Method for measuring three-dimensional spatial magnetic field distribution using algebraic reconstruction and convergence

A method for measuring three-dimensional spatial magnetic field distribution comprising the steps of:

• (a) selecting a reference axis in a measurement space in which the magnetic field distribution is to be measured and wherein several planes to be measured are set in said measurement space which are perpendicular to said reference axis;
• (b) successively scanning an electron beam in each of said planes to be measured with predetermined various incident angles and successively measuring the magnitude of deviation of the electron beam due to the action of the magnetic field distributed in each of said planes to be measured;
• (c) algebraically reconstructing the magnetic field distributed in each of said planes to be measured on the basis of the corresponding measured magnitude of deviation;
• (d) calculating the trajectory of said electron bean to obtain a calculated magnitude of deviation corresponding to each of said successive measured magnitudes of deviation;
• (e) calculating the difference in the calculated magnitude of deviation of said electron beam and the corresponding measured magnitude of deviation of said electron beam;
• and
• (f) correcting the reconstructed magnetic field on the basis of said difference, until said difference is decreased below a value previously set.