The level of a laser beam is controlled to the maximum level detectable by a sensor, and light transmitted through the pattern is normalized with branched light. The laser beam level is made up for variations, and noise at zero and saturation levels are removed. Data thus can be taken out, in which noise...http://www.google.de/patents/US6326606?utm_source=gb-gplus-sharePatent US6326606 - Method and apparatus for checking shape
