Angular diversity illumination method for effective suppression of speckle decorrelation noise in speckle interferometry

Speckle decorrelation noise significantly reduces the quality of phase fringe patterns in speckle interferometry. Conventional filtering methods often involve a trade-off between noise suppression and computational efficiency. To address this limitation, we propose a speckle noise suppression approach based on angular diversity in illumination. A spatial light modulator (SLM) is employed to precisely and repeatably modulate the illumination angle while simultaneously enabling temporal phase shifting. Multiple uncorrelated speckle fields are acquired and coherently averaged to reduce noise. Theoretical analysis shows that the standard deviation of the speckle noise scales inversely with the square root of the number of averages 1/<i>N</i>. The experimental results validate the theoretical predictions and demonstrate that the proposed method significantly suppresses speckle decorrelation noise, improving the practical performance of speckle interferometry.