Abstract: A magnetic resonance imager has a magnetically permeable core and two pole pieces, each pole piece having a face. The pole pieces are arranged on the core such that the pole piece faces are in opposed relationship forming a first gap therebetween. At least one of the pole pieces is comprised of an outer element 23 connected to the core and an inner element 24 connected between the outer element and the first gap. The outer element 23 forms a cup inside which the inner element 24 is disposed. A plurality of screws 11, 12 and 13 are disposed through the outer element 23 and engage the inner element 24 such that a second gap is formed between the inner and outer element. The homogeneity of the magnetic field in the first gap is affected by adjusting the position of the inner element relative to the outer element via screws 11, 12 and 13.

Abstract: Two opposite iron core pole pieces of a magnetic resonance medical imager generate a static magnetic field in a patient imaging volume disposed between the pole pieces. Gradient coils are positioned in the face of a pole piece. Thin disc shaped (42, 44) or ring shaped (41) ferromagnetic parts laminated of layers cut favorably from transformer sheet material are attached to the face of the pole piece. Each layer is electrically insulated from adjacent layers and surfaces by enamel or fixing glue. To reduce eddy currents in these layers, narrow, radially oriented slots (43, 45) are cut in these layers before lamination. The slots are oriented in the adjacent layers so as not to coincide resulting in improved conduction of the magnetic flux in the imaging volume during the production of gradient magnetic fields by the gradient coils.