Digital projector is a main component in Fringe projection profilometry (FPP). To acquire precise 3D profiles, it is crucial to accurately calibrate and compensate projector distortion. In this paper, we propose a new method to improve the accuracy of projector compensation. Coefficients of projector distortion are first accurately calibrated. And based on the calibration results, non-uniform fringe patterns are designed to compensate the projector distortion. With the non-uniform fringe patterns, phase errors in absolute phase map can be automatically and effectively offset. Experimental results are shown to demonstrate the validity of the proposed method.
In order to obtain accurate position of the inner key components in the experimental advanced superconducting tokamak (EAST), a combined optical measurement method which is comprised of a laser tracker (LT) and articulated coordinate measuring machine (CMM) has been brought forward. LT, which is an optical measurement instrument and has a large measurement range and high accuracy, is employed for establishing the precision measurement network of EAST, and the articulated CMM is also employed for measuring the inner key components of EAST. The measurement uncertainty analyzed by the Unified Spatial Metrology Network (USMN) is 0.20 mm at a confidence probability of 95.44%. The proposed technology is appropriate for the inspection of the reconstruction of the EAST.