METHOD FOR MARKING BAR CORD BY LASER BEAM

摘要

PROBLEM TO BE SOLVED: To reduce physical and chemical changes occurring in bar-cord part on the surface of an object and to facilitate and speedify writing operation of further information. SOLUTION: The surface 21 of a nuclear fuel coating tube 20 is irradiated with laser beam LR and this laser beam LR is scanned to form fine lines 11 on its surface 21. A heavy line 15 (or 16) is formed by arraying plural fine lines 11 in parallel, and the bar cord 10 is formed by arraying plural heavy lines 15 (or 16). Plural fine lines 11, 11... forming the heavy line 15 (or 16) are formed by spacing mutually gaps G in the range where the heavy line 15 (or 16) can be optically recognized.