 Magnetic beam separator is needed to resolve the illuminating and imaging beam (while in turn spatially separating the optics for each).There has been much development on the technology of electron beam separators; the early separators introduced distortion in either the image or diffraction plane.However, IBM recently developed a hybrid prism array/nested quadratic field design, focusing the electron beams both in and out of the plane of the beampath, allowing for deflection and transfer of the image and diffraction planes without distortion or energy dispersion.