# US 10,312,068 B2 · Charged particle detector > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,312,068 B2 - Document ID: US10312068B2 - Status: Granted - Kind: B2 - Application number: 15/740,164 - Filed: 2016-06-30 - Published: 2018-06-21 - Granted: 2019-06-04 - Earliest claimed: 2015-07-02 - Assignees: Hamamatsu Photonics K.K. - Applicants: Hamamatsu Photonics K.K. - Inventors: Motohiro Suyama; Hiroshi Kobayashi; Shinya Hattori - Web page: https://patentgrep.com/patent/US10312068B2 ## CPC - H01J 49/025: {Detectors specially adapted to particle spectrometers (data acquisition H01J49/0036; detectors per se G01T, e.g. G01T1/28, G01T1/29)} - G01T 1/241: {Electrode arrangements, e.g. continuous or parallel strips or the like} - G01T 1/28: with secondary-emission detectors - H01J 43/24: Dynodes having potential gradient along their surfaces - H01J 49/067: {Ion lenses, apertures, skimmers} - H01J 49/06: Electron- or ion-optical arrangements - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00) ## Abstract A charged particle detector according to the embodiment is provided with an MCP and a PD arranged with a focus electrode interposed therebetween in order to improve a response characteristic as compared to a conventional one in a configuration in which the MCP having a bias angle and the PD are combined. The MCP includes a plurality of through holes each inclined by a bias angle θ and the PD is eccentrically arranged such that a center of an electron incident surface deviates by a predetermined distance in a bias angle direction S3 with respect to a central axis AX1 of the MCP. ## Claims ### Claim 1 A charged particle detector comprising: a microchannel plate having: an input surface on which charged particles are incident; an output surface from which secondary electrons are emitted; and a plurality of through holes each communicating the input surface with the output surface and having a secondary electron emission surface on an inner wall thereof, the plurality of through holes arranged such that a central axis of each is inclined at least by a bias angle defined by an acute angle with respect to the output surface; an electron impact diode arranged so as to face the microchannel plate and having an electron incident surface whose area is smaller than an area of an effective region of the microchannel plate; and a focus electrode provided between the microchannel plate and the electron impact diode, the focus electrode having a shape to continuously surround trajectories of the secondary electrons directed from the microchannel plate to the electron impact diode, wherein, where a bias angle direction is, on a reference plane coincident with the electron incident surface, defined as a direction from an intersection between a reference axis and the reference plane to an intersection between a central axis of a reference through hole and the reference plane, the reference axis passing through a center of an opening coincident with the output surface out of openings of the reference through hole and orthogonal to the output surface, the reference through hole selected from the plurality of through holes, the electron impact diode is eccentrically arranged such that, with respect to an intersection between a central axis of the microchannel plate and the reference plane, a center of the electron incident surface deviates by a predetermined distance in the bias angle direction, the central axis of the microchannel plate being an axis passing through a center of the effective region and orthogonal to the output surface. ### Claim 2 (depends on 1) The charged particle detector according to claim 1, wherein the focus electrode is set to have the same potential as the output surface of the microchannel plate. ### Claim 3 (depends on 1) The charged particle detector according to claim 1, wherein the focus electrode is set to have the same potential as the electron incident surface of the electron impact diode. ### Claim 4 (depends on 1) The charged particle detector according to claim 1, further comprising: a mesh electrode provided between the microchannel plate and the focus electrode. ### Claim 5 (depends on 1) The charged particle detector according to claim 1, wherein a maximum width of the electron incident surface in the electron impact diode is 3 mm or shorter. ### Claim 6 (depends on 1) The charged particle detector according to claim 1, wherein a spot diameter of the secondary electrons reaching the electron incident surface of the electron impact diode from the output surface of the microchannel plate is 1 mm or shorter. ### Claim 7 (depends on 1) The charged particle detector according to claim 1, wherein the focus electrode is constituted by: a body portion continuously surrounding the trajectories of the secondary electrons directed from the microchannel plate to the electron impact diode; and a flange member for defining a center position and a size of the second opening. ### Claim 8 (depends on 7) The charged particle detector according to claim 7, wherein the body portion is constituted by a plurality of hollow members sequentially arranged from the microchannel plate to the electron impact diode. ### Claim 9 (depends on 1) The charged particle detector according to claim 1, further comprising: a board on a main surface of which the electron impact diode is mounted; and a resin flange having an opening for allowing the secondary electrons directed from the microchannel plate to the electron impact diode to pass therethrough, the resin flange arranged between the focus electrode and the board. ### Claim 10 A charged particle detector comprising: a microchannel plate having: an input surface on which charged particles are incident; an output surface from which secondary electrons are emitted; and a plurality of through holes each communicating the input surface with the output surface and having a secondary electron emission surface on an inner wall thereof, the plurality of through holes arranged such that a central axis of each is inclined at least by a bias angle defined by an acute angle with respect to the output surface; an electron impact diode arranged so as to face the microchannel plate and having an electron incident surface whose area is smaller than an area of an effective region of the microchannel plate; and a focus electrode provided between the microchannel plate and the electron impact diode, the focus electrode having: a first opening located on a side of the microchannel plate; a second opening located on a side of the electron impact diode; and a shape to continuously surround trajectories of the secondary electrons directed from the microchannel plate to the electron impact diode, wherein, where a bias angle direction is, on a reference plane coincident with the electron incident surface, defined as a direction from an intersection between a reference axis and the reference plane to an intersection between a central axis of a reference through hole and the reference plane, the reference axis passing through a center of an opening coincident with the output surface out of openings of the reference through hole and orthogonal to the output surface, the reference through hole selected from the plurality of through holes, at least a part of the focus electrode is eccentrically arranged such that, with respect to an intersection between a central axis of the microchannel plate and the reference plane, a center of the second opening deviates by a predetermined distance in the bias angle direction, the central axis of the microchannel plate being an axis passing through a center of the effective region and orthogonal to the output surface. ### Claim 11 (depends on 10) The charged particle detector according to claim 10, wherein the focus electrode is set to have the same potential as the output surface of the microchannel plate. ### Claim 12 (depends on 10) The charged particle detector according to claim 10, wherein the focus electrode is set to have the same potential as the electron incident surface of the electron impact diode. ### Claim 13 (depends on 10) The charged particle detector according to claim 10, further comprising: a mesh electrode provided between the microchannel plate and the focus electrode. ### Claim 14 (depends on 10) The charged particle detector according to claim 10, wherein a maximum width of the electron incident surface in the electron impact diode is 3 mm or shorter. ### Claim 15 (depends on 10) The charged particle detector according to claim 10, wherein a spot diameter of the secondary electrons reaching the electron incident surface of the electron impact diode from the output surface of the microchannel plate is 1 mm or shorter. ### Claim 16 (depends on 10) The charged particle detector according to claim 10, wherein the focus electrode is constituted by: a body portion continuously surrounding the trajectories of the secondary electrons directed from the microchannel plate to the electron impact diode; and a flange member for defining a center position and a size of the second opening. ### Claim 17 (depends on 16) The charged particle detector according to claim 16, wherein the body portion is constituted by a plurality of hollow members sequentially arranged from the microchannel plate to the electron impact diode. ### Claim 18 (depends on 10) The charged particle detector according to claim 10, further comprising: a board on a main surface of which the electron impact diode is mounted; and a resin flange having an opening for allowing the secondary electrons directed from the microchannel plate to the electron impact diode to pass therethrough, the resin flange arranged between the focus electrode and the board.