Charged particle-optical component

摘要

A method of focusing a plurality of charged particle beamlets, the method comprises:
transmitting at least one of a charged particle beam and a plurality of charged-particle beamlets through a first multi-aperture plate and a second multi-aperture plate, each having a plurality of apertures, with centres of the first and second multi-aperture plates being spaced a distance w 0 apart,
applying a first electric potential U 1 to the first multi-aperture plate,
applying a second electric potential U 2 to the second multi-aperture plate, the second electric potential being different from the first electric potential;
at least one of generating an electrical field traversed by the beam path upstream of the first multi-aperture plate and an electrical field traversed by the beam path downstream of the second multi-aperture plate, such that a first field strength E 1 of an electrical field upstream and in the vicinity of the first multi-aperture plate differs from a second field strength E 2 of an electrical field downstream and in the vicinity of the second multi-aperture plate by at least about 200 V/mm,
wherein for charged particles having a charge q and having and a kinetic energy E kin upon traversing the first multi-aperture plate, the following relationship is fulfilled: 0.0001 ‰¤ 3 4 ‹ q w 0 ‹ E k �¢ i �¢ n �¢ U 1 - U 2 2 E 1 - E 2 ‰¤ 0.2.