In Chapter 3, we move to a semiclassical treatment (quantum theory) of light absorption and scattering, specifically from atoms. We start with a description of how lidar measures Doppler shift, and the fundamental difference between the measurement when the laser is in resonance with an atomic transition (resonant) and when it is not (nonresonant). We follow with a treatment of quantum polarizability and the resulting absorption cross section, leading to the differential resonance scattering cross section and its contrast with the classical result. After quantum polarizability, we demonstrate the radiation pattern of coherently excited atoms. This takes us to an interpretation of the Hanle Effect. Following these descriptions of the phenomena that impact resonance lidar, we extend our understanding by closing the chapter with an overview of the rudimentary physics of sodium laser guide stars.

In Chapter 5, having introduced the physics behind light scattering, we present the lidar equation. This sets the stage for consideration and simulation of various types of lidar. These include the following broadband lidars: Rayleigh–Mie, polarization, vibrational Raman and fluorescence, and differential absorption. They also include high–spectral resolution (narrowband) lidars: Lidar ratio and aerosol properties, temperature profiling by integration Rayleigh+Raman, temperature profiling with rotational Raman and Cabannes scattering, Rayleigh–Mie wind profiling, and mesopause–region resonance fluorescence wind+temperature profiling.

In Chapter 7, we present lidars for profiling atmospheric parameters such as aerosol optical properties, temperatures, and winds. We start with a description of methods for profiling the lidar aerosol-molecular ratio and determining aerosol optical properties. We present and compare techniques for these measurements, including Rayleigh and vibrational Raman integration, rotational Raman technique, and the use of multiple receiver channels with custom-built interference filters. We follow with a description of high-spectral resolution lidar (HSRL), including a detailed discussion of notch (atomic or molecular vapor) filters in the Cabannes scattering detection channels and what is required to make an “ideal” or near-ideal filter. From there, we describe wind profiling methods using Cabannes–Mie scattering, comparing coherent versus incoherent lidars. For HSRL, we describe a near-ideal filter based on absorption in potassium vapor at 770 nm. Following parameter profiling with Cabannes–Mie lidar, we close by describing temperature and wind profiling with laser-induced fluorescence. Here, we focus on Na and Fe lidars. We give summaries of daylight measurements and data processing algorithms, including uncertainty in measurements. We close by discussing scientific contributions by and challenges for these lidars.

In Chapter 2, we present classical light scattering theory. We show the classical electric dipole and how it leads to a model of atomic polarizability and differential scattering cross section. This leads us to the two principal divisions of atomic and molecular scattering, resonant and nonresonant. From here, we close with the causes of broadening of the scattering spectrum, as compared to the laser excitation.

Chapter 1 is an introduction, reviewing the current state of instructional texts on atmospheric lidar. We point to the lack of a treatment of light scattering as employed by lidar from fundamental physics, the motivation for writing this book. We then summarize the scattering processes, Rayleigh, Raman, Mie, and fluorescence, that enable us to probe the state of the atmosphere with lidar. We include a description of the structure and content of the chapters that follow.