Measurement of the 3-D Shape and Refractive Index of a Transparent Object by a Laser Rangefinder

In this paper, we propose a new method of measuring 3-D shape and refractive index of a transparent object using a triangulation-based rangefinder. The rangefinder is based on the fact that the light projected onto the surface of a transparent object is partly reflected by the surface, though the majority of the projected light is transmitted through the surface. The basic principle for measuring 3-D shape and refractive index is to detect the reflected light and the transmitted light from a transparent object using specially developed image sensor for this measurement, and to apply our proposed triangulation equation and refractive index equation to these lights. We built a prototype rangefinder and confirmed the efficacy of this method. As a result, we conclude that the proposed approach has great potential for a wide range of industrial applications