Patent ID: 7374826

Claim:
A planar magnetic field gradient source structure comprising: a plurality of magnetic laminae having a longitudinal length, L, are layered in a magnetic stack, said longitudinal length, L, being greater than a stack thickness, t; said magnetic stack having a top outer lamina surface, a bottom outer lamina surface and a stack center; each of said plurality of magnetic laminae being thinner than a radius of said plurality of magnetic laminae and having a magnetic charge distribution, a perpendicular magnetic orientation and a variable magnetic strength, M(r); said magnetic stack being configured to cancel unpaired negative surface charges generated by said top outer lamina surface and said bottom outer lamina surface; said variable magnetic strength, M(r), varies linearly with a normal distance, r, from said stack center; said perpendicular magnetic orientation and said variable magnetic strength, M(r), generating a uniform volume magnetic charge density, ρ, for said magnetic stack, a magnetic field, M, perpendicular to said magnetic stack, a maximum stack magnetization, M(t), and a magnetic gradient with a linear dependence of magnetic field; said uniform volume magnetic charge density, ρ, varies abruptly from a one of said plurality of magnetic laminae to another one of said plurality of magnetic laminae; and said top lamina surface and said bottom lamina surface acting in opposition to each other with an equal strength that mutually cancels said unpaired negative charges.