An apparatus and a method for calibrating and normalizing a stereolithographic apparatus so that a reaction means directed by a positioning means supplied with positioning means information may be positioned accurately on a designated surface of a working medium. One or more sensors fixed in location...http://www.google.ca/patents/US5495328?utm_source=gb-gplus-sharePatent US5495328 - Apparatus and method for calibrating and normalizing a stereolithographic apparatus
