Research On Laser Ranging System Based On High-speed Pulse Modulation And Echo Sampling

The technology of laser ranging has received extensive attention for its high precision,high resolution and strong anti-interference.For the long-distance detection in the aeronautic and aerospace,the high-reliable short-range detection in the field of industry and the high-speed and high-precision detection in civilian application domains,there are great challenges in the ranging performance,the size,the weight and the cost of the laser ranging system.Therefore,in order to obtain a good performance in large dynamic range and satisfy the demands of the cost,the size and the detection precision,the laser ranging system was studied comprehensively.Firstly,the recent development of the laser ranging and its several implementation methods are introduced.With the analysis and comparison of the working principle and the characteristics of each method,the laser ranging system based on high-speed pulse modulation and echo sampling is proposed.Secondly,related to the actual demands for ranging,the performance of laser ranging system is analyzed by means of the lidar equation.Besides,the specific parameters and the corresponding circuits and other hardware of the proposed laser ranging system are determined and designed.In order to ranging in a large dynamic range,the high-sensitivity single photon detector MPPC(Multi-Pixel Photon Counter)accumulating the echo photon signals is used in the system.In this way,the ranging ability is improved.For the signal processing unit,by means of the high-speed signal acquisition,the full waveform acquisition of the echo signal is realized.Also,the jitter noise and the corresponding distance deviation are eliminated by accumulating the echo waveform.With the method of the rising/falling edge threshold judgment,the peak position of the echo signal is obtained.In aim to achieving the high-precision distance information,the inaccurate judgment of the arrival time of the echo signal deduced by the deviation of the amplitude is eliminated.According to the specific parameters of the designed laser ranging system,the performance of the system is analyzed and verified theoretically.Meanwhile,the capability and the distance measuring error are analyzed systematically.Finally,the experiment platform for laser ranging is built and the ranging experiments are carried out.The experimental results show that its ranging dynamic range is up to 10~7 and the ranging accuracy is 0.6mm.Besides the long-distance measuring,the system is able to satisfy the demands of the high-precision ranging in the short distance measurement,and the experimental results are consistent with the theoretical ones very well.