The use of TEM*01 ("donut") mode laser beam has been proposed as a means of focusing an atomic beam to nanometer scale spot diameters. We have analyzed the classical trajectories of atoms through a donut mode laser beam using methods developed for particle optics. The differential equation describing the first order paraxial lens properties has exactly the same form as the "bell-shaped" magnetic Newtonian lens first analyzed by Glaser for the focusing of electrons in an electron microscope objective. We calculate the first order properties of the lens, obtaining cardinal elements vaid over the entire operating range of the lens, including the "thick" and immersion regimes. Contributions to the ultimate spot size are discussed, including four aberrations plus diffraction and atom beam collimation effects. Explicit expressions for spherical, chromatic, spontaneous emission, and dipole fluctuation aberrations are obtained. Examples are discussed for a sodium atomic beam, showing that sub-nanometer diameter spots may be achieved with reasonable laser and atom beam parameters. Optimization of the lens is also discussed.
Conference Dates: July 29-August 3, 1990
Conference Location: Ann Arbor, MI
Conference Title: 12th International Conference on Atomic Physics, Abstracts of Contributed Papers
Pub Type: Conferences