非合作目标光子计数激光测距技术研究

Analysis of Non-Cooperative Target Photon Counting Laser Ranging

为了实现对远距离非合作目标距离的精确测量,将光子计数测距法与脉冲测距法相结合,利用多像素光子计数器(MPPC)进行了远距离非合作目标测距实验研究。在实验室内模拟远距离非合作目标返回的微弱信号,利用MPPC接收。通过分析返回光子信号特性,研究目标反射回随机光子的统计分布特性;利用不同的算法计算测距起始和终止脉冲间隔,分析不同算法对测距精度的影响。实验室利用MPPC,4 GHz采样率示波器和脉宽为5 ns的脉冲激光器进行测距实验,获得7220个脉冲信号,统计结果验证了目标返回信号为泊松分布;利用恒比鉴别法得到了最优测距结果:测距结果与被测距离偏差2.8 cm,加权均值标准差为0.9 cm,而固定幅值法和自相关法得到的测距结果偏差都超过了40 cm。通过分析各算法与恒比鉴别法之间的差异,给出了不同算法产生较大偏差的原因。

In order to analyze the faraway non-cooperative target,the research of faraway non-cooperative target ranging experiment is proceeded by using multi-pixel photon counter（MPPC） where photon counting laser ranging method and pulse ranging method is combined.Weak signal reflected by faraway non-cooperative target MPPC is simulated in the laboratory.By analyzing the return photons which are detected by MPPC,the distribution of photons reflected from the target is studied.The interval of start and stop pulses is calculated with different algorithms,and the influence of these algorithms on the ranging result is analyzed.7220 pulses have been obtained by MPPC,4 GHz sample rate oscillograph and pulsed laser with 5 ns pulse width.The statistic results prove that the return signals obey Poisson distribution.The optimal ranging result has been obtained by constant fraction discrimination method： the deviation of ranging result and measured distance is 2.8 cm,the weighted standard deviation is 0.9 cm,and the ranging result deviation obtained by constant amplitude method and autocorrelation method are both over 40 cm.The reasons why different methods do not produce the same results are given by comparing the constant fraction discrimination method with other algorithms.