Experiments to Control Atom Number and Phase-Space Density in ...

Signal
0
Signal
(a) (b)
Signal
Frequency Frequency
(c) (d)
0 0
ω-ω m
0
Signal
ω ω+ωm ω-ωm ω
Frequency Frequency
ω+ω m
Figure 2.23: (a) Lorentzian lineshape of an atomic signal. (b) Dispersive signal of an
atomic transition. (c) In-phase / amplitude contribution of the FM error signal. The
two lines are centered around ω±ωm. (d) Out-of-phase / dispersive contribution of the
FM error signal. The three dispersion lines are centered around ω−ωm, ω and ω+ωm.
2.13 Imaging Techniques
The standard technique to obtain information about an ultracold ensemble of
atoms is to use various imaging techniques. In-situ and time-of-flight imaging techniques
allow the study of trapped atomic samples. Two forms of imaging known as absorption
and fluorescence imaging are used in the experiments described in this dissertation.
Additional imaging techniques include phase-contrast imaging, dark-ground imaging,
and polarization-contrast imaging [51].
2.13.1 Absorption Imaging
Absorption imaging relies on imaging a resonant or near-resonant laser beam that
passes through the atomic cloud. When passing through the atomic cloud, the atoms
will scatter photons out of the beam, leaving a shadow of the cloud on the laser beam
profile.
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