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

Area of Science:

• Optical Metrology
• Interferometry
• Speckle Imaging

Background:

• Digital speckle pattern interferometry (DSPI) enables high-precision measurements.
• Speckle decorrelation noise is a primary limitation in DSPI, reducing reliability.
• Existing noise suppression methods lack a comprehensive statistical understanding.

Purpose of the Study:

• To develop an analytical model for speckle decorrelation noise in DSPI.
• To elucidate the relationship between noise statistics and speckle field correlation.
• To investigate the influence of displacement and system parameters on decorrelation.

Main Methods:

• Analytical modeling of speckle decorrelation noise.
• Incorporation of out-of-plane displacement, in-plane translation, and point spread function.
• Validation via diffraction-limited simulations and optical experiments with controlled displacement.

Main Results:

• An analytical model was established, linking decorrelation noise distribution to the complex correlation coefficient.
• The model accurately predicts noise behavior considering various displacement types and system optics.
• Simulations and experiments confirmed the model's predictions, showing excellent agreement.

Conclusions:

• The study provides a systematic understanding of speckle decorrelation noise mechanisms in DSPI.
• The developed model enhances the reliability of phase retrieval in challenging environments.
• This work offers a foundation for advanced noise reduction strategies in optical metrology.