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Laser-Excited Acoustics for Contact-Free Inspection of Aerospace Composites

Ultrasonic testing (UT) is widely used for the nondestructive testing (NDT) of composite materials in the aerospace industry. Liquid-coupled piezoelectric ultrasonic transducers are the most common technology used in this field; however, liquid coupling agents are not always practical, economical, or compatible with materials that cannot get wet. Alternative couplant-free technologies such as air-coupled ultrasound or laser ultrasound (LUS) are available, but either lack the required sensitivity and resolution, or are very costly, large, and sensitive to surface condition and properties. In this paper, we introduce a new couplant-free approach using laser excitation and a commercially available optical micro-phone. This technique is termed laser-excited acoustics (LEA) NDT, which combines the advantages of a contact-free ultrasound technology with the potential for improved sensitivity and resolution required for NDT in industrial environments. We will demonstrate the capabilities of LEA on aerospace composite parts made of carbon and glass fiber–reinforced polymer (CFRP/GFRP) under realistic conditions.



Cuevas Aguado, E., C. Galleguillos, C. García Ramos, and F. Lasagni, 2015, “Laser Ultrasonics Inspections of Aero-nautical Components Validated by Computed Tomography,” 7th International Symposium on NDT in Aerospace, 16–18 November, Bremen, Germany.

Fischer, B., 2016, “Optical Microphone Hears Ultrasound,” Nature Photonics, Vol. 10, pp. 356–358,

Fischer, B., F. Sarasini, J. Tirillo, F. Touchard, L. Chocinski-Arnault, D. Mellier, N. Panzer, R. Sommerhuber, P. Russo,  I. Papa, V. Lopresto, and R. Ecault, 2019, “Impact Damage Assessment in Biocomposites by Micro-CT and Innovative Air-Coupled Detection of Laser-Generated Ultrasound,” Composite Structures, Vol. 210, pp. 922–931,

Gaal, M., D. Kotschate, and K. Bente, 2019, “Advances in Air-Coupled Ultrasonic Transducers for Non-Destructive Testing,” Proceedings of Meetings on Acoustics, Vol. 38, No. 1,

Scruby, C.B., and L.E. Drain, 1990, Laser Ultrasonics Techniques and Applications, CRC Press.

Thomson, C.D., I. Cox, M.T.A. Ghasr, K.P. Ying, and R. Zoughi, 2015, “Ultrasonic, Microwave, and Millimeter Wave Inspection Techniques for Adhesively Bonded Stacked Open Honeycomb Core Composites,” AIP Conference Proceedings, Vol. 1650,

Vanderheiden, B., C. Thomson, I. Ivakhnenko, and C. Garner, 2018, “Transition to High Rate Aerospace NDI Processes,” AIP Conference Proceedings, Vol. 1949, No. 1,

Vandenrijt, J.-F., F. Languy, C. Thizy, and M. Georges, 2018, “Laser Ultrasound Flexible System for Non-contact Inspection of Medium Size and Complex Shaped Composite Structures Made of Carbon Fiber Reinforced Polymer,” Proceedings of the 18th International Conference on Experimental Mechanics, Vol. 2, No. 8, /ICEM18-05377.


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