Nondestructive spatial heterodyne imaging of cold atoms

We, demonstrate a new method for nondestructive imaging of laser-cooled ato ms. This spatial heterodyne technique forms a phase image by interfering a strong reference laser beam with a weak probe beam that passes through the cold atom cloud. The figure of merit equals or exceeds that of phase-contra st imaging, and the technique can be used over a wider range of spatial sca les. We show images of a dark-spot magneto-optic trap taken with imaging fl uences as low as 61 pJ/cm(2) at a detuning of 11 Gamma, resulting in 0.0004 photons scattered per atom. (C) 2001 Optical Society of America.