Enhanced Fourier-transform method for high-density fringe analysis by iterative spectrum narrowing.

Area of Science:

• Optical Metrology
• Image Processing
• Interferometry

Background:

• Fourier transform fringe analysis is limited by spectral broadening in dense patterns with large phase variations.
• This broadening prevents separation of Fourier spectra by spatial carrier frequency, restricting dynamic range.

Purpose of the Study:

• To develop a model-based fringe analysis technique to overcome limitations of the conventional Fourier transform method.
• To enable analysis of dense fringe patterns with significant phase variations.

Main Methods:

• A novel model-based iterative technique is proposed.
• This technique effectively narrows broadened Fourier spectra.
• The method reduces phase errors inherent in conventional approaches.

Main Results:

• Simulations and experimental results validate the proposed spectrum-narrowing technique.
• The technique demonstrates effectiveness for high-density fringe patterns.
• Phase errors are significantly reduced compared to conventional methods.

Conclusions:

• The proposed model-based technique enhances the Fourier transform method for fringe pattern analysis.
• It expands the dynamic range for measuring large phase variations in dense fringe patterns.
• This advancement offers improved accuracy and applicability in optical metrology.