METHOD AND DEVICE FOR DETECTING LOW-CONTRAST AND HIGH-CONTRAST DEFECTS IN TRANSPARENT OR TRANSLUCENT OBJECTS

摘要

The invention relates to an in-line optical method of inspecting transparent or translucent objects (2) running at high speed between a light source (3) and means (4) for taking images of the objects and for analyzing the images taken, so as to detect defects in the objects. According to the invention the method consists: in controlling the single light source (3) so that said source produces in succession two types of illumination for each object running past said source, the first type being a homogenous illumination whereas the second type is formed from alternate dark zones and light zones with a discontinuous spatial variation; in taking images of each running object when each of them is illuminated in succession by the two types of illumination; and in analyzing the images taken with the illuminations of the first and second types for the purpose of detecting high-contrast defects and low-contrast defects respectively.