Abstract
We present what is, to the best of our knowledge, the first detailed calculation of the reverse trapping force acting on a dielectric sphere when it is illuminated by a strongly focused laser beam. The calculation is carried out within the geometrical optics approximation. The phenomenon of laser trapping was discovered experimentally by Ashkin, et al. [ Opt. Lett. 11, 288 ( 1986)] and is of great practical interest in view of the possibility it offers for freely manipulating biological particles, such as viruses and bacteria, in a nondestructive manner. We support our calculations by a qualitative experiment that clearly shows the accessibility of the trapping effect in practice. We use, as an experimental improvement, an objective with a central field stop producing a conical dark field. This enhances the relative contribution from high-N.A. illumination and makes it easier to achieve optical trapping.
© 1992 Optical Society of America
Full Article | PDF ArticleMore Like This
Shaohui Yan and Baoli Yao
J. Opt. Soc. Am. B 24(7) 1596-1602 (2007)
Ryota Omori, Tamiki Kobayashi, and Atsuyuki Suzuki
Opt. Lett. 22(11) 816-818 (1997)
E. Almaas and I. Brevik
J. Opt. Soc. Am. B 12(12) 2429-2438 (1995)