Robust and fast filtering method for enhancement of two-dimensional quality-guided path unwrapping algorithms

Area of Science:

• Optical Metrology
• Signal Processing

Background:

• Phase noise is a significant challenge in interferometric measurements.
• Accurate phase unwrapping is crucial for quantitative analysis of surface topography.

Purpose of the Study:

• To develop and evaluate a novel filtering algorithm for phase noise reduction.
• To enhance the accuracy of phase map unwrapping using bicubic interpolation methods.

Main Methods:

• Implementation of bicubic interpolation filtering (BIF) and bicubic interpolation smoothed filtering (BISF).
• Integration of BIM with conventional phase unwrapping algorithms.
• Utilizing a Mirau interferometer for performance evaluation.

Main Results:

• BIF and BISF effectively convert noise distributions to Gaussian distributions.
• The proposed methods enhance unwrapped phase map accuracy.
• A root mean square error of approximately 31 nm was achieved with the BISF method when combined with quality-guided path unwrapping algorithms.

Conclusions:

• Bicubic interpolation methods offer powerful low-pass filtering for phase noise reduction.
• The proposed filtering algorithms significantly improve phase map accuracy in interferometric measurements.
• The combination of BIM with quality-guided unwrapping provides a robust solution for precise phase measurement.