Xiang'e Han

Characterization of initial disturbances in a liquid jet by rainbow sizing

The development of initial disturbances is relevant to the understanding of atomization processes in which droplets are generated by the breakup of a liquid jet. We theoretically and experimentally demonstrate that such disturbances can be characterized by rainbow sizing. More specifically, for a liquid jet with a diameter of 600 mum, disturbances in the range from 10 nm to 0.2 mum are accessible.

Debye series for Gaussian beam scattering by a multilayered sphere

The Debye series has been a key tool for the understanding of light scattering features, and it is also a convenient method for understanding and improving the design of optical instruments aimed at optical particle sizing. Gouesbet has derived the Debye series formulation for generalized Lorenz-Mie theory (GLMT). However, the scattering object is a homogeneous sphere, and no numerical result is provided. The Debye series formula for plane-wave scattering by multilayered spheres has been derived before. We have devoted our work to the Debye series of Gaussian beam scattering by multilayered spheres. The integral localized approximation is employed in the calculation of beam-shape coefficients (BSCs) and allows the study of the scattering characteristics of particles illuminated by the strongly focused beams. The formula and code are verified by the comparison with the results produced by GLMT and also by the comparison with the result for the case of plane-wave incidence. The formula is also employed in the simulation of the first rainbow by illuminating the particle with one or several narrow beams.

Debye series of normally incident plane-wave scattering by an infinite multilayered cylinder.

We derive the formula of the Debye-series decomposition for normally incident plane-wave scattering by an infinite multilayered cylinder. A comparison of the scattering diagrams calculated by the Debye series and Mie theory for a graded-index polymer optical fiber is given and the agreement is found to be satisfied. This approach permits us to simulate the rainbow intensity distribution of any single order and the interference of several orders, which is of good use to the study of the scattering characteristics of an inhomogeneous cylinder and to the measurement of the refractive index profile of an inhomogeneous cylinder.

Message-passing-interface-based parallel FDTD investigation on the EM scattering from a 1-D rough sea surface using uniaxial perfectly matched layer absorbing boundary

A message-passing-interface (MPI)-based parallel finite-difference time-domain (FDTD) algorithm for the electromagnetic scattering from a 1-D randomly rough sea surface is presented. The uniaxial perfectly matched layer (UPML) medium is adopted for truncation of FDTD lattices, in which the finite-difference equations can be used for the total computation domain by properly choosing the uniaxial parameters. This makes the parallel FDTD algorithm easier to implement. The parallel performance with different processors is illustrated for one sea surface realization, and the computation time of the parallel FDTD algorithm is dramatically reduced compared to a single-process implementation. Finally, some numerical results are shown, including the backscattering characteristics of sea surface for different polarization and the bistatic scattering from a sea surface with large incident angle and large wind speed.

Surface waves/geometrical rays interferences : numerical and experimental behaviour at rainbow angles

Abstract This article is devoted to the study of the behaviour of interferences between geometrical rays and surface waves. The measurement of surface waves is a potential key for very accurate characterization of particle surface and sphericity. The use of a generalized Lorenz–Mie theory provides new insights on involved phenomena.

Scattering of a high-order Bessel beam by a sphere

The rigorous theory for the scattering of a high-order Bessel beam (HOBB) by a sphere is presented. The Beam Shape Coefficients (BSCs) for HOBB are calculated using Integral Localized Approximation (ILA), and the scattering coefficients are expanded using Debye series (DSE). The far-field scattered intensities are simulated, and the effect of angle of axicon and the order of HOBB on the scattered intensity is studied.

Scattering of an arbitrary shaped object by using vectorial complex ray model

Vectorial complex ray model has been developed to describe the scattering of smooth surface object of arbitrary shape. In this model, the property of a wave - curvature of wavefront is integrated in ray model, such that all waves are described as vectorial complex rays of five parameters: amplitude, phase, direction of propagation, polarization and curvature matrix of its wavefront. At each interaction of a ray with the surface of the object, the ray direction is determined by the vector Snell law, the divergence or convergence of the wave is calculated by the wavefront curvature (WFC) and the phase shift due to focal line is evaluated according to CWF. The total scattered field is the superposition of the complex amplitude of all orders of the rays emergent from the object. Thanks to the simple representation of the wave, this model is very suitable for the description of the interaction of an arbitrary wave with an object of smooth surface and complex shape. The applications of the model to 2D scattering of a plane wave by an infinite elliptical cylinder and a spheroid particle are presented. The particle can be absorbing and its refractive index can also be less than unity.

Debye series analysis of radiation pressure force exerted on a spherical particle

Optical trapping is of great practical importance in various fields such as physics, biology and nanofluidics or microfluidics. In order to trap and move particles efficiently, it is necessary to theoretically study the radiation pressure face exerted on the particles firstly. We introduce Debye series expansion (DSE), which can give physical explanation of each scattering process, to analyze radiation pressure force exerted on a spherical particle generated by focused beams. The DSE is employed to the study of radiation pressure force corresponding to single scattering process, and to the research on the effect of various parameters such as beam position and mode p on radiation pressure force.

Rayleigh scattering property of an anisotropic medium particle

The finite difference equation is developed, which may be used to calculate the electric field of the inhomogeneous anisotropic medium. The validity of the equation is tested. The distributions of the electric potential and the electric field are presented for an anisotropic trihedron body. Its Rayleigh scattering property is researched. Simulations show that the dielectric constant in the polarizing direction of the incident electric field has an obvious impact on scattering, the dielectric constant in the perpendicular direction has not much effect on it. The arithmetic is not confined by the factors such as the targets shape and electric parameter etc. and has the peculiarities of briefness and versatility.