Patent ID: 7145163
Filing Date: 2006-12-05
Classification: G01D,G01N

Abstract:
1. An apparatus for detecting a light-transmissive sheet-like body, comprising: a light source unit for emitting illuminating light; light detecting means for detecting the illuminating light; and an optical system for leading the illuminating light as parallel-beam light to the light-transmissive sheet-like body and converging the illuminating light to said light detecting means, wherein an edge of the light-transmissive sheet-like body placed between said light source unit and said optical system is detected based on a difference between two types of information, said two types of information including information of said illuminating light which is led to said light detecting means through said edge and another information of said illuminating light which bypasses said edge and is led to said light detecting means, and wherein said illuminating light passes twice through said light-transmissive sheet-like body.