We introduced the attenuation of rays in the absorbing medium. The proposed model was used to analyze the radial position change in the lens focus due to the optical element's heat absorption in the semiconductor processing process through simulation calculations, such as ray power, lens surface temperature distribution, thermodynamic property, deposition power, and lens refractive index change. The radial focus position deviation of the ultraviolet laser fine processing equipment with a laser source power of 20 W was calculated to be 14 μm; the simulation analysis results were verified by laser processing experiments, laser confocal microscope observation, and step meter measurement. Problems commonly overlooked in the semiconductor industry were analyzed and demonstrated in this article.