# US 7,609,311 B2 · Automatic calibration of electron multiplying CCDs > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,311 B2 - Document ID: US7609311B2 - Status: Granted - Kind: B2 - Application number: 11/335,889 - Filed: 2006-01-19 - Published: 2006-07-27 - Granted: 2009-10-27 - Earliest claimed: 2005-01-20 - Assignees: Andor Technology Limited - Inventors: Donal Denvir - Web page: https://patentgrep.com/patent/US7609311B2 ## CPC - H04N 17/002: {for television cameras} - G11C 19/285: {Peripheral circuits, e.g. for writing into the first stage; for reading-out of the last stage} - H04N 25/00: Circuitry of solid-state image sensors [SSIS]; Control thereof - H04N 25/713: Transfer or readout registers; Split readout registers or multiple readout registers - H04N 25/72: using frame transfer [FT] - H10F 39/153: {Two-dimensional or three-dimensional array CCD image sensors} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G11C: STATIC STORES (semiconductor memory devices H10B) - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION ## Abstract A method of determining the gain of an electron multiplier, especially in an Electron Multiplying Charge Coupled Device (EMCCD). The electron multiplier multiplies, in use, signals received from a device, typically a CCD, comprising photodetectors. A test signal is input to the electron multiplier from the device, and the gain of the electron multiplier is determined from the output of the electron multiplier. The test signal comprises, or is derived from, electrical charge generated by the photodetectors other than as a result of the incidence of an electromagnetic signal on the photodetectors. The test signal comprises, or is derived from, dark current, or clock induced charge. ## Claims ### Claim 1 A method of determining the gain of an electron multiplier, the electron multiplier being arranged to multiply, in use, signals received from a device comprising at least one photodetector, the method comprising causing a test signal to be input to the electron multiplier from the device; and determining the gain of the electron multiplier from the output of the electron multiplier, wherein said test signal comprises, or is derived from, electrical charge generated by said at least one photodetector other than as a result of the incidence of an electromagnetic signal on said at least one photodetector, and wherein said test signal comprises, or is derived from, dark charge or dark current. ### Claim 2 (depends on 1) A method as claimed in claim 1, further including adjusting the gain of the electron multiplier in response to the determined, or measured, gain. ### Claim 3 (depends on 1) A method as claimed in claim 1, wherein said device comprises at least one charge coupled device (CCD). ### Claim 4 (depends on 1) A method as claimed in claim 1, further including causing dark current to be promoted in said device. ### Claim 5 (depends on 4) A method as claimed in claim 4, further including unpinning at least one control signal for effecting charge transfer in said device. ### Claim 6 (depends on 4) A method as claimed in claim 4, further including operating at least one clock signal in a non-inverted mode such that charge transfer is effected in said device. ### Claim 7 A method of determining the gain of an electron multiplier, the electron multiplier being arranged to multiply, in use, signals received from a device comprising at least one photodetector, the method comprising causing a test signal to be input to the electron multiplier from the device; and determining the gain of the electron multiplier from the output of the electron multiplier, wherein said test signal comprises, or is derived from, electrical charge generated by said at least one photodetector other than as a result of the incidence of an electromagnetic signal on said at least one photodetector, and wherein said test signal comprises, or is derived from, clock induced charge, or spurious charge. ### Claim 8 (depends on 7) A method as claimed in claim 7, further including adjusting the gain of the electron multiplier in response to the determined, or measured, gain. ### Claim 9 (depends on 7) A method as claimed in claim 7, wherein said device comprises at least one charge coupled device (CCD). ### Claim 10 (depends on 7) A method as claimed in claim 7, further including causing clock induced charge to be promoted in said device. ### Claim 11 (depends on 10) A method as claimed in claim 10, further including configuring at least one control signal for effecting charge transfer in said device to promote clock induced charge. ### Claim 12 (depends on 10) A method as claimed in claim 10, wherein said at least one control signal is a periodic signal, the method further including setting said period set to promote clock induced charge during charge transfer. ### Claim 13 (depends on 10) A method as claimed in claim 10, wherein the amplitude of said at least one control signal is set to promote clock induced charge during charge transfer. ### Claim 14 (depends on 13) A method as claimed in claim 13, wherein said amplitude is at least 25% and preferably at least 50% above the amplitude required to effect charge transfer. ### Claim 15 A method of determining the gain of an electron multiplier, the electron multiplier being arranged to multiply, in use, signals received from a device comprising at least one photodetector, the method comprising causing a test signal to be input to the electron multiplier from the device; and determining the gain of the electron multiplier from the output of the electron multiplier, wherein said test signal comprises, or is derived from, electrical charge generated by said at least one photodetector other than as a result of the incidence of an electromagnetic signal on said at least one photodetector, the method further including causing the test signal to be input to the electron multiplier when the gain of the electron multiplier is enabled, and when the gain of the electron multiplier is disabled; and determining the gain by comparing the output of the electron multiplier in response to said test signal when the gain of the electron multiplier is enabled to the output of the electron multiplier in response to said test signal when the gain of the electron multiplier is disabled. ### Claim 16 (depends on 15) A method as claimed in claim 15, further including adjusting the gain of the electron multiplier in response to the determined, or measured, gain. ### Claim 17 (depends on 15) A method as claimed in claim 15, wherein said device comprises at least one charge coupled device (CCD). ### Claim 18 A method of determining the gain of an electron multiplier, the electron multiplier being arranged to multiply, in use, signals received from a device comprising at least one photodetector, the method comprising causing a test signal to be input to the electron multiplier from the device; and determining the gain of the electron multiplier from the output of the electron multiplier, wherein said test signal comprises, or is derived from, electrical charge generated by said at least one photodetector other than as a result of the incidence of an electromagnetic signal on said at least one photodetector, the method further including determining the gain of the electron multiplier by analysing the characteristics of the output of the electron multiplier in response to said test signal when the gain of the electron multiplier is enabled. ### Claim 19 (depends on 18) A method as claimed in claim 18, wherein said characteristics include events caused by the input of respective single electrons to said electron multiplier. ### Claim 20 (depends on 18) A method as claimed in claim 18, wherein the analysis involves comparing the characteristics of the detected or measured output against known output results or predicted output results. ### Claim 21 (depends on 18) A method as claimed in claim 18, further including adjusting the gain of the electron multiplier in response to the determined, or measured, gain. ### Claim 22 (depends on 18) A method as claimed in claim 18, wherein said device comprises at least one charge coupled device (CCD). ### Claim 23 An apparatus for detecting the gain of an electron multiplier, the apparatus comprising means for causing a test signal to be input to the electron multiplier from a device comprising at least one photodetector; and means for determining the gain of the electron multiplier from the output of the electron multiplier, wherein said test signal comprises, or is derived from, electrical charge generated by said at least one photodetector other than as a result of the incidence of an electromagnetic signal on said at least one photodetector, and wherein said test signal comprises, or is derived from, dark charge or dark current. ### Claim 24 An apparatus for detecting the gain of an electron multiplier, the apparatus comprising means for causing a test signal to be input to the electron multiplier from a device comprising at least one photodetector; and means for determining the gain of the electron multiplier from the output of the electron multiplier, wherein said test signal comprises, or is derived from, electrical charge generated by said at least one photodetector other than as a result of the incidence of an electromagnetic signal on said at least one photodetector, and wherein said test signal comprises, or is derived from, clock induced charge, or spurious charge.