High Speed UV Laser Beam Scanning by Polygon Mirror

Since the stereolithograpy system appeared on the market, various rapid prototyping machines based on the layer laminated manufacturing process have emerged one after the other, the range of applications of which is classified according to their features. Of these, stereolithogrraphy methods which make use ofphotocurable resin as material and laser beam as processing tools are gradually being established. They are currently the most widespread with a rich variety of models available. The scanning device used in stereolithography serves as the key technology for this method but consists basically of only the galvanometer mirror known for outstanding high speed ability and the XY plotter known for outstanding scanning position accuracy1),2). Lately, many models are seen to use the galvanometer mirror due to improved accuracy, but still this scanning device is used only when the fabrication size allows, etc. From such reasons, the authors have developed a laser stereolithograpy system capable of high speed high accuracy position scanning by the high speed raster scanning method using a polygon mirror as the scanning device3). The polygon mirror, which has a higher scanning speed than the galvanometer mirror, is moved along the NC servo shaft and the raster scanning spacing is made considerably smaller than the laser beam spot diameter. This paper describes this system and the results of fabrication experiments with this system.