Patent ID: 6768544
Filing Date: 2004-07-27
Classification: B29C,G01N

Abstract:
A method for detecting impurities in transparent material wherein the material is scanned line-by-line and the light transmission through the material is measured, said method comprising the steps of:(a) comparing the measured light transmission values and a reference value to indicate the occurrence of an impurity in the transparent material at one location thereof; (b) determining the extent and shape of the located impurity; and (c) comparing light transmission values in the central area of the located impurity with light transmission values measured in parts of said located impurity surrounding the located impurity said central area of the impurity to determine whether the impurity is a gel or an impurity of some type other than a gel, wherein said gel is an impurity in the transparent material having a central part with greater light transparency than surrounding parts and said impurity of a type other than a gel is an impurity in the transparent material having a central part with lesser light transparency than surrounding parts.