Variable focal-length lens for atoms

A near-resonant standing laser light field is used to focus a diverging beam of sodium atoms onto the atomic-beam axis. The investigations presented here distinguish between channeling of atoms with trajectories close to the axis and imaging of the atomic source. For laser detunings close to resonance, acceleration of the atoms in the transverse direction occurs. The amount of acceleration changes as either the intensity or the detuning of the standing wave is varied, thereby altering the position at which the atoms are imaged. This results in a variable focal-length lens for atoms. The experimental results are in good agreement with a theoretical model based on a continued-fraction solution for the standing-wave light forces. (C) 1996 Optical Society of America