Diffusion of resonance radiation in atomic vapor imaging

Abstract

The effect of resonance radiation diffusion due to radiation trapping has been studied in an atomic vapor imaging filter. Using a cesium resonance fluorescence imaging monochromator, the spatial distortions due to resonance radiation trapping by Cs atoms in the pumping/imaging region have been investigated. It was found that the spatial distortions were dependent on the number density of the Cs atoms, as well as the irradiance of the signal photons at 852.12 nm (6 2S 1/2→6 2P o 3/2). The pump laser (917.23 nm, 6 2P o 3/2→6 2D 5/2) did not influence the radiation diffusion to the same degree as the signal beam. It is shown that there is a compromise between maximum optical density and spatial resolution. The number density of the Cs resonance fluorescence imaging monochromator was optimized to obtain the highest spatial resolution and signal-to-background ratio.