Laser method for marking bar codes on glass substrates
Hirotoshi Hayakawa · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2000
A method that uses a Nd:YAG laser was developed to mark bar codes on glass substrates. In this method, bar codes are created by a combination of laser deposition and laser trimming; a film for the black bars of the bar code is deposited on the glass substrate, and part of the deposited film is trimmed to expose the white bars of the code. The resulting bar code has high contrast and high resolution. The measured transmission coefficient of the black bars was 2%. When the transmission coefficient was less than 70%, the bar codes were identified at an acceptable level, i.e. the code identification rate was at least 70%, with an average of 91%. The bar code was impossible to identify when the transmission coefficient was 78%. The laser power tolerance of the film deposition for code identification was about (formula available in paper)at optimum laser power.