Fringe-variable interferometry used for the detection of domain structure in LiTaO3

We design a fringe-variable Jamin interferometer to detect the reversed domain of a ferroelectric crystal in real time. In contrast to the Mach-Zehnder interferometer, this setup is compact and tunable in fringe frequency. In experiments, we use it to detect the partly reversed domains of Stoichiometric LiTaO3 (SLT). Selecting the proper fringe cycle, we can estimate the average phase shift between the original and reversed domains through eyeballing. Furthermore, in the interferogram processing, we use the FFT methods to reconstruct the phase according to the original fringe and deformed fringe, and obtain the phase variance at the domain wall. The results show that the average phase variance at the domain wall is in good agreement with the theoretical value.