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Journal of Undergraduate Research

Keywords

poisson optical trap, volumetric display, photophoretic trap

College

Ira A. Fulton College of Engineering and Technology

Department

Electrical and Computer Engineering

Abstract

The purpose of this project was to develop a new type of optical trap based on Poisson’s famous “Poisson Spot” experiment. The two main methods currently for creating a photophoretic trap are to use dark spots created by spherical aberration (see Fig. 1) or to use vortex beams. In the case of a trap caused by spherical aberration which occurs when using spherical lenses to focus a beam, the particle stays in the dark regions due to photophoretic forces [1,2]. Vortex beams are created by doughnut modes of a laser beam. These are modes of the laser which can be created using holograms or phase plates to shape the profile of the beam into a doughnut shape with the dark middle being surrounded by a bright ring [3]. When these doughnut modes propagate downstream, they create a vortex within which multiple particles can be trapped. The problem with this method is that particles are free to move up and downstream along the beam. For applications where the particle needs to stay still at a fixed point, this is not the best method to use.

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