Calibration of a RASNIK system for the ATLAS Muon Spectrometer

We propose a scheme for the absolute calibration of a set of three individual RASNIK elements and of their bench supports. The RASNIK elements consist of three precision cubic blocks carrying the mask, the lens or the CCD. Simulations and measurements on a dedicated bench show that this procedure leads to the required precision on the relevant RASNIK parameters (< 5 microns). These calibrated RASNIK blocks can be used later as references for a fast calibration of the RASNIK sensors to be used in the alignment system of the ATLAS muon spectrometer.