Design Of Wide-spectrum Visible-infrared Integrated Optical System

With the continuous advancement of science and technology,the exploration of space in various countries has intensified.Potential threats such as the threat of space debris to spacecraft,the spy satellite’s spying on the territory and the application of space-based weapons put forward higher requirements for the development of space imaging technology.The imaging recognition of space-based targets is mainly realized by the space imaging optical system.The traditional space imaging optical system uses visible light as the working spectrum,and there are deficiencies in the imaging of space targets.For some special material targets,there may be insufficient observation,and observation and imaging cannot be achieved at night,even for clear imaging targets.Maybe because the shape is universal,it is difficult to recognize its core function,so that the target recognition cannot be achieved.Compared with the traditional visible light imaging optical system,due to the characteristics of infrared photothermal imaging,the infrared imaging optical system can realize all-day and all-weather observation of space targets,and can realize the differentiated observation of target temperature,and its internal core components and functions The speculation provides an effective basis for accurate identification of space targets.However,due to the long wavelength of infrared light,it is difficult to achieve high-resolution imaging,resulting in insufficient target observation and insufficient recognition accuracy.Combining the advantages of traditional visible light imaging and infrared imaging,the visible-infrared integrated imaging optical system can simultaneously image multiple spectral bands of the same space target when environmental conditions permit,and obtain detailed information to achieve accurate identification;Under bad conditions,the imaging observation function of the traditional visible light and infrared optical system can also be used.In order to achieve complex information acquisition and accurate recognition of space targets,a design of a wide-spectrum visible-infrared integrated optical system is proposed.Starting from the application scenario analysis,a reasonable photodetector was selected,and then the optical indicators were analyzed and calculated,and then the system performance was reasonably estimated.Finally,the optical system was completed by first designing the sub-system and then performing the integrated design.design.The optical system selects 0.45μm～0.85μm visible spectrum,1.0μm～1.6μm shortwave infrared spectrum and 3.8μm～4.6μm midwave infrared spectrum as the working spectrum.The system adopts the integrated design form of common aperture integrated correction mirror for light splitting,and the common part adopts R-C structure.After light splitting,lens groups are set to correct aberrations,and the detectors are used for imaging.The entrance pupil diameter of the integrated system is1 m,and the blocking ratio is less than 12.3%;the effective focal length of the visible light sub-system is 9m,the relative aperture is 1/9,the pixel size is 5 μm,the detector array is 2560×2560;the effective focal length of the short-wave infrared sub-system is9 m,Relative aperture 1/9,pixel size 15 μm,detector array 640×512;mid-wave infrared sub-system effective focal length 3m,relative aperture 1/3,pixel size 10 μm,detector array 1024×768.The image quality of the designed system was evaluated according to the existing standards,and the image quality of the three sub-systems was obtained to meet the design requirements and application standards;the defocus analysis of the official system was carried out,and the point map and MTF within the focal depth were obtained.The changes are within a reasonable range and do not affect the imaging quality;the system has been analyzed for wave aberration to obtain the accuracy requirements of the system’s processing surface;the system has been analyzed and tolerance tightened,and the tolerances that can be processed under existing conditions are obtained Parameters;thermo-optical analysis was performed on the system,and it was obtained that within a reasonable temperature range,the system maintained the image quality by focusing on the focal plane;the ghost image analysis was performed on the system,and the ghost images produced by each sub-system did not affect their respective images.Surface imaging;Finally,the stray light suppression design and stray light analysis of the system are carried out,and the primary lens hood,secondary lens hood and outer hood,as well as light blocking ring and stray light stop are designed,and the range of 0.5°～80° is simulated.The stray light simulation trace is drawn,and the PST curve of each sub-system is drawn.The above results show that the system design tolerance allocation is reasonable,the reliability is good,and the imaging quality is high.It can realize the acquisition and accurate recognition of the complex information of the space target,and provides a good hardware foundation for the later technical analysis.