Design And Analysis Of Infrared Dual-band Spectral Imaging System

Spectral imaging technology is a technology that uses multi-channel to detect and image the target spectrum,which can identify targets based on the spectral characteristics of different objects.For complex detection environments,infrared dual-band spectral imaging detection has obvious advantages.The mid-wave infrared system can not only be used to obtain the radiation spectrum characteristics of high-temperature objects,and also has more obvious advantages in observations in hygrothermal environments.The long-wave infrared system is mainly used to observe objects at normal atmospheric temperature and form contour images of objects.In the case of strong stray light radiation,the long-wave infrared reconnaissance capability is stronger.Therefore,the research of infrared dual-band spectral imaging technology is of great significance to the development of military and civilian technology.In this paper,an infrared dual-band common image plane imaging spectrometer is designed.The working bands include the mid-wave band of 4.4?m?5.4?m and the long-wave band of 7.8?m?9.2?m.The system,f-number is 2.5,is composed of a front telephoto objective lens,a spectral beam splitting system and a relay system.The front telephoto objective lens adopts an off-axis two-mirror system to solve the problem of serious chromatic aberration.The spectral beam splitting system adopts the Offner structure type,which uses the double diffraction orders of the convex grating to perform common optical path splitting,which is convenient for the miniaturization of the system.At the same time,the diffraction efficiency of the convex grating is analyzed,and the appropriate blaze wavelength is obtained to make the dual-band diffraction efficiency above 80%.Because the system selects the refrigeration infrared double-color detector,this paper designs the transmission-type relay system to ensure the stop of the optical system matches the cold stop of the detector,so that the whole system can meet the 100% cold stop efficiency and suppress the influence of stray radiation interference.The three components are all telecentric systems,which are convenient for connection and matching,and easy for assembly and testing.We design each component separately.And we combine them to obtain an infrared dual-band spectral imaging system after completing the design of each subsystem.The design results show that the root mean square radius of the spot array is smaller than the size of one pixel of the detector,the spectral resolution is high,the modulation transfer function is close to the diffraction limit,and the imaging quality is good,which can meet the design requirements of the infrared detection system.Inaddition,the tolerance of the optical system is analyzed,and the tolerance distribution is reasonable.