Study On Broadband Multitarget Simulation System And Key Techniques

Space exploration and missile defense are the extremely difficult engineering, the science integrating with the national defense industry and the advanced technology achievements in many areas. To improve the abilities of anti-jamming, target-recognition, anti-stealth and survivability in hostile environment of missiles, the infrared-based and multimode compound homing guidance have become a research hotspot currently. Due to the high-cost, slow-feedback and low-efficiency of outfield tests, researchers increasingly pay the emphasis on the simulation technique and use simulation systems to test and identify missile performances during the design and test process of missiles. Studies on modern and future wars reveal that targets and environments of the missile are becoming increasingly diverse, complex and harsh. Development direction of target and environment simulation technology is broadband, multi-target, complex-background and high-dynamic. Therefore, the simulation system with characteristics of the broadband, multi-target and high-dynamic has become a key application of the target and environment simulation. However, the lack of studies on theoretical models and design methods for broadband multi-target simulation system limits its applications and developments. As a result, researches on the broadband multi-target simulation system and its key techniques have very significance for the development of hardware-in-the-loop simulation system and play a positive role in promoting the multimode combined guidance technology.The thesis carried out researches on the broadband multi-target simulation system and its key techniques, including theoretical models of beam-expanding technique, aberration characteristics of broadband target simulator and stability designs of the simulation system. The main research contents of this dissertation include as follows.Studies of the overall design for broadband multi-target simulation system including the working principle, the optical structures, as well as key techniques overview of the simulation system were carried out.Researches on the beam-expanding theoretical model of broadband multi-target compounding system were performed. The beam-expanding theoretical model for multi-target compounding system based on the dimpled mirror is established: under the paraxial condition, according to relationship between geometry architecture and small-mirror, the ideal beam-expanding expression was derived; for off-axis case, the ideal beam-expanding expression was modified using the imaging theory of small-mirror and the critical effect of beamwidth dependence on off-axis distance was found. By defining performance evaluation function, the performance evaluation model of the broadband multi-target compounding system was established.Studies of aberration characteristics of the broadband target simulator were executed. To solve fifth-order aberration effects on the aberration balance for the case of large Field-of-View and large off-axis distance, the fifth-order nodal aberration field was analyzed. Based on vector aberration theory, the fifth-order aberrations were broadened by applying pupil decentration vector. Equations of the fifth-order nodal aberrations field dependent on pupil decentration vector were derived. Modification formulas to the five-order aberration nodes position vector were established by solving the fifth-order nodal aberrations field equations.Researches on the stability design for the broadband multi-target simulation system were performed. Stability design of the focal plane position for the refractive target simulator was established, and focus-shift formula of refractive target simulators was derived. Design method of the surface stability of large-aperture reflecting mirror was executed. Image quality assessments of the broadband multi-target simulation system were completed. Relationship of stray light coefficient and refrigeration temperature of key optical elements was achieved，which guides the stability design of the broadband multi-target simulation system.Emulational and experimental verifications of key techniques of the broadband multi-target simulation system were performed. Optical simulation model for multi-target system based on the dimpled mirror was established, and simulation results demonstrated that the theoretical beam-expanding formula was correct. Under laboratory condition, the experimental verification of a multi-target compounding system based on dimpled mirror was completed, and the beamwidth theoretical model for the broadband multi-target compounding system was demonstrated by experimental data. The credibility of the focus-shift formula of a refractive target simulator was executed by the athermalization test equipment and experimental results demonstrated that the focus-shifted formula can be used for the stability design of refractive target simulators.