| The infrared multi-targets compounding hardware in the loop simulation system isone of the important tools for the research of the Infrared-guided missiles, which canprovide realistic battlefield environment for the infrared seeker. The reflectors arenecessary to achieve the requirement of multispectral infrared target simulation. Inrecent years, with the increase of the diameter of the infrared seeker, the diameter of themirror in the simulation system is increased sequently. However, the use oflarge-diameter mirror causes a series of practical problems. Firstly, the deformation ofreflection mirror surface deteriorates because of the gravity. In addition, to eliminate theinfluence of stray light, the infrared simulation system requires cooling system.However, the larger the diameter of the mirror is, the greater the effect of temperaturevariation on its surface deformation is. Therefore, the structure-thermal-optical researchof the large aperture reflecter in the hardware in the loop simulation system has becomeone of the key technologies.In this paper, the study mainly focused on two aspects, one of which is the supportmethod of large aperture mirror in low temperature and the other is its impact on imagequality.Firstly, considering the cryogenic vacuum environment of the large aperturereflector of the infrared hardware in the loop simulation system, we designed a mirrorsupport structure. During the design process, we chose Crystallized Glass as thematerial of the mirror, and calculated the basic parameters of the mirror using the platetheory. The support force distribution on the back of the mirror and lateral supportangles of the mirror were optimized using the optimization feature of Ansys, the finiteelement analysis software. We designed two support structure, steel strip supportstructure on the mirror side and comprehensive support structure, according to the finiteelement optimized results. Use the finite element method to analyze the deformation ofthe mirror under its own weight, and under uniform temperature field and transienttemperature field in large temperature difference environment. and according to thefinite element analysis results, the mirror support structure was improved usingWhiffle-tree axial positioning support method and Bipod flexible support method.Then, we import the data of finite element analysis into the optical design softwareusing the structure thermal optical integration method and analyze the imagingperformance of the multi-target compound optical system under the designed mirrorsupport structure. Noticing the three factors causing dimensional instability of themirror, the rigid body displacement, the change of parameters of mirror and the change of surface roughness, we extracted the first factor using homogeneous coordinatetransformation method, and fitted the data of others to Zernike polynomial. Finally, weimported the coefficients of the Zernike polynomial we obtained into Code Vusing.INT method, verifying that the designed support structure can meet theperformance requirements for the optical system. |
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