Capacitive position sensor with simultaneous, linear X-Y readout

A design is presented for a compact capacitive position sensor suitable for operation at cryogenic temperatures and high magnetic fields. The four qua drants of a base electrode are excited with phases differing by 90 degrees; from its in- and out-of-phase components, the current injected into the mo vable electrode yields simultaneous information about the x and y sensor po sitions. This current is also linear in the position of the sensor. The eff ects of possible sensor imperfections are analyzed in detail. (C) 2000 Amer ican Institute of Physics. [S0034-6748(00)05506-4].