Spatial distribution of the internal and near-field intensities of large cylindrical and spherical scatterers

Abstract

Spatial distributions of the near-field and internal electromagnetic intensities have been calculated and experimentally observed for dielectric cylinders and spheres which are large relative to the incident wavelength. Two prominent features of the calculated results are the high intensity peaks which exist in both the internal and near fields of these objects, even for nonresonant conditions, and the well-defined shadow behind the objects. Such intensity distributions were confirmed by using the fluorescence from iodine vapor to image the near-field intensity distribution and the fluorescence from ethanol droplets impregnated with rhodamine 590 to image the internal-intensity distribution.

Thermophoresis and Photophoresis of an Aerosol Cylinder with Thermal Stress Slip

“…2 pp. 85-103 96 Appendix A for the cylinder (Owen et al 1981;Benincasa et al 1987;Sun et al 2005;Liu et al 2010) and a typical but similar formulism for the sphere (Bohren and Huffman 1983;Mackowski 1989;Allen et al 1991). For a particle of high absorptivity, as shown in Figure 7a, the photophoretic velocity increases with an increase in the value of the particle size parameter  / π 2 a as expected for both cases of cylindrical and spherical particles with a fixed value of * k .…”

High-order interior caustics produced in scattering of a diagonally incident plane wave by a circular cylinder

“…18,19 The interior p ϭ 2 cusp caustic and the turning point of the p ϭ 4 axial spike caustic have been observed by both SRS 20,21 and by fluorescence of rhodamine 590 dye molecules in water droplets. 2 The full p ϭ 2 axial spike caustic has also been observed in a spherical globe filled with water into which a small amount of milk had been added. 15 For scattering by an oblate spheroidal particle with side-on incidence, the rainbow evolves into a higherdimensional optical caustic whose full structure unfolds as the spheroid refractive index and eccentricity are varied.…”

“…For scattering by a sphere, the most familiar exterior caustic is the p ϭ 1 near-zone spherical aberration caustic. 1,2 For p у 2, far-zone rainbow caustics and forward-scattering and backscattering glory caustics occur as well.…”

Enhanced coupling to microsphere resonances with optical fibers

“…If the incident plane wave is resonant with a MDR (i.e., on resonance), there will be, in addition, a uniform intensity distribution within the rim of the microsphere in the volume determined by the MDR. 5 However, if an off-axis Gaussian beam is used at a resonant wavelength, the internal intensity is distributed only within the rim of the microsphere in the volume determined by the MDR and is no longer concentrated near the front and the back surfaces of the microsphere. 6 Therefore a resonant off-axis Gaussian beam excites the MDR's of a microsphere more uniformly and more efficiently than does a plane wave.…”