Optical methods of laser ultrasonic testing technology in the industrial and engineering applications: A review

Laser ultrasonic testing (LUT) technology is one of the most powerful techniques in the field of non-destructive testing (NDT) or structural health monitoring (SHM). Contactless excitation, multimode-guided wave generation, and rapid detection of various structures are its main advantages. The optical LUT method has the advantages of high detection bandwidth, controllable laser power, and less likely to cause secondary damage to the material under test. Moreover, it can adaptively adjust the optical path according to the structural characteristics of the actual material under test to meet the detection requirements. Therefore, this type of LUT has gained more and more attention in recent years. This paper introduces the LUT and its advantages, and briefly summarizes the different types of optical method LUT systems. Categorized examples are given to illustrate the mainstream methods of LUT in the industry as well as specific cases, and an outlook on the direction of development is given. This paper has a certain reference value for the latter research on LUT.