A method of determining a local electric field and/or a local magnetic field in a sample and/or the dielectric constant of a material and/or the angle between the input and output surfaces of the sample, comprising illumination of the sample by an electron beam in precession mode using an illumination device, generation of a diffraction pattern, determination of the offset of the disk corresponding to the transmitted beam due to the electric field and/or the magnetic field, by comparison of the diffraction pattern and a reference diffraction pattern, determination of a deflection angle of the transmitted beam, and determination of the value of the local electric field and/or the local magnetic field of the sample and/or determination of the dielectric constant of materials and/or determination of the angle between the input and output surfaces of the sample.