Research On Design And Optimization Of Laser Communication Optical Antenna Opto-mechanical Support Structure Based On Wavefront Aberration

Laser communication is a technology in which a laser beam is used as a carrier wave,and an optical modulator is used to modulate the information to be transmitted on the laser beam for communication,possessing high transmission data rate,strong anti-interference ability and the anti-interception ability.So it's an effective technical way to solve the speed bottleneck of the traditional microwave communication,construct space-based broadband,achieve the real-time transmission of massive data for earth observation,assist and maintain quantum communication to establish communication links,which has become a research hotspot in the field of high-speed communication and high-secure information transmission in the future.The laser communication optical antenna has an important influence on the performance of the entire laser communication system due to the function of compressing the far-field beam to ensure the intensity of the far-field beam and the reception of weak signals by quasi-compression of the received optical signal.And because the laser communication optical antenna works near the diffraction limit,the system wavefront aberration caused by temperature fluctuations and other factors will seriously affect the laser communication optical antenna to receive weak signal light and enhance the far-field beam under such high image quality requirements.In this paper,from a system level perspective and relying on a pre-researched laser communication terminal project,the opto-mechanics integration technology is adopted to deeply study the opto-mechanical characteristics of the laser communication optical antenna,which is influenced by internal mechanical loads and external environmental disturbances,providing strong supports for the design and optimization of opto-mechanical structures.The main research contents are as follows:1.The theoretical basis of the integrated design and analysis method of optomechanical structures is studied in detail.Firstly,the theoretical basis of the optomechanical system design is elaborated,including the opto-mechanical system's characteristics,design principles,general design process and structural optimization method,which provides theoretical guidance for the laser communication optical antenna opto-mechanical structure design.Secondly,the method of the optomechanical system analysis is outlined and the theory of structural dynamics analysis is expounded,which lay the theoretical foundation for the simulation analysis of the optical antenna's opto-mechanical structure.Finally,from the aspects of finite element theory,opto-mechanical data conversion method and optical system performance evaluation,the theoretical basis of opto-mechanical integrated analysis method is studied,based on which the technical route of laser communication optical antenna opto-mechanical structure optimization design is proposed.2.The integrated optimization design based on the surface error is adopted to study the laser communication optical antenna primary mirror assembly.Firstly,under the temperature range of 20±2°C and in 1-g gravity environment,the variation trend between the primary mirror surface error and the quantity of light-weight holes are simulated and the scheme of the primary mirror structure is determined.Secondly,considering the position characteristics of the main reflection mirror,the topology optimization theory model with maximizing the stiffness as the optimization goal is established to reduce the dynamic response of the primary mirror,based on which the preliminary configuration of the primary mirror support structure is designed.Finally,based on the above research,the integrated optimization model based on the surface error of the primary mirror is established to reduce the influence of the optomechanical deformation on the primary mirror.3.The integrated optimization based on the wavefront aberration of the optical antenna system is conducted to study the design of the secondary mirror assembly.The characteristics of the laser communication secondary mirror assembly design are analyzed,based on the which,a new type of flexible hinge that meets the requirements of use is proposed.By establishing a theoretical model of the flexible hinge,the rotary characteristic is studied and the key parameters of controlling the rotational flexibility are determined.According to the deformation characteristics and stiffness requirements of the secondary mirror,the influence of the two flexible hinge layouts of the secondary mirror support structure on its stiffness characteristics is studied.Finally,based on the above research work of the secondary mirror assembly,an integrated optimization method based on the wavefront aberration of the laser communication optical antennae is proposed to optimize the deformation direction of the secondary mirror to reduce the system wavefront difference.4.The structural dynamics simulation calculation is conducted and the experimental principle of the laser communication optical antenna is carried out to measure the wavefront difference under temperature change conditions.The modal analysis,sinusoidal vibration response analysis and random vibration response analysis of the laser communication optical antenna were carried out to evaluate the reliability of the structure under different vibration conditions.The wavefront aberration variation characteristics of the optical antenna under temperature changing conditions are studied experimentally,and the correctness of the integrated optimization design of the primary and secondary mirror components is verified.