Non-destructive characterization of automobile car paints using terahertz pulsed imaging and infrared optical coherence tomography

Terahertz pulsed imaging (TPI) and Optical Coherence Tomography (OCT) are two powerful techniques that can be used to non-destructively acquire high quality three-dimensional images from within scattering media. In this paper, we report experimental results of using TPI and infrared OCT for characterizing automobile car paints. We found that the individual layer thickness of all four layers of real-world car paint samples could be determined from TPI measurements whilst OCT measurements can only image the top two layers of the car paints albeit with a better image resolution. OCT is able to reveal additional information such as the shape and orientation of metallic flakes in the base coat of the car paints.