The Optical And Mechanical Structure Design Of The Long-wave Infrared Doppler Differential Interferometer

The middle and upper atmosphere wind field detection is an important means to characterize the atmospheric environment and atmospheric dynamics.It is of great significance for the accurate weather forecasting and the smooth progress of the aerospace industry.The Doppler heterodyne interference technique is based on Michelson's interference technique and is improved on the basis of the spatial heterodyne interference technique.The Fourier transform is used to invert the phase of the interference fringes to obtain wind speed and other informatior.It has developed rapidly in recent years and has become a hot spot in passive wind field detection technolbgy.As a spectral range of Doppler heterodyne interferometer,the long-wave infrared spectrum have an airreplaceable advantage in the detection of trace gas components and gas-beam lines in the middle and upper atmosphere.Based on the technical requirements of long-wave infrared Doppler heterodyne interference technology,this paper uses 150K tow tenperature environment to suppress the thermal background radiation unique to long-wave infrared,and studies the structure design of tong-wave infrared Doppler heterodyne interferometer.Firstly,based on the detection principle of Doppler heterodyne interference technolbgy,the research and development of spatial heterodyne interference technology is combed,and the irregular shape structure design scheme of interferometer under low temperature environment conditions at home and abroad is introduced.Secondly,based on the 160K low temperature working environment of long-wave infrared Doppler heterodyne interferometer,the design index and design principle of the whole system are clarified,and the detailed structural design scheme and design idea based on independent modular structure design and integrated assembly and adjustment technology are proposed.The elastic support structure is designed for the cold optical system(interferometer assembly,front mirror assembly and rear imaging mirror assembly),wihich effectively reduces the influence of thermal stress caused by the thermal expansion coefficient of the structural member and the optical member on the optical member.At the same time,the correctness of the component structure design was verified by finite element simulation.According to the structural design characteristics of each component,the layout design of the whole machine is carried out,including the support structure of each component of the cold optical system,the whole structure of the cold optical system,and the structure of the refrigeration system.Finally,through the finite element simulation analysis of the long-wave infrared Doppler heterodyne interferometer,the axial distortion of the interferometer component and the surrounding point of the grating and the center point of the mirror are extracted,and the optical components are cooled.The deformation direction in the process is convenient for obtaining the interference fringes that meet the requirements by adjusting the spacers in the later assembly process,and then calculating the prism and grating angle change amount and the air gap between the lens groups,and then studying the thermal deformation compensation scheme of the mirror group.At the same time,the analysis data is simulated by the optical design software Zemax,which serves as the basis for verifying the reliability and correctness of the whole structure.Finally,the temperature distribution of the whole machine was analyzed to verify the thermal stability of the structure.