METHOD FOR DISCRIMINATING BETWEEN AIR BUBBLE AND CRYSTAL IN COLUMNAR TRANSPARENT OBJECT

摘要

PROBLEM TO BE SOLVED: To discriminate between the air bubble and crystal present in a columnar transparent object such as an optical fiber matrix or the like in a non- destuctive manner. SOLUTION: Laser beam 4 is projected on a columnar transparent object 1 from the light source 3 arranged on the lateral side of the columnar transparent object 1 and beams scattered and emitted by the foreign matter 2 in the columnar transparent object 1 when the projected beam 4 passes through the columnar transparent object 1 are detected at a plurality of positions different from the position of the light source and the brightness difference between these detected beams is detected to discriminate between an air bubble and a crystal.