Device cylindrical permanent magnet induced magnetic field of predetermined orientation and method of manufacture

The inducing device in a central area of ​​interest a homogeneous magnetic field of predetermined orientation, comprises two annular magnetic structures (111, 121) symmetrically disposed with respect to a plane (P) which contains the central area of ​​interest, and a third annular magnetized structure (112, 122) interposed between the other two structures (111, 121) and also arranged symmetrically relative to the plane (P) of symmetry. The various structures (111, 121, 112, 122) are divided into components in the form of sectors. The third structure (112, 122) is divided into at least two parts (112A, 112B, 122A, 122B) and all the elements of the various structures (111, 121, 112, 122) are magnetized in the same direction.