Multi-mode laser-ultrasound imaging using Time-domain Synthetic Aperture Focusing Technique (T-SAFT)

Photoacoustics

Lu-Nan Dai¹  Chen-Yin Ni²  Kai-Ning Ying³  Wei-Wei Kan³  Ling Yuan³  Zhong-Hua Shen³ 

[1] Corresponding authors.;School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China;School of Science, Nanjing University of Science and Technology, Nanjing 210094, China;

关键词: Laser ultrasound;    Non-destructive Testing;    Synthetic Aperture Focusing Technology (SAFT);    Defect detection;   

DOI  :  

来源: DOAJ

【 摘 要 】

The Synthetic Aperture Focusing Technique (SAFT) is an imaging algorithm used in laser ultrasonics (LU) to visualise the appearance of defects. However, ultrasound excited by a pulsed laser has the characteristics of wide bandwidth and multi-mode directivity patterns, leading to common problems in the SAFT process, such as low utilisation of ultrasound information and possible artefacts. To solve these problems, a Multi-mode Time-domain SAFT (MMT-SAFT) algorithm is proposed in this paper. The influence of ultrasonic directivity is discussed according to the imaging depth range, and imaging with multiple LU modes is performed to reduce artefacts. Simulations and experimental results prove the feasibility of the MMT-SAFT algorithm, which not only presents a clearer image of the upper part of defects but also improves image quality compared with time-domain SAFT using a single ultrasonic mode. The proposed technique can provide feasible directions for laser ultrasonic defect imaging.

【 授权许可】

Unknown