Microchannel plate gain uniformity testing device and method

Abstract

The invention discloses a micro-channel plate gain uniformity testing device and method. The device comprises an incident light source, a pinhole template located on a light path of the incident light source, a photoelectric cathode, a to-be-tested micro-channel plate assembly, a collection anode, and a processing electronics and data processing system electrically connected with the collection anode. The incident light source is monochromatic parallel light, and the hole central axis of the pinhole template is perpendicular to the plane of the photoelectric cathode and is perpendicular to the input surface of the micro-channel plate assembly to be measured; the electric displacement platform is used for adjusting the positions of the photoelectric cathode, the to-be-measured micro-channel plate assembly and the collection anode; and the processing electronics and data processing system is positioned outside the vacuum cavity. According to the scheme, the gains and differences of different areas of the micro-channel plate assembly, especially the gain characteristics and differences in a saturated working mode, can be accurately obtained, and the gain uniformity of the to-be-measured micro-channel plate assembly in the whole effective area can be accurately calculated.

Description

Technical Field

[0001] This invention relates to the field of precision optical system testing technology, and in particular to a microchannel plate gain uniformity testing device and method. Background Technology

[0002] Photon counting imaging detectors based on microchannel plates and position-sensitive anodes have advantages such as high signal-to-noise ratio, good drift resistance, radiation resistance and time stability. They also have excellent temporal and spatial resolution and ultra-high detection sensitivity, making them valuable for applications in space astronomy, biomedicine and quantum information.

[0003] In this type of detector, the position-sensitive anodes used for decoding the incident photon position include charge-splitting and time-transfer types. Charge-splitting anodes include wedge-shaped anodes, vernier anodes, and cross-strip anodes. These anodes require high gain in the electron multiplication section to collect as much charge as possible for high decoding accuracy. In the detector, the multiplication amplification process is handled by a microchannel plate. To obtain uniform and consistent detector image information, the detector microchannel plate assembly not only requires high gain but also high gain uniformity. If the microchannel plate gain is uneven, it will lead to inconsistent decoding accuracy across the effective area of ​​the detector, thus affecting the spatial resolution performance within the entire effective area of ​​the detector.

[0004] Therefore, it is necessary to test the gain uniformity performance of the detector's microchannel plate in advance to solve the problem of poor detector imaging performance caused by uneven gain of the microchannel plate. Summary of the Invention

[0005] The present invention aims to at least solve the technical problems existing in the prior art. To this end, the first aspect of the present invention proposes a microchannel plate gain uniformity testing device, the device comprising: an incident light source, a pinhole template located in the optical path of the incident light source, a photocathode, a microchannel plate assembly to be tested and a collecting anode, and a processing electronics and data processing system electrically connected to the collecting anode;

[0006] The incident light source is monochromatic parallel light, and the central axis of the pinhole template is perpendicular to the plane of the photocathode and to the input surface of the microchannel plate assembly under test.

[0007] The photocathode, the microchannel plate assembly under test, and the collecting anode are connected to a high-voltage power supply and are fixed sequentially on an electric displacement platform. The electric displacement platform is used to adjust the position of the photocathode, the microchannel plate assembly under test, and the collecting anode.

[0008] The pinhole template, the photocathode, the microchannel plate assembly to be tested, the collecting anode, and the electric displacement platform are assembled in a vacuum chamber; the processing electronics and the data processing system are located outside the vacuum chamber.

[0009] Optionally, the incident light source is ultraviolet light, which is the ultraviolet band portion of the light wave emitted by a deuterium lamp or xenon lamp, and the wavelength range of the ultraviolet band is 100–300 nm.

[0010] Optionally, the photocathode is fabricated on a light-transmitting substrate material, the substrate material corresponding to the wavelength range of the ultraviolet band.

[0011] Optionally, the pinhole template is a light-transmitting hole etched on a metal thin film material, and the diameter of the light-transmitting hole ranges from 0.1 mm to 0.2 mm.

