Abstract
In this note, the applications of a photothermal effect to nondestructive testing are reported. Irradiation of chopped laser light generates the flexural vibration of a plate-like sample by the thermoelastic bending effect. The vibration is sensitive to sample irregularity and mechanical conditions such as fixed ends or adhesively bonded structure. Hence the vibration has been used advantageously for (1) imaging the irregularity of a clamped plate-like sample, (2) detecting the delamination in layered materials, (3) inspecting the strength of soldered connections and (4) sensing the external force acting on a small mechanical beam. These techniques are all optical and noncontact since the vibration is monitored by probe beam deflection or with a optical interferometer. The driving force of the vibration is explained theoretically from the viewpoint of temperature moment.
