Experimental validation of the vectorial complex ray model on the inter-caustics scattering of oblate droplets.

Fabrice R A Onofri,Quentin Gaubert,Chantal Pelcé,Kuan Fang Ren,Matthias Sentis

doi:10.1364/oe.23.015768

Abstract

We report the first experimental validation of the Vectorial Complex Ray Model (VCRM) using the scattering patterns of large oblate droplets trapped in an acoustic field. The two principal radii and refractive index of the droplets are retrieved with a minimization method that involves VCRM predictions and experimental light scattering patterns. The latter are recorded in the droplet equatorial plane between the primary rainbow region and the associated hyperbolic-umbilic diffraction catastrophe. The results demonstrate that the VCRM can predict the fine and coarse stuctures of scattering patterns with good precision, opening up perspectives for the characterization of large non-spherical particles.

Highlights

The present authors introduced the Vectorial Complex Ray Model (VCRM) to predict the light scattering patterns of large and arbitrary shaped particles with a smooth surface [1,2,3]
We report the first experimental validation of the Vectorial Complex Ray Model (VCRM) using the scattering patterns of large oblate droplets trapped in an acoustic field
Far-field scattering patterns, two rather unusual trends emerge when compared to the spherical case: the elliptical curvature of the primary rainbow fringe and the complex pattern associated to the HUDC [6,7,8]

Summary

Introduction

The present authors introduced the Vectorial Complex Ray Model (VCRM) to predict the light scattering patterns of large and arbitrary shaped particles with a smooth surface [1,2,3]. In VCRM a ray possesses four properties: direction, polarization, amplitude and phase as in classical ray models [4], and a new one – wave front curvature which is governed by the wave front equation [1]. The direction and the Fresnel coefficients are all calculated by the wave vector and its components. Because all current electromagnetic models are still limited to particles of moderate size parameters (less than 600), experimental data are needed to further validate the VCRM

Objectives

Methods

Results

Conclusion