M. Scafidi et alii, Frattura ed Integrità Strutturale, 34 (2015) 622-629; DOI: 10.3221/IGF-ESIS.34.68 622 2D size, position and shape definition of defects by B-scan image analysis Michele Scafidi, Donatella Cerniglia, Tommaso Ingrassia Università degli Studi di Palermo, Dipartimento di Ingegneria Chimica, Gestionale, Informatica, Meccanica – 90128 Palermo, Italy A BSTRACT . The non-destructive evaluation of defects by automatic procedures is of great importance for structural components. Thanks to the developments of the non-contact ultrasonic techniques, the automation of the inspections is gaining a progressively important role. In this work, an automatic inspection technique for the evaluation of defects by the analysis of B-scan images obtained by a laser ultrasonic system is presented. The data are extracted directly from a B-scan map obtained for a panel with internal defects, and are used to build an image of the cross section of the panel. The proposed automatic procedure allows the definition of size, position and shape of defects in panels of known thickness. K EYWORDS . NDE; laser UT system; B-scan image analysis; defect size definition; 2D defect shape definition. I NTRODUCTION he laser Ultrasonic Testing ( UT ) systems are becoming more common among the Non-Destructive Evaluation ( NDE ) techniques thanks to the possibility to carry out non-contact inspections [1-3]. One of the most important advantage of this technique is related to the use of high frequency ultrasonic waves, that allow the detection of defects with very fine spatial resolution. Moreover, laser UT systems can be effectively used for remote inspections with no contact conditions influence and, if proper delivery optics are used to guide the laser beam, they can operate also in hostile environments. Since the propagation mechanism of the ultrasonic waves is not influenced by the angle of incidence of the laser beam on the material surface, this kind of system can be used to inspect parts where access is limited. The laser beam, in fact, can be directed to the surface with high angles off axis. The presence of defects, corners and curved surfaces, modifies the waves propagation, causing reflection and mode conversion. The waves resulting from different sources (i.e. reflected or converted waves) can interfere each other, generating very complex patterns. For this reason, the inspection of complex structures by means of laser UT systems can become extremely hard. Nevertheless, by knowing the analytical models of the waves propagation in solid structures, the experimental layout can be designed to optimize the results post-processing analysis. With this purpose, laser UT systems can be used to automate the scanning procedure and to make a rapid acquisition of the ultrasonic data by creating B-scan maps in real time [1]. The analysis of the B-scan image allows determining in an automated way the presence of defects in the tested component as well as the characteristics of the defects. A technique of particular importance in the analysis of defects in plates is the Time Of Flight Diffraction ( TOFD ) [4-9]. This technique allows to determine the presence of cracks in the material and to determine the position and length of the crack even in T