[0012] Optionally, the number of microchannel plates in the microchannel plate assembly under test can be one, two, or three; when the number is two, the two microchannel plates are assembled in a "V" cascade; when the number is three, the three microchannel plates are assembled in a "Z" cascade.

[0013] Optionally, the processing electronics includes a charge-sensitive preamplifier, a shaping amplifier, a pole-zero cancellation circuit, and a data acquisition section. The processing electronics are used to filter, amplify, shape, and acquire the amplitude of the current pulses output from the anode.

[0014] Optionally, the distance between the photocathode and the microchannel plate assembly under test is 0.5-2 mm, and the distance between the microchannel plate assembly under test and the collecting anode is 1-10 mm.

[0015] Optionally, the collecting anode is located at the output end of the microchannel plate assembly under test, and the collecting anode and the processing electronics are connected through a vacuum system trans-chamber connector; an SMA connector is soldered onto the collecting anode, and the SMA connector is used to lead out the signal output by the collecting anode.

[0016] A second aspect of the present invention provides a method for testing the gain uniformity of a microchannel plate, the method being applied to the apparatus described in the first aspect, the method comprising:

[0017] The vacuum chamber is evacuated to a level greater than or equal to a preset vacuum level.

[0018] Turn on the incident light source, and after the incident light source stabilizes, turn on the high voltage power supply of the photocathode, the microchannel plate assembly under test, and the collecting anode;

[0019] Open the input window aperture of the incident light source so that the incident light emitted by the incident light source passes through the pinhole template and is perpendicularly incident on the surface of the photocathode.

[0020] The photocathode converts the incident light into photoelectrons, the microchannel plate assembly under test amplifies the photoelectrons and outputs an electron cloud, and the collecting anode converts the collected electron cloud into a current pulse.

[0021] The position of the photocathode is adjusted by moving the electric displacement platform so that the entire surface of the photocathode is irradiated and covered by the incident light, and the microchannel plate assembly under test covers the entire effective area of ​​the photocathode; the collecting anode converts the electron cloud output from each position of the microchannel plate assembly under test into current pulses.

[0022] The processing electronics acquire the current pulse, convert the current pulse into processable pulse data, and upload the pulse data to the computer;

[0023] The computer analyzes and processes the pulse data to obtain the gain distribution uniformity of the microchannel plate assembly under test.

[0024] Optionally, the computer analyzes and processes the pulse data, including:

[0025] The amplitude information of all current pulses in the pulse data is statistically analyzed, and the number of pulses corresponding to each amplitude information is counted.

[0026] Using the amplitude information as the horizontal axis and the number of pulses corresponding to the amplitude information as the vertical axis, a pulse height distribution curve corresponding to each amplitude information is plotted.

[0027] Based on the pulse height distribution curve, obtain the pulse height peak information corresponding to each amplitude information, and determine the variation range of the peak information corresponding to each amplitude information;

[0028] The uniformity of the gain distribution of the microchannel plate assembly under test is determined based on the size of the variation range.

[0029] The above scheme has the following beneficial effects:

[0030] This invention provides a microchannel plate gain uniformity testing device, comprising: an incident light source, a pinhole template located on the optical path of the incident light source, a photocathode, a microchannel plate assembly under test, and a collecting anode, as well as processing electronics and a data processing system electrically connected to the collecting anode; the incident light source is monochromatic parallel light, the central axis of the pinhole template is perpendicular to the plane of the photocathode and to the input surface of the microchannel plate assembly under test; the photocathode, the microchannel plate assembly under test, and the collecting anode are connected to a high-voltage power supply and sequentially fixed on an electric displacement platform, which is used to adjust the position of the photocathode, the microchannel plate assembly under test, and the collecting anode; the pinhole template, the photocathode, the microchannel plate assembly under test, the collecting anode, and the electric displacement platform are assembled in a vacuum chamber; the processing electronics and the data processing system are located outside the vacuum chamber. This solution can accurately obtain the gain magnitude and difference in different regions of the microchannel plate assembly, especially the gain characteristics and differences in saturated operating mode, and can accurately calculate the gain uniformity performance of the microchannel plate assembly under test over the entire effective area. Attached Figure Description

