For the purpose of realizing a fast and cost-efficient manipulation of the laser beam in production applications, such as welding, marking, and cutting, scanner systems in combination with F-Theta objectives are state-of-the-art. Owing to the absorption of the laser beam power and the resulting heat load acting on the optical system, a change of the focal plane (the so-called focal shift) occurs, significantly affecting the behavior during the application process. A linear correlation between the temperature on the optical surface of a standard F-Theta objective and the focal shift was determined whereby the coefficient of determination R2 is higher than 0.99. Furthermore, two industrial welding applications were investigated using this standard objective, and the resulting temperature distribution along the optical surfaces was also investigated. The results show that a single measurement point appears to be sufficient to obtain a capable input signal for a compensation method. A compensation device was implemented and a sufficient reduction of the focal shift was realized for the examined time range.