Design Of A Laser Scanning System Based On Spatial Light Modulator

Li DAR technology has revolutionized various fields,such as target range measurement,atmospheric detection,vehicle driving assistance,and region reconnaissance.With its high resolution and precision,Li DAR is among the top solutions for 3D imaging systems.Meanwhile,various sensors and beam scanners have also emerged,and spatial light modulators have the advantages of high precision and no mechanical inertia in beam deflection control.In this paper,a reflective spatial light modulator is used as a beam scanning device to develop a laser radar transceiver split scanning system with a scanning field of view of 5.4°,a detection distance of 1km,an angular resolution of 0.06°,and a working wavelength of 1.064 μm.Firstly,the principle of beam deflection using spatial light modulators is introduced.Based on the structural characteristics of a reflective spatial light modulator,the optical structure of the scanning system is designed.Design specifications for the collimation optical system,emission optical system,and receiving optical system are established,along with evaluation criteria for image quality.The specifications for the three subsystems are matched with the parent system optical structure.Secondly,Using the currently typical optical system as the initial system structure,the aberration characteristics of the collimation optical system,emission optical system,and receiving optical system are analyzed.Merit function are then written based on design specifications and structural parameters as limiting conditions.Optical design software Zemax is used to optimize the three systems,resulting in image quality that meets design requirements for all three systems.Thirdly,because there are errors in the actual processing and assembly of the scanning system,a tolerance analysis is performed on the three subsystems.Based on the known accuracy of optical cold fabrication and mechanical part processing,tolerance ranges were set according to their precision,and 200 Monte Carlo analyses are performed on each of the three subsystems.The tolerance analysis report showed that over 90% of the Monte Carlo analysis cases met the requirements,and the overall design results met the processing requirements.Afterward,the mechanical structure of the laser radar scanning system is designed,and a simple focusing method is set for each optical system,leaving allowance for subsequent adjustments.Finally,after the assembly of the system is completed,the maximum deflection Angle of the reflective spatial light modulator,the angular magnification of the transmitting optical system and the scanning field of the Li DAR scanning system are tested by using a laser with a wavelength of 0.65μm instead of 1.064μm.The experimental results show that the system structure meets the design requirements.