Introduction The VERTEX Fourier Transform Infrared (FTIR) spectrometer series are applied for the accurate Transmittance, Absorbance and Reflectance measurements of solid samples at room and low temperatures. Therefore such FTIR spectrometers are used in the area of solid state physics as a research measurement tool for the development of detector material commonly [1, 2 and 3]. Beside the analysis of detector material as well there is the need to characterize the finally designed detector devices. Bruker provides the necessary optical, electronics and software adaptations to apply the VERTEX high-end R&D FTIR for general principles of detector characterization.