Optothermal effects of laser modes in laser materials processing

All laser materials processing involves two fundamental phenomena: the conversion of optical energy into thermal energy, and the generation of thermal stresses in the laserprocessed materials. The distributions of the thermal energy and stresses in the substrate depend on the laser mode used for materials processing. A proper understanding of the temperature and stress distributions is essential for producing high-quality products using the laser technology. The solution of the complete thermoelastic problem is very complex and requires numerical methods. This paper presents simple analytic expressions for the temperature and thermal stress distributions in the substrate processed with TEM₀₀ and TEM _inf01 ^sup* mode laser beams. The temperature is found to be maximum at the point that encounters the maximum laser intensity. The thermal stress distributions are found to be different owing to the differences in the laser modes used for this study.