496
F. Bordry et al.
Fig. 8.94 Fiducials and local magnet co-ordinate system
Fig. 8.95 LHC fiducials and fiducialisation equipment
equipped with forced centering system. It allows not only the measurements of a
Taylor-Hobson sphere located on top of it but also the installation of a theodolite
or any specific device, considering then this point as part of the network (Fig.
8.95).
The “fiducialisation” is the operation during which the position of the fiducials is
determined with respect to a reference axis (magnetic or mechanic). It can be done
using:
• Magnetic measurements for most of the main magnetic components (quadrupoles
and dipoles) which are realized by magnet people;
• Coordinate Measuring Machine (CMM) Mechanical measurements in a metrology laboratory;
• Laser tracker measurements when the size of the component is such that a
metrological control is inadequate or impossible (Fig. 8.95).
For CLIC components, the fiducialisation has to be performed with an accuracy
better than 10 microns. To achieve it, several techniques and instruments have been
developed. Among them, one has to mention the micro-triangulation and the Frequency Scanner Interferometry (FSI). The principle of the micro-triangulation (Fig.
F. Bordry et al.
Fig. 8.94 Fiducials and local magnet co-ordinate system
Fig. 8.95 LHC fiducials and fiducialisation equipment
equipped with forced centering system. It allows not only the measurements of a
Taylor-Hobson sphere located on top of it but also the installation of a theodolite
or any specific device, considering then this point as part of the network (Fig.
8.95).
The “fiducialisation” is the operation during which the position of the fiducials is
determined with respect to a reference axis (magnetic or mechanic). It can be done
using:
• Magnetic measurements for most of the main magnetic components (quadrupoles
and dipoles) which are realized by magnet people;
• Coordinate Measuring Machine (CMM) Mechanical measurements in a metrology laboratory;
• Laser tracker measurements when the size of the component is such that a
metrological control is inadequate or impossible (Fig. 8.95).
For CLIC components, the fiducialisation has to be performed with an accuracy
better than 10 microns. To achieve it, several techniques and instruments have been
developed. Among them, one has to mention the micro-triangulation and the Frequency Scanner Interferometry (FSI). The principle of the micro-triangulation (Fig.