Patent ID: 9689796
Date: 2017-06-27
CPC Classifications: G01B,G01N

Claim:
1. A method of characterizing a wet paint layer of a painted body by paint layer parameters based on fitting to a physical model, the method being carried out by a sensor system in a non-contact manner, the sensor system comprising an emitter system for emitting THz radiation, a detector system for detecting THz radiation, and a processing unit operationally coupled to the emitter system and the detector system, the method comprising: emitting, by the emitter system, a THz radiation signal towards the painted body such that the THz radiation interacts with the wet paint layer, the wet paint layer having not yet finished a drying process during which the wet paint layer becomes a dry paint layer; detecting, by the detector system, a response signal being the detected THz radiation signal having interacted with the wet paint layer; determining model parameters of the physical model by optimizing the model parameters such that a predicted response signal of the physical model is fitted to the detected response signal, wherein the model parameters are indicative of optical properties of the wet paint layer describing the interaction of the THz radiation signal with the wet paint layer, the determined model parameters including a parameterization of the index of refraction of the wet paint layer; and determining, from the determined model parameters, the paint layer parameters, wherein the paint layer parameters include a predicted dry layer thickness of the wet paint layer.