Thickness determination of wet coatings using self-calibration method

Terahertz measurement techniques reveal a high potential for non-destructive and contactless thickness determination of thin-coated plastics, ceramics, paper and tablets as well as painted car bodies. While for these applications the thickness is measured at the end of the complete coating process, we here investigate the suitability of this technique in order to determinate the thickness immediately after application of the wet paint. With a self-calibration algorithm, we are able to determine not only the thickness but also the refractive index and extinction coefficient of the coating in wet state simultaneously.