# US 2019/0378680 A1 · Transmission charged particle microscope with adjustable beam energy spread > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0378680 A1 - Document ID: US20190378680A1 - Status: Published application - Kind: A1 - Application number: 16/197,448 - Filed: 2018-11-21 - Published: 2019-12-12 - Earliest claimed: 2017-11-27 - Assignees: FEI Company - Applicants: FEI Company - Inventors: Peter Christiaan Tiemeijer - Web page: https://patentgrep.com/patent/US20190378680A1 ## CPC - H01J 37/244: Detectors; Associated components or circuits therefor - H01J 37/28: with scanning beams {(H01J37/268, H01J37/292, H01J37/2955 take precedence)} - H01J 37/05: Electron or ion-optical arrangements for separating electrons or ions according to their energy {or mass}(particle separator tubes H01J49/00) - H01J 37/10: Lenses - H01J 37/20: Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support - H01J 37/22: Optical {, image processing} or photographic arrangements associated with the tube - H01J 37/26: Electron or ion microscopes; Electron or ion diffraction tubes - H01J 2237/1534: Aberrations - H01J 2237/2003: Environmental cells - H01J 2237/24485: Energy spectrometers - H01J 2237/2802: Transmission microscopes - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A method of using a Transmission Charged Particle Microscope comprising: A specimen holder, for holding a specimen; A source, for producing a beam of charged particles; An illuminator, for directing said beam along an optical axis so as to irradiate the specimen, the illuminator comprising: a monochromator, which is configured to produce an output beam with a given energy spread ΔE0; and a condenser lens assembly; An imaging system, for receiving a flux of charged particles transmitted through the specimen and directing it onto a sensing device; A controller, for controlling at least some operational aspects of the microscope, comprising the following steps: In a first use session, selecting at least one of: (a) an excitation of a first lens of said condenser lens assembly; (b) a width of a condenser aperture downstream of said first lens, so as to produce a first width W1—and associated first energy spread ΔE1—of an emerging beam exiting said aperture; In a second use session, selecting at least one of said parameters (a) and (b) so as to produce a second, different width W2—and associated second, different energy spread ΔE2—of said emerging beam. ## Claims ### Claim 1 A method of using a Transmission Charged Particle Microscope comprising: a source, for producing a beam of charged particles; an illuminator, for directing said beam along an optical axis so as to irradiate a specimen, the illuminator comprising: a monochromator having a monochromator slit and which is configured to produce an output beam with a given energy spread ΔE0; and a condenser lens assembly downstream of said monochromator; an imaging system, for receiving a flux of charged particles transmitted through the specimen and directing it onto a sensing device; a controller, for controlling at least some operational aspects of the microscope, wherein the controller is configure to perform a method including: in a first use session, selecting at least one of: (a) an excitation of a first lens of said condenser lens assembly; (b) a width of a condenser aperture downstream of said first lens, so as to produce a first width W1 and associated first energy spread ΔE1 of an emerging beam exiting said aperture; in a second use session, selecting at least one of said parameters (a) and (b) so as to produce a second, different width W2 and associated second, different energy spread ΔE2 of said emerging beam. ### Claim 2 (depends on 1) A method according to claim 1, wherein adjustment of at least one of parameters (a) and (b) causes a virtual image of said condenser aperture, formed at a location of said monochromator, to vary in width. ### Claim 3 (depends on 1) A method according to claim 1, wherein a second lens of said condenser lens assembly is disposed between said first lens and said condenser aperture. ### Claim 4 (depends on 1) A method according to claim 1, wherein at least one of ΔE1 and ΔE2 is less than 0.05 eV, preferably less than 0.03 eV. ### Claim 5 (depends on 4) A method according to claim 4, wherein ΔE0≥0.1 eV. ### Claim 6 (depends on 1) A method according to claim 1, wherein said sensing device is comprised in an Electron Energy Loss Spectroscopy (EELS) module. ### Claim 7 A Transmission Charged Particle Microscope, comprising: a source, for producing a beam of charged particles; an illuminator, for directing said beam along an optical axis so as to irradiate a specimen, the illuminator comprising a monochromator having a monochromator slit that is configured to produce an output beam with a given energy spread ΔE0 and a condenser lens assembly downstream of said monochromator; an imaging system, for receiving a flux of charged particles transmitted through the specimen and directing it onto a sensing device; a controller, for controlling at least some operational aspects of the microscope, wherein said controller is configured to: in a first use session, select at least one of: (a) an excitation of a first lens of said condenser lens assembly; (b) a width of a condenser aperture downstream of said first lens, so as to produce a first width W1 and associated first energy spread ΔE1 of an emerging beam exiting said aperture; and in a second use session, select at least one of said parameters (a) and (b) so as to produce a second, different width W2 and associated second, different energy spread ΔE2 of said emerging beam. ### Claim 8 (depends on 7) The Transmission Charged Particle Microscope of claim 7, wherein adjustment of at least one of parameters (a) and (b) causes a virtual image of said condenser aperture, formed at a location of said monochromator, to vary in width. ### Claim 9 (depends on 7) The Transmission Charged Particle Microscope of claim 7, wherein a second lens of said condenser lens assembly is disposed between said first lens and said condenser aperture. ### Claim 10 (depends on 7) The Transmission Charged Particle Microscope of claim 7, wherein at least one of ΔE1 and ΔE2 is less than 0.05 eV, preferably less than 0.03 eV. ### Claim 11 (depends on 10) The Transmission Charged Particle Microscope of claim 10, wherein ΔE0 0.1 eV. ### Claim 12 (depends on 7) The Transmission Charged Particle Microscope of claim 7, wherein said sensing device is comprised in an Electron Energy Loss Spectroscopy (EELS) module. ### Claim 13 A method of operating a transmission charged particle microscope (TCPM), the method comprising: in a first operating mode, configuring a condenser assembly of the TCPM to provide a charged particle beam having first energy spread and a first beam width; and in a second operating mode, configuring the condenser assembly to provide the charged particle beam having a second energy spread and a second beam width, the second energy spread less than the first energy spread and the second beam width smaller than the first beam width. ### Claim 14 (depends on 13) The method of claim 13, wherein the first beam energy and the first beam width are determined in response to either a first excitation of a first condenser lens of the condenser assembly and/or a first width of a condenser aperture of the condenser assembly. ### Claim 15 (depends on 14) The method of claim 14, wherein the condenser lens is disposed between an exit aperture of a monochromator slit and the condenser aperture. ### Claim 16 (depends on 14) The method of claim 14, wherein the first excitation causes the condenser lens to mildly expand the charged particle beam, and wherein the first width of the condenser aperture allows most or all of the charged particle beam to pass. ### Claim 17 (depends on 13) The method of claim 13, wherein the second beam energy and the second beam width are determined in response to either a second excitation of a first condenser lens of the condenser assembly and/or a second width of a condenser aperture of the condenser assembly. ### Claim 18 (depends on 17) The method of claim 17, wherein the second excitation causes the condenser lens to strongly expand the charged particle beam, and wherein the second width of the condenser aperture allows a small, central portion of the charged particle beam to pass.