1) inject near resonant projection pulse and image the absorption profile,When measuring relatively low density atoms, the 1st technique is easier than the 2nd one. I use the 1st technique in my laboratory and measure the temperature, density, and, etc of atoms in both MOT and MT.
2) inject far off-resonant pulse and image the phase contrast.
Fig. 1 is the experimental setup of this absorption imaging technique. The projection pulse duration is 10 micro-second, and the peak intensity is about 60% of the transition saturation, i.e. about 9 photons per atom for a measurement are absorbed and about 100 micro-kelvin heat up is introduced for a measurement. For this reason this is a demolision measurement.
Fig.1 : Experimental set-up for the absorption imaging. (35KB GIF)
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