Bright Material Distribution in Car Body Panels Analyzed by Low Coherence Digital Holography

Abstract

In this paper, the method to evaluate the distribution of bright materials contained in multilayer coating on car body panels using low coherence digital holography is proposed. In comparison with the conventional methods based on either confocal microscopy or optical coherent tomography, the proposed method can achieve both surface profile measurement and wider measurement area of car body panels. In this method, the reconstructed amplitude and the phase distribution of the object wave reflected from each paint layer can be obtained and used for investigating both the surface profile of the coating film and the distribution of bright materials in the desired paint layer. It is shown that the thickness of the clear paint layer on two pieces of gray car-body-panels having the different appearance is different and the depth distribution of the bright materials shows a local variation in both body-panels. In addition, by comparing the results with optical microscope observation, it is suggested that the paint appearance depends on the thickness of the clear coat layer in the car-body-panel.