The Design And Analysis Of Medium Wave Infrared Spectral Imaging System

Spectral imaging technology is a technology which uses multiple channels to detect and image the target spectrum,and can identify the target according to the spectral characteristics of different objects.And the medium-wave infrared(MWIR)spectral imaging system is widely used in military,civil and medical fields.In order to obtain the spectral information while adapting to the application requirements of different fields of view,to achieve the purpose of large field of view tracking and small field of view aiming,and to detect the target's medium-wave infrared spectrum information,a medium-wave infrared(MWIR)spectral imaging system is designed in this paper.The working band of this system is 3~5?m and F#=4.0,and the system consists of front zoom system,spectral imaging system and relay system.The front zoom system to achieve continuous zooming in the range of 60~300 mm,and the spectral imaging system uses a grating-type offner concentric structure for spectral splitting and imaging.The detector in this system is the refrigerated medium wave infrared detector and the secondary imaging relay system is used to achieve matching of cold stop between the optical system and the detector.According to the principle of object-image exchange and the principle of focal power distribution,the initial structure of the front zoom system and the relay system are calculated.Based on the combination of wave aberration theory and the macro-language function of Zemax,the design theory of small aberration system is proposed.And the optimization model of small aberration system is constructed by macro language,so that the wavefront aberration of the system can be accurately controlled.After completing the design of the molecular system,a mid-wave infrared imaging system with a spectral resolution of 25 nm is obtained by combining the molecular system.The design results show that the system's MTF is closes to the diffraction limit at the detector cut-off frequency of 33 lp/mm at each focal length position and each spectral segment.The root mean square radius of the spot is smaller than one pixel of the detector,and the image quality of the system is good,which meets the requirement of the design index.Finally,the tolerances of the components in the optical system are analyzed and reasonable tolerance distribution is obtained.