Dresden 2006 – scientific programme

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AKB: Biologische Physik

AKB 23: Photo-Biophysics

AKB 23.2: Talk

Thursday, March 30, 2006, 16:30–16:45, ZEU 255

Interactions of Biological Cells with Coherent Light — •Kort Travis and Jochen Guck — Universität Leipzig, Fakultät für Physik und Geowissenschaften, Abteilung Physik der weichen Materie; Linnéstrasse 5, 04103 Leipzig, Germany

Understanding near-field interactions of coherent infrared light with biological cells is critically important for modern optical manipulation and trapping applications, such as the optical stretcher or the optical tweezers. With respect to classical scattering theory, considerations of refractive index and size classify cells in the “anomalous diffraction” regime. Although there is significant published work applying numerical techniques such as the finite difference time domain (FDTD) technique to analyze these electrodynamic interactions, the use of higher order, more analytic techniques such as Mie theory, has been quite limited. In the present discussion, the system transfer operator (T-matrix) formalism is used to evaluate general features of optical fields in and around cells. Specifically, the discussion will cover: electrodynamic characteristics of all objects in this optical size range; effects of surface deviations from ideal shape; effects of the inclusion of large organelles such as the nucleus and mitochondria; and finally, effects associated with local inhomogeneities in the refractive index. Key points in the analytical discussion are illustrated with examples from numerical simulation and from experimental results.