Figure 4: Measurement of the profile of the dipole beam.
Fluorescence rate of an ion trapped in an rf field providing maximal confinement (ωy=2π × (307±0.1) kHz) in dependence on the potential applied to the piezo actuators and the displacement of the centre of the dipole beam along the y-direction, respectively. The dipole beam is inducing an a.c. Stark shift on the electronic energy levels of the ion, increasing the detuning of the cooling laser from the atomic transition and, thus, decreasing the fluorescence rate. The dependence of fluorescence in the vicinity of the centre of the (Gaussian shaped) dipole beam, is approximated quadratically and its centre determined by a least square fit (solid line) with an uncertainty of 26 nm. The vertical error bars denote the statistical error after an integration time of 1 s per data point (1σ).
