Correct Derivation and Analysis of the Lidar Equation: BothDirect and Coherent Detection

使用激光对大气层进行遥感被称为激光雷达，是“光探测和测距”的首字母缩写，类似于雷达。传输短脉冲激光之后，接收来自大气成分的后向散射信号，如气溶胶、尘埃、云或分子。有关大气组成和物理状态的信息可以从激光雷达数据中推断出来。此外，接收信号的时间滞后决定了散射物质的范围。这项研究是为了推导和计算激光雷达系统的接收功率，包括相干检测和直接检测。将确定脉冲形状、湍流、发射机、接收器和本地振荡器的影响；将调查大气运动的影响；并确定重要机制的物理学。在一种体制下，湍流是主要的物理机制。此外，还将研究在这种情况下利用激光雷达测量来估计湍流水平的可行性。理论结果将从最近的随机介质中传播的波的统计级数解中获得。这为非常一般的情况提供了一种具有最小近似的解。基于这些结果，将对相干检测和直接检测进行比较，并将研究相干检测的激光雷达方程中的明显误差。此外，还将研究从激光雷达测量中推断湍流剖面的可行性。

Remote sensing of the atmosphere using lasers is referred to as lidar, an acronym for "light detection and ranging" and is analogous to radar. The transmission of short pulses of laser light is followed by reception of backscattered signals from atmospheric constituents such as aerosols, dust, clouds or molecules. Information about the composition and physical state of the atmosphere can be deduced from the lidar data. In addition, the time lag of the received signal determines the range of the scattering species. This research is to derive and calculate the received power from a lidar system, both coherent and direct detection. The effects of pulse shape, turbulence, transmitter, receiver and local oscillator will be determined; the effects of the motion of the atmosphere will be investigated; and physics of the important mechanisms will be identified. There is a regime where turbulence is the dominating physical mechanism. The feasibility of estimating turbulence levels from lidar measurements in this regime will also be investigated. The theoretical results will be obtained from a recent series solution for statistics of waves propagating in random media. This provides a solution for very general conditions with a minimum of approximations. Based on these results, comparison between coherent and direct detection will be performed and an apparent error in the lidar equation for coherent detection will be investigated. The feasibility of deducing turbulence profiles from lidar measurements will also be investigated.