Research On Circular-scanning Algorithm In Laser-Marking Based On Mathematical Morphology

Scanning algorithm is of great importance to Laser-marking industry, because it directly prescribes path information of laser machine and determines the efficiency and product effect of laser marking. Although widely used as a typical scanning mode, Zigzag-scanning has the weakness of too much jumping of laser beam due to excessive lines in a path, thus reducing marking efficiency. Worse than that, a bad product effect will be induced if timing on the starting and end points are not precise. Comparatively, Circular-scanning mode could make up for these shortcomings but it is tough to implement. Consequently, finding a solution to implement circular scanning mode is essential for improving laser marking efficiency and product results.Reviewing related implementations of Circular-scanning algorithm, three methods are provided as follows:(1)First, decompose initial graphics object into convex sub-regions with triangle or convex decomposing methods; Secondly, generate Circular-scanning path for each convex sub-region because it is easily done. Nevertheless, this is a method to generate Circular-scanning path locally, not globally.(2)Create the Voronoi diagrams for the initial graphics object and then acquire circular path by computing parallel lines of initial contour. Although applicable to curved graphics objects, this method will behave ill-efficiently, sometimes even collapse, when applying to multi-connected area, namely, simple connected area with islands.(3)Calculate equidistance curves of initial contour directly. It necessitates related calculation such as line-intersection, interference check and clipping to ensure the correct connecting between equidistance curves, thus making it poor efficient.Enlightened by the complementing principles of laser trough in laser carving, the mathematical morphology essence of circular scanning is analyzed. Combined erosion and dilate algorithm in mathematical morphology with the algorithm of calculating equidistance curves of initial contour directly, a new implementation for circular scanning algorithm which adapts to simple and multi-connected area are provided on the basis of Windows GDI+ platform. Practically, this algorithm has been embodied in the algorithm module of HGLaser, which is one of laser marking control software successfully employed upon the Nd:YAG Type Marking System, and circular scanning path can be generated accurately.