Research On The Key Technology Of Laser Range Finder

With the rapid development of the national economy, the demand of intelligent traffic system is more and more urgent. And Laser Range Finder(LRF) plays an important role in this industry. Compared to the other distance measuring method, LRF is widely used for its high precision and powerful anti-jamming performance. Based on the requirement of 3D laser scanning system, this thesis puts forward the solutions of pulsed Laser Range Finder. The main content of the thesis is divided into four parts,amplifier circuit, time discrimination circuit, time measurement circuit and the main control circuit. In order to get closer to the needs of Aircraft Automatic Docking Guidance System, the design also takes the scalability of the Laser Range Finder into consideration for other functions, such as scanning servo control module.Laser Range Finder is a complicated photoelectric, mixed-signal system. It is a interdisciplinary studies related to multi-disciplines. This thesis focus on the circuit part of it. At first, the thesis puts forward preamplifier, transimpedance amplifier in the same, based on the analysis of laser ranging equation. It is used to convert current to voltage. And the output pulse of preamplifier is sent to the main amplifier and the main amplifier is a voltage amplifier. At last, the pulse is sent to the discrimination unit and the differential time is get by constant fraction discriminator method. Time interval measurement is a key module of LRF. Based on the discussion of analog interpolation method, time-to-amplitude conversion method, time-to-digital method and some other methods, the time interval measurement circuit based on TDC-GP21 is come out. The test results show that the time measurement error is about 100 ps. The corresponding distance of 100 ps is about 15 mm. This thesis also introduces other modules of laser 3D scanning system and the software design of it. The LRF experiment platform and the prototype of the aircraft automatic docking guidance system are produced.The FPGA logic of the design is completed based on the QuartusII, and the circuit and the PCB is completed based on AltiumDesigner.Software is developed in the AtmelStudio6 integrated development environment.Circuit simulation and experiment are given at the end of this thesis. And the experimental results show that the method discussed in the thesis can satisfy the requirement of the parent system.