Path-independent phase unwrapping of subsampled phase maps.

Area of Science:

• Optical metrology
• Image processing

Background:

• Phase-shifting interferometry (PSI) is a common technique for measuring surface topography.
• Subsampled interferograms in PSI can lead to wrapped phase maps, complicating analysis.
• Existing phase unwrapping methods may struggle with noisy or subsampled data.

Purpose of the Study:

• To present a new technique for unwrapping subsampled phase maps.
• To enable accurate wavefront reconstruction from phase data obtained via phase-shifting methods.
• To address challenges associated with noise and subsampling in interferometric measurements.

Main Methods:

• Estimation of wrapped local curvature from subsampled phase maps.
• Application of a free-boundary low-pass filter to reduce phase noise.
• Integration of the filtered local curvature using a least-squares technique for wavefront reconstruction.

Main Results:

• Successful unwrapping of subsampled phase maps.
• Demonstration of noise reduction through low-pass filtering.
• Accurate reconstruction of continuous wavefronts from processed phase data.

Conclusions:

• The presented technique effectively unwraps subsampled phase maps.
• This method offers a robust approach to wavefront reconstruction in the presence of noise and subsampling.
• The technique has potential applications in various optical metrology fields.