Patent ID: 8648318
Filing Date: 2014-02-11
Classification: H01J

Abstract:
1. Multiple beam charged particle optical system, comprising: a beam source for emitting a diverging charged particle beam; an aperture plate comprising a plurality of apertures and arranged for splitting said charged particle beam into a plurality of non-parallel charged particle beamlets, each beamlet having an optical axis; and a planar electrostatic lens structure comprising a corresponding plurality of lens holes for said plurality charged particle beamlets; said aperture plate and said electrostatic lens structure being aligned and arranged in a path of said plurality of non-parallel charged particle beamlets, wherein corresponding apertures of the aperture plate and the electrostatic lens structure are aligned with said optical axes of the corresponding beamlets, such that for each beamlet a virtual aperture of the electrostatic lens structure is symmetrical along an optical axis of a corresponding lens in said planar electrostatic lens structure.