Study of calibration technique for hybrid structured-light metrology system

Numerous structured surfaces with composite materials are widely applied in advanced manufacturing. Hybrid structured-light metrology system has been proposed for in-line form measuring of the structured surfaces with both reflective and diffuse characters. A hybrid structured-light metrology system contains a fringe projection profilometry (FPP) subsystem and a phase
measuring deflectometry (PMD) subsystem. Each subsystem measures rough surfaces and specular surfaces based on structuredlight projection and reflection principle, respectively. Accurate calibration of the system is a challenge and highly influences the data stitching accuracy of the subsystems. In this paper, calibration technique is studied for the hybrid structured-light system to achieve good measurement accuracy. Specific targets are designed and manufactured for the calibration. Novel calibration algorithms are studied based on the calibration targets. Details of the calibration procedure are presented and discussed. Experiments have been conducted and verified the effectiveness of the proposed calibration technique by measuring structured composite samples with a calibrated portable hybrid structured-light metrology prototype. Experimental results demonstrate that the proposed calibration technique can significantly improve the data fusion accuracy and the prototype can achieve good measurement accuracy based on the proposed calibration technique.