摘要
为更好满足空间远距离跟踪成像的要求,设计了一种可调焦的主被动复合光学成像系统,实现了高缩束比、高分辨成像的目的。前端光学系统以共轴三反系统为基础,通过离轴优化设计了焦距为2500 mm,视场角0.12°×0.12°,F数为8.33的共轴偏光瞳系统。后端光学系统采用共孔径分光结构,由分光镜分为两路。一路为被动可见光成像,工作谱段为450~850 nm,成像端采用5片透镜作为成像镜组,后两片透镜为补偿镜组可实现1 km~无穷远范围的连续调焦。另一路主动成像采用激光外差相干成像,工作波长为1550 nm,通过孔径分光完成收发一体的成像系统设计。设计结果表明,被动成像系统在100 lp/mm时各视场调制传递函数均大于0.34,接近衍射极限,主动成像系统波像差优于1/300λ,满足成像质量要求。
Along with the continuous development of aerospace technology,human exploration of outer space has made great progress.During this period,a large number of vehicles have been launched into orbit around the Earth by various countries,led by the United States,but due to a lack of awareness and technology to recover them,they have resulted in space garbage and debris remaining in outer space.According to incomplete statistics,there are thousands of pieces of space debris with a diameter of 10 cm around the Earth,which pose potential hazards for future space exploration and research.Early detection and identification of space debris and timely avoidance are the primary means to ensure the safe operation of satellites and spacecraft.Long-range detection and imaging technology is key to obtaining the relative position information of space debris.For space-based detection and imaging tasks,a reflection system without chromatic aberration is generally used due to the strict requirements on aberration.Among these systems,the three-mirror anastigmat system(Three-Mirror Anastigmat,TMA)is a reflective optical system that can meet the requirements of anastigmatism and a flat image field.Generally,it can be divided into a coaxial threereflection optical system and an off-axis three-reflection optical system.The coaxial tri-reflective system has the advantages of small size,light weight,good thermal stability,and mature technology,but the disadvantage of reduced system resolution due to central blocking;while the off-axis tri-reflective optical system has a large field of view,no central blocking,and a simple structure,but is difficult to process and adjust and is also susceptible to the influence of external environmental factors,which limits its use under certain conditions.In this paper,by designing the co-axial eccentric-pupil,the center blocking is avoided.The structure is simpler than the traditional coaxial system,while retaining the advantages of the coaxial system in processing and assembly.To further improve space utilization and achieve lightweight and miniaturization,a common aperture spectroscopic structure is adopted.This allows for both high-resolution passive visible light imaging and three-dimensional imaging capabilities using active short-wave infrared imaging.The working principles of the two detection methods differ,as do their applicable occasions,thus eliminating the limitations of a single detection mode and greatly extending the application scope of the entire system.In the front-end optical system design,through the optimization of the initial off-axis structure,we complete the design of the co-axial eccentric-pupil afocal system,with an entrance pupil aperture of 300 mm,an F-number of 8.33,and a full field of view of 0.12°×0.12°.The reflected light from the beam splitter enters the passive imaging system in the back-end optical system.The passive imaging system operates in the 450~850 nm spectral range;the energy distribution within the circular area surrounding the image element is greater than 80%,and the dispersion spots for each field of view are within the Airy disk,indicating strong system detection capabilities and long-distance detection imaging capabilities.Additionally,the optical system's MTF is close to the diffraction limit,providing high-resolution imaging.Furthermore,this paper adopts 4^(th)、5^(th) lens as the compensation mirror group,realizing the design of a continuously adjustable focusing system under conditions ranging from 15℃ to 25℃ and from 1 km to infinity.The image plane position remains unchanged,so there is no need to adjust the position of the focusing plane,reducing the power consumption of the camera.The light transmitted through the beam splitter enters the active imaging system.The active imaging system adopts a common aperture beam splitter structure with integrated transceiver,which improves the coaxial stability of the system and reduces the processing and assembly requirements.The working wavelength of the active imaging system is 1550 nm,and the wave aberration is better than 1/300λ,which can meet the requirements of laser heterodyne coherent imaging.Finally,the tolerance analysis shows that the system meets the design parameters and actual processing requirements,thus,the design is both effective and rational.In summary,the system has the advantages of high resolution,long focal length,short total length,strong thermal resistance,continuous focus adjustment,and fine imaging quality.To realize long-range tracking imaging of space debris,this design provides a reference for the realization of an integrated optical system for detection and imaging.
作者
张力
李旭阳
袁灏
陆志贤
许彤裕
边立国
ZHANG Li;LI Xuyang;YUAN Hao;LU Zhixian;XU Tongyu;BIAN Liguo(Space Optics Technology Lab,Xi′an Institute of Optics and Precision Mechanics of CAS,Xi′an 710119,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《光子学报》
北大核心
2025年第2期58-70,共13页
Acta Photonica Sinica
基金
国家重点研究发展计划(No.2021YFC2202100)。
关键词
光学设计
偏光瞳
主被动复合
连续调焦
无焦系统
Optical design
Eccentric-pupil
Active-passive composite
Continuous focusing
Afocal system
