Accurate calibration of a fringe projection system by considering telecentricity

Autor: Haskamp, Klaus, Kästner, Markus, Reithmeier, Eduard
Zdroj: Proceedings of SPIE; May 2011, Vol. 8082 Issue: 1 p80821B-80821B-12, 8001292p
Abstrakt: Fringe projection systems can be used for the measurement of complex workpiece geometries. Virtual fringe projection systems can be used for the calculation of optimal measurement strategies with respect to criteria like a minimal measurement uncertainty. This is the main field of research of the subproject B5 of the collaborative research centre 489 (CRC 489), funded by the German Research Foundation (DFG). The main task of the subproject is to develop a virtual multisensor assistance system for the calculation of workpiece adapted measurement strategies. This paper focuses on the model and calibration of the used fringe projection sensor. The sensor has to be modelled and the system parameters have to be identified by an accurate calibration procedure. The used fringe projection system has a camera lens with an object-sided telecentricity. Usually, the components projector and camera were described using a pinhole model, which does not reflect the telecentricity. This means, that the existing physical formulations and calibration procedures cannot be used, here. In this paper, the model and calibration strategy for the calculation of the system parameters are described in detail. In order to get a precise simulation model, each intrinsic and extrinsic parameter is considered. To verify the virtual model and the calibration strategy, the calibration was repeated and the standard deviation of the parameters was calculated. Furthermore an optical flat and a groove artefact will be measured and the planarity of the optical flat and the depth of the groove artefact will be determined and compared to the calibrated values.
Databáze: Supplemental Index