Abstract: An imaging system for directing a flux of charged particles transmitted through a specimen onto a spectroscopic apparatus, wherein the flux is dispersed by a dispersing device into an energy-resolved array of spectral sub-beams propagating substantially parallel to a propagation axis. An adjustable aperture device defines an aperture in a path of the array so as to select a subset of the array to be admitted to a detector, which aperture is delimited in a dispersion direction perpendicular to the propagation axis to allow independent adjustment of both of: a width of the aperture parallel to the dispersion direction; and a position of a center of the aperture relative to the propagation axis.

Abstract: A method of performing spectroscopy in a Transmission Charged-Particle Microscope comprising: a specimen holder; a source, for producing a beam of charged particles; an illuminator, for directing said beam so as to irradiate the specimen; an imaging system, for directing a flux of charged particles transmitted through the specimen onto a spectroscopic apparatus comprising a dispersing device for dispersing said flux into an energy-resolved array of spectral sub-beams, the method comprising: using an adjustable aperture device to admit a first portion of said array to a detector, while blocking a second portion of said array; providing; using a radiation sensor in said flux upstream of said aperture device to perform localized radiation sensing in a selected region of said second portion of the array, simultaneous with detection of said first portion by said detector; using a sensing result from said sensor to adjust a detection result from said detector.

Abstract: A Transmission Charged-Particle Microscope includes an imaging system, for directing a flux of charged particles transmitted through the specimen onto a spectroscopic apparatus including: a dispersing device, for dispersing said flux into an energy-resolved array of spectral sub-beams propagating substantially parallel to a propagation axis; a detector; an adjustable aperture device for defining an aperture in a path of said array, so as to select a subset of said array to be admitted to the detector, which aperture is delimited in a dispersion direction perpendicular to said propagation axis by first and second opposed edges, each of which edges is independently positionable relative to said propagation axis, thereby allowing independent adjustment of both of: a width of said aperture parallel to said dispersion direction; and a position of a center of said aperture relative to said propagation axis.

Abstract: A method of performing spectroscopy in a Transmission Charged-Particle Microscope comprising: a specimen holder; a source, for producing a beam of charged particles; an illuminator, for directing said beam so as to irradiate the specimen; an imaging system, for directing a flux of charged particles transmitted through the specimen onto a spectroscopic apparatus comprising a dispersing device for dispersing said flux into an energy-resolved array of spectral sub-beams, the method comprising: using an adjustable aperture device to admit a first portion of said array to a detector, while blocking a second portion of said array; providing; using a radiation sensor in said flux upstream of said aperture device to perform localized radiation sensing in a selected region of said second portion of the array, simultaneous with detection of said first portion by said detector; using a sensing result from said sensor to adjust a detection result from said detector.