Calibration of probe misalignment in point-diffraction interferometer

The fiber point-diffraction interferometer provides a feasible method for the measurement of three-dimensional absolute displacement, in which the fiber point-diffraction sources generating coherent spherical reference waves are required to be parallel placed in the testing probe. However, the misalignment in the actual probe could introduce significant error in the displacement measurement result, and it also places high requirement on the adjustment of testing probe. A method based on phase difference in the axial displacement is proposed to calibrate the probe misalignment, and the numerical simulation is carried out to demonstrate the feasibility of the proposed method. The proposed method lowers the requirement on the processing of testing probe.