[0031] Figure 1 A schematic diagram of a microchannel plate gain uniformity testing device provided in an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of a processing electronics provided for an embodiment of the present invention;

[0033] Figure 3 A flowchart illustrating the steps of a microchannel plate gain uniformity testing method provided in this embodiment of the invention;

[0034] Figure 4 This is a pulse height distribution curve at a certain location of a microchannel plate provided in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of various positions of the microchannel plate assembly under test provided in an embodiment of the present invention;

[0036] Figure 6 The overall pulse height distribution curve of the microchannel plate provided in the embodiment of the present invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, the use of "based on" or "according to" implies openness and inclusiveness, because processes, steps, calculations, or other actions "based on" or "according to" one or more of the stated conditions or values ​​may in practice be based on additional conditions or beyond the stated values.

[0039] To test and screen the gain uniformity performance of microchannel plate components for position-sensitive anode photon counting imaging detectors, this invention provides a device and method for testing the gain uniformity of microchannel plate components. It is particularly suitable for testing the gain uniformity of microchannel plate components under saturated operating mode and has important application value for improving detector imaging performance and survival rate.

[0040] Figure 1 This is a schematic diagram of a microchannel plate gain uniformity testing device provided in an embodiment of the present invention.

[0041] like Figure 1 As shown, the device includes: an incident light source 1, a pinhole template 2 located in the optical path of the incident light source, a photocathode 3, a microchannel plate assembly to be tested 6 and a collecting anode 7, as well as processing electronics 10 and a computer 11 electrically connected to the collecting anode;

[0042] The incident light source 1 is monochromatic parallel light, and the central axis of the hole in the pinhole template 2 is perpendicular to the plane of the photocathode 3 and to the input surface of the microchannel plate assembly 6 to be tested.

[0043] The photocathode 3, the microchannel plate assembly under test 6, and the collecting anode 7 are connected to the high-voltage power supply 5 and are fixed in sequence on the electric displacement platform 8. The electric displacement platform 8 is used to adjust the position of the photocathode 3, the microchannel plate assembly under test 6, and the collecting anode 7.

[0044] The pinhole template 2, photocathode 3, microchannel plate assembly to be tested 6, collecting anode 7, and electric displacement platform 8 are assembled in the vacuum chamber; the processing electronics 10 and computer 11 are located outside the vacuum chamber.

[0045] In this embodiment of the invention, the incident light source 1 is monochromatic parallel light, used to provide a stable and uniform photon stream to simulate an actual detection scenario. Using monochromatic light of a single wavelength can avoid signal fluctuations caused by differences in the response of the photocathode 3 to different wavelengths. Parallel light ensures that the size of the light spot on the photocathode 3 and the input surface of the microchannel plate is uniquely determined by the pinhole diameter, avoiding blurring or enlargement of the light spot due to divergent light.

[0046] The pinhole template 2 is a small hole etched onto a thin metal film material to generate a collimated or dot-shaped light beam to scan and test different areas of the microchannel plate. The pinhole template 2 can be designed as a single pinhole or a multi-pinhole array. The pinhole size should be as small as possible (usually less than 0.2 mm in diameter) to avoid the light spot covering more channels.

[0047] The photocathode 3 is used to convert incident photons into photoelectrons. It is based on the external photoelectric effect. When the photon energy is higher than the work function of the cathode material, the photon is absorbed and free electrons are excited.

[0048] The microchannel plate assembly 6 (MCP) is a miniature electron multiplier composed of a glass or semiconductor plate with millions of micrometer-scale channels. When electrons generated by the photocathode 3 strike the microchannel plate assembly 6 under test, initial secondary electrons are produced. Under high voltage, these electrons collide multiple times within the channels, exciting more secondary electrons, resulting in exponential multiplication and the formation of an electron cloud. The final output electron cloud is converted into a current pulse by the collecting anode 7.

[0049] Processing electronics 10 is an electronic system that converts electrical signals output by the MCP or other detectors into processable data. Processing electronics 10 converts electrical signals into processable data and uploads it to computer 11. Computer 11 further analyzes and processes the processable data to obtain the gain distribution uniformity of the microchannel plate assembly 6 under test.

