Weighted least-squares phase unwrapping algorithm based on a non-interfering image of an object

Area of Science:

• Optics and Photonics
• Image Processing
• Metrology

Background:

• Conventional quality maps in weighted least-squares phase unwrapping are inadequate for regions with abnormal fringes.
• Accurate phase unwrapping is crucial for various interferometric applications.

Purpose of the Study:

• To propose a novel algorithm for robust phase unwrapping in the presence of abnormal fringes.
• To enhance the reliability of phase unwrapping by utilizing a non-interfering image.

Main Methods:

• A non-interfering image of the object is used to create an improved reliability map.
• The conventional weighted least-squares algorithm is applied, and unreliable regions are identified.
• Iterative unwrapping is performed on unreliable regions using the non-interfering image.
• Phase maps are combined and smoothed using a continuity operation.

Main Results:

• The proposed reliability map effectively identifies unreliable regions in phase unwrapping.
• Iterative unwrapping with the non-interfering image successfully resolves phase ambiguities in abnormal fringe areas.
• The combined and smoothed phase map demonstrates improved accuracy and robustness.

Conclusions:

• The developed algorithm provides a robust solution for phase unwrapping with abnormal fringes.
• The use of a non-interfering image significantly improves the reliability of phase unwrapping.
• This method offers a valuable advancement for applications requiring precise phase measurements from interferograms.