可变远距离荧光激光雷达系统的设计

Design of fluorescence lidar system over variable long distance

为了实现对农作物生长状况的监测,结合荧光激光雷达技术的发展趋势,采用了激光诱导荧光技术,搭建了一套适用于农作物监测的荧光激光雷达系统。此系统为了提高系统稳定性及简化系统结构,将激光发射系统与接收光学系统合二为一,通过调节负透镜到卡塞格林系统的位置,可对远距离物体进行激光发射及信号接收。同时为了提高系统稳定性,提出了一种激光雷达系统同轴的校正方法和装置,通过在接收光学系统中加入与视场匹配的二维可调光阑,实现在距离变化场景下的焦距调节难题,增强接收目标信号的探测能力。本研究对荧光激光雷达系统的整体进行搭建并进行同轴性装调,并对叶片的荧光光谱进行测量验证,分别在80 m,100 m,150 m处检测到了叶片主要的荧光特征峰。实验证明,通过同轴性装调之后,获取的荧光信号质量好,系统稳定,在农作物距离变化之后,通过调节系统可直接实现不同距离样品高信噪比荧光测量,为荧光激光雷达系统在农业作物检测方面提供理论和技术支持。

In order to realize the monitoring of crop growth and combine with the development trend of fluorescent lidar technology,a set of fluorescent lidar system suitable for crop monitoring is built by using laser induced fluorescence technology in this paper.In order to improve the stability of the system and simplify the structure of the system,the laser transmitting system and the receiving optical system are combined into one.By adjusting the negative lens to the position of the cassegrain system,the laser transmitting and signal receiving of distant objects can be carried out.At the same time,in order to improve the stability of the system,a coaxial correction method and device of the lidar system are proposed.By adding a two-dimensional adjustable stop matching the field of view to the receiving optical system,the focal length adjustment problem is realized in the scene of distance change,and the detection ability of the received target signal is enhanced.In this study,the whole fluorescence lidar system was constructed and coaxial installation was carried out,and the fluorescence spectra of the blades were measured and verified.The main fluorescence characteristic peaks of the blades were detected at 80 m,100 m and 150 m respectively.The experiment proves that the fluorescence signal obtained by coaxial adjustment is of good quality and the system is stable.After the crop distance changes,the high SNR fluorescence measurement of samples at different distances can be directly realized by adjusting the system,which provides theoretical and technical support for the fluorescence lidar system in agricultural crop detection.