Estimating Model On SNR Of Infrared Imaging Target

During the Second World War,the military competition between countries caused by the first use of the infrared system caused the rapid development of the infrared imaging system.In the next few decades,the infrared imaging system was gradually developed from the non real-time display system of two-dimensional slow frame scanning to the Jiao Ping real-time display system.The modern infrared imaging system is not only applied in the military field,but also widely used in the fields of industry and medical treatment.For a wide range of infrared imaging systems,the prediction of imaging quality and range of action is of great significance to the performance evaluation of the infrared system and the design and optimization of the subsequent system.In this paper,a target signal to noise ratio model of infrared imaging system is established to evaluate the ability of the system to detect targets.The signal to noise ratio(SNR)is the radiation response of the infrared imaging system.It is related to the quality of the infrared image.It can be used as a parameter to calculate the operating distance of the system.It is the basis of the design of infrared imaging system.The target signal-to-noise ratio model is related to the radiation characteristics of the target and background and the signal processing of the system.The main influencing factors include the radiation characteristics of the detected objects,the radiation characteristics of the background,the noise interference,the attenuation effect of the atmosphere on the transmission of infrared radiation,and the performance of the infrared imaging system itself including the optical system.Attenuation,signal processing,detector response performance and so on.The infrared radiation characteristics of the target will be analyzed in two directions from the radiation and the ambient radiation of the target itself.This paper considers the experimental target(unmanned aerial vehicle)as the calculation of the Lambert radiant.The influence of atmosphere on infrared imaging system can be divided into two aspects.On the one hand,it is the attenuation in the atmosphere transmission of infrared radiation,and the other is the noise effect caused by the atmosphere's own radiation characteristics.Atmospheric attenuation is due to the absorption,scattering and reflection of water vapor and carbon dioxide in the atmosphere.Therefore,the atmospheric attenuation coefficient is a quantity related to the composition and distance of the atmosphere.Therefore,the atmospheric attenuation coefficient is often needed to calculate the operating distance of the infrared system.The atmosphere,like other substances in nature,has its own heat radiation,because the target shielded the radiation from the atmosphere to the detector,so the effect of atmospheric heat radiation on the detectors receiving the target radiation and the detectors with the pure reception background radiation were different.In this paper,the target signal to noise ratio(SNR)of infrared imaging system is modeled from the perspective of background radiation difference.According to the image of the target,the number of pixels is different,which is divided into point target and surface source target.According to the two different imaging results,different signal to noise ratio model is set up.On this basis,the calculation method of action distance is given.The experimental verification of the model is that the vehicle type gaze infrared search and tracking system of North China photoelectric technology institute is an observation system.With the low and slow small targets representing the UAV as the observation target,the validity of the model is verified through the acquisition of experimental data in the two seasons of winter and summer.