Single-shot phase-shifting interferometry: methods, challenges, and future perspectives

Single-shot phase-shifting interferometry (SSPSI) has emerged as a powerful solution for quantitative phase retrieval in situations where conventional multi-step phase-shifting techniques fail due to vibration, motion, or limited acquisition speed. By encoding the required phase diversity within a single interferogram, either spatially or computationally, SSPSI enables real-time and full-field measurement without sacrificing spatial resolution. This paper provides a comprehensive overview of the theoretical foundations, current methodologies, and remaining challenges of SSPSI. The basic principle of interferometric phase extraction is first revisited to establish the transition from classical N-step algorithms to single-frame strategies. Existing approaches are then classified according to the mechanism used to introduce phase shifts, including spatial-carrier encoding and digital or computational techniques such as Hilbert, Riesz, wavelet, and monogenic-signal–based analysis. Each family of methods is examined in terms of phase accuracy, robustness to noise, implementation complexity, and suitability for dynamic measurements. Particular attention is given to recent advances in digital and hybrid techniques that numerically generate π/2-shifted fringe patterns from a single image, enabling precise phase recovery without experimental modulation.