Automation of 3d Measurements for the Final Assembly Steps of the Lhc Dipole Magnets

Due to the mechanical and beam optics requirements, the geometry of the LHC dipole cold masses is submitted to very tight tolerances (few tenths of millimeters) over the magnet’s length (more than 15 meters). Different parts of the cold mass have to be either measured or properly positioned throughout the assembly (see reference [1]), implying the use of a portable system. The measurement system needs to be controlled by adequate software in order to allow data acquisition and data analysis so as to keep under control, in an efficient and reliable way, the real geometry of the dipole during the cold mass assembling. The only systems having all the necessary functions and responding to all precision requirements are based on optical methods as the interferometric (IFM) laser tracking and absolute distance measuring (ADM) techniques. A laser tracker combining these two techniques was chosen to perform the geometrical measurements related to the cold mass assembly: Leica LTD500 with its associated software Axyz.