Processing and phase analysis of fringe patterns with contrast reversals

Area of Science:

• Optical Metrology
• Signal Processing
• Materials Science

Background:

• Fringe pattern analysis is crucial for quantitative phase retrieval in interferometry.
• Contrast reversals in fringe patterns pose significant challenges for traditional demodulation algorithms.
• Existing methods often require multiple images or specific fringe pattern designs.

Purpose of the Study:

• To propose a novel method for demodulating fringe patterns with contrast reversals.
• To develop a robust phase extraction technique requiring only a single interferogram.
• To validate the method's effectiveness on experimental data from vibrating silicon micromembranes.

Main Methods:

• Preprocessing: Calculation of the absolute value of background-removed fringe intensity.
• Phase Extraction: Application of 2D continuous wavelet transform with enhanced ridge extraction.
• Validation: Experimental testing using time-averaged interferograms of vibrating silicon micromembranes.

Main Results:

• Successfully demodulated fringe patterns containing contrast reversals without phase jumps.
• Demonstrated the ability to extract accurate fringe phase maps from a single image.
• Confirmed the method's robustness and validity through experimental interferogram analysis.

Conclusions:

• The proposed method effectively overcomes phase jump issues caused by contrast reversals.
• This single-image approach simplifies fringe pattern analysis and broadens its applicability.
• The technique is suitable for analyzing dynamic events, such as the vibration of microstructures.