Renewed interest in laser communication systems has sparked development of useful new analytic models. This book discusses optical scintillation and its impact on system performance in free-space optical communication and laser radar applications, with a detailed look at propagation phenomena and the role of scintillation on system behavior. Intended for practicing engineers, scientists, and students.
Renewed interest in laser communication systems has sparked development of useful new analytic models. This book discusses optical scintillation and its impact on system performance in free-space optical communication and laser radar applications, with a detailed look at propagation phenomena and the role of scintillation on system behavior. Intended for practicing engineers, scientists, and students.
Log-amplitude variance and covariance of the scintillation of a diverging optical beam have been measured over a 48-hr period at a wavelength of 0.63[mu], on a 490 and 1000 m optical paths 2 m above the surface of a flat mesa near Boulder, Colorado. Simultaneous measurements of the refractive-index structure of the atmosphere have been obtained from temperature-structure-function measurements at spacings of 1, 3, and 10 cm. A saturation of scintillation occurs for values of log-amplitude variance between 0.5 and 1. After reaching a peak, the log-amplitude variance then decreases with both increasing range and increasing refractive-index turbulence. The spatial covariance of the fluctuations tends to increase in the saturation region. In the unsaturated region, the log-amplitude variance is approximately that predicted by the spherical-wave propagation theory of Tatarski.
Since publication of the first edition of this text in 1998, there have been several new, important developments in the theory of beam wave propagation through a random medium, which have been incorporated into this second edition. Also new to this edition are models for the scintillation index under moderate-to-strong irradiance fluctuations; models for aperture averaging based on ABCD ray matrices; beam wander and its effects on scintillation; theory of partial coherence of the source; models of rough targets for ladar applications; phase fluctuations; analysis of other beam shapes; plus expanded analysis of free-space optical communication systems and imaging systems.
The practice of shaping the irradiance profile of laser beams goes back more than three decades, and the applications of beam shaping are as diverse as they are numerous. However, until Dickey and Holswade's groundbreaking and highly popular Laser Beam Shaping: Theory and Techniques was published, there was no single, detailed treatment available on the underlying theory and basic techniques of beam shaping. Building on the foundations of this previous work, these esteemed editors have teamed with recognized expert David L. Shealy to produce the first in-depth account of beam shaping applications and design. Laser Beam Shaping Applications details the important features of beam shaping and exposes the subtleties of the theory and techniques that are best demonstrated through proven applications. In chapters contributed by prominent, active leaders in their respective specialties, the book discusses applications in lithography, laser printing, optical data storage, stable isotope separation, adaptive mirrors, and spatially dispersive lasers. The contributors share major insights, knowledge, and experience, reveal the advantages of the technologies, and include extensive references to the literature. The book concludes with a summary of beam shaping theory and techniques as well as the history of the field. Providing practical expertise, Laser Beam Shaping Applications is an extremely helpful guide to improving current laser processes, optimizing application-specific technologies, and advancing future development in the field.
