US Patent 11804355 Apparatus for multiple charged-particle beams

Systems and methods of observing a sample in a multi-beam apparatus are disclosed. The multi-beam apparatus may include an electron source configured to generate a primary electron beam, a pre-current limiting aperture array comprising a plurality of apertures and configured to form a plurality of beamlets from the primary electron beam, each of the plurality of beamlets having an associated beam current, a condenser lens configured to collimate each of the plurality of beamlets, a beam-limiting unit configured to modify the associated beam current of each of the plurality of beamlets, and a sector magnet unit configured to direct each of the plurality of beamlets to form a crossover within or at least near an objective lens that is configured to focus each of the plurality of beamlets onto a surface of the sample and to form a plurality of probe spots thereon.