Effect of polarization to directional surface color measurement

Abstract

The colorimeter of 45:0 and 0:45 geometry conditions are usually utilized for color measurement of samples such as automotive parts, plastics, paint, raw materials, and packaging. The measurement result of this kind directional colorimeter is easy affected by polarization property of the measured surface. This paper shows the relationship between polarization and color measurement error. First, a preliminary theoretical analysis of the polarization effect is established basing on the Fresnel reflection equation. Then, an error model of the directional colorimeter is proposed, which include the polarization property of samples. After that, an experiment is taken on the reference colorimetry apparatus of NIM China, and the result verifies the error model. The conclusion shows that the effect of polarization should carefully treated for colorimetry, and designer need to minimize the polarization of colorimeter, and the end user should choose a fit colorimeter according to the characteristic of the test surface.