Remote, 3D ultrasonic imaging in extreme environments using 2D laser induced phased arrays

“相控阵超声波”的应用对科学和医学产生了深远的影响。它是所有医疗超声成像系统和声纳的核心技术。这一建议将相控阵技术等同于激光超声技术，用于远程、体积、3D超声成像。在激光超声中，由于入射激光辐射，被测材料快速受热和膨胀，从而产生声音。然而，存在与该技术相关联的严重的信噪比限制，这可以使用阵列配置来解决，就像传统的基于换能器的阵列一样。到目前为止，用激光器执行相控阵超声是非常困难的，因为聚焦和操纵用于生成或检测的超声体波的技术对硬件（用于超声生成的多个激光器或复杂的实验设置）和成本提出了严格的要求。拟议的工作将基于在后处理中合成激光诱导相控阵（LIPA），首先获取全矩阵，然后应用合适的成像算法（例如，总聚焦方法- TFM）。在LIPA中对基于光学的数据进行后处理，使实验装置保持简单且具有成本效益。这些远程、无耦合剂的超声波阵列由光制成，可应用于极端环境中，用于在线过程监测或在线体积检测。拟议研究的目的是开发一种基于激光的超声波测量能力，用于在极端环境中进行远程，无损，定量评估和3D超声波成像，用于安全关键应用，传统阵列无法应用。2D LIPA将能够从一系列角度对给定的缺陷进行成像，获得远远超过1D阵列所能实现的特征细节。该项目的核心研究目标是：* 开发用于3D超声成像的激光诱导相控阵列，使用FMC和TFM。*优化激光超声波的数据采集方法，提高加工速度。*优化TFM成像算法以实现激光超声成像，从而实现高效超声成像。*展示系统在极端环境下检测和过程监控的工业应用潜力。这项工作的成功将使无损检测界、激光超声界受益，并将使需要技术的工程师和材料科学家能够应对极端环境和限制进入的地方，测试其结构的性能，无论是在制造过程中（例如增材制造）还是在使用中（例如放射性废物容器的现场检查）。潜在应用的例子包括：焊接和增材制造等极端环境下制造的过程理解和控制，提高过程可靠性，这对增材制造的未来至关重要;航空发动机或发电机的现场超声检测。其他应用领域，如化学，生物学和生物医学成像，其中远程超声成像需要在消毒或腐蚀性环境中。

The application of "phased array ultrasonics" has had a profound impact on science and medicine. It is the technology at the heart of all medical ultrasonic imaging systems and sonars. This proposal brings the equivalent of phased array technology to laser ultrasonics for remote, volumetric, 3D ultrasonic imaging.In laser ultrasonics the sound is generated through the rapid thermal heating and expansion of the material under test, due to the incident laser radiation. However, there are serious signal-to-noise limitations associated with this technique, which could be addressed using an array configuration just as it happens with conventional, transducer based arrays. Up to now it has been very difficult to perform phased array ultrasonics with lasers because the technology to focus and steer the ultrasonic bulk waves for generation or detection puts severe demands on hardware (multiple lasers for ultrasonic generation or complicated experimental setups) and cost. The proposed work will be based on synthesising the Laser Induced Phased Arrays (LIPAs) in post processing, by first acquiring the Full Matrix and then applying a suitable imaging algorithm (e.g. the Total Focusing Method - TFM). The post processing of the optical based data in LIPAs, keeps the experimental setup simple and cost effective. These remote, couplant-free ultrasonic arrays, made of light, can be applied in extreme environments, for in-line process monitoring or in-service volumetric inspection. The aim of the proposed research is to develop a laser based ultrasonic measurement capability for remote, nondestructive, quantitative evaluation and 3D ultrasonic imaging in extreme environments for safety critical applications, where conventional arrays cannot be applied. 2D LIPAs will be able to image a given defect from a range of angles, obtaining characterisation detail far beyond what is achievable with a 1D array.The core research objectives within this project are:* Development of laser induced phased arrays for 3D ultrasonic imaging using FMC and TFM.* Optimisation of the data collection method to laser ultrasonics to improve speed of process.* Optimisation of the TFM imaging algorithm to laser ultrasonics for efficient ultrasonic imaging.* Demonstration of system's industrial application potential for inspection and process monitoring in extreme environments.The success of this work will benefit the non-destructive testing community, the laser ultrasonics community and will enable engineers and material scientists in need of a technique to address extreme environments and places of restricted access, to test the performance of their structures, either during the manufacturing process (e.g. additive manufacturing) or in-service (e.g. in situ inspection of radioactive waste containers). Examples of potential applications include: process understanding and control for manufacturing in extreme environments such as welding and additive manufacturing, increasing process reliability which is crucial for the future of additive manufacturing; in situ ultrasonic inspection in aero-engines or power generators. Other applications are expected in fields such as chemistry, biology and biomedical imaging where remote ultrasonic imaging is needed in sterilised or corrosive environments.