Non-destructive testing of complex materials and structures using optical techniques

The increasing use ofboth advanced composite materials and complex shaped structures has led to a great demand for a complete inspection system to deal with increasing quality control issues. Non-destructive inspection techniques are needed to provide information about the inner quality of a component with sufficient resolution. If such an NDT technique can be utilised to deliver data about the quality, or even the contour while testing a component, such a technique may provide huge potential cost savings not only in manufacturing and in-service monitoring, but also for inspection, especially of bondings. Nowadays, optical methods can be an interesting alternative to conventional measurement techniques. With the advantage of receiving full-field information, the capability to inspect metallic and non-metallic parts or to provide data without contact, marking or object preparations, these techniques are, for some applications, the only ones able to provide a measurement result. Some optical NDT methods are described in this paper, for example laser-generated ultrasonics, shearography, thermography and others. The main part focuses on practical examples of applications, covering from material testing in research up to on-site inspection of aircraft.