scholarly journals Phase-Shifting Projected Fringe Profilometry Using Binary-Encoded Patterns

Photonics ◽  
2021 ◽  
Vol 8 (9) ◽  
pp. 362
Author(s):  
Nai-Jen Cheng ◽  
Wei-Hung Su
Keyword(s):  
Phase Unwrapping ◽  
Phase Shifting ◽  
Phase Extraction ◽  
Fringe Order ◽  
Surface Color ◽  
Large Depth ◽  
Phase Shifting Technique ◽  
Depth Discontinuities ◽  
Fringe Patterns

A phase unwrapping method for phase-shifting projected fringe profilometry is presented. It did not require additional projections to identify the fringe orders. The pattern used for the phase extraction could be used for phase unwrapping directly. By spatially encoding the fringe patterns that were used to perform the phase-shifting technique with binary contrasts, fringe orders could be discerned. For spatially isolated objects or surfaces with large depth discontinuities, unwrapping could be identified without ambiguity. Even though the surface color or reflectivity varied periodically with position, it distinguished the fringe order very well.

scholarly journals A Fringe Phase Extraction Method Based on Neural Network

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1664
Author(s):  
Wenxin Hu ◽  
Hong Miao ◽  
Keyu Yan ◽  
Yu Fu
Keyword(s):  
Neural Network ◽  
Fringe Pattern ◽  
Phase Shifting ◽  
Optical Metrology ◽  
Phase Extraction ◽  
Transform Method ◽  
The Neural Network ◽  
Phase Map ◽  
Phase Shifting Method ◽  
Fringe Patterns

In optical metrology, the output is usually in the form of a fringe pattern, from which a phase map can be generated and phase information can be converted into the desired parameters. This paper proposes an end-to-end method of fringe phase extraction based on the neural network. This method uses the U-net neural network to directly learn the correspondence between the gray level of a fringe pattern and the wrapped phase map, which is simpler than the exist deep learning methods. The results of simulation and experimental fringe patterns verify the accuracy and the robustness of this method. While it yields the same accuracy, the proposed method features easier operation and a simpler principle than the traditional phase-shifting method and has a faster speed than wavelet transform method.

An Innovative Phase Shifting System for Non-Destructive Testing

1998 ◽  
Vol 14 (1) ◽  
pp. 31-39 ◽  
Author(s):  
C. W. Chen ◽  
H. Y. Chang ◽  
C. K. Lee
Keyword(s):  
Cellular Automata ◽  
Speckle Pattern ◽  
Surface Profile ◽  
Phase Unwrapping ◽  
Phase Shifting ◽  
Phase Mask ◽  
Electronic Speckle Pattern Interferometry ◽  
Practical Applications ◽  
Phase Shifting Technique ◽  
Phase Map

ABSTRACTPhase shifting technique is one of the most important technologies in the metrology field. Simply by performing an interferogram measurement, and then adopting the phase shifting technique to unwrap the interferogram into a phase map, tasks such as object surface profile reconstruction, holographic interferometry, electronic speckle pattern interferometry, etc., can all be easily accomplished. An innovative phase shifting system, which uses piezoelectric actuators to execute phase shifting first and then implementing a cellular automata algorithm to unwrap phase data, was designed, built, and tested. Since cellular automata is a true parallel process, and noise appearing within the interferogram will not get propagated, this novel system is far more robust than the systems based on the traditional path following phase-unwrapping algorithm. In addition, this new algorithm also provides us with a way to adopt phase-masks within the cellular automata implementations of the phase unwrap operations. All these newly developed techniques make this newly developed system adaptable to many metrology applications, even when high noise is present or when lateral shear exists within the image field. The successful incorporation of the phase-mask approach into the cellular automata phase unwrapping algorithm essentially makes this newly developed system adaptable to take phase map measurements in many practical applications.

scholarly journals Phase extraction from two phase-shifting fringe patterns using spatial-temporal fringes method

2016 ◽  
Vol 24 (7) ◽  
pp. 6814 ◽  
Author(s):  
Ronggang Zhu ◽  
Bo Li ◽  
Rihong Zhu ◽  
Yong He ◽  
Jianxin Li
Keyword(s):  
Phase Shifting ◽  
Phase Extraction ◽  
Two Phase ◽  
Fringe Patterns

Multi-view phase unwrapping with composite fringe patterns

2017 ◽  
Author(s):  
Tianyang Tao ◽  
Qian Chen ◽  
Yuzhen Zhang ◽  
Yan Hu ◽  
Jian Da ◽  
...  
Keyword(s):  
Phase Unwrapping ◽  
Fringe Patterns

scholarly journals An Error-Reduction Method for Temporal Phase Unwrapping Based on Double Three-Step Phase-Shifting and Least-Squares Fitting

2012 ◽  
Vol 6-7 ◽  
pp. 76-81
Author(s):  
Yong Liu ◽  
Ding Fa Huang ◽  
Yong Jiang
Keyword(s):  
Least Squares ◽  
Reduction Method ◽  
Intermediate Phase ◽  
Error Reduction ◽  
Phase Unwrapping ◽  
Phase Shifting ◽  
Surface Measurement ◽  
Acquisition Time ◽  
Least Squares Fitting ◽  
Temporal Phase

Phase-shifting interferometry on structured light projection is widely used in 3-D surface measurement. An investigation shows that least-squares fitting can significantly decrease random error by incorporating data from the intermediate phase values, but it cannot completely eliminate nonlinear error. This paper proposes an error-reduction method based on double three-step phase-shifting algorithm and least-squares fitting, and applies it on the temporal phase unwrapping algorithm using three-frequency heterodyne principle. Theoretical analyses and experiment results show that this method can greatly save data acquisition time and improve the precision.

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