Thermal error analysis and compensation in structured light system by virtual-point-based method

Fringe Projection Profilometry (FPP) is considered to be one of the most reliable and accurate 3D measurement methods. However, in many applications, changes in ambient temperature or self-heating effects will cause different components expansion and contraction in optical systems. Owing to the the fact that parameters of structured light system are usually considered to be fixed after calibrated, the precision of high-accuracy measurement will be greatly reduced if the influence related to thermal error is ignored. In this study, we analyze the thermal error model of the structured light system, and verify our theory by simulation and experiment. Secondly, we propose an improved calibration method, based on traditional method with an additional virtual estimation points in the calibration process. The parameters are compensated at each temperature, and the experiments demonstrated that the thermal error can be greatly reduced after compensation, and the changes of parameters tend to be linear, it is in accordance with the physical phenomenon. Finally, our proposed method could effective compensate the error caused by temperature drift by over 85%.