Author: P. Leteurtre
Capacitance-based high accuracy sensors for leveling and alignment; Actuators for closed-loop control
These capacitance-based sensors use the water-free surface for leveling reference, or the stretched carbon wire for alignment reference; these sensors can have measurement uncertainties lower than +/- 1 micrometer. In addition, 2 axis tiltmeters can measure up to 10^-7 radian repeatability, in (0-100 Hz) bandwidth. All these sensors, that are fully insensitive to high magnetic field and to radiation environments, are operated every day in Cern, ESRF, Desy, KEK, ANL. They are programmed for Clic alignment (4 km long, micrometer accuracy). Actuators have been used to position a 23 ton block with closed loop control, to within 1 micrometer in X, Y, Z, and 1 microrad in 0x, 0y, 0z, without any backlash.