Application of narrow band laser ultrasonics to the nondestructive evaluation of thin bonding layers

Abstract

In this paper, a modified laser induced grating technique (LIG) has been utilized to generate narrow band surface waves in an epoxy-bonded copper-aluminum layered structure. A high performance optical interferometer system was utilized to detect the laser-generated surface waves. The dispersion of surface wave in an epoxy-bonded copper-aluminum specimen was measured and compared with the theoretical solution. An inverse algorithm based on the simplex method was then introduced to determine the bonding thickness as well as the elastic properties of the bonding layer. The inversion results demonstrated that the thickness in the microm range or the elastic properties of the bonding layer could be successfully determined.

Laser-ultrasound-based non-destructive testing—optimization of the thermoelastic source

“…A regular line array has been obtained thanks to the interference of two plane waves that is used, for instance, in the non-destructive evaluation of thin bonding layers [10]. Other set-ups produce identical results such as the ones based on a mask [11], a micro-lens array [12], or a diffraction grating [13].…”

Polymer acoustic matching layer for broadband ultrasonic applications

“…Several techniques, e.g., the capacitance transducer, 9,10 the electromagnetic acoustic transducer, 11 and laser ultrasound, 12,13 are able to generate and receive ultrasound without using a liquid medium, but these techniques are restricted in their ability to transmit high-frequency, broadband ultrasound. The development of dry techniques has recently been reported, in which the transduction of high-frequency ultrasound is accomplished via a solid layer such as a polymer or an elastomeric layer, and the acoustic imaging of electronic packages has been successfully achieved by these dry technologies.…”

Theory and applications of high frequency broadband ultrasound via a thin layer in contact with a solid

“…To realize ultrasonic testing without the use of water, several techniques, e.g., the air-coupled capacitance transducer (Schindel, et al, 1995), (Alvarez-Arenas, et al, 2012), (Gan, et al, 2003), , (Robertson, et al, 2002) and (Oralkan, et al, 2003), the electromagnetic acoustic transducer (Houck, et al, 1967), (Ludwig, et al, 1993), (Ogi, et al, 1995) and (Ogi, et al, 2001), laser ultrasound (White, 1963), (Rose, 1984), (Liu, et al, 2002), (Green, 2004) and (Arias and Achenbach, 2004), and microphone array (Chu, et al, 2014), (Rigelsford and Tennant, 2006) and (Brandes and Benson, 2007), have been proposed. Several megahertz broadband ultrasound can be transmitted and received by the aircoupled capacitance transducer (Alvarez-Arenas, et al, 2012) and the electromagnetic acoustic transducer (Ogi, et al, 1995), and this type of transducers are applicable for inspection of high temperature objects (Gan, et al, 2003).…”