Non-spherical particles in optical tweezers: A numerical solution.

We present numerical methods for modeling the dynamics of arbitrarily shaped particles trapped within optical tweezers, which improve the predictive power of numerical simulations for practical use. We study the dependence of trapping on the shape and size of particles in a single continuous wave beam setup. We also consider the implications of different particle compositions, beam types and media.

Scattering And Absorption of Light in Planetary Regoliths.

Theoretical, numerical, and experimental methods are presented for multiple scattering of light in macroscopic discrete random media of densely-packed microscopic particles. The theoretical and numerical methods constitute a framework of Radiative Transfer with Reciprocal Transactions (RT). The RT framework entails Monte Carlo order-of-scattering tracing of interactions in the frequency space, assuming that the fundamental scatterers and absorbers are wavelength-scale volume elements composed of large numbers of randomly distributed particles.

Radiative transfer with reciprocal transactions: Numerical method and its implementation.

We present a numerical method for solving electromagnetic scattering by dense discrete random media entitled radiative transfer with reciprocal transactions (R2T2). The R2T2 is a combination of the Monte Carlo radiative-transfer, coherent-backscattering, and superposition T-matrix methods. The applicability of the radiative transfer is extended to dense random media by incorporating incoherent volume elements containing multiple particles.

Multiple scattering of light in discrete random media using incoherent interactions.

We consider the scattering and absorption of light in discrete random media of densely packed spherical particles. In what we term "radiative transfer with reciprocal transactions" (RT), we introduce a volume element of the random medium, derive its scattering and absorption characteristics using the superposition T-Matrix method (STMM), and compute its frequency-domain incoherent volume-element scattering characteristics. Using an order-of-scattering approach, we then compute a numerical Monte Carlo solution for the scattering problem with an exact treatment of the interaction between two volume elements.

Polarized backscattering by clusters of spherical particles.

The linear and circular polarization ratios for clusters of spherical particles averaged over multiple orientations show a systematic pattern as a function of the refractive index and the size parameter. We show that, at backscattering, the depolarizing behavior of orientation-averaged clusters of spheres can be approximated by second-order scattering of bispheres. The pattern is relatively invariable in terms of the number of particles.