A cylindrical permanent magnet device that induces in a central area of interest a homogeneous magnetic field of predetermined orientation relative to a longitudinal axis (z) of the device comprises first and second annular magnetized structures (111, 121) disposed symmetrically relative to a plane (P) that is perpendicular to the longitudinal axis (z) and contains the central area of interest, and a third annular magnetized structure (112, 122) disposed between the first and second structures (111, 121) and also disposed symmetrically relative to the plane (P) of symmetry. The first, second, and third annular magnetized structures (111, 121, 112, 122) are divided into components in the form of sectors. The third annular magnetized structure (112, 122) is divided into at least two slices (112A, 112B, 122A, 122B) along the longitudinal axis (z) and in that all the components of the first, second and third annular magnetized structures (111, 121, 112, 122) are magnetized in the same direction to create in the central area of interest a homogeneous induced magnetic field at a predetermined angle to the longitudinal axis (z). The parts of the device may be assembled before the assembly is magnetized.