The synthetic aperture focusing technique (SAFT) is used as a laser ultrasonic imaging algorithm for non-destructive internal defect testing, and multi-mode time domain SAFT (MMT-SAFT) imaging is developed to enhance the imaging capability of defect detection. However MMT-SAFT algorithm has the problem of artifacts caused by the laser ultrasound (LU) modes waves. Thus to solve this problem, an automatic imaging technique based on MMT-SAFT called Reconstructed synthetic aperture focusing technique (Re-SAFT) is proposed. This technique consists of two steps: a preliminary MMT-SAFT is firstly performed to locate the defect position tentatively and futher separate LU modes wave signals using the defect-reflected signal; then a secondary reconstructed MMT-SAFT based on the priori defect location information is achieved for artifacts removal. In addition, directivity patterns of LU modes wave have been used in Re-SAFT to achieve more accurate defect imaging in the second step. Results indicate that by using Re-SAFT, the typical artifact caused by laser ultrasonic waves can be removed and the imaging quality can be significantly improved from 19.67 to 33.85 dB. Further, the consumed time of Re-SAFT is economized by optimizing the imaging pixel size without compromising the image quality. Therefore, Re-SAFT has potential applications in industrial laser ultrasonic testing.
SunXCroxfordAJDrinkwaterBW. Continuous monitoring with a permanently installed high-resolution ultrasonic phased array. Struct Health Monit2023; 22: 3451–3464.
2.
PanJZhangBLiuZ, et al. Microbubble resonators combined with a digital optical frequency comb for high-precision air-coupled ultrasound detectors. Photon Res2020; 8(3): 303–310.
3.
WeberTDKhetanNYangR, et al. Ultrasound differential phase contrast using backscattering and the memory effect. Appl Phys Lett2021; 118: 124103.
4.
HervinFFrommeP. Anisotropy influence on guided wave scattering for composite structure monitoring. Struct Health Monit2023; 22: 2626–2640.
5.
SpytekJZiaja-SujdakADziedziechK, et al. Evaluation of disbonds at various interfaces of adhesively bonded aluminum plates using all-optical excitation and detection of zero-group velocity lamb waves. NDT E Int2020; 112: 102249.
6.
ZhangXFinckeJRWynnCM, et al. Full noncontact laser ultrasound: first human data. Light: Sci Appl2019; 8(1): 119.
7.
PyzikPZiaja-SujdakASpytekJ, et al. Detection of disbonds in adhesively bonded aluminum plates using laser-generated shear acoustic waves. Photoacoustics2021; 21: 100226.
XiongJXuXGlorieuxC, et al. Imaging of transient surface acoustic waves by full-field photorefractive interferometry. Rev Sci Instrum2015; 86:053107.
10.
PelivanovIŁukaszAKhomenkoA, et al. High resolution imaging of impacted CFRP composites with a fiber-optic laser-ultrasound scanner. Photoacoustics2016; 4: 55–64.
11.
ReadyJF. Effects due to absorption of laser radiation. J Appl Phys1965; 36(2): 462–468.
12.
NiCYChenCYingKN, et al. Non-destructive laser-ultrasonic synthetic aperture focusing technique (SAFT) for 3d visualization of defects. Photoacoustics2021; 22: 100248.
13.
ZhangSZhangEZBeardPC, et al. Dual-modality fibre optic probe for simultaneous ablation and ultrasound imaging. Commun Eng2022; 1(1): 20.
14.
TruongTCAbetewADLeeJR, et al. Thermo-elastic model of epicenter displacement by laser pulse irradiated on metallic surfaces. ASME J Nondestr Eval2018; 1(2): 021001–021001-6.
15.
AbetewADTruongTCHongSC, et al. Parametric optimization of pulse-echo laser ultrasonic system for inspection of thick polymer matrix composites. Struct Health Monit2020; 19(2): 443–453.
16.
ScrubyCBDrainLE. Laser ultrasonics techniques and applications, 1990.
17.
StratoudakiTClarkMWilcoxPD. Adapting the full matrix capture and the total focusing method to laser ultrasonics for remote non destructive testing. In: IEEE international ultrasonics symposium, IUS, Washington, DC, USA, 2017, pp. 29–32. New York: IEEE.
18.
LukacsPDavisGStratoudakiT, et al. Remote ultrasonic imaging of a wire arc additive manufactured Ti-6AI-4V component using laser induced phased array. In: Conference record - IEEE instrumentation and measurement technology conference, Glasgow, United Kingdom, 1 May–6 May 2023.
19.
AriasIAchenbachJD. A model for the ultrasonic detection of surface-breaking cracks by the scanning laser source technique. Wave Motion2004; 39(1): 61–75.
20.
BychkovASimonovaVZarubinV, et al. The progress in photoacoustic and laser ultrasonic tomographic imaging for biomedicine and industry: a review. Appl Sci2018; 8(10):1931.
21.
