Full-field stress measurement based on phase-shifting ptychographic iterative engine

Stress measurement is significant to evaluate and predict optical behaviour of the birefringence components. The separation of two principal stress components is a difficult problem due to the coupling between them. A new PIE-based stress measurement method is proposed. Combining with the four-step phase-shifting measuring method, the complex amplitude transmittance functions of the sample in different phase-shifting states are reconstructed. Then the quantitative stress birefringence information are extracted respectively from the amplitude information and phase information. This method can achieve the complete stress information measurement and is especially suitable for the large-size samples.