9 Russells Crescent

Horley, United Kingdom

9 Russells Crescent

Horley, United Kingdom
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Lock J.A.,Cleveland State University | Laven P.,9 Russells Crescent | Adam J.A.,Old Dominion University
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2015

We calculated scattering of an electromagnetic plane wave by both a radially-inhomogeneous particle and bubble, the square of whose refractive index profile is parabolic as a function of radius. Depending on the value of the two adjustable parameters of the parabola, the particle or bubble can have either a refractive index discontinuity at its surface, or the refractive index can smoothly merge into that of the exterior medium. Scattering was analyzed in ray theory, and various novel features of the scattering, including the details of the curved ray paths, transmission rainbows, and near-critical-angle scattering were apparent and were contrasted with their behavior for scattering by a homogeneous sphere. © 2015 Elsevier Ltd.


Laven P.,9 Russells Crescent | Lock J.A.,Cleveland State University | Adam J.A.,Old Dominion University
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2015

We calculated scattering of an electromagnetic plane wave by a radially inhomogeneous particle and a radially inhomogeneous bubble when the square of the refractive index profile is parabolic as a function of radius. Such a particle or bubble is called a generalized Luneburg lens. A wide variety of scattering phenomena can occur, depending on the value of the two adjustable parameters of the parabola. These phenomena, including transmission rainbows, the weak caustic for near-critical-angle scattering by a bubble, surface orbiting, the interior orbiting paths of morphology-dependent resonances, and the separation of diffraction are studied here using wave theory and time domain scattering. These phenomena are also compared with their appearance or absence for scattering by a homogeneous sphere. © 2015 Elsevier Ltd.


Lock J.A.,Cleveland State University | Laven P.,9 Russells Crescent
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2011

We computed the Debye series p = 1 and p = 2 terms of the Mie scattered intensity as a function of scattering angle and delay time for a linearly polarized plane wave pulse incident on a spherical dielectric particle and physically interpreted the resulting numerical data. Radiation shed by electromagnetic surface waves plays a prominent role in the scattered intensity. We determined the surface wave phase and damping rate and studied the structure of the p = 1; 2 surface wave glory in the time domain. © 2011 Optical Society of America.


Lock J.A.,Cleveland State University | Laven P.,9 Russells Crescent
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2011

The p = 0 term of the Mie-Debye scattering amplitude contains the effects of external reflection and diffraction. We computed the reflected intensity in the time domain as a function of the scattering angle and delay time for a short electromagnetic pulse incident on a spherical particle and compared it to the predicted behavior in the forward-focusing region, the specular reflection region, and the glory region. We examined the physical consequences of three different approaches to the exact diffraction amplitude, and determined the signature of diffraction in the time domain. The external reflection surface wave amplitude gradually replaces the diffraction amplitude in the angular transition region between forward-focusing and the region of specular reflection. The details of this replacement were studied in the time domain. © 2011 Optical Society of America.


Lock J.A.,Cleveland State University | Laven P.,9 Russells Crescent
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2012

Although scattering of light by a coated sphere is much more complicated than scattering by a homogeneous sphere, each of the partial wave amplitudes for scattering of a plane wave by a coated sphere can be expanded in a Debye series. The Debye series can then be rearranged in terms of the various reflections that each partial wave undergoes inside the coated sphere. For a given number of internal reflections, it is found that many different Debye terms produce the same scattered intensity as a function of scattering angle. This is called path degeneracy. In addition, some of the ray trajectories are repeats of those occurring for a smaller number of internal reflections in the sense that they produce identical time delays as a function of scattering angle. These repeated paths, however, have a different intensity as a function of scattering angle than their predecessors. The degenerate paths and repeated paths considerably simplify the interpretation of scattering within the coated sphere, thus making it possible to catalog the contributions of the various paths. © 2012 Optical Society of America.


