General iterative algorithm for phase-extraction from fringe patterns with random phase-shifts, intensity harmonics...

Area of Science:

• Optical metrology
• Interferometry
• Phase-shifting algorithms

Background:

• Advanced iterative algorithm (AIA) is a flexible phase-shifting algorithm (PSA) for extracting phase from fringe patterns with unknown phase-shifts.
• AIA accuracy degrades with intensity harmonics and phase-shift non-uniformity.
• Existing PSAs often restrict fringe models, sacrificing robustness against specific error sources.

Purpose of the Study:

• To propose a general iterative algorithm (GIA) with a more comprehensive fringe model.
• To enhance accuracy and convergence in phase extraction under challenging conditions.
• To provide a robust alternative to existing phase-shifting algorithms.

Main Methods:

• Developed a general iterative algorithm (GIA) with a generalized fringe pattern model.
• Divided unknowns into fringe amplitudes, phase, and phase-shift parameters.
• Employed group-wise optimization using the Levenberg-Marquardt method for enhanced accuracy and convergence.

Main Results:

• GIA demonstrated superior accuracy compared to existing phase-shifting algorithms.
• Performance improvements were validated through extensive simulations.
• Real-world experiments using a Fizeau interferometer confirmed GIA's enhanced accuracy.

Conclusions:

• The proposed GIA offers improved accuracy and robustness for phase extraction in interferometry.
• GIA effectively handles intensity harmonics and phase-shift non-uniformity.
• GIA represents a significant advancement over previous iterative phase-shifting algorithms.