High-precision projection moiré measurement method for the large depth of field with significant distortion

Abstract

The projection moiré method is a high-precision optical topography measurement method. Because the reception system has the complex characteristic of two-stage imaging, the nonlinearity of phase-height mapping is severe, and imaging errors are substantial. Therefore, many existing solutions consider measurement scenes with the small depth of field and distortion. In this paper, we propose a two-stage imaging model, which can accurately describe the imaging process of the reception system under various distortion conditions. Furthermore, we derive a strongly nonlinear moiré model based on the imaging model, which fully represents the nonlinear effects caused by the depth of field and distortion. Several experiments are conducted for measurement scenarios with varying depths of field and distortion using various imaging models and nonlinear moiré models. The outcomes demonstrate that the proposed imaging and moiré model can reduce the corresponding imaging and model errors and improve the measurement accuracy and practicality in different environments.