Double-Telescope Atmospheric Turbulence Lidar System Based on Backscattering Enhancement Effect
Objective Lidar remote sensing technology possesses significant advantages in detecting atmospheric parameters(such as clouds and aerosols,temperature,and wind speed)with high precision and high timeliness.However,atmospheric turbulence can affect the transmission characteristics of laser in the atmosphere,causing a series of turbulence effects such as light intensity fluctuations,phase fluctuations,beam wander,and beam spread.Based on the backscattering enhancement effect of laser transmission in turbulent atmosphere,a double-telescope hard-target reflection lidar system for detecting atmospheric turbulence intensity is proposed.The system realizes the measurement of backscattering enhancement coefficient by receiving the diffuse reflection echo signals of hard-target with the double telescope.The biggest advantage of this system is the utilization of small-aperture double-telescope receiving channels,greatly simplifying the complexity of the system and reducing equipment costs.Methods The application of double-telescope lidar technology based on backscattering enhancement effect in atmospheric turbulence detection is studied.First,a double-telescope hard-target reflection lidar for detecting atmospheric turbulence intensity is proposed and designed based on the backscattering enhancement effect.The system consists of one transmission channel and two receiving channels,where one receiving channel aligns with the transmitting channel and the other is offset by 15 cm.Then,the backscattering enhancement coefficient of hard-target reflected signal at the receiving telescope is established based on the generalized Huygens-Fresnel principle.Finally,the experimental system is constructed,and the preliminary experiments are conducted in calm weather with uniform turbulence intensity.The effects of turbulence intensity,laser transmission distance,temperature,and wind speed on the backscattering enhancement coefficient are studied.Results and Discussions The detection principle of the proposed backscattering enhancement effect lidar is presented.It breaks through the limitation of traditional lidar using a large-aperture receiving telescope,which leads to complex system structures,particularly in terms of the optical path.Meanwhile,this system features simple structure,mobility,and low cost(Fig.1).Table 1 presents the main parameters of the lidar system.By simulating various turbulence intensity changes through the distance between the beam and the heater,the relationship between backscattering enhancement coefficient and turbulence intensity is analyzed(Fig.3).Under the same observation conditions,the relationship between different laser integration paths and the backscattering enhancement coefficient is studied(Fig.4).The correlation between nighttime wind speed and temperature changes with the backscattering enhancement coefficient is observed and analyzed.The results show that,due to the gradual decline trend of night ground temperature is consistent with the conventional turbulence intensity,they show a strong correlation[Fig.5(b)].However,the random variation of wind speed is different from the decline trend of conventional turbulence intensity,and the correlation is poor[Fig.6(b)].Conclusions We propose a double-telescope hard-target reflection lidar based on the backscattering enhancement effect to study the transmission characteristics of laser beam in turbulent atmosphere.The biggest advantage of this system is that a small-aperture double-telescope receiving channel can be employed to simplify the structure and reduce costs.The theoretical analysis of the backscattering enhancement coefficient of the echo signal is performed by receiving reflected signal of the double telescope.Additionally,the preliminary experiments are conducted in calm weather with uniform turbulence intensity.The results show that the backscattering enhancement coefficient increases monotonically with the increase of simulated turbulence intensity,exhibiting a saturation trend.Under the same observation conditions,the backscattering enhancement coefficient also shows a saturation trend as the integral path increases.The nighttime temperature shows a good correlation with backscattering enhancement coefficient,and its Pearson correlation coefficient R is 0.95.However,the correlation between wind speed and backscattering enhancement coefficient is relatively poor,and its Pearson correlation coefficient R is 0.67.The double-telescope hard-target reflection lidar proposed in this paper possesses significant research and practical value for the detection of atmospheric turbulence.
NETL
NSTL
万方数据
