Some Calculations Of Light Scattering By Non Spherical Particles Using Approximate Theories

Some Calculations of Light Scattering by Non-spherical Particles Using Approximate Theories

Light Scattering by Nonspherical Particles

There is hardly a field of science or engineering that does not have some interest in light scattering by small particles. For example, this subject is important to climatology because the energy budget for the Earth's atmosphere is strongly affected by scattering of solar radiation by cloud and aerosol particles, and the whole discipline of remote sensing relies largely on analyzing the parameters of radiation scattered by aerosols, clouds, and precipitation. The scattering of light by spherical particles can be easily computed using the conventional Mie theory. However, most small solid particles encountered in natural and laboratory conditions have nonspherical shapes. Examples are soot and mineral aerosols, cirrus cloud particles, snow and frost crystals, ocean hydrosols, interplanetary and cometary dust grains, and microorganisms. It is now well known that scattering properties of nonspherical particles can differ dramatically from those of "equivalent" (e.g., equal-volume or equal-surface-area) spheres. Therefore, the ability to accurately compute or measure light scattering by nonspherical particles in order to clearly understand the effects of particle nonsphericity on light scattering is very important. The rapid improvement of computers and experimental techniques over the past 20 years and the development of efficient numerical approaches have resulted in major advances in this field which have not been systematically summarized. Because of the universal importance of electromagnetic scattering by nonspherical particles, papers on different aspects of this subject are scattered over dozens of diverse research and engineering journals. Often experts in one discipline (e.g., biology) are unaware of potentially useful results obtained in another discipline (e.g., antennas and propagation). This leads to an inefficient use of the accumulated knowledge and unnecessary redundancy in research activities. This book offers the first systematic and unified discussion of light scattering by nonspherical particles and its practical applications and represents the state-of-the-art of this important research field. Individual chapters are written by leading experts in respective areas and cover three major disciplines: theoretical and numerical techniques, laboratory measurements, and practical applications. An overview chapter provides a concise general introduction to the subject of nonspherical scattering and should be especially useful to beginners and those interested in fast practical applications. The audience for this book will include graduate students, scientists, and engineers working on specific aspects of electromagnetic scattering by small particles and its applications in remote sensing, geophysics, astrophysics, biomedical optics, and optical engineering. - The first systematic and comprehensive treatment of electromagnetic scattering by nonspherical particles and its applications - Individual chapters are written by leading experts in respective areas - Includes a survey of all the relevant literature scattered over dozens of basic and applied research journals - Consistent use of unified definitions and notation makes the book a coherent volume - An overview chapter provides a concise general introduction to the subject of light scattering by nonspherical particles - Theoretical chapters describe specific easy-to-use computer codes publicly available on the World Wide Web - Extensively illustrated with over 200 figures, 4 in color

Light Scattering by Irregularly Shaped Particles

This volume contains most of the invited papers presented at the International Workshop on Light Scattering by Irregularly Shaped Particles held on June 5-7, 1979. at the State University of New York at Albany (SUNYA). Over seventy participants representing many dis ciplines convened to define some of the ever-increasing number of resonant light-scattering problems associated with particle shape and to relate their most recent investigations in this field. It is obvious from the two introductory papers that an investi gator's primary discipline determines his/her approach to the light scattering problem. The meteorologist, Diran Deirmendjian, advocates an empirical methodology: to model the scattering by atmospheric aerosols, using equivalent spheres as standards, in the most effi cient and simplest manner that is consistent with remote sensing, in situ, and laboratory· data. Because of the almost infinite variety of particle shapes, he questions not only the possibility but even the usefulness of the exact solution of scattering by a totally arbitrary particle. The astrophysicist, J. Mayo Greenberg, is primarily concerned with the information content carried by the scattered light because this radiation is the sole clue to under standing the nature of interstellar dust. What measurements (polar ization, color dependence, etc ••• ) should be made to best determine a given particle characteristic (size, surface roughness, refractive index, etc ••• )? Thus, he considers the physics of the scattering process to be of paramount interest.