Opto-mechanical Structure Design Of Micro-sweep Lidar Transmitting System

The MEMS lidar has many advantages such as controllable field of view and resolution,small size and light weight,which makes the demand for it in military and civil fields increase continuously.It puts forward new requirements and challenges to the field of opto-mechanical structure design and related coordination,and is an important development direction of li DAR.In this paper,based on the development of micro-sweep lidar,the optical-mechanical structure of laser collimating transmitting system based on micro-sweep mirror is studied,aiming to provide optical-mechanical design scheme for the function realization of transmitting system.The main research work is as follows:In order to enable the lidar transmitting system to realize the scanning effect of large field of view and high density,an opto-mechanical structure based on micromirror scanning is designed in this paper.Firstly,in view of the lidar imaging technology,the influencing factors related to the design index of the transmitting system were analyzed,and the key parameters of the laser module and the collimation scanning module were deduced according to the theory.In order to avoid the problem of insufficient resolution and optical signal when scanning the target with a single beam,as well as the requirement of field expansion,A refraction and reflection optomechanical system based on multi-channel laser emission scanning was proposed.Secondly,based on the system to complete the parts selection,on the basis of the combination of optical basic theory research,the optical system of the flat convex cylindrical lens,coupling the focus lens,optical fiber structure parameters of the collimating lens were calculated by optical design software,and complete based on the single channel optical system,rised to multi-channel integration and analysis of optical system,And the tolerance division of optical components was carried out.Then,the mechanical structure of the launching system was designed,including the design of the lens tube,the disturbing ring and the supporting structure.The design of folding mirror structure and supporting structure;The design of micro-scanning mirror support structure;And the design of box base housing structure for fixing and protecting the refraction unit and reflection unit.Finally,the finite element model of the optical mechanical structure of the transmitting system was established.The finite element method is used for dynamic and static analysis,and the natural frequency and mode of vibration,as well as the deformation and stress of the mechanical structure and optical elements under random vibration,temperature change and overload conditions were obtained.In this paper,the working wavelength of the micro-scanning lidar emission optical machine system designed is 905 nm,and the action range is 200 m.By using the simulation evaluation of the software,the system can realize the high resolution scanning of horizontal 40° and vertical30° field of view,meet the requirement of beam divergence Angle of 0.5mrad,and the beam distribution is uniform and the quality is good.The natural frequency of the system is greater than300 Hz,avoiding the resonance phenomenon caused by the interference of the external environment.Under random vibration load,the total displacement of opto-mechanical structure has little influence on the optical path precision,and the structural design meets the requirements of random vibration environment.Under uniform temperature load,the mirror deformation is less than 0.02 mm of tolerance distribution,and the stress meets the ultimate yield strength of the material.The optical and mechanical structure of the whole system is reasonable and meets the requirements of the design index.