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.

9909170KATZTHZTHIS海洋科学技术开发项目基于先前的工作，以开发和测试使用激光生产全息图的潜水全息相机系统，可以从中研究小颗粒的运动和分布。 一种可用于在海洋中记录原地全息图的潜水“ Holocamera”系统，目前以在线模式运行，利用红宝石激光作为光源。它由机载电池提供动力，并通过两条光纤电缆进行控制，该电缆还提供了来自其他板载环境传感器的实时数据。该系统旨在最大程度地减少系统对采样水量的影响。目前的工作着重于增强全息图分析程序的开发。全息图是一种独特的工具，可以在较大的样品体积以及每个粒子的形状，大小和方向上提供微观颗粒的瞬时位置。一系列全息图还可以用于确定该样品体积中液体的完整3 -D速度场和较大颗粒的相对速度。数据分析过程包括重建记录的全息图，以创建原始样品体积的3- d冷冻图像。通过在高放大倍率的情况下扫描重建的图像，可以在约1000 cm3的样品体积中观察并测量所需的细节至小于10 mm。通过合并和开发将执行和开发使用各种基于直方图的，非线性和形态过滤器的图像增强的软件工具，将进行自动化和提高分析程序效率的工作； 2）涉及使用BLOB分析子例程的粒子检测； 3）基于尺寸和形状的粒子分类。 进一步的增强将通过为Holocamera提供单独的，离轴参考光束以及在样品体积和膜之间插入的空间高通滤波器，提供全息粒子图像速度法的能力。将使用用于实验室应用的方法来开发海洋中3-D液体速度分布以及所选颗粒的相对运动的能力，其中使用小颗粒的位移测量了液体流场。将开发原位方法，以通过使用其在空间中的确切位置（粒子跟踪）准确地确定颗粒的轴向位移来从单个全息图获得所有三个速度成分；并使用连续性方程，该方程能够从其他两个的空间分布中计算轴向分量。提出了解决在线全息和外轴全息图的重叠问题的方法。将与Harbour Branch海洋学研究所的研究人员一起进行场测试。他们的研究需要有关浮游生物量表的局部剪切菌株（即3- d速度分布）的数据，以及copepod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Holocamera同时提供。该传感器可以应用于其他物理和生物海洋学问题，例如小规模的湍流，生物体的微观斑块，捕获食物颗粒的斑点以及描述气泡的大小和运动，包括那些小于多频性声学技术小的气泡。