Denise Reichel studies the delicate subject of temperature measurement during lamp-based annealing of semiconductors, in particular during flash lamp annealing. The approach of background-correction using amplitude-modulated light to obtain the sample reflectivity is reinvented from rapid thermal annealing to apply to millisecond annealing. The author presents a new method independent of the lamp operation to obtain this amplitude modulation and derives a formula to describe the process. Further, she investigates the variables of the formula in depth to validate the method’s suitability for background-corrected temperature measurement. The experimental results finally proof its power for elevated temperatures.