Analysis of sub-pixel laser spot detection in laser triangulation systems

摘要

Laser spot detection is an important step of laser triangulation and limits its accuracy. Common methods todetermine the center position include circle fitting, the Hough transformation, the gray centroid method orGaussian fitting. As these algorithms were often tested in different set-ups and under various conditions, theygenerally lead to diverse results.The aim of this contribution is to investigate the algorithms in a more objective and realistic approach. Aftera short introduction to laser triangulation, basic information about laser spot center detection is given. Fundamentallimitations of the laser spot detection are then considered and analyzed. The investigations are followedby evaluations of measurements in a real laser triangulation setup.Through this approach we could show that the inuence of the spatial quantization and the quantization dueto the limited bit depth of the detector can be in a similar range as the deviation due to speckle noise in theimage. By using adapted image processing steps, the performance of the laser spot center determination couldbe improved significantly.