High-contrast, high-resolution focusing of neutral atoms using light forces

We show that light force lenses can be used to focus a thermal beam of neutral atoms with extremely high resolution ({~}20 nm) and high contrast ({~}10:1), finally making such atom-optical lenses viable for proposed applications. Our (cylindrical) lenses for sodium atoms are created by the dipole force within each period of a standing wave. We determine the spatial distribution of the focused atoms (with nanometer resolution) by allowing the atoms to deposit on a substrate and scanning with a UHV scanning tunneling microscope. We find that the requirements for optimum focusing are very large, positive detuning; short focal lengths; and a well-collimated atomic beam. These dependences can be thoroughly understood from a simple theoretical model. {}1996 The American Physical Society.