单光子激光测距的漂移误差理论模型及补偿方法

单光子激光测距系统采用高灵敏度的单光子探测器作为接收器件,更易实现高密度、高覆盖率的目标采样,是未来激光测距系统的发展方向.漂移误差作为限制单光子激光测距精度提高的瓶颈问题,其主要由平均回波信号光子数的变化引起.以激光雷达方程、单光子探测器的概率与统计理论为基础,建立了漂移误差的理论模型,给出了漂移误差与平均信号光子数、均方根脉宽等系统参数之间的理论关系式.同时,结合单光子探测概率模型给出了一种漂移误差的修正方法,并搭建实验系统对漂移误差模型和修正方法进行了验证.在回波信号均方根脉宽为3.2 ns、平均回波信号光子数为0.03到4.3个情况下,未经修正的漂移误差最大达到46 cm,经修正后的均方根误差为1.16 cm,平均绝对误差为0.99 cm,达到1 cm量级,漂移误差对测距精度的影响基本可以忽略.该方法可以解决漂移误差制约单光子激光测距精度提高的瓶颈问题.

Theoretical model and correction method of range walk error for single-photon laser ranging

Single-photon laser ranging is a new generation of lidar which represents the future lidar development trend.It uses the single photon detector as the receiving device.Due to the fact that single-photon detector possesses the ultra-high sensitivity,the single-photon laser ranging is much easier to achieve the high density as well as the high coverage target sampling.However,the existence of the range work error in single-photon laser ranging,resulting from the fluctuation in the number of signal photoelectrons restricts the improvement of the ranging accuracy.In this paper,the range walk error model based on the lidar equation and the statistical property of single-photon detector is established.Then the relation between the range walk error and the number of signal photoelectrons is also derived.The range walk error of single-photon laser ranging is predicted and the corresponding compensation for the original result is obtained,with the derived function and the detection probability model of single-photon laser ranging.The experiment for its proof is also carried out.In the experiment,the number of signal photoelectrons is changed by the different attenuators for the same target and at the same distance.When the attenuator is changed,the pulse width of echo signal changes very little (about 3.2 ns).However,the average number of signal photoelectrons varies between 0.03 counts and 4.3 counts.So the range walk error,resulting from the fluctuation in the number of signal photoelectrons cannot be ignored.For example, when using an attenuation of 1/10 pass rate,the average number of signal photoelectrons is about 4.3 counts and the range walk error is almost 46 cm,which is the main factor of the range error.The reduction of the range walk error is achieved by applying the correction of the range walk error in this paper.After correction,the standard deviation of the range walk error decreases significantly from 15.17 cm to 1.16 cm.The mean absolute error is also reduced from 11.56 cm to 0.99 cm.Generally,the range walk error has an unnegligible influence on the ranging accuracy.The experimental result confirms that the theoretical model is accurate.It also shows that the bigger the number of the received signal photoelectrons,the greater the range walk error is,and the accuracy of single-photon laser ranging is improved by applying the technique proposed in this paper.Briefly,this paper presents the technical method of optimizing the design and evaluating the performance of single-photon laser ranging.