Thermal Imager Non-Uniformity Sources Modeling

The raw output of a generic infrared vision system, based on staring arrays, is spatially not uniform. This spatial noise can be much greater than the system NETD, and determines a strong drop in system performance.Therefore we need to model all system non-uniformity (NU) sources to highlight the parameters that should be controlled by optical and mechanical design, the ones depending on the focal plane array and those that can be corrected in post-processing.In this paper, we identify the main NU sources (optical relative irradiance, housing straylight, detector pixel-pixel differences and non linearity), we show how to model these sources and how they are related to the design and physical parameters of the system. We then describe the total signal due to these sources at the detector output. Applying different NUC algorithms to this signal, the final results on the image can be simulated finding a proper correction algorithm. At the end we show the agreement between the model with the experimental data taken on a real system.Changing a limited set of parameters, this model can be applied to many third generation thermal imager configurations.