# Scattering force in optical trapping

by pen
Tags: force, optical, scattering, trapping
 Share this thread:
 P: 6 hello, reading about the theoretical background of optical trapping. I was wondering how the scattering force originates. Often it is written, that the scattering force is due to reflection, but also the central rays refracted by a dielectric object should contribute ? So the scattering force is due to specular reflection of the incoming rays and refraction of the central rays ? thanks.
 Sci Advisor P: 5,523 For single-beam optical traps, the ray-optics limit (particle much larger than wavelength of trapping light) is treated here: http://www.ncbi.nlm.nih.gov/pmc/arti...00105-0286.pdf The other limit, corresponding to Rayleigh scattering, requires use of physical optics and is treated here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1523313/ and also Mazolli, Neto, Nussenzveig, Proc. R. Soc. Lond. (2003) 459, 3021-3041
 P: 6 thanks a lot! now I think: in the ray optics regime: The net force exerted on a microsphere by one ray is calculated considering the contribution of forces due to reflection and due to refraction, (depending on the incident angle of the ray). The net force can be decomposed into scattering (defined as parallel to the incident ray) and the gradient force (defined as perpendicular to the incident ray). A ray of large incident angles (with respect to the optical axis) has a higher ratio of gradient force/scattering force. hope it`s not that wrong ?
 Sci Advisor P: 5,523 Scattering force in optical trapping Close enough, I'd say.

 Related Discussions General Physics 9 General Physics 12 Advanced Physics Homework 0 Advanced Physics Homework 4 General Physics 0