High-precision phase extraction and unwrapping method for MEMS mirror structured light system

Phase extraction and unwrapping is an important part of structured light three-dimensional (3D) measurement. High-precision phase extraction and unwrapping methods are of great significance for realizing high-precision structured light 3D measurement. In this paper, the following researches are made on the phase extraction and unwrapping method in the structured light 3D measurement system based on micro-electromechanical system (MEMS) mirror. This paper adopts the standard N-step phase-shift method to extract phase. Considering the measurement time and measurement accuracy, the four-step phase-shift method is finally selected after the phase error experiment and analysis. The phase unwrapping algorithm selects the multi-frequency step-by-step unwrapping method which is not sensitive to the phase error. For the nonlinear error of the system, phase error compensation based on Hilbert transform is carried out, and the phase error after compensation is reduced by 64.5% compared with that before compensation. Finally, a three-dimensional reconstruction experiment was carried out using the above method and a structured light three-dimensional measurement system based on MEMS mirror. The experimental results show that the measured objects have been effectively 3D reconstructed.