posted on 2024-07-09, 23:38authored bySmitha Kuriakose, Xiaosong Gan, James ChonJames Chon, Min Gu
We propose a ray optics model to calculate the trapping force on a dielectric particle located on the interface between two media and illuminated by a focused evanescent field beam. Such a focused evanescent beam is produced by a high numerical aperture objective with a central obstruction whose size satisfies the total internal reflection condition on the interface. The dependence of the lifting force on the obstruction size, the particle size, and the distance of the particle from the interface is revealed.