于大小和形状的颗粒分类。 进一步的增强将提供全息粒子图像测速的能力，通过提供一个单独的，离轴的参考光束，和一个空间，高通滤波器之间的样品体积和电影插入的全息照相机。测量海洋中三维液体速度分布和选定颗粒的相对运动的能力将使用用于实验室应用的方法来开发，其中使用小颗粒的位移来测量液体流场。将开发现场方法，通过使用粒子在空间中的确切位置（粒子跟踪）准确确定粒子的轴向位移，并通过使用连续性方程，从其他两个的空间分布中计算轴向分量，从单个全息图中获得所有三个速度分量。提出了同轴全息和离轴全息重叠问题的解决方法，并将与海港分支海洋研究所的研究人员一起进行现场试验。他们的研究需要关于浮游生物规模的当地剪切应变（即三维速度分布）的数据以及桡足类丰度与海洋雪和/或其他资源丰度之间的相关性。两者都可以由全息照相机同时提供。该传感器可应用于其他物理和生物海洋学问题，如小尺度湍流，微尺度斑块的生物体，捕获食物颗粒，并描述气泡的大小和运动，包括那些小于多频声学技术可以测量。