IMAGING WITH AN ATOMIC-BEAM

FOCUSING of atomic beams has been investigated for more than 40 years( 1-9). The formation of images of simple objects such as points or slit s has been demonstrated(7-9), but only with long focal lengths and lar ge chromatic aberrations oiling to the velocity distribution of the th ermal beam. Lasers can be used to slow and cool the atomic beam(10), r educing the focal length; and by optically narrowing the velocity spre ad of the beam, chromatic aberrations can be reduced substantially. He re rye report the construction of an atomic imaging device, using a he xapole lens made from permanent magnets, which produces images in the same way as an optical slide projector. A mask is illuminated by a bea m of caesium atoms prepared using a laser diode, and its image appears on a 'resonant light screen', where a sheet of laser light excites at omic fluorescence. We can obtain magnified and demagnified images with remarkable resolution, suggesting that this technique might be used t o create sub-micrometre atomic structures.