Concentric circles grating-based telecentric 3D profile measurement system

A concentric circles grating-based telecentric 3D profile measurement system was proposed to satisfy the needs for simplification of system models, removal of system constraints and increase of calculation speed. The method utilized a Fresnel lens and a projector to generate paralleled structured light so as to establish a linear projecting model and reduce the calculating complexity. Wrapped phase information was obtained by using Fourier transform method and through concentric circles grating-based calibrating method, unwrapping phase was obtained point by point at the same time. The whole process got rid of traditional phase unwrapping procedure and effectively repressed the diffusion of errors. When a tested object with 20mm maximal height was measured, the maximal error was 0.23mm and the relative error was 1.15%. The validity was verified by experiments and 3D information of an object could be obtained accurately and rapidly.