Phase unwrapping through demodulation by use of the regularized phase-tracking technique

Area of Science:

• Optical Metrology
• Signal Processing

Background:

• Interferogram demodulation often results in wrapped phase due to arctangent functions.
• Phase unwrapping is essential for obtaining continuous phase data from wrapped interferograms.

Purpose of the Study:

• To introduce a novel phase-unwrapping technique based on a regularized phase-tracking (RPT) system.
• To demonstrate the simultaneous unwrapping and demodulation of phase data.
• To evaluate the noise robustness of the RPT technique.

Main Methods:

• The proposed method utilizes two phase-shifted fringe patterns (sine and cosine) derived from the demodulated wrapped phase.
• Phase unwrapping is achieved concurrently with demodulation using the RPT technique.
• The RPT method is compared against least-squares integration of wrapped phase differences.

Main Results:

• The RPT technique effectively performs phase unwrapping simultaneously with demodulation.
• The RPT method exhibits substantial noise robustness.
• Comparison with least-squares integration highlights the advantages of RPT in noisy conditions.

Conclusions:

• The regularized phase-tracking (RPT) system provides an effective solution for phase unwrapping in interferometry.
• The RPT technique offers improved performance, particularly in the presence of noise.
• Simultaneous demodulation and unwrapping simplify the phase retrieval process.