White light heterodyne principle for 3D-measurement

3D-measurement systems based on active triangulation using projection of structured light and recording by CCD-cameras are gaining more and more importance in industrial application. Their advantages compared to conventional coordinate measurement machines are the non-contact measurement and the fast acquisition of dense point clouds. This paper presents an alternative method to the well-known combination of Graycode and phase-shift projection, It will be shown how to use the heterodyne principle for overcoming the unwrapping problem of phase functions and for estimating the parameters for a reliable unwrapping procedure. The redundant phase information is used to increase the accuracy of the photogrammetrical 3D-coordinate determination. Finally the heterodyne principle is used to realize on-line measurement based on color-coded fringe projection.