Calibration method of a laser beam based on discrete point interpolation for 3D precision measurement.

A laser beam used as a visualizing measuring axis is an important technique in 3D shape measurement. A highly accurate calibration method of a laser beam based on discrete point interpolation is proposed in this paper. A flexible control field constructed by a laser tracker, a theodolite and a target plane with 5 high-precision machining holes is presented. The discrete point interpolation model is established by the coordinates of holes measured by a laser tracker and the angles of holes measured by a theodolite. The coordinates of laser spots on the target plane are obtained based on the angles and discrete point interpolation model, and the direction vector of the laser beam is obtained by linear fitting. The optimal measurement pose of a theodolite is analyzed by the simulation results. The experimental results show that the RMSE of linear fitting of laser beams is no more than 14 µm within a 5 m distance, the RMSE of the spatial points is 0.09 mm and the RMSE of the reconstructed distance is 0.09 mm.