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Optical forces to levitate objects against gravity
The goal of this project is to design and build a demonstration experiment, where a dielectric sphere is levitated against gravity by weakly focused laser beam.
Electromagnetic radiation generates forces when interacting with matter. Despite the fact that
these forces are minute by human standards, the radiation pressure force has been known for hundreds of years, since it bends the tails of comets away from the sun. Within Maxwell’s theory of electromagnetism, the momentum of electromagnetic radiation is related to the Poynting vector and for a simple plane wave the optical momentum is directed along the wavevector.
During the last few decades, optical forces have entered laboratories as handles to manipulate meso- and microscopic objects. Some of the earliest demonstrations of the radiation pressure force are at the same time the most illustrative: a spherical dielectric particle is levitated by the radiation
pressure generated by a laser beam, balancing the gravitational force.
The goal of this project is to design and build a demonstration experiment, where a dielectric sphere is levitated against gravity by weakly focused laser beam. The successfully accomplished project includes a stably trapped particle, a reliable loading mechanism to get the particle into the trap, a quantitative description of the physics, and a safe viewing mechanism to illustrate the effect of radiation pressure.
[1] A. Ashkin, Optical Trapping and Manipulation of Neutral Particles Using Lasers: A Reprint Volume
with Commentaries, World Scientific Publishing
Electromagnetic radiation generates forces when interacting with matter. Despite the fact that these forces are minute by human standards, the radiation pressure force has been known for hundreds of years, since it bends the tails of comets away from the sun. Within Maxwell’s theory of electromagnetism, the momentum of electromagnetic radiation is related to the Poynting vector and for a simple plane wave the optical momentum is directed along the wavevector. During the last few decades, optical forces have entered laboratories as handles to manipulate meso- and microscopic objects. Some of the earliest demonstrations of the radiation pressure force are at the same time the most illustrative: a spherical dielectric particle is levitated by the radiation pressure generated by a laser beam, balancing the gravitational force. The goal of this project is to design and build a demonstration experiment, where a dielectric sphere is levitated against gravity by weakly focused laser beam. The successfully accomplished project includes a stably trapped particle, a reliable loading mechanism to get the particle into the trap, a quantitative description of the physics, and a safe viewing mechanism to illustrate the effect of radiation pressure. [1] A. Ashkin, Optical Trapping and Manipulation of Neutral Particles Using Lasers: A Reprint Volume with Commentaries, World Scientific Publishing