ChenSL. Review of laser-generated ultrasound transmitters and their applications to all-optical ultrasound transducers and imaging. Appl Sci2017; 7(1):25.
22.
FeliceMVFanZ. Sizing of flaws using ultrasonic bulk wave testing: a review. Ultrasonics2018; 88: 26–42.
23.
QinLZhangSSongY, et al. 3D ultrasonic imaging based on synthetic aperture focusing technique and space-dependent threshold for detecting submillimetre flaws in strongly scattering metallic materials. NDT E Int2021; 124: 102523.
24.
WuestMSchwarzMEisenhartJ, et al. A matched model-based synthetic aperture focusing technique for acoustic microscopy. NDT E Int2019; 104: 51–57.
25.
LukomskiTStepinskiTKowalJ. Synthetic aperture focusing technique with virtual transducer for immersion inspection of solid objects. Insight Non-Destr Test Cond Monit2012; 54(11): 623–627.
26.
DaiLNNiCYYingKN, et al. Defect imaging based on laser ultrasonic frequency domain synthetic aperture focusing technology with separated generation–detection and 2-D equivalent velocity mapping. Opt Laser Technol2022; 156: 108485.
27.
YingKNNiCYDaiLN, et al. Multi-mode laser-ultrasound imaging using time-domain synthetic aperture focusing technique (T-SAFT). Photoacoustics2022; 27: 100370.
28.
BrownWM. Synthetic aperture radar. IEEE Trans Aerosp Electron Syst1967; AES-3(2): 217–229.
29.
StepinskiT. An implementation of synthetic aperture focusing technique in fequency domain. IEEE Trans Ultrason Ferroelectr Freq Control2007; 54(7): 1399–1408.
30.
BlouinALévesqueDNéronC, et al. SAFT data processing applied to laser-ultrasonic inspection. Boston, MA: Springer US, 1998, pp. 611–617.
31.
YangCQinKLiY. Real-time ultrasonic imaging for multi-layered objects with synthetic aperture focusing technique. In: Conference record - IEEE instrumentation and measurement technology conference, Montevideo, Uruguay, 2014, pp. 561–566.
32.
PerrotVPolichettiMVarrayF, et al. So you think you can DAS? A viewpoint on delay-and-sum beamforming. Ultrasonics2021; 111: 106309.
33.
YardibiTBahrCZawodnyN, et al. Uncertainty analysis of the standard delay-and-sum beamformer and array calibration. J Sound Vibr2010; 329(13): 2654–2682.
34.
ReimerTSolis-NepoteMPistoriusS. The application of an iterative structure to the delay-and-sum and the delay-multiply-and-sum beamformers in breast microwave imaging. Diagnostics (Basel)2020; 10(6): 411.
35.
RoyerDFinkMA. Shear-wave focusing with a laser-ultrasound phased-array. IEEE Trans Ultrason Ferroelectr Freq Control1995; 42(6): 981–988.
36.
RobinsonAR. Wave propagation in solids. Proc Eng Mech1992: 633–636.
37.
BaiXMaJXuW, et al. Off-epicentral measurement of laser-ultrasonic shear-wave velocity and its application to elastic-moduli evaluation. Ultrasonics2023; 127: 106850.
38.
SterniniSPauADi ScaleaFL. Minimum-variance imaging in plates using guided-wave-mode beamforming. IEEE Trans Ultrason Ferroelectr Freq Control2019; 66(12): 1906–1919.
39.
DewhurstRJEdwardsCMcKieAD, et al. Estimation of the thickness of thin metal sheet using laser generated ultrasound. Appl Phys Lett1987; 51(14): 1066–1068.
40.
AindowAMDewhurstRJPalmerSB. Laser-generation of directional surface acoustic wave pulses in metals. Opt Commun1982; 42(2): 116–120.
41.
LévesqueDBlouinANéronC, et al. Performance of laser-ultrasonic F-SAFT imaging. Ultrasonics2002; 40(10): 1057–1063.
42.
TaoCLiuX. Reconstruction of high quality photoacoustic tomography with a limited-view scanning. Opt Express2010; 18(3): 2760.
43.
WuDTaoCLiuXJ, et al. Influence of limited-view scanning on depth imaging of photoacoustic tomography. Chin Phys B2012; 21(1): 014301.
44.
AbbasSHLeeJRKimZ. FPGA-based design and implementation of data acquisition and real-time processing for laser ultrasound propagation. Int J Aeronaut Space Sci2016; 17: 467–475.
PelivanovIBumaTXiaJ, et al. NDT of fiber-reinforced composites with a new fiber-optic pump–probe laser-ultrasound system. Photoacoustics2014; 2(2): 63–74.
47.
BernsteinJRSpicerJB. Line source representation for laser-generated ultrasound in aluminum. J Acoust Soc Am2000; 107(3): 1352–1357.
48.
StratoudakiTClarkMWilcoxPD. Laser induced ultrasonic phased array using full matrix capture data acquisition and total focusing method. Opt Express2016; 24(19): 351–357.
