Apparatus for passive control of magnet homogeneity
AssigneeFonar Corporation
InventorThomas Datsikas
Life of this patent
Estimating the term…
Abstract
A method and apparatus for passively shimming a magnet. A magnetic field produced by the magnet is measured and modeled in the form of a Legendre polynomial expansion having a predetermined number of harmonic terms. The degree of non-homogeneity in the measured field is determined by examining the harmonic terms. A shim is then designed to correspond to a magnitude change of a harmonic term of the polynomial expansion in order to improve the homogeneity of the magnetic field. A metal plate is connected to or placed near a pole of the magnet, the shim is placed against the metal plate, and a plastic plate is attached to the metal plate such that the shim is held in place in a predetermined location against the metal plate.
Claims10
An apparatus for changing homogeneity of a magnetic field, comprising:
- a magnet that produces the magnetic field;
- a first plate disposed over a pole face of the magnet, wherein the first plate has a first, substantially flat face;
- a shim disposed near enough to the first plate so as to have an effect on the magnetic field;
- and
- a second plate, attached to the first plate such that the shim is held in place in a predetermined location between the first plate and the second plate, wherein the second plate includes means for holding the shim in the predetermined location.
Dependencies are inferred from the claim text.