Speckle photography with different pupils in a multiple-exposure scheme

Area of Science:

• Optics
• Experimental Mechanics
• Digital Image Processing

Background:

• Speckle photography is a widely used technique for measuring small displacements.
• Traditional methods often struggle with analyzing multiple displacement fields simultaneously.
• The need for advanced techniques to process complex speckle data is growing.

Purpose of the Study:

• To propose and validate a novel multiple-aperture pupil approach for speckle photography.
• To enable the simultaneous recording and analysis of multiple specklegrams.
• To extend the capabilities of speckle photography for complex displacement measurements.

Main Methods:

• Utilizing different multiple-aperture pupils for recording individual images.
• Introducing spatial frequency carriers by modulating imaged speckles.
• Applying Fourier plane analysis to isolate and combine spectral content.
• Calculating cross-correlation functions for object displacement analysis.
• Deriving ensemble-average intensity and investigating fringe visibility.

Main Results:

• Successfully demonstrated the selective isolation and combination of spectral content from multiple specklegrams.
• Extended speckle photography to depict several specklegrams of multiple uniform in-plane displacements.
• Validated theoretical calculations with experimental results.
• Analyzed statistical properties for cross-correlation functions and derived Fourier plane intensity.

Conclusions:

• The proposed multiple-aperture pupil method enhances speckle photography for multi-displacement analysis.
• This technique offers a powerful tool for researchers in optics and mechanics.
• Further investigation into fringe visibility provides insights into measurement accuracy.