Experiment of Laser Pointing Stability on Different Surfaces to validate Micrometric Positioning Sensor

CLIC requires 10 μm precision and accuracy over 200m for the pre-alignment of beam related components. A solution based on laser beam as straight line reference is being studied at CERN. It involves camera/shutter assemblies as micrometric positioning sensors. To validate the sensors, it is necessary to determine an appropriate material for the shutter in terms of laser pointing stability. Experiments are carried out with paper, metal and ceramic surfaces. This paper presents the standard deviations of the laser spot coordinates obtained on the different surfaces, as well as the measurement error. Our experiments validate the choice of paper and ceramic for the shutter of the micrometric positioning sensor. It also provides an estimate of the achievable precision and accuracy of the determination of the laser spot centre with respect to the shutter coordinate system defined by reference targets.