Introduction

The scattering of light from spherically shaped particles has been well characterized: it has been derived analytically, modeled computationally and measured experimentally. However, many natural and man-made particle systems are not spherical and these have formed the basis of many recent investigative programs. Modeling the light scattered by non-spherical particle systems using numerical algorithms often is limited by the computational power required to attain a mathematical solution, although increasing capacity and enhanced algorithm sophistication continually extend our capabilities. Experimental measurements can require expensive apparatus and can seldom simultaneously and accurately record all the scattering characteristics. Therefore, computational and experimental approaches often complement one another and enhance our knowledge of the light scattering and the particle systems. Theoreticians and modelers often seek experimental data for verification and to find regions of applicability of their models, and experimentalists may use theoretical results for calibration and performing inversions. Research collaborations between the camps inevitably develop.

This focus issue came about largely due to such research collaborations. The intricacies of both experimental and theoretical scattering signals often cannot be captured using traditional print media, and many researchers find themselves passing multimedia, video clips, etc. that demonstrate the complex features contained within the scattering signals. Eventually, it was realized that the light-scattering community could benefit from the publication of some of these and other multimedia presentations, and we came upon the idea of a special issue of Optics Express for this purpose.

At the same time that this idea was being discussed, the Conference on Light Scattering by Nonspherical Particles: Theory, Measurements, and Applications was being prepared in Halifax, Canada, August 28 – September 1, 2000 [1]. The conference was the fifth in the series of international meetings on light scattering by non-spherical particles. The first was organized by Joop Hovenier in Amsterdam in 1995 [2]. The second was organized by Kari Lumme in Helsinki in 1997 [3]. The third was organizeded by Michael Mishchenko, Larry Travis and Joop Hovenier in New York City in 1998 [4]. The fourth was organized by Fernando Obelleiro, José Luis Rodríguez and Thomas Wriedt in Vigo in 1999 [5]. Traditionally, high quality manuscripts from this series have been published in the Journal of Quantitative Spectroscopy and Radiative Transfer (JQSRT) [2–4]. In addition to this special issue of JQSRT, we took advantage of this opportunity to solicit contributions for Optics Express from conference attendees whose manuscripts could benefit from such multimedia presentations. This Optics Express issue is intended to complement the JQSRT special issue due to be published later this year [6].

The light-scattering conference series covers all aspects of light scattering by non-spherical particles. The Optics Express manuscripts therefore cover a wide range of research topics within this realm. Secker et al., for instance, experimentally show how the spatial light scattering of droplets is dependent on the particle morphology [7]. Kaasalainen et al. develop methods for characterizing astronomical bodies from polarimetric data [8]. Crosta et al., analyze spatial scattering measurements of some specific particulate materials [9]. Prabhu et al. show the dependence of the spatial scattering from a spherical particle containing an inclusion as a function of inclusion size and position [10]. Braun and Krieger analyze intensity fluctuations of light scattered by crystals to study the crystals’ dynamic behavior [11]. These manuscripts are indicative of some of the many aspects and applications of light scattering by non-spherical particles. We hope the reader will find them useful, stimulating, and entertaining.

Gorden Videen

David Secker