The ultimate performance of the Rasnik 3-point alignment system

The Rasnik system is a 3-point optical displacement monitor with sub-nanometer precision. The CCD-Rasnik alignment system was developed in 1993 for the monitoring of the alignment of the muon chambers of the ATLAS Muon Spectrometer at CERN. Since then, the development has continued as new CMOS imaging pixel chips became available. The system's processes and parameters that limit the precision have been studied in detail. We conclude that only the quantum fluctuations to which the light level content of sensor pixels are subject to, is limiting the spatial resolution. The results of two Rasnik systems are compared to results from simulations, which are in good agreement: the best reached precision of \SI{7}{pm/\sqrt{Hz}} is reported. Finally, some applications of high-precision Rasnik systems are set out

Tensio+: a fabric tension meter for the paper industry

Paper is produced in vast quantities in paper mills. The properties of the produced paper critically depend on the parameters of the mill, especially the properties of the fabric belt transporting the fibre-water mixture that is converted into paper through the mill. The belt properties are currently monitored by indirect methods and imprecise measurement devices. The company Feltest Equipment BV aims to improve this situation by developing measurement equipment to monitor the belt properties in a direct fashion

The ultimate performance of the Rasnik 3-point alignment system

The Rasnik system is a 3-point optical displacement monitor with sub-nanometer precision. The CCD-Rasnik alignment system was developed in 1993 for monitoring the alignment of the muon chambers of the ATLAS Muon Spectrometer at CERN. Since then, the development has continued as new CMOS imaging pixel chips became available. In this work the system processes and parameters that limit the precision are studied. We conclude that the spatial resolution of Rasnik is only limited by the quantum fluctuations of the photon flux arriving at the pixels of the image sensor. The results of two Rasnik systems are compared to results from simulations, which are in good agreement. The best spatial resolution obtained was 7 pm/Hz. Finally, some applications of high-precision Rasnik systems are set out.ImPhys/Hoogenboom grou