This paper describes an automated measuring system using reversal two-step phase algorithm. An automated analysis package has been developed for phase-stepped fringe fields. Factors limiting the measuring accuracy and reliability are discussed. This system has been applied to the measurements of thermal deformation, in-plan deformation, resonant vibration amplitude measuring, and nondestructive testing of carbon fiber honeycomb structure.
"Phase-stepping digital speckle-pattern interferometry and its applications", Proc. SPIE 1755, Interferometry: Techniques and Analysis, (5 February 1993); doi: 10.1117/12.140783; https://doi.org/10.1117/12.140783