Digital phase-shifting atomic force microscope Moiré method

In this study, the digital atomic force microscope (AFM) Moiré method with phase-shifting technology is established to measure the in-plane displacement and strain fields. The Moiré pattern is generated by the interference between the specimen grating and the virtual reference grating formed by digital image processes. The overlapped image is filtered by two-dimensional wavelet transformation to obtain the clear interference Moiré patterns. The four-step phase-shifting method is realized by translating the phase of the virtual reference grating from 0 to 2π. The principle of the digital AFM Moiré method and the phase-shifting technology are described in detail. Experimental results show that this method is convenient to use and efficient in realizing the microscale measurement.