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Path-independent phase unwrapping using phase gradient and total-variation (TV) denoising
Howard Y H Huang1, L Tian, Z Zhang
1Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore 117543, Singapore. ngeehao@gmail.com
Optics Express
|June 21, 2012
Summary
This study introduces a novel path-independent phase unwrapping method for interferometry. It effectively removes noise by denoising the unwrapped phase gradient, improving accuracy in shearography and electronic speckle pattern interferometry.
Area of Science:
- Optical Metrology
- Image Processing
- Interferometry
Background:
- Phase unwrapping is critical for interferometric techniques but is hindered by noise.
- Existing path-following methods struggle with noisy data and erroneous pixels.
Purpose of the Study:
- To propose a novel path-independent phase unwrapping method.
- To overcome limitations of traditional path-following techniques in noisy environments.
Main Methods:
- Determining the unwrapped phase gradient from the wrapped phase.
- Denoising the gradient using Total Variation (TV) minimization.
- Integrating the denoised gradient to obtain an approximate unwrapped phase.
- Reconstructing the final phase map by adding low-order modes.
Main Results:
- The method effectively separates the smooth phase gradient from amplified noise.
- Demonstrated capability on numerical data and experimental shearography/ESPI data.
- Achieved accurate phase unwrapping in the presence of noise.
Conclusions:
- The proposed path-independent method offers a robust alternative for phase unwrapping.
- It is particularly suitable for phase maps without abrupt changes.
- Validated effectiveness in real-world interferometric applications.
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