Quantitative model and experimental validation of speckle decorrelation in digital speckle pattern interferometry

High-precision phase retrieval in digital speckle pattern interferometry is fundamentally limited by speckle decorrelation noise, which degrades measurement reliability in complex environments. Although various suppression strategies have been proposed, a systematic understanding of their statistical characteristics remains incomplete. This study establishes an analytical model that reveals the intrinsic relationship between the statistical distribution of decorrelation noise and the complex correlation coefficient of speckle fields before and after displacement. The model considers key factors, including out-of-plane displacement, in-plane translation, and the system point spread function. Theoretical predictions were verified through diffraction-limited simulations and optical experiments, in which a precision rotation stage and a differential micrometer platform introduced controlled displacement. The analytical and experimental results demonstrate excellent agreement and clarify the mechanisms of speckle decorrelation in digital speckle pattern interferometry.