Study On Athermal Properties Of Infrared Wavefront Coding System And Optimization Design

With the continuous development of infrared optical imaging technology,it is used in more complex application scenarios,and the range of operating temperatures becomes wider.On the one hand,in all-weather and all-season applications,the system is required to adapt to the wide range of uniform temperature changes.On the other hand,in special applications such as guided missile,fire fighting,search and rescue operations and high-temperature industry,the system is required to adapt to the internal temperature gradient caused by complex environment.However,the infrared optical material is easy to change its characteristics under the influence of temperature,and the corresponding imaging technology has a higher demand for athermal technique.By adding a phase mask at the aperture stop of the system,wavefront coding technique can effectively ensure that the defocusing in the range of high temperature difference does not affect the imaging stability,as well as keep the system compact and low cost.Therefore,it is possible to realize the athermal purpose of the scene of uniform temperature change.However,the modulation ability of wavefront coding technique to the temperature gradient still require further research.Based on the detailed analysis of related technical overview and comparison of conventional optical system and wavefront coding system imaging theory,the following work is mainly completed in this paper.(1)Based on the uniform athermal theory,theoretical analysis is made on the modulation capacity of wavefront coding technology for temperature gradient,and the feasibility of realizing athermalization is explored.Based on the thermal effects caused by temperature gradient,the effect of temperature gradient is equivalent to that of aberration by combining with the aberration theory.Therefore,the feasibility of realizing athermalization of temperature gradient is explored while the modulation capability of wavefront coding is analyzed.(2)Based on the temperature environment and application of military demand,the infrared wavefront coding system is designed and optimized.According to the specific application background,the conventional infrared optical system with clear imaging at room temperature and the corresponding wavefront coding system are optimized and designed.The appropriate decoding algorithm is used to recover the simulated image.(3)Optical,mechanical and thermal integrated analysis is used to analyze the wavefront coding athermal system.With the cooperation of Zemax and SolidWorks software,the integrated analysis process is simplified.The thermal effects and imaging quality of conventional infrared optical system and corresponding wavefront coding system were quantitatively analyzed based on the finite element analysis.(4)An experimental platform is set up to perform equivalent experiments on visible light systems with common structures.By applying proper uniform temperature variation and temperature gradient to the visible system and observing the image quality change,the validity of the thermal effect and the adaptive of wavefront coding are verified qualitatively.