New displacement measurement method based on digital Moiré fringes formed by a single grating

A new method for displacement measurement with a single grating was proposed in the present study. In this method, the magnified grating image was received by image sensor and sent into the computer. Then, the digital Moir fringes were generated by overlaying the grating image with its mirror image, and the Moir fringe pitch was directly subdivided by image sensor pixels, which had a good space consistency. Compared with the traditional displacement measurement method that generated Moir fringes with the superposition of two gratings, this method totally eliminated the interval between two gratings, was easier to assemble and adjust, and had a lower cost for subdivision. The subdivision system with the resolution of 0.04 m, which consisted of the grating with 20 m pitch and the CMOS image sensor with the pixels of 2 0481 536, was tested on the Abbe comparator platform. The results show that the maximum displacement error is less than 0.18 m.