Patent ID: 7474976

Claim:
A device for compensating field disruptions in magnetic fields of electromagnets with high field homogeneity for stabilizing an H0 field of an MR measuring system, the device comprising: at least one field detector for detecting interfering signals; at least one control loop for processing detected interfering signals; at least one compensation coil to which detected and processed interfering output signals are transferred to generate a correction field for compensating said interfering signals; and a selective filter system disposed in at least one of said control loops, said selective filter system comprising one or more selective filter elements which are connected in parallel, each selective filter element having a center frequency tuned to a frequency value of a respective interfering signal to be compensated for by that selective filter element, thereby strongly suppressing frequencies other than those of said interfering signals, wherein outputs of said filter elements are connected to at least one of said compensation coils, at least one of said field detectors being part of an NMR-lock, said lock having an additional regulation branch comprising said selective filter system, wherein tuning of said center frequencies of said filter system is effected once or in an adaptive manner.