NON-CONTACT PHOTOACOUSTIC WAVE DETECTION TECHNIQUES FOR INSPECTION OF METALS STRUCTURES

Abstract

The Photoacoustic (PA) detection technique is a non-destructive inspection technique, which can be grouped into two operating modes, contact and non-contact. The contact mode has restrictions such as slow detection speed, possible contamination from couplants and difficulties in detecting irregular objects. On the other hand, the non-contact mode can overcome these restrictions, but it has low detection efficiency when encountering rough sample surfaces. In this thesis, to overcome the limitations of non-contact detections, all-optical detection is studied, and then an enhanced all-optical detection with an elliptical reflector on rough surfaces is proposed. Secondly, to improve the limitations of contact-based ultrasonic detection, a waterjet is proposed to enable non-contact detection for ultrasonic transducers. The proposed non-contact PA techniques can empower functionalities of PA detection in more demanding environments and conditions and may pave the road for more biomedical or industrial applications.