An advanced phase retrieval algorithm in N-step phase-shifting interferometry with unknown phase shifts.

Area of Science:

• Optical metrology
• Interferometry
• Phase retrieval

Background:

• Phase-shifting interferometry (PSI) is a key technique for precise surface measurement.
• Accurate phase retrieval in PSI is often challenged by unknown or non-uniform phase shifts.
• Existing algorithms struggle with deviations in phase shifts, impacting measurement accuracy.

Purpose of the Study:

• To introduce a novel algorithm for phase retrieval in phase-shifting interferometry with unknown phase shifts.
• To enhance the accuracy, speed, and stability of phase retrieval.
• To develop a method robust against phase shift deviations.

Main Methods:

• The proposed algorithm utilizes normalization and orthogonalization processing.
• It leverages the orthogonality of complex sinusoidal functions to eliminate interferogram background.
• The method addresses phase shift deviations through normalization and orthogonalization.

Main Results:

• The normalization and orthogonalization phase-shifting algorithm (NOPSA) achieves accurate phase retrieval.
• NOPSA demonstrates significantly faster computation speed compared to existing methods.
• The algorithm exhibits improved accuracy, stability, and non-sensitivity to phase shift deviations.

Conclusions:

• NOPSA offers a superior solution for phase retrieval in phase-shifting interferometry with unknown phase shifts.
• The algorithm's robustness and efficiency make it a valuable tool for optical metrology.
• This advancement enhances the reliability and applicability of interferometric measurements.