The stable levitation of small transparent glass spheres by the forces of radiation pressure has been demonstrated experimentally in air and vacuum down to pressures ∼1 Torr. A single vertically directed focused TEM00‐mode cw laser beam of ∼250 mW is sufficient to support stably a ∼20‐μ glass sphere. The restoring forces acting on a particle trapped in an optical potential well were probed optically by a second laser beam. At low pressures, effects arising from residual radiometric forces were seen. Possible applications are mentioned.
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C. B. Strang of the Martin‐Marietta Corp. (private communication);
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The interference observed in the 90° Mie scattering of Fig. 2 can be ascribed to the interference from these two bright sources. One can determine the particle diameter d by measuring its distance from the observing screen and the fringe spacing, since the separation between the two near‐field sources is
8.
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© 1971 The American Institute of Physics.
1971
The American Institute of Physics
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