Study on the influence of vibration on phase-shifting interferometry and the suppression methods

Phase-shifting interferometry (PSI) is known as a promising method for measuring surface morphology. A study of PSI-based strategy for diagnosing the surface of first mirrors in Tokamak device is in progress. However, the vibration environment of the fusion device seriously affects the measurement accuracy of PSI and solutions must be explored. This paper presents a quantitative study of the influence of vibration on measurement, along with an investigation of vibration suppression methods from the perspectives of optimizing the phase extracting algorithms and experimental parameters. To enhance the precision of phase calculation, a least-squares iterative algorithm (LSI) was utilized to derive the phase angle; to minimize the number of required interferograms, a combination of Gram-Schmidt (GS) and Least-Squares Ellipses Fitting (LSEF) was employed. Additionally, selecting an optimal exposure time for image acquisition can facilitate enhanced measurement accuracy in vibrating environments.