RUI: Detection of Ultrasound Waves in Water and Air using a Laser Interferometer

超声成像是一种用于医学诊断和损伤检测的重要技术，在各种工业应用中都有应用。在大多数常规超声成像系统中，脉冲是从超声换能器发射的，而发射或反射的超声脉冲是用类似的换能器测量的。在本项目中，将使用基于激光的系统来测量超声，而不是使用传统的换能器。这是一种潜在的变革性方法，与传统方法相比可能具有独特的优势，包括减少测量误差，以及创建行波前的全场视频的能力。该项目将解决使基于激光的超声波测量能够用于工业应用和生物医学研究所需的根本挑战。一项强有力的外展工作将使用声学领域的测量视频来激励中学生对科学和工程感兴趣。这些视频将让学生学习超声波成像的工作原理，为什么打桩产生的冲击波会引起建筑工地附近的海洋生物的关注，以及军队和海洋哺乳动物如何利用海洋中的分层进行远程通信。为了光学探测超声波，激光干涉仪的测量臂对准固定的后向反射表面。当声波通过测量激光束时，S波的密度变化会产生相移，干涉仪可以检测到。该项目预期会有广泛的成果。超声场的干涉测量通常是使用商用激光多普勒振动仪进行的。然而，振动仪是为测量振动表面而设计的；它们并不是为测量声场而优化的。该项目将调查实施开放源码声学干涉探测器的设计，以使其他研究人员能够构建一个针对超声场干涉测量进行优化的系统。一项重要成果将是一项积极监测和控制超声波驻波形成的协议。这将使超声辐射力激励所施加的力加倍。其他结果将使多种测量相结合，以获得比以前研究中获得的频率更高的高保真和深度敏感的干涉测量。这些单点和全场测量不会受到使用传统换能器测量超声时观察到的某些伪影的影响。超声场的干涉测量将被用来研究当波脉冲通过物体时导致马赫激波形成的流体/结构相互作用。

Ultrasound imaging is an important technique utilized for medical diagnosis and damage detection in a variety of industrial applications. In most conventional ultrasound imaging systems, a pulse is emitted from an ultrasonic transducer, and transmitted or reflected ultrasound pulses are measured with a similar transducer. In this project, instead of using a conventional transducer, a laser-based system will be utilized to measure the ultrasound. This is a potentially transformative method that may have unique advantages relative to conventional methods, including reduction of measurement errors, and the ability to create full-field videos of traveling wavefronts. The project will address the fundamental challenges needed to enable laser-based ultrasonic measurements to be utilized for industrial applications and biomedical research. A strong outreach effort will use measured videos of acoustics fields to motivate secondary students to become interested in science and engineering. These videos will allow students to engage in topics such as how ultrasound imaging works, why shock waves produced by pile driving are of concern for marine life near construction sites, and how layering in the ocean is used for long-range communication by both the military and marine mammals.To detect ultrasonic waves optically, the measurement arm of a laser interferometer is directed at a stationary retroreflective surface. When an acoustic wave passes through the measurement laser beam, the wave?s density variations produce phase shifts that can be detected by the interferometer. This project anticipates a wide range of outcomes. Interferometric measurements of ultrasonic fields have often been performed using a commercial laser Doppler vibrometer. However, vibrometers are engineered to measure vibrating surfaces; they are not optimized for measuring acoustic fields. The project will investigate designs for implementing an Open Source Acoustic Interferometric Detector to enable other researchers to construct a system optimized for interferometric measurements of ultrasound fields. An important outcome will be a protocol to actively monitor and control ultrasonic standing wave formation. This will produce a doubling of the force applied by ultrasound radiation force excitation. Other outcomes will enable multiple measurements to be combined to obtain high-fidelity and depth-sensitive interferometric measurements at higher frequencies than have been obtained in previous studies. These single-point and full-field measurements will not be susceptible to some of the artifacts observed when ultrasound is measured with conventional transducers. Interferometric measurements of ultrasonic fields will be used to investigate the fluid/structure interactions that lead to Mach shock formation when a wave pulse passes through an object.