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为提高脉冲激光3D成像系统中提取目标距离和强度信息的精度,对时刻鉴别和峰值保持电路进行了深入研究。在简要分析激光测距体制及探测器选择的基础上,给出了激光3D成像系统结构框图:激光器输出信号经半反半透棱镜,反射光线触发参考APD作为计时起始信号,以提高计时基准。给出了恒定阈值鉴别与恒比定时鉴别相结合的时刻鉴别电路,在提高时刻鉴别精度的同时可有效消除噪声对电路的影响。峰值保持选取基于OPA861的跨导型峰值保持电路。在实验室搭建了回波信号模拟系统,并在此基础上对电路性能进行测试。最后,给出了实验结果。结果显示:时刻鉴别电路精度优于1ns;当输入窄脉冲峰值信号低于800mV时,峰值保持电路保持精度优于2.63%。整个结果满足后续实验要求。
In order to improve the precision of extracting the target distance and intensity information in the pulsed laser 3D imaging system, the time identification and peak hold circuit are studied deeply. Based on the brief analysis of laser ranging system and detector selection, a block diagram of the laser 3D imaging system is given. The output signal of the laser is triggered by the APD as a timing start signal through a semi-transflective prism to improve the timing reference . The time identification circuit combining constant threshold identification and constant ratio timing identification is given, which can effectively eliminate the influence of noise on the circuit while improving the time identification accuracy. Peak Hold Select the transconductance peak hold circuit based on the OPA861. Echo signal simulation system is set up in the laboratory, and on this basis, the circuit performance is tested. Finally, the experimental results are given. The result shows that the accuracy of time-discriminating circuit is better than 1ns, and the peak-hold circuit maintains the accuracy of better than 2.63% when the input narrow-pulse peak signal is lower than 800mV. The results meet the follow-up experiment requirements.