Career Program: New Approaches of Holographic Particle Velocimetry for Studying Turbulence

摘要CTS-9625307是全息粒子测速仪（HPV）的研究热点。目前，由于缺乏获得时间分辨的全场瞬时三维流场速度和涡度数据的能力，对湍流现象的理解受到了阻碍。全息粒子测速技术很有希望提供这种能力。目前的HPV方法集中于解决一个直接问题（全息图像与斑点噪声），系统配置正变得越来越复杂和用户友好。HPV技术的主要瓶颈是大量的数据处理，这一问题尚未得到认真解决。拟议的HPV方法采用了两个新想法：(1)带通“在线记录离轴观看”全息术，它提供了出色的信噪比性能和几何和操作简单性，特别是在脉冲激光全息图记录过程中；(2)混合光学数字处理系统，其特点是通过大规模并行光学相关实现1011级的图像压缩，提供了大幅降低数据处理速度的潜力。除了让本科生参与HPV研究外，计划将光学引入机械工程课程，包括教学光学实验室和高级设计项目。流体力学课程将采用交互式多媒体的新学习方法。

ABSTRACT CTS-9625307 The research focuses on the development of Holographic Particle Velocimetry (HPV). The understanding of turbulence phenomena is currently hampered by the lack of capability to obtain time-resolved full-field instantaneous three-dimensional (3-D) flow velocity and vortiaity field data. Holographic Particle Velocimetry is highly promising to provide this capability. Current approaches to HPV focus on the solution of one immediate problem (the holographic images vs. speckle noise) and the system configuration are becoming increasingly more complex and user-friendly. The major bottleneck in the HPV technique, is the huge quantity of data processing, that has not been seriously addressed. The proposed HPV approach uses two new ideas: (1) band-pass" In-line Recording Off-axis Viewing" holography, which provides both excellent signal-to-noise performance and geometric and operational simplicity, especially in the pulsed-laser hologram recording process, and (2) hybrid optical-digital processing system, characterized by image compression of the order of 1011 achieved by massively parallel optical correlation, offering a potential for substantial reduction of data processing speed. Besides involving undergraduate students in HPV research, it is planned to introduce optics to Mechanical Engineering curriculum including an instructional optics laboratory and senior design projects. New learning methodologies using interactive multimedia will be developed for a Fluid Mechanics course.