Application of the discrete dipole approximation to optical trapping calculations of inhomogeneous and anisotropic particles

SH Simpson, S Hanna

Research output: Contribution to journalArticle (Academic Journal)

54 Citations (Scopus)

Abstract

The accuracy of the discrete dipole approximation (DDA) for computing forces and torques in optical trapping experiments is discussed in the context of dielectric spheres and a range of low symmetry particles, including particles with geometric anisotropy (spheroids), optical anisotropy (birefringent spheres) and structural inhomogeneity (core-shell spheres). DDA calculations are compared with the results of exact T-matrix theory. In each case excellent agreement is found between the two methods for predictions of optical forces, torques, trap stiffnesses and trapping positions. Since the DDA lends itself to calculations on particles of arbitrary shape, the study is augmented by considering more general systems which have received recent experimental interest. In particular, optical forces and torques on low symmetry letter-shaped colloidal particles, birefringent quartz cylinders and biphasic Janus particles are computed and the trapping behaviour of the particles is discussed. Very good agreement is found with the available experimental data. The efficiency of the DDA algorithm and methods of accelerating the calculations are also discussed. (C) 2011 Optical Society of America
Translated title of the contributionApplication of the discrete dipole approximation to optical trapping calculations of inhomogeneous and anisotropic particles
Original languageEnglish
Pages (from-to)16526 - 16541
Number of pages16
JournalOptics Express
Volume19
DOIs
Publication statusPublished - Aug 2011

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