A focussing funnel for metastable helium
Laboratoire Charles Fabry de l'Institut d'Optique, B.P. 147, 91403 Orsay Cedex, France
Revised: 27 January 1999
Published online: 15 October 1999
We have constructed a magneto-optical funnel for He atoms and studied its properties using a laser cooled, highly mono-energetic atomic beam. A simple model of its action allows us to quantitatively understand the observed spot size and "focal length" . We show that for a fast beam, the velocity damping coefficient plays an important role in determining the focal length of the device. The observed spot size is limited mainly by transverse heating processes which impose a transverse velocity spread. The device also permits easy scanning of the focussed spot.
PACS: 42.50.Vk – Mechanical effects of light on atoms, molecules, electrons, and ions / 32.80.Pj – Optical cooling of atoms; trapping
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999