The amount of force produced in an optical trap depends on the electromagnetic interaction of the focused beam with the particle. This interaction is a complicated function of numerical aperture, beam power, wavelength, particle geometry, and refractive index. Previous attempts to quantify trapping forces have been limited by simplifying assumptions-namely that the particles are homogeneous, spherical objects. This assumption allows the forces to be solved analytically, but does not provide useful information for nonspherical particles, such as chromosomes. The primary difficulty in predicting the trapping forces for nonspherical particles lies in the calculation of the scattered electromagnetic fields. If the fields are known, the trapping forces can be quantified. Aside from a few selected geometries, MaxwellUs equations must be solved numerically to compute the fields. In this work the finite-difference time-domain(FDTD) technique will be used to quantify the fields for objects of arbitrary shape. Although the FDTD method is computationally intensive, it provides a way to compute the fields under a variety of conditions. The calculated forces will then be compared with measured forces.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
5P41RR001192-22
Application #
6438825
Study Section
Project Start
2001-04-01
Project End
2002-03-31
Budget Start
Budget End
Support Year
22
Fiscal Year
2001
Total Cost
Indirect Cost
Name
University of California Irvine
Department
Type
DUNS #
161202122
City
Irvine
State
CA
Country
United States
Zip Code
92697
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