A Method of Measurement of Minimum Resolvable Temperature Difference as a Function of Magnification and Defocusing of a Thermal Camera

Temperature measurement of allergic skin reactions requires meeting certain criteria regarding temperature resolution between small areas. The usual criterion of temperature resolution is NETD. However, this metric does not take into account the limitations of the spatial resolution of the optical system or the detector. In this paper, a model is presented that allows for selection of camera parameters based on the required spatial thermal resolution and size of the object being imaged. The method has been implemented and compared to results obtained in commercial software and has been applied to evaluate spatial thermal resolution of a prototype objective designed for the LWIR band.