Logo der Physikalisch-Technischen Bundesanstalt

The first industrial THz application: a THz-based Paint Layer Analyzer

Kolloquium der Abteilung 7

In this seminar I will give an overview of the industrial development of THz spectroscopy at ABB from scouting studies to the development of a THz-based paint analyzer for the automotive industry. First, I will present the initial years of industrial maturation of THz technology (2011-2015), exemplified by the case of quality control of paper sheets during production. THz spectroscopy during this time was still considered as a hype technology thought to readily solve various metrological problems. The study of the determination of the (basis) weight, caliper, moisture and ash concentration of paper sheets, however, clearly demonstrates the difficulties to equal existing mature technologies.


The quality control of paint layers on automotive car bodies turned out to be a more realistic application. In this talk I present in several stages the scientific and technical achievements of the development of a THz-based paint analyzer. In Stage I, we investigated the light-matter interaction with (wet) colloidal dispersions. Subsequently, we built a novel method to determine its properties with high accuracy and speed, using a scheme where the Fresnel equations are fitted, without approximations, to the entire experimental THz time trace. Stage II dealt with the determination of the industrially relevant parameters. Of particular interest for the industry is the prediction of the dry thickness, measured on a wet coating at any moment of the drying process. Hereto, we modeled the drying coating as an effective medium within the Bruggeman approximation to determine the amount of dry and wet paint. In Stage III, the scientific findings are integrated in a physical demonstrator that functions in its application environment.


In conclusion, we have performed the science and technology of the first industrial application of optical THz technology, which is foreseen to disruptively impact the automotive industry by strongly enhancing the efficiency of its paint shop. For this specific application, I will show that the industry pull and technology push are strong enough to create an innovative industrial solution with an attractive business perspective.