Compensation Technique Of Atmospheric Backscattering For Measurement On Laser Radar Cross Section

Because the laser radar is worked in outdoors or even battlefield environment, it may not only experience both the complex weather conditions and the interference of obstacles, but also face the situation of sudden changes of the complex working environment. In the measurement of laser radar cross section, the backscattered echo signal of the target will be difficultly detected since the backscattered echo signal is quite weak and may be influenced by the noise on receiving system and the background noise, such as the scattering light generated by the particles in the atmospheric transmission. The atmospheric backscattering generated in the laser atmospheric transmission is the noise that has direct influences on the measurement. A new method to eliminate the influence of the atmospheric backscatter is proposed to reduce the overall noise, and to improve the signal to noise ratio and improve the feasibility and accuracy of the measurement of laser radar cross section, this method may be important in improving and enhancing of weak signal detection in the measurement of laser radar cross section.The mechanism of the generation of the atmospheric backscattering in the laser atmospheric transmission is analyzed and the laser atmosphere backscattering is defined. Besides, the influence of the atmospheric backscattering on the measurement of laser radar cross section is analyzed and discussed in detail. Then, the laser atmosphere backscattering model is developed. Based on the calculation and analysis of the model, the atmospheric backscattering in different distance range relative to the total proportion of the atmospheric backscattering is given, which may provide the theoretical guidance and data support to eliminate the influence of the atmospheric backscattering. Next, a new experimental method based on the spatial filtering is proposed to eliminate the influence of the atmospheric backscattering and applied to making experiment under the fog and haze, and sunny weather conditions, and the experimental result is also discussed. Finally, comparing the theoretical model with the experiment results, the atmospheric backscattering which can enter the detection system is mainly within a certain distance range. Combining the theoretical model with the experiment results, we analyze the outfield experiment date and find out that the atmospheric backscattering can be restrained by adjusting the distance between the transmitting and the receivingsystem and the residue scattering signals can be eliminated by the proposed spatial filtering method.In this dissertation the theoretical model is built based on the atmospheric backscattering theory and a new method based on the spatial filtering is proposed to eliminate the atmospheric backscattering, which can improve the feasibility and accuracy of the measurement of laser radar cross section. However, the theoretical model may have difference with the actual engineering application. Thus, in our next work, the theoretical model need to be optimized to meet the requirements,the actual engineering and the experimental analysis method should be modified for the actual engineering application. In addition, the difference between the experimental weather conditions and the theoretical weather conditions must be considered to reduce the error between the theoretical value and the experimental data.