The ALFA sub-detector is located at 240m from the interaction point in Roman Pots, its purpose is the measurement of elastic pp-scattering and small angles in the Coulomb-Nuclear Interference (CNI) region. The set-up consists of four Roman Pot stations, two on both sides of the interaction point each housing two vertically movable detectors. In order to measure the impacts of elastic protons each detector is equipped with 1500 scintillating fibres arranged in 20 u/v detection planes, providing a spatial resolution of 30 μm. The luminosity calibration will be obtained during special runs using a dedicated high-β* optics which features a parallel-to-point focusing to allow for a direct reconstruction of the t-spectrum from the measured proton impacts. The detector system was installed in 2010/11 and is currently in the commissioning phase.