Calibration and Measurement Method Based on Optical Lenses for Large-Scale 3-D Precise Measurement

Laser is becoming an increasingly important tool in 3-D precise measurement. To reduce the measurement error, the size of the laser spot should be as small as possible. Aiming at the problem mentioned above, a calibration and measurement method based on optical lenses is proposed. Limited to manufacturing and installing errors, the decentration, and tilt among the laser beam, planoconcave lens (PL) and liquid lens (LL) cannot be avoided exactly. The analysis of the optical path with the decentration and tilt is performed. Regarding the complicated calculation, MATLAB is utilized to obtain the motion law of the target spot. The calibration experiment shows that the root mean square error (RMSE) of points used for line fitting is no more than 0.116 mm at a range of 10 m. Moreover, the measurement experiment shows that the RMSE of point measurement and distance measurement of the system is 0.425 and 0.219 mm, respectively. We demonstrate that the calibration and measurement method with optical lenses is feasible for 3-D measurement.