We propose and demonstrate a spatial version of the cavity ring-down concept in which a photon flux decay is displayed along the spatial coordinate at the exit of a plane Fabry-Perot cavity. The photon decay signals are simulated based on a simple theoretical model combining ray optics and diffraction involved in the spatial ring-down generation, which are found to be in good accordance with the results of a proof-of-principle expermient. (C) 2001 American Institute of Physics.