Correlations Between Levels For Stellar Scintillometer Derived Profiles Of C2n

A stellar scintillometer measures the variance of stellar intensity for a first magnitude or greater star. This variance can be converted, by the use of spatial filters, into a profile of (c sub n) -sq, the index of refraction structure constant, for 7 different altitudes or levels. The (c sub n) -sq values are not entirely instrument independent because there will be some overlap in the weighting functions used to separate the spatial frequencies. It is usually assumed that readings from levels 1, 4, and 7 are instrument independent. When linear correlation coefficients are calculated between levels for (c sub n) -sq and Log (c sub n) -sq of this data set, results obtained seem to contradict the above stated assumption. Much less correlation is observed when calculated on a nightly basis. In fact, some nightly coefficients are significantly negative, which could not be due to weighting function overlap. We have investigated other mechanisms which could lead to a high degree of correlation across the entire data set. During the measurement program, atmospheric conditions changed from evening to evening. For example, the jet stream passed through several times affecting the entire altitude range of the scintillometer. Correlation studies do not indicate that, except for low lying adjacent levels, (c sub n) -sq values obtained using the scintillometer are instrument dependent.

This is a comprehensive tutorial on the emerging technology of free-space laser communications (FSLC). The book offers an all-inclusive source of information on the basics of FSLC, and a review of state-of-the-art technologies. Coverage includes atmospheric effects for laser propagation and FSLC systems performance and design. Free-Space Laser Communications is a valuable resource for engineers, scientists and students interested in laser communication systems designed for the atmospheric optical channel.

This monograph is concerned with the direct-scattering of electromagnetic waves by one- and two-dimensional objects, and the use of this technique in one-dimensional inverse profiling. It discusses results of research into the method of this technique and its application to specific problems. Several techniques are presented for solving transient electromagnetic direct-scattering problems. These problems are solved indirectly, via a Fourier or Laplace transformation to the real- or complex-frequency domain, as well as directly in the time domain. For the one-dimensional case it is described how the special features of the respective techniques are also exploited to tackle the inverse problem of determining obstacle properties from the scattered field excited by a known incident field. The problems of both identification and of inverse profiling are addressed. For a range of specific problems representative numerical results are presented and discussed. Particular attention is devoted to the numerical implementation and to the physical interpretation of the theoretical numerical results obtained. With respect to inverse-scattering the emphasis is on the band-limiting effects that may arise due to approximation errors in the various inversion schemes employed.

Opto-Mechanical Systems Design, Fourth Edition is different in many ways from its three earlier editions: coauthor Daniel Vukobratovich has brought his broad expertise in materials, opto-mechanical design, analysis of optical instruments, large mirrors, and structures to bear throughout the book; Jan Nijenhuis has contributed a comprehensive new chapter on kinematics and applications of flexures; and several other experts in special aspects of opto-mechanics have contributed portions of other chapters. An expanded feature—a total of 110 worked-out design examples—has been added to several chapters to show how the theory, equations, and analytical methods can be applied by the reader. Finally, the extended text, new illustrations, new tables of data, and new references have warranted publication of this work in the form of two separate but closely entwined volumes. This second volume, Design and Analysis of Large Mirrors and Structures, concentrates on the design and mounting of significantly larger optics and their structures, including a new and important topic: detailed consideration of factors affecting large mirror performance. The book details how to design and fabricate very large single-substrate, segmented, and lightweight mirrors; describes mountings for large mirrors with their optical axes in vertical, horizontal, and variable orientations; indicates how metal and composite mirrors differ from ones made of glass; explains key design aspects of optical instrument structural design; and takes a look at an emerging technology—the evolution and applications of silicon and silicon carbide in mirrors and other types of components for optical applications.

This significant compendium of technical literature traces the development of low-light-level and infrared imaging technologies and system modeling and performance over the past 30 years. It presents an excellent selection of the pioneering work in the U.S. and abroad that forms the theoretical underpinnings of electro-optical imaging. Copublished with ONTAR Corp. Originally published as a hardcover, this is a two-volume softcover version of PM96.