Accurate phase expansion on reference planes in grating projection profilometry

Abstract

A novel phase expansion technology based on a binary quadratic rational polynomial model is proposed. Firstly, the unwrapped phase distribution on reference planes parallel with a zero reference plane in a different grating project profilometry measurement system is analyzed and synthesized. Then a binary quadratic rational polynomial model is proposed to express the uneven phase distribution on every reference plane. The least-squares iterative estimation method based on a first-order Taylor series expansion is employed to obtain the polynomial coefficients. Finally, accurate phase expansion of reference planes is implemented according to the rational polynomial model. The results of the experiments proved that the method proposed in this paper can recover the phase distribution on the full field from parts reference planes, and the measurement errors such as the geometrical parameter error, system structure error, real reference plane profile error and random error can be decreased.