Optimal Design Of MEMS Lidar Transmitting Optical System Based On Genetic Algorithm

MEMS micro mirror for the increasing maturity of the laser radar scanning optical path design provides a new train of thought,but its effective restrictions on the size of mirror makes it hard for collimating light beam scanning optical path design of both small divergence Angle,the large scanning range and high emission efficiency,laser radar transmitting optical system design to bring very great difficulty.Therefore,this paper introduces the genetic algorithm to study the optimal design of the ideal lens set parameters of the MEMS lidar scanning transmitting optical system,and obtains the optimal design results satisfying the constraint conditions of the optical system.On the basis of in-depth data investigation,this paper combs out the existing MEMS lidar scanning emission path mathematical model,and deduces the coupling efficiency formula of emission path.A method for optimizing the parameters of MEMS lidar scanning emission optical system was established based on genetic algorithm.In the MATLAB software environment,the optimization design program based on the genetic algorithm was written,and the optimal design of the ideal lens set parameters of the scanning emission path required by the development of a certain MEMS lidar was carried out.Results for the light beam transform lens focal lengthf₁=12.17 mm lens focal length,image point compensation f₂=17.002 mm,the collimating lens focal lengthf₃=10.613 mm lens,beam transformation groups focus and light source distance x=3.682 mm,MEMS micro mirror center and focal point of the light beam distance R=34.014 mm lens aperture,beam transformation D₁=9.735 mm,like some compensation,collimating lens aperture D₂=8.544 mm lens aperture D₃=8.49 mm,the ZEMAX software simulation,The divergence Angle reaches 0.0312rad,the scanning range reaches 28.47°and the emission efficiency reaches 75.39%.On this basis,the lens parameters such as surface shape,material and thickness were designed in detail by ZEMAX software,and the assembly position parameters were given.In the experiment,a theoretical experimental system of scanning emission path was built with SPLLL90-3 laser diode as the light source,and emission spot,Angle scanning range and emission efficiency were measured,reaching 0.04rad,28°and 65.3%respectively,which was basically consistent with the theoretical design results and verified the correctness of the optimization of MEMS lidar emission optical system.The results of this paper have important reference value for the optimization design of MEMS lidar scanning emission optical system and other beam scanning systems.