Design Of A Fully Polarized Simultaneous Imaging Optical System Based On Split Aperture

With the advancement of science and technology,air control and space control have played an increasingly important role in the military system of air,space and land integration.The threat of space debris to spacecraft,the spy satellite’s spying on territory,and the potential threats of space-based weapons during the process of space exploration make it urgent to develop space detection technology.The imaging and identification of space targets are mainly realized through space-based detection technology.Light intensity imaging and spectral imaging,which are the two main forces of traditional imaging technology,are not capable of working in complex cosmic environments.The former is a bit more difficult to detect camouflage targets,and the latter is easily affected by cosmic radiation.Therefore,the traditional imaging technology is more difficult to meet the precise imaging of the target’s orbital information,the surface material,structure and target situation awareness.Compared with the traditional light intensity imaging system,the polarized light imaging system can achieve the target recognition function of the traditional long focal length optical system.With the addition of multi-dimensional information such as the degree of polarization,the accuracy of the polarization imaging optical system for target recognition has also been significantly improved.Meanwhile,on the basis of realizing light intensity imaging,the polarizing optical system can additionally obtain information such as edge effect information,surface material information,and surface roughness of a space object through calculation processing.Based on the above information,the characteristics of the space target can be restored through simulation technology,the purpose of accurate three-dimensional modeling of the target can be achieved,and the advanced stage of technical analysis in the Jason criterion can be achieved.In order to realize the imaging and identification and technical analysis of spatial targets in the imaging area,a space-based compact polarization imaging optical system with divided aperture is proposed,which is based on the traditional ground-based polarization imaging system.The effective focal length of this optical system is 2000mm,the relative aperture is 1/10,The size of pixel 10 μm,and the size of a single detector is 512 × 512.The optical system can be equivalently decomposed into three parts.The front telephoto lens group is used to detect space targets.The compressed optical path of the collimating objective lens group is a front system for the imaging objective lens group to collect target information.After processing,it can obtain multi-dimensional information of the target for technical analysis.Based on the theory of polarization imaging,analyze the advantages and disadvantages of time-series,space-type,and interference-type polarized light imaging and recognition methods.Based on the analysis of space size,energy and reliability,the interference type images are susceptible to crosstalk and does not meet the stability requirements.Finally,the imaging method of the sub-aperture in the final airspace type is adopted;For the selection of the structural form,the transmissive type is not suitable for the space environment due to its shortcomings such as heavy weight and long length.The off-axis reflective type not only has difficulty in installation but also increases the complexity of the system.Therefore,the reflection structure of the Cassegrain system is adopted as the final subsystem.Due to the introduction of off-axis non-rotational symmetric systems,the traditional aberration theory is no longer applicable.This paper proposes a scheme to convert the off-axis system to a coaxial optical system.Based on the pupil matching theory,the calculation of subsystem optical system parameters is completed.Based on the geometric aberration theory and quadric surface equations,the initial structural parameters of the subsystem can be solved.Then based on the aberration theory and comprehensive indicators,the subsystem design is completed through simulation software.The article expounds the principle of residual aberration distribution of the front system and the stitching details of the subsystems,and details the difficulties in designing the corresponding subsystems and the precautions when stitching.Finally,the imaging quality of the system was analyzed using MTF curve,field curvature and distortion as evaluation criteria.The work of presetting reasonable tolerances,adjustments and analysis of the system was completed,and reliability analysis such as defocus was also completed;The corresponding three-dimensional structure diagram is drawn according to the structural parameters of the optical system,and according to the simulated optical path of the system,the inner lens hood and the secondary lens hood of the primary mirror are completed.The stray light tracking of the system was completed,and the PST of the system off-axis angle of 0.1 °～80° was calculated and evaluated.The above results show that the imaging system has reasonable tolerance distribution,good reliability,and good imaging quality.It can achieve high-resolution imaging in the imaging range and provide a good hardware foundation for later technical analysis.