A scanning transmission electron microscope that scans a specimen with an electron probe to acquire an image. The scanning transmission electron microscope includes: an optical system which includes a condenser lens and an objective lens; an imaging device which is arranged on a back focal plane or a plane conjugate to the back focal plane of the objective lens and which is capable of photographing a Ronchigram; and a control unit which performs adjustment of the optical system. The control unit is configured or programed to: acquire an image of a change in a Ronchigram that is attributable to a change in a relative positional relationship between the specimen and the electron probe; and determine a center of the Ronchigram based on the image of the change in the Ronchigram.

A particle beam system includes a multiple beam particle source to generate a multiplicity of charged individual particle beams, and a multi-pole lens sequence with first and second multi-pole lens arrays. The particle beam system also includes a controller to control the multi-pole lenses of the multi-pole lens sequence so related groups of multi-pole lenses of the multi-pole lens sequence through which the same individual particle beam passes in each case altogether exert an individually adjustable and focussing effect on the respective individual particle beam passing therethrough.

A charged particle optical system includes an aberration corrector 209 that corrects aberration of a charged particle beam and has multipoles of a plurality of stages. The aberration corrector generates a plurality of multipole fields in a superimposed manner for each of the multipoles of the plurality of stages in order to correct the aberration of the charged particle beam. In order to reduce the influence of a parasitic field due to distortion of the multipole, for a first multipole field to be generated in a multipole of any stage among the plurality of stages, a value of a predetermined correction voltage or correction current to be applied to a plurality of poles for generating the first multipole field is corrected so as to eliminate movement of an observation image obtained based on electrons detected from a detector 215 by irradiating a sample with the charged particle beam before and after the first multipole field is generated.

An improved source conversion unit of a charged particle beam apparatus is disclosed. The source conversion unit comprises a first micro-structure array including a plurality of micro-structures. The plurality of micro-structures is grouped into one or more groups. Corresponding electrodes of micro-structures in one group are electrically connected and driven by a driver to influence a corresponding group of beamlets. The micro-structures in one group may be single-pole structures or multi-pole structures. The micro-structures in one group have same or substantially same radial shifts from an optical axis of the apparatus. The micro-structures in one group have same or substantially same orientation angles with respect to their radial shift directions.

A charged-particle assessment tool comprising a plurality of beam columns. Each beam column comprises: a charged-particle beam source configured to emit charged particles; a plurality of condenser lenses configured to form charged particles emitted from the charged-particle beam source into a plurality of charged-particle beams; and a plurality of objective lenses, each configured to project one of the plurality of charged-particle beams onto a sample. The beam columns are arranged adjacent one-another so as to project the charged particle beams onto adjacent regions of the sample.

A multi-beam apparatus for observing a sample with high resolution and high throughput is proposed. In the apparatus, a source-conversion unit forms plural and parallel images of one single electron source by deflecting plural beamlets of a parallel primary-electron beam therefrom, and one objective lens focuses the plural deflected beamlets onto a sample surface and forms plural probe spots thereon. A movable condenser lens is used to collimate the primary-electron beam and vary the currents of the plural probe spots, a pre-beamlet-forming means weakens the Coulomb effect of the primary-electron beam, and the source-conversion unit minimizes the sizes of the plural probe spots by minimizing and compensating the off-axis aberrations of the objective lens and condenser lens.

The invention relates to a method for electron microscopy. The method comprises providing an electron microscope, generating an electron beam and an image beam, adjusting one of the beam and of the beam and the image beam to reduce off-axial aberrations and correcting a diffraction pattern of the resulting modified beam. The invention also relates to a method for reducing throughput time in a sample image acquisition session in transmission electron microscopy. The method comprises providing an electron microscope, generating a beam and an image beam, adjusting one of the two to reduce off-axial aberrations and filtering the resulting modified image beam. The invention further relates to an electron microscope and to a non-transient computer-readable medium with a computer program for carrying out the methods.

Provided is an aberration corrector having a plurality of magnetic poles including a first magnetic pole and further magnetic poles, a ring that magnetically connects the plurality of magnetic poles with one another, the ring having a constant spacing to at least the first magnetic pole, a plurality of magnetic field modulators including a first magnetic field modulator and further magnetic field modulators, and a plurality of guides including a first guide and further guides; wherein the first magnetic field modulator includes a soft magnetic material, wherein the first magnetic field modulator is disposed in a first position, the first position being one of the following: adjacent to a first air gap separating the first magnetic pole and the ring, or at an inner ring surface or radially outward of the inner ring surface along an axis of the first magnetic pole, and wherein the first guide constrains the first magnetic field modulator to positions along a first axis substantially parallel to or coincident with the axis of the first magnetic pole.

The invention provides a charged particle beam device capable of reducing a positional shift between secondary beams generated in a beam separator. The charged particle beam device includes a charged particle beam source configured to irradiate a sample with a plurality of primary beams, a plurality of detectors configured to detect secondary beams emitted from the sample in correspondence to the primary beams, and a beam separator configured to deflect the secondary beams in a direction different from that of the primary beams. The charged particle beam device further includes a deflector provided between the beam separator and the detector to correct a positional shift between the secondary beams generated in the beam separator.

An electron optical module for providing an off-axial electron beam with a tunable coma, according to the present disclosure includes a structure positioned downstream of an electron source and an electron lens assembly positioned between the structure and the electron source. The structure generates a decelerating electric field, and is positioned to prevent the passage of electrons along the optical axis of the electron lens assembly. The electron optical module further includes a micro-lens that is not positioned on the optical axis of the electron lens assembly and is configured to apply a lensing effect to an off-axial election beam. Aberrations applied to the off-axial electron beam by the micro-lens and the electron lens assembly combine so that a coma of the off-axial beam has a desired value in a downstream plane.