Research On Key Technology Of Optical System For Remote Weak Target Detection

The detection of long-distance weak target has attracted much attention in the fields of astronomical scientific observation,navigation and safety defense,and optical detection technology is one of the most effective detection means for obtaining information about long-distance weak target,which has been widely used in target status monitoring and target characteristic measurement.In the case of certain target and background characteristics,no matter what platform it works on,the optical detection system,as the core equipment for energy harvesting and photoelectric conversion of the weak target,is facing the problem of "detection","accurate sighting" and "accurate detection" of the optical detection of the weak target.Therefore,in order to improve the detection ability of weak target,it is necessary and urgent to carry out research on the key technologies of optical detection systems in view of the optical detection problems of weak target.This project will focus on the detection needs of long-distance weak and weak targets,focus on optical detection problems,carry out research on the theoretical model of long-distance weak and weak target detection,stray radiation suppression theory and method,the influence mechanism of the shape of the energy distri bution of the optical aberration to point spread function(PSF),and the change law between PSF ellipsoid rate and the positioning error of the centroid,and explore the theoretical detection limit of the system.The optimal design method of the optical de tection system based on PSF ellipticity is used to optimize the diffusion function of the detection optical system,improve the accuracy of the center of mass positioning of the target image point,and evaluate the change of PSF ellipticity under offset in the optical system of the survey telescope.The above research results are applied to the design and manufacture of optical active and passive composite detection optical systems,so the problems of optical active and passive composite detection systems i n optimizing the design,the balance and suppression of stray light and its own radiation,and the active and passive co-optical axes were solved.Through experiments,the research results of this topic in terms of detection mechanism,design theory and technical methods were verified,and the breakthrough of key technologies of long-distance weak target detection optical system was of great research significance for promoting the development and application of optical detection technology.Specifically,this paper mainly includes the following work content:1.The characteristics of the target and background were analyzed,and the radiation characteristics of long-distance weak targets such as air targets,space targets and stellar targets,as well as the sky light background and atmospheric spectral transmittance were simulated and analyzed.A general model of optical detection theory of weak target was established and the limit detection condition of weak target is proposed,which lays a theoretical foundation for the design of optical systems for detection of faint and weak target.According to different detection targets and different detection systems,the expression of stray light or self-radiated noise outside the optical detection system was derived,which provides a theoretical basis for balancing and suppressing the optical background noise of the detection system.2.Based on the imaging theory model of optical system,zernike polynomial was used to characterize different aberrations of optical systems,the mechanism model of the influence of various primary aberrations of optical systems on the PSF of optical systems was constructed,the influence of different aberrations and pixelation effects on the PSF oval rate was studied,the relationship between the PSF oval rate and the positioning accuracy of the centroid was summarized,and the optical detection system can be optimized and designed according to the correspondence between the PSF oval rate,the PSF elliptic rate change rate and the centroid positioning accuracy.It provides a theoretical basis for the optimal design of detection optical system.3.The optimization design process of optical detection system based on PSF ellipticity was elaborated,the calculation,analysis and evaluation method model of PSF ovality of optical system was constructed,and the optical system of dark matter dark energy detection survey telescope was taken as an example,and the distribution trend of full field RMS wave aberration and PSF ellipticity was analyzed and compared.The evaluation method of PSF oval rate change under offset was proposed,respectively,RMS wave aberration and PSF oval rate were used as the evaluation parameters of image quality change,the RMS wave aberration and PSF oval rate change under optical system offset were analyzed,and the control requirements fo r system stability error were corrected through the comparison of the analysis results,under the comprehensive aberration,the maximum change rate of PSF elliptical rate is 4.47/pixel,and the centroid positioning accuracy of the example optical system will be better than 1/30 pixel.4.The composition and working principle of single-photon laser ranging and medium-wave infrared detection composite system were discussed,the optimization design of single-photon laser and medium-wave infrared composite detection system was completed,the simulation and analysis model of internal and external stray radiation of optical system was established,the simulation,analysis and iterative optimization of stray radiation inside and outside the system were completed,a nd the balance and control of external stray light and internal radiation noise were realized;the development of composite detection system prototypes and the test work in the laboratory were carried out,and the active and passive detection experiments o f long-distance targets were carried out in the field,and the detection distance reached225 km,which verified the detection ability of the composite detection system.At the same time,infrared passive detection was carried out on the space station at an orbital altitude of 400 km,and the detection distance was expected to reach more than 1,050 km.