Infrared Thermal Imaging Field MRTD Target Research

Aiming at the limitations of the MRTD index test model of the infrared imaging system,this paper analyzes the temperature characteristics of the MRTD test target in the field,and carries out the correction of the MRTD model and the design of the target structure under the conditions of the field.Finally,this paper studies the estimation model of the infrared imaging system for the actual target range.By constructing the performance evaluation model of the infrared imaging system in the field,this paper analyzes the influence of the infrared radiation characteristics of the target source composed of the target and the black body,the atmospheric environment and the infrared imager's own performance parameters on the MRTD value and the operating distance of the infrared imager.Firstly,based on the target thermal equilibrium equation,this paper establishes the target temperature model under external field conditions and calculates the temperature distribution of the target surface at different times by substituting the actual parameters of the external field into FLUENT software one day;An atmospheric infrared transmission model was developed to obtain atmospheric transmittance at different detection altitudes and zenith angles;the MRTD calculation model was modified using target temperature data and atmospheric transmittance data to determine the size of a four-rod target for MRTD testing in an external field environment,and an infrared imaging system action distance estimation model was developed to predict the MRTD values and action distances of the infrared detection system for actual military targets at different detection probabilities,target temperatures and zenith angles.The temperature distribution of the target demonstrates that the difference between the target surface temperature and the atmospheric temperature is large when the target surface is exposed to daytime solar radiation,while the difference between the target surface temperature and the atmospheric temperature is not large when the parameters of the external field tend to stabilise in the absence of solar radiation.The revised MRTD model can be applied to the design of target size,the performance test of infrared imaging system in the external field and the estimation of action distance.