Experimental measurement study of laser collimation of a chromium beam by Doppler cooling scheme

In this paper,a size detecting system based on Laser induced fluorescence(LIF)is designed to measure the Cr atomic beam divergence of laser collimation by using one-dimensional transverse Doppler cooling scheme.Under the parameters of cooling laser power of 45mW,interaction distance of 24mm and detuning of-0.5Γ,we observe the angular distribution of Cr atoms(50%quantile) on the beam axis is from 1.07±0.10mrad to 0.46±0.10mrad by laser collimation.we also present detailed measurements of collimation angles over different laser powers and compare and analysis our results with numerical calculation based on the semiclassical model.