Noise Reduction in White Light Lidar Signal Using a One-Dim and Two-Dim Daubechies Wavelet Shrinkage Method

A 1-D and 2-D Daubechies 5 (db5) discrete wavelet shrinkage methods using a 10 level decomposition was applied to white light lidar data particularly at 350 nm and 550 nm backscattered signal. At 350 nm, the backscattered signal is very weak as compared to 550 nm backscattered signal because of the spectral intensity distribution of the generated white light. The 1-D and 2-D wavelet shrinkage method gave a much better result as compared with the moving average method. However, the 2-D wavelet shrinkage method produced a much better denoised lidar signal compared with the 1-D wavelet shrinkage method. This is indicated by the 142% increase in correlation coefficient between the 2-D denoised lidar signal and the 800 nm original lidar signal as compared with only 12% increase in correlation coefficient for the 1-D denoised lidar signal. The 2-D wavelet shrinkage method also gave a much higher SNR value of 65.9 compared to 1-D which is 38.8.

新型遥感探测系统--白光激光雷达

设计了一种新型的大气遥感探测系统——自光激光雷达，发展了一种雷达模式的宽谱范围长程差分吸收光谱探测方法。介绍了白光激光雷达系统结构和时间分辨光谱探测技术；阐述了飞秒激光在大气中自导光丝传输和产生的超连续白光的特性；利用该自光激光雷达系统对大气中氧气成分在685～694nm和759--769nm范围的长程差分吸收光谱进行了探测，并与Hitran数据库拟合计算的标准值进行比对，结果一致，验证了白光激光雷达遥感探测系统的正确性和实验方法的可行性。

白光激光雷达的发展与应用

飞秒激光脉冲在空气中传输时产生独特的成丝现象,伴随着波长从紫外到中红外的超连续光谱辐射.高强度的光丝能继续与物质发生强烈的非线性相互作用,诱导多光子荧光和等离子体光谱等非线性光谱辐射.白光激光雷达以飞秒激光脉冲大气传输特性为基础,能提供多种遥感探测方法。文章阐述了飞秒激光脉冲成丝机理与白光激光雷达系统结构特点,介绍了国内外主要白光激光雷达的性能特点、白光激光雷达的主要探测方法与应用情况,最后分析了白光激光雷达的发展趋势。

飞秒强激光大气遥感新技术的原理和研究进展

飞秒强激光脉冲在大气中传输时,会形成狭长的、具有高激光强度、高等离子体密度、可远程产生和操控的通道,即光丝。光丝与物质相互作用时,高激光强度可激发物质辐射具有指纹特征的荧光谱线,成丝过程可产生覆盖整个大气光学传输窗口的超连续谱激光,通过光学差分吸收实现多组分大气成分的检测分析。飞秒强激光非线性成丝为多相态、多组分大气遥感提供了新的技术途径。主要围绕飞秒激光大气成丝远程诱导击穿光谱技术和光丝超连续谱激光雷达技术两种基于飞秒激光的大气遥感新技术,综述了两种技术的原理、光谱测量和分析方法及其相关研究进展,分析了飞秒强激光大气遥感应用存在的关键科学和技术问题并对未来发展进行了展望。