| Due to the excellent monochromaticity,strong coherence,precise direction and high brightness of laser,it has been widely applied in microwave radar,thus creating a new type of laser radar.Compared with microwave radar,laser radar has two advantages:smaller light spot and higher resolution.At present,the frequency modulated continuous wave(FMCW)lidar is an innovative ranging method,which shows unique advantages compared with other ranging methods.In this paper,the ranging technology of linear FMCW lidar is studied and the ranging experimental system based on beat frequency method is designed.At the same time,we examined the impact of background noise on the ranging accuracy of the system.Finally,the feasibility of the Faraday Anomalous Dispersion Filter(FADOF)in FMCW lidar is proved through the verification experiment.Firstly,this paper provides,a detailed discussion of the principle of FMCW LIDAR.In this section,we investigate the impact of background light noise on the FMCW ranging system.To mitigate the impact of background noise on ranging accuracy,we introduce the working principle of FADOF.At the same time,its development and application status are described.The working state of FADOF is simulated and the theoretical transmission curves are given.In order to successfully apply FADOF to FMCW lidar ranging,a dynamic frequency stabilization method integrating frequency stabilization and frequency modulation is proposed in this paper.The frequency stabilization method uses the potassium atom vapor cell as the external frequency standard to stabilize the laser.Finally,the FMCW lidar anti-interference experiment is designed and the background light noise in the experiment is simulated by using a randomly modulated LED cold light source.After adding FADOF to the FMCW ranging experiment under the interference of noise,we can observe that the signal-to-noise ratio of the receiving end of the system has been significantly improved after using FADOF.In the experiment,a 767 nm distributed feedback(DFB)laser was used and the distance of the object to be measured was set to 2 m.The final experimental results show that FADOF successfully eliminates the influence of background noise on ranging results and verified the effectiveness of FADOF in countering noise in FMCW lidar ranging systems. |
