Isotropic and anisotropic elastic scatterers of underwater sound

Object and purpose of research. This paper discusses diffraction parameters of isotropic and anisotropic elastic scatterers, demonstrating that transversally isotropic bodies with a certain orientation of their planes of isotropy might be regarded as isotropic scatterers with similar size, shape and physical parameters. Materials and methods. Diffraction theory methods in solution of boundary problems and equations of dynamic elasticity theory for isotropic and anisotropic bodies. Main results. Calculation of moduli for angular parameters, as well as of relative back-scattering sections for isotropic and anisotropic scatterers of various shapes. Conclusion. The studies demonstrated that if transversally isotropic bodies of various shapes have a certain orientation of their planes of isotropy and a certain vector of a plane wave falling onto them, their reflection parameters, like relative backscattering sections and angular scattering characteristic of an anisotropic body are the same as those for isotropic bodies of similar size, shape and elasticity.

Experimental Study and Analysis of Light Scattering Patterns of Bragg Fibers Fabricated in PECVD

Light scattering patterns are commonly used in industry to assess fiber quality. In this work, scattering patterns of Bragg fibers are studied. Optical fibers are coated with alternating layers of Silicon Nitride and Silica using Plasma Enhanced Chemical Vapor Deposition. A laser beam incident perpendicular to the fiber axis scatters off creating patterns distinct from that of uncoated fibers which exhibit continuous front lobe. Effect of variation in layer properties, polarization, wavelength and fiber symmetry is observed in the patterns. Anomalous suppression and enhancement in angular scattering pattern is explained through a scattering angle diagram. Features in the pattern are mapped to reflectance of the Bragg stack and it is found that a stopband creates the anomalous features in the scattering.

PHIPS-HALO: the airborne Particle Habit Imaging and Polar Scattering probe – Part 3: Single-particle phase discrimination and particle size distribution based on the angular-scattering function

A major challenge for in situ observations in mixed-phase clouds remains the phase discrimination and sizing of cloud hydrometeors. In this work, we present a new method for determining the phase of individual cloud hydrometeors based on their angular-light-scattering behavior employed by the PHIPS (Particle Habit Imaging and Polar Scattering) airborne cloud probe. The phase discrimination algorithm is based on the difference of distinct features in the angular-scattering function of spherical and aspherical particles. The algorithm is calibrated and evaluated using a large data set gathered during two in situ aircraft campaigns in the Arctic and Southern Ocean. Comparison of the algorithm with manually classified particles showed that we can confidently discriminate between spherical and aspherical particles with a 98 % accuracy. Furthermore, we present a method for deriving particle size distributions based on single-particle angular-scattering data for particles in a size range from 100 µm ≤ D ≤ 700 µm and 20 µm ≤ D ≤ 700 µm for droplets and ice particles, respectively. The functionality of these methods is demonstrated in three representative case studies.

• Glories, hidden rainbows and nearside-farside interference effects in the angular scattering of the state-to-state H + HD → H2 + D reaction

Yuan et al. [Nature Chem., 2018, 10, 653] have reported state-of-the-art measurements of differential cross sections (DCSs) for the H + HD → H2 + D reaction, measuring for the...