Multi-position calibration method for laser beam based on cyclicity of harmonic turntable

Abstract

Laser beam used as a visualizing measuring axis has emerged as a major candidate technology for 3D shape measurement. Until now, a prime limitation has been the highly-accurate positioning of laser beam in the whole measurement space. A multi-position calibration method for laser beam based on the cyclical error of harmonic turntable is proposed in this paper. A flexible calibration field constructed by CMM and PSD-based laser receiving board is presented. The coordinate of laser spot on PSD is obtained and transformed into CMM coordinate system. The direction vector of laser beam is obtained by linear fitting from a set of calibrated laser spots. Then the laser beams are calibrated in multiple positions. Based on the cyclicity of harmonic turntable, the error model of rotation angle is established by Fourier series function. The rotation angles are compensated in whole-space and the positioning of laser beam is obtained with highly-accurate. The experimental results demonstrate that the RMSE of linear fitting of laser beams is no more than 0.006 mm, the RMSE of the compensated rotation angles is no more than 0.003°, the RMSE of the spatial points is 0.089 mm and the RMSE of the reconstructed distances is 0.060 mm.