Combining photoacoustic and optical coherence tomography imaging for nondestructive testing applications

Robust, non-destructive testing imaging instruments, capable to provide valuable information from within the body of materials is important for both quality control and the development of new materials, for industrial and medical applications. Conventional non-destructive testing (NDT) methods, such as radiographic or ultrasound-based techniques, allow for deep axial range imaging, however, they are either using non-safe radiation or/and exhibit low imaging resolutions. The speed at which the standard NDT methods deliver images is also limited. The development of photoacoustic (PA) and optical coherence tomography (OCT) applications in the field of NDT have grown exponentially over the past years, offering faster, higher resolution images. Both techniques, PA and OCT bring a plethora of benefits to the current methods. However, a multitude of challenges still needs to be addressed to truly make either of them the technique of choice for NDT applications. In this manuscript, a short overview of the challenges that these two imaging techniques are facing when used for NDT applications is presented. Illustrative high-resolution images, produced by a dual PA/OCT imaging instrument developed within the Applied Optics Group at the University of Kent are presented. These images demonstrate unique capabilities for NDT applications.