In situ calibration of phase shift in digital speckle pattern interferometry based on fringe skeleton

Miscalibration of phase shift in digital speckle pattern interferometry results in significant measurement errors. We propose an in situ phase shift calibration method that is used in speckle pattern interferometry based on fringe skeleton. No additional devices are required during the calibration, making the method is easy to perform. Good calibration results are obtained even if the phase fringes are irregular, which shows the wide adaptability of this method. Experimental results show that the phase error after the calibration is less than 0.08 rad, which satisfies most practical engineering measurement needs.