The Research Of Integrated Optical-Structural-Thermal Analysis Method Of Infrared Lens

With the wide application of infrared thermal imaging technology in various fields, the performance of the infrared lens has been asked to higher requirements. The influence of temperature on the optical performance of system is the most serious factor than any other. In the traditional thermal-optical analysis of infrared lens, the temperature usually is the final target, and the performance of optical system only can be analyzed by optical design software after the structural parameters of lens is changed, but the influence of the thermal deformation of mechanical structure on the optical system can’t be considered completely. Therefore, in order to more comprehensive analyze the imaging quality of infrared lens in the thermal environment, we need to comprehensively consider the influence of the deformation of optical element and mechanical structure on the optical performance of system.The integrated optical-structural-thermal analysis method was applied to ordinary infrared lens. Firstly, the geometric model of infrared lens was established by mechanical design software PRO/E, and based on the numerical analysis theory of the thermal field, the finite element software ANSYS was used to the thermal field analysis of infrared lens, and the deformation of lens in different temperature was obtained, especially the change of lens’ mirror surface, which embodies the influence of the thermal deformation of mechanical structure about optical system. Secondly, in order to make the deformation data of mirror surface export to the optical design software, the Zernike polynomial was used to fit the mirror surface of optical lens as interface tool between optical analysis and finite element analysis, the Zernike coefficients was obtained,which can represent the change of mirror surface. At last, the Zernike coefficients, the variation of material’s refractive index and the lens’interval were substituted into the optical design software ZEMAX, the optical performance evaluation index was used to analyze the influence of all kinds of factors about the performance of infrared lens. In order to observe the actual performance of lens on thermal temperature, the thermal imaging experiments on lens were carried out, the imaging quality of infrared lens in normal temperature and others were consistent with the results of analysis, which shows that the integrated optical-structural-thermal analysis method on the infrared lens is efficient.In order to make the infrared lens has the characteristics of high rigidity, lightweight and good adaptability about thermal environment, the optimization design module of ANSYS was used to improve the key structure of the lens barrel, the volume of infrared lens as the objective function. The analysis results show that the mass, thermal deformation and surface aberration of infrared lens have been greatly improved after the optimization, the aim of optimization design is achieved.The integrated optical-structural-thermal analysis is used to analyze the infrared lens, the optical, mechanical and thermal analysis can be effectively integrated together, all the analysis can be applied to the same model, and we can predict the using performance of the infrared lens in the thermal environment during the design phase, which has an important guiding significance for the integrated design of optical-mechanical system.