| Lidar is an effective means of atmospheric detection,which is often used to detect atmospheric aerosol distribution,air pollutant distribution,atmospheric composition,atmospheric meteorological parameters and other scenarios.Lidar has many outstanding advantages,such as good real-time,high spatial and temporal resolution and good repeatability.In order to improve the mobility of lidar and increase the detection range,more attention has been paid to vehicle scanning lidar.According to the actual project requirements,this paper takes the development of a large aperture scanning lidar transceiver for a vehicle as the research content,and discusses the design theory,design model and installation results of the system.The optical system of the on-board large aperture scanning lidar transceiver device consists of a laser beam expanding transmitting system,a receiving main system and a fiber collimation coupling system.The rotating disc is controlled by a stepping motor to realize one-dimensional scanning.Off-axis non-focus reflection structure is used in the laser beam expanding transmitting system,and Cassegrain structure is used in the receiving main system.The optical effective aperture is 680 mm.PW method is used to distribute the optical focus,and the initial structure of the optical collimation part is given.Tolerance analysis was carried out after iterative optimization,and the tolerance range was given.In order to compensate the influence of ambient temperature change on the wave aberration of the laser beam expanding transmitting system,a temperature compensation structure was fabricated using special metal materials.Ambient temperature has little effect on the precision of the main receiving system,so temperature compensation is not needed.The optical element of the on-board to aperture scanning lidar transceiver device involves a plurality of aspheric mirrors.According to the mirror shape of each aspheric surface,the detection light path was designed and constructed,and the non-contact detection was carried out with an interferometer.The primary and secondary mirrors of the laser beam expanding transmitting system are off-axis paraboloid,and the surface precision RMS is less than λ/40(λ=632.8nm).The primary mirror of the receiving system is a paraboloid,and the secondary mirror is a hyperboloid.The surface precision RMS is less than λ/40(λ=632.8nm).The laser beam expanding transmitting system and the main receiving system were installed and debuged.The interferometer and standard plane mirror were used to set up the self-collimating detection optical path.The final debugging wave aberration RMS of the two units was less than λ/12(λ=632.8nm). |
