The Design Of Short-range Pulse Laser Rangefinder

With the full implementation of the urbanized intelligent traffic,laser ranging technology as one of the core technologies to realize the monitoring system has attracted the attention of the whole world.Compared with phase laser ranging,pulsed laser ranging has rapidly become a research hotspot in the traffic field because of its rapid measurement and no cooperative target.Based on the application background of intelligent transportation industry,this paper studies and designs the laser rangefinder in detail.In the aspect of theoretical research,the influence factors of the system echo detection are determined by setting up the distance equation of the laser action.Based on this,the noise caused by sand dust scattering and background light in the environment is discussed,and the output signal to noise ratio of the detection system is determined by combining the internal noise of the device.In terms of technical implementation,this paper firstly analyzes the defects of traditional pulse laser rangefinder,and puts forward an improved technical scheme.Subsequently,the principle of laser driving circuit is studied.A laser launch system based on SPL LL90-3 is designed,and the implementation method of the improved transmitting time extraction circuit is explained.The receiving system uses AD500-9 as a photodetector and has the bias voltage circuit with temperature compensation.The detector output signal was amplified by the low noise amplifier OPA657,and enter the Constant Fraction Discriminator to extract laser end time.The timing system adopts the microcontroller STM32F103RCT6 and the high precision timing chip TDC-GP21,which realizes the function of measurement of laser flight time interval through the combination of hardware and software.In order to meet the dynamic range of system measurement,emitting and receiving optical systems are developed and the optical axis consistency and the solution are discussed in detail.Finally,the feasibility of the system scheme is verified by making a prototype.The results show that the system has good linearity and stability,and lays the foundation for the wide application of laser ranging technology in the transportation industry.