多波段光谱接收与可见光成像共孔径光学系统设计

Design of a common aperture optical system for multiband spectral reception and visible imaging

为满足对飞行目标的多维光谱探测和可见光成像需求,设计了一款基于卡塞格林望远镜结构的共孔径光学系统。系统前端由同轴两反系统组成,主镜为抛物面,次镜为双曲面,后端通过平板分光的方式由各子系统接收。在可见光成像端,利用两片柱面镜成功解决了分光平板引起的像散问题,并通过添加反向倾斜的补偿平板,校正了分光平板引起的光轴偏移问题,可实现对距离为0.5~1.5 km、直径为0.5m的飞行目标进行可见光成像和多波段光谱接收(200~400nm、400~760nm及760~2500 nm)。成像模块各视场在奈奎斯特频率35 lp/mm处均实现了MTF>0.5,趋近于衍射受限曲线,各光谱接收模块也均满足光纤耦合要求。通过无热化设计,该共孔径系统可实现在-20~50℃温度范围内正常工作。公差分析结果表明,该系统能够满足实际加工和装调要求。

To meet the requirements of multidimensional spectral detection and visible-light imaging of flight targets,a common-aperture optical system based on the Cassegrain telescope was designed.The front end of the system was composed of bi-reflective system.The primary mirror is a paraboloid and the secondary mirror is a hyperboloid.The light beam in the back end was split by tilted flat plates and received by the following subsystems.The problem of astigmatism caused by tilted flat plates was solved successfully by utilizing two cylindrical lenses in the visible-light imaging system.The deviation of the optical axis caused by the tilted flat plate was compensated by adding reversed tilted flat plates.Visible-light imaging and mutispectrum(200-400 nm,400-760 nm and 760-2500 nm)reception could be realized for flying targets with diameters less than0.5 m within 0.5-1.5 km.The MTF values of each field of view in the imaging module were all greater than0.5 at a Nyquist frequency of 35 lp/mm.This result is extremely close to the diffraction limit curve.All coupling modules meet the coupling requirements of optical fibers.Through athermal design,the common-aperture system can work normally in the temperature range from-20℃to 50℃.The tolerance analysis results show that the system can meet the requirements of manufacture,installation and adjustment.