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A Multimodal Wide-Field Fourier-Transform Raman Microscope
Published on: December 30, 2025
The empirical mode decomposition: a must-have tool in speckle interferometry?
Sébastien Equis1, Pierre Jacquot
1Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne EPFL-STI-NAM, Station 11, CH-1015 Lausanne, Switzerland. sebastien.equis@epfl.ch
Optics Express
|January 23, 2009
Summary
This study introduces a fast Empirical Mode Decomposition (EMD) method for enhancing speckle interferometry (SI) phase computation. The technique improves accuracy and speed for dynamic behavior characterization using full-field measurements.
Area of Science:
- Optical Metrology
- Materials Science
- Signal Processing
Background:
- Growing demand for full-field, nanometric sensitivity techniques for dynamic behavior characterization.
- Speckle Interferometry (SI) shows promise but faces limitations like correlation length and complex unwrapping.
- Need for efficient processing techniques to improve accuracy and computation speed in SI.
Purpose of the Study:
- To present a fast implementation of Empirical Mode Decomposition (EMD) for speckle interferometry (SI) signal processing.
- To enable accurate phase computation from SI data by reshaping the pixel signal.
- To develop an improved phase extraction procedure for SI raw data.
Main Methods:
- Fast implementation of Empirical Mode Decomposition (EMD) for SI signal processing.
- Utilizing the analytic method based on the Hilbert transform (HT) for phase computation.
- Introducing a zero-crossing technique for phase evaluation based on EMD extrema.
- Developing a method to discard under-modulated pixels causing erroneous phase evaluation.
Main Results:
- The proposed EMD-based method reshapes SI pixel signals for accurate phase computation.
- The Hilbert transform (HT) approach is reviewed for phase extraction from the EMD-processed signal.
- A zero-crossing technique offers a rapid evaluation method.
- A novel technique effectively discards unreliable pixel data, improving overall phase accuracy.
Conclusions:
- The developed phase extraction procedure leverages 3D information (2 space, 1 time) from SI data.
- This approach aims to maximize the utility of raw SI data for dynamic characterization.
- The fast EMD implementation offers a significant advancement in SI data processing for research and engineering.
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