Design Of Low-light And Infrared Fusion Common Aperture Optical System

Today's battlefields have increasingly strict requirements for target detection and identification.However,battlefield camouflage has made target detection face more severe challenges.If only a single band of imaging is used,it cannot meet the needs of the battlefield.Low-light imaging and long-wave infrared imaging are complementary to each other.Dual-band fusion imaging technology has become an important direction for future development.First,this article explains two methods that can achieve dual-band imaging:dual-channel imaging and common-aperture imaging.Through a comparative analysis of the two methods,it is found that the common-aperture imaging system achieves low-light /infrared imaging for the same target in the same field of view,and the dual-band image formed by it is favorable for later image fusion.In order to meet the needs of battlefield use,this paper identifies vehicles 5km away and proposes a high-resolution common-aperture solution: in the front of the optical system adopts the Cassegrain system common-aperture design,and the light emitted by the detection target surface is reflected by the card reflection system.Then use the spectroscopic system to split the light and transmit the low-light and long-wave infrared to their respective optical path structures for imaging.Secondly,this paper makes a theoretical calculation of the technical parameters of the optical system.According to the selection of the optical system and the specific parameters of the detector,the basic parameters of the low-light optical system and the long-wave infrared optical system were calculated.After detailed calculations,the parameters of the optical system in this paper are as follows: the working range of the low-light optical system is 0.4 to 0.8 ?m,the focal length is 164 mm,and the F / # is 4;the working wavelength of the long-wave infrared optical system is 8 to 12 ?m,the focal length is 125 mm,F / # Is 3.1.Then,the optical design is performed according to the basic parameters of the optical system.The design results show that the MTF at the Nyquisy frequency of 28lp/mm in low-light optical system is greater than 0.5,and the MTF at the Nyquisy frequency of28lp/mm in long-wave infrared is greater than 0.2,which meets imaging requirements.For the long-wave infrared optical system,it adopts the athermal difference method of active electromechanical.So the system has good imaging quality in the operating temperature range.The rang of operating temperature is 40? to 60?.Finally,this paper designs the mechanical structure of the completed optical system.The mechanical structure is divided into four parts: a common-aperture Cassegrain system,a spectroscopic system,a low-light imaging system,and an infrared imaging system.The mechanical structure has a focusing structure,which can achieve clear images of targets at different distances,and it can be processed and adjusted.