Laven P.,9 Russells Crescent | Lock J.A.,Cleveland State University
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2012

Numerical computations were made of scattering of an incident electromagnetic pulse by a coated sphere that is large compared to the dominant wavelength of the incident light. The scattered intensity was plotted as a function of the scattering angle and delay time of the scattered pulse. For fixed core and coating radii, the Debye series terms that most strongly contribute to the scattered intensity in different regions of scattering angle-delay time space were identified and analyzed. For a fixed overall radius and an increasing core radius, the first-order rainbow was observed to evolve into three separate components. The original component faded away, while the two new components eventually merged together. The behavior of surface waves generated by grazing incidence at the core/coating and coating/exterior interfaces was also examined and discussed. © 2012 Optical Society of America.


Lee Jr. R.L.,U.S. Naval Academy | Laven P.,9 Russells Crescent
Applied Optics | Year: 2011

Naturally occurring tertiary rainbows are extraordinarily rare and only a handful of reliable sightings and photographs have been published. Indeed, tertiaries are sometimes assumed to be inherently invisible because of sun glare and strong forward scattering by raindrops. To analyze the natural tertiary's visibility, we use Lorenz-Mie theory, the Debye series, and a modified geometrical optics model (including both interference and nonspherical drops) to calculate the tertiary's (1) chromaticity gamuts, (2) luminance contrasts, and (3) color contrasts as seen against dark cloud backgrounds. Results from each model show that natural tertiaries are just visible for some unusual combinations of lighting conditions and raindrop size distributions. © 2011 Optical Society of America.


Laven P.,9 Russells Crescent
Journal of Nanophotonics | Year: 2010

Craig Bohren has offered a million-dollar prize to anyone who can devise a detector that accepts scattered light but rejects diffracted light. This challenge was examined from a theoretical perspective by considering the scattering of red light by a spherical droplet of water with diameter 20 μm. Illumination of the droplet by short pulses (e.g. a duration of 5 fs) could allow a detector to distinguish between light scattered by various mechanisms, such as diffraction, transmission, reflections and surface waves. Although such techniques would not satisfy the precise terms of the challenge, the time domain approach can deliver remarkable insights into the details of the scattering processes. © 2010 Society of Photo-Optical Instrumentation Engineers.


Laven P.,9 Russells Crescent
Applied Optics | Year: 2015

The atmospheric corona is a well-known diffraction phenomenon, typically seen as colored rings surrounding the Sun or Moon. In many respects, Fraunhofer diffraction provides a good explanation of the corona. As the angular sizes of the corona's rings are inversely proportional to the radius, r, of the spherical particles causing the corona, it should be easy to estimate the particle size from observations and photographs. Noting that some of the techniques commonly used for particle sizing based on diffraction theory can give misleading results for coronas caused by the scattering of sunlight, this paper uses Mie theory simulations to demonstrate that the inner 3 red rings of the corona have angular radii of θ ≈ 16/r, 31/r, and 47/r, when θ is measured in degrees and r is measured in μm. © 2014 Optical Society of America.


Laven P.,9 Russells Crescent
Springer Series in Optical Sciences | Year: 2012

Rainbows, coronas and glories are examples of atmospheric optical phenomena caused by the scattering of sunlight from spherical drops of water. It is surprising that the apparently simple process of scattering of light by spherical drops of water can result in this wide range of colourful effects. However, the scattering mechanisms are very complicated. Eminent scientists (such as Descartes, Newton, Young, Airy and many others) offered various explanations for the formation of rainbows-thus making major contributions to our understanding of the nature of light. The basic features of rainbows can be explained by geometrical optics but, in the early 1800s, supernumerary arcs on rainbows provided crucial supporting evidence for the wave theory of light. In 1908, Mie provided a rigorous (but very complicated) solution to the problem of scattering of light by spherical particles. More than 100 years later, Mie's solution can now be used to produce excellent full-colour simulations. Examples of such simulations show how the appearance of these phenomena vary with the size of the water drops, as well as describing the scattering mechanisms that are responsible for their formation. © 2012 Springer-Verlag Berlin Heidelberg.

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