Double structured light with divergent projection for surface topometry

A simultaneous double divergent projection of structured light to measure large and complex surfaces at short illumination distances is reported. When the structured and divergent lighting is projected, a moiré pattern is created, with the variable period associated with the out-of-plane surface that is analyzed. A theoretical description of the mathematical model and an algorithm to correct the measurements due to the divergence of the illumination are presented, which aim to establish the correct phase–height relationship. The mathematical model and the proposed method are verified numerically and experimentally. Measurements of the complex surfaces show high accuracy with low uncertainty. The system has been shown to allow rapid measurements in an efficient and easy way using a single camera. (paper)