Design of a projection moiré system based on a nonuniform grating projection

In the projection moiré method based on equally spaced grating projection, the moiré pattern is often nonlinear and nonuniform because of oblique-angle projection. A new measurement method based on a newly designed nonuniform grating projection is proposed. A model of the projection moiré system based on the designed nonuniform grating projection was built, and the phase-to-height relationship of the proposed system was adjusted. High-quality periodic moiré patterns were obtained in the full measurement field in this system. Experiments demonstrated the precision and validity of the projection moiré system based on the designed nonuniform grating. The measurement resolution of the proposed system was 0.006 mm in an 800 × 600 mm2 area, i.e., one hundred thousandths of the measurement field of view.