Infrared simulation and performance validation of pinhole and 4-bar collimator targets for static performance evaluation of thermal imaging systems

Abstract

The minimum resolvable temperature difference (MRTD) and minimum detectable temperature difference (MDTD) are widely accepted static performance test parameters that best describe the field performance of thermal imaging systems. MRTD test is measured by determining the minimum temperature difference between the 4-bar target and the background required to resolve the thermal image of the bars by an observer. On the other hand, MDTD test is measured by determining the minimum temperature difference between the target and the background, which is required to detect the target from the thermal image. Different temperature differences between the target and the background with different target spatial dimensions were used while conducting both MRTD and MDTD measurements using collimator test systems. In this study, to evaluate the field performance of various thermal imaging systems, MRTD and MDTD tests were applied. Then, infrared simulations of pinhole and 4-bar collimator static test system targets were described based on the electro-optical parameters of unit under test (UUT) including detector resolution, system SiTF (Signal Transfer Function), system MTF (Modulation Transfer Function) and total optical transmission. With these inputs, the infrared simulation images of pinhole and 4-bar targets, which have adjustable temperature difference and different spatial frequency, were obtained in MATLAB environment. Then, the infrared simulations of pinhole and 4-bar target images were verified with thermal imaging system.