An Integrated Optical System For Detection And Imaging Based On Freeform Surface

Space targets mainly include satellites operating in orbit,various space debris and space vehicles.Space-based detection and identification of space targets mainly uses space-based detection to detect space targets.Its main task is to carry out important space targets.Capturing,tracking,and thus target characteristics such as the type,size,and orbital parameters of the target.In order to strengthen the surveillance capability of space targets,countries are actively establishing space target surveillance systems.Visible light detection is widely used as a relatively mature means.The space target surveillance system in the United States and Canada also uses visible light as the main detection means.Therefore,it is suitable to use visible light detection and imaging as the first development of space-based target detection means.At present,most space target surveillance systems can only perform imaging observations on a small number of targets,and other targets can still only perform spot tracking observations.Due to limitations in optical resolution,the system does not accurately obtain the orbit information of the target,the structure of the target itself,and the surface material information.In order to make a good image of the detected target,this paper builds an integrated optical system for imaging observation based on the detection system,and designs an integrated optical system for detection and imaging.That is to say,the integrated optical system is composed of two parts: the detecting optical system and the imaging optical system.When the target system is used to capture the target,the satellite turntable is rotated to make the imaging system aim at the target for imaging,thereby accurately identifying the target and achieving clear imaging.Because the F-number of the detection subsystem and the imaging subsystem is large,the aberration is difficult to correct.In order to expand the field of view and effectively correct the system aberrations,this paper will apply more freeform surfaces with design freedom to the design of optical systems.In this paper,the description of the freeform surface is described.Comparing the advantages and disadvantages of various freeform surfaces,the freeform surface shape suitable for the design of the integrated system is selected.Secondly,in order to realize the integrated design,according to the characteristics of the system,the paper first determines the optical system structure.According to the requirements of the mission indicators,the focal length,field of view and effective aperture of each subsystem are calculated based on the characteristics of the target,system noise and detector performance parameters under the premise of ensuring the system's field of view capture capability and detection capability.Then,the design of the integrated optical system for detection and imaging is determined,and the selected freeform surface is applied to the integrated system design.The detection subsystem and the imaging subsystem are optimized respectively.After the optimization is completed,the two subsystems are spliced together.Finally,the integrated optical system based on freeform surface detection and imaging is realized.The surface shape of the primary mirror's freeform surface and the tertiary mirror of each subsystem is fitted,and the freeform surface gradient is calculated.Finally,the image quality evaluation and detection capability analysis of the integrated system are performed.The results show that the integrated system has high energy concentration and good imaging quality.The system can not only can the detection of larger stars be realized for spatial targets at longer distances,but also the imaging resolution of the detected targets is high.