Abstract

Light scattering is a useful technique for deriving information on particle size and internal structure. Herein, we report on the use of theoretical calculations and experimental measurements to study the effects of particle and laser spot size for dielectric particles confined to a tightly focused Gaussian-beam optical trap. Calculations based on a generalized Lorenz-Mie theory¹ using fifth- order radial Gaussian field expressions² are correlated with measured far-field irradiance profiles for spot sizes of order λ/2n. Based upon the measured and calculated values, it appears that three distinct scattering regimes exist, one of which is evident in the measured profiles. These results demonstrate that optical traps can be used to simultaneously hold and measure light scattering from individual particles.

© 1992 Optical Society of America