Thermal Characteristic Analysis And Thermal Control Design Of Infrared Thermal Imager

With the development of infrared thermal imaging technology,infrared thermal imager has been widely used in all walks of life.For the infrared thermal imager that used for security,which is required work outdoors all year long,so the imaging quality of internal infrared optical system will be changed when the ambient temperature is disturbed.Therefore,it is necessary to study the distribution of temperature field in the infrared thermal imager when the ambient temperature is superimposed with its internal heat source,and the influence of the thermal deformation and stress of the bare engine element on the imaging quality of infrared optical system.It is important to design the thermal control measures for infrared thermal imager,which will greatly improve the working stability of infrared thermal imager.The integrated optical-structural-thermal analysis method was applied to analyze the infrared thermal imager in various ambient temperature fields.Firstly,the finite element model of infrared thermal imager was established,which was used in the ANSYS ICEPAK to obtain the temperature distribution of infrared thermal imager in different ambient temperature.Based on the analysis results of ANSYS ICEPAK,the thermal-structural coupling analysis was finished in ANSYS WORKBENCH,and the thermal deformation and stress of the bare engine element in the inhomogeneous temperature field was obtained.In the same time,the change of lens center thickness and lens spacing in the optical system was acquired.Secondly,in order to analyze the influence of the change of lens surface shape on the imaging quality of infrared optical system,the Zernike polynomial was used as interface between the finite element software and the optical analysis software.The lens surface node data were extracted from the finite element analysis result and the first 37 Zernike coefficients was obtained by Zernike polynomial fitting.Finally,the changes of the imaging quality of the infrared optics system were analyzed by bringing the change of center thickness and interval of lens,and the Zernike coefficients of each surface into the optical design software ZEMAX.According to the results of imaging quality analysis,the thermal control design of infrared thermal imager was designed to ensure the internal temperature when the ambient temperature changes.In order to verify the accuracy of the analysis results,the thermal imaging experiment on the infrared thermal imager was carried out.The experimental results show that the imaging quality of infrared thermal imager in high and low temperature was consistent with the results that obtained by simulation analysis,and the accuracy of the analysis method was proved.