An Evaluation Method for Surface Texture of Transparent and Translucent Objects by Stripe Pattern Projection

Abstract

This paper presents an evaluation method for surface texture of transparent and translucent objects. In our method, we project a stripe pattern onto a sample and evaluate a surface property from its contrast. Our method has a good point that measurement data do not depend on brightness of surrounding disturbance light, because the brightness affects only bias component of the contrast. As a measurement sample of transparent object, we chose glass diffusers. Experimental results showed that a decrease in the surface roughness of glass diffuser causes a decrease in the contrast of projected stripe pattern also. Moreover it was confirmed that our method was hard to be affected from the surrounding disturbance light, by the experiment using the fluorescent lamp as disturbance light. Next, our method was applied to not only transparent object but also translucent object. As a measurement sample of translucent object, we used two kinds of acrylic plates, i.e. white and milk-white. From the experiment result, in the case of a translucent measurement object, it was shown that the transparency of measurement samples affected our method.