Characterization of Transducer Performance and Narrowband Transient Ultrasonic Fields in Metals by Rayleigh-Sommerfeld Backpropagation of Compression Acoustic Waves Measured with Double-Pulsed TV Holography

This paper presents a method aimed at the characterization of the narrowband transient acoustic field radiated by an ultrasonic plane transducer into a homogeneous, isotropic and optically opaque prismatic solid, and the assessment of the performance of the acoustic source. The method relies on a previous technique based on the full-field optical measurement of an acoustic wavepacket at the surface of a solid and its subsequent numerical backpropagation within the material. The experimental results show that quantitative transversal and axial profiles of the complex amplitude of the beam can be obtained at any plane between the measurement and excitation surfaces. The reconstruction of the acoustic field at the transducer face, carried out on a defective transducer model, show that the method could also be suitable for the nondestructive testing of the performance of ultrasonic sources. In all cases, the measurements were performed with the transducer working under realistic loading conditions.

本论文提出一种方法，用于表征超声平面换能器（ultrasonic plane transducer）向均匀、各向同性且光学不透明的棱柱形固体辐射的窄带瞬态声场，并评估该声学声源的性能。该方法依托于一项已有技术，即对固体表面的声波包（acoustic wavepacket）开展全场光学测量，并随后在材料内部对其进行数值反向传播（numerical backpropagation）。实验结果表明，可在测量表面与激发表面之间的任意平面上，获取该波束复振幅（complex amplitude）的横向与轴向定量分布轮廓。针对带缺陷的换能器模型完成的换能器表面声场重建结果显示，该方法同样可用于超声声源性能的无损检测（nondestructive testing）。所有实验均在换能器处于实际工作负载条件下进行。