Equivalent distortion imaging model-based calibration method for a projection moir system using combined lenses

The projection moire method is a noncontact full-field optical topography measurement technique, which requires a precise model and corresponding calibration method; however, the existing models and calibration methods are either incompatible with system distortion or involve complex experimental operations. This study presents an equivalent distortion imaging model coupled with a flexible calibration method that overcomes such shortcomings. The proposed model is constructed by considering the stacking effect of the distortions of the two lenses and the misalignment between the optical axes. The corresponding calibration method leverages the existing camera calibration method to avoid complex operations. The proposed model has high precision owing to its ability to describe the complex imaging of the system. Moreover, the calibration is flexible and requires far fewer operations than with the two-stage calibration method. Both simulations and experiments verify the effectiveness of the proposed method.