Sensitive Force Measurements With Optically Trapped Micro-Spheres in High Vacuum
AuthorAtherton, David Patrick
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This dissertation details our work on optically levitating and cooling microspheresin vacuum for use as force sensors. We have extensively modeled variousoptical trap congurations to determine stable trap geometries for m sized spheresin a dual-beam optical trap. Techniques have been developed for overcoming instabilitieswhich occur when pumping trapped micro-spheres from low to high vacuum.We have also improved on methods for depositing micro-spheres in optical traps.We have shown that optically levitated micro-spheres are excellent force sensors.By eliminating the need to tether the spheres to a solid substrate, excellentenvironmental decoupling is achieved. In this work we present the realization of aNforce sensitivity. The intended use for the technology developed is to extend thesearch for non-Newtonian gravity by several orders of magnitude at the micrometerlength scale . This technology is also suitable for investigating the Casimir eectin the unexplored regime where neither the Proximity Force Approximation or theCasimir-Polder limits are valid.