[0050] The central axis of the pinhole template 2 is perpendicular to the plane of the photocathode 3 and to the input surface of the microchannel plate assembly 6 under test. This ensures that the incident light is perpendicular and the light spot is ideally circular. The initial direction of the photoelectrons emitted by the photocathode 3 is consistent with the axis of the MCP channel, which avoids gain differences caused by oblique electron incidence.

[0051] The electric displacement platform 8 is used to adjust the position of the photocathode 3, the microchannel plate assembly under test 6, and the collecting anode 7, specifically to achieve horizontal and vertical position adjustment.

[0052] The photocathode 3 converts photons into photoelectrons through the external photoelectric effect. In an atmospheric environment, gas molecules can chemically react with the cathode's sensitive material, leading to a decrease in quantum efficiency or even failure. Furthermore, gas molecules can scatter or adsorb photoelectrons, reducing the effective number of electrons.

[0053] MCPs rely on multiple collisions of electrons within the channel to achieve gain. If gas molecules are present, collisions between electrons and gas molecules result in energy loss, reducing gain. Ionization of gas molecules produces positive ions, which bombard the cathode or the MCP channel wall, causing permanent damage.

[0054] Furthermore, electrons traveling freely from the photocathode 3 to the MCP and then to the collecting anode 7 must travel in a vacuum. Gas molecules can cause electrons to deviate from their paths, affecting spatial resolution. Therefore, the pinhole template 2, photocathode 3, microchannel plate assembly 6, and collecting anode 7 need to be assembled in a vacuum environment. Meanwhile, the processing electronics 10 and computer 11 require an atmospheric environment to function properly.

[0055] As an optional embodiment, the incident light source 1 is ultraviolet light, which is the ultraviolet band portion of the light wave emitted by a deuterium lamp or xenon lamp light source, and the wavelength range of the ultraviolet band is 100 to 300 nm.

[0056] Because the ultraviolet photocathode 3 has high quantum efficiency in the ultraviolet band, and the inner wall material of the MCP channel is insensitive to ultraviolet light, it can be ensured that the signal comes only from the photoelectron emission of the photocathode 3, rather than the direct response of the MCP. Therefore, ultraviolet light is selected as the incident light source 1.

[0057] Deuterium lamps have an emission spectrum ranging from 160 to 400 nm, with a peak at 200 to 250 nm, perfectly matching the 100 to 300 nm response band of ultraviolet cathodes. Xenon lamps have an emission spectrum ranging from 200 to 2500 nm, with higher intensity in the ultraviolet band (200 to 300 nm), making them suitable for rapid testing or high count rate scenarios.

[0058] As an optional embodiment, the photocathode 3 is fabricated on a light-transmitting substrate material, the substrate material corresponding to the wavelength range of the ultraviolet band.

[0059] Specifically, the photocathode 3 needs to be matched with the wavelength of the input light source. Different wavelengths of incident light source 1 require the use of corresponding photocathode 3. In the 100-200nm range, CsI or KBr photocathode 3 is used, and in the 200-300nm range, it can be a metal Au, Al cathode or Cs2Te cathode.

[0060] The photocathode 3 is fabricated on a light-transmitting substrate material. Depending on the wavelength of the incident light source 1, the substrate material can be magnesium fluoride or fused silica.

[0061] As an optional embodiment, the pinhole template 2 is a light-transmitting hole etched on a metal thin film material, and the diameter of the light-transmitting hole ranges from 0.1 mm to 0.2 mm.

[0062] Etching processes, such as photolithography or laser drilling, can achieve micron-level aperture precision on thin metal films, ensuring smooth edges and regular shapes of the holes and avoiding stray light scattering.

[0063] When the diameter of the aperture is close to 0.1 mm, the light spot is smaller, allowing for the testing of finer areas of the MCP with high resolution. When the diameter of the aperture is close to 0.2 mm, the light throughput is high, the signal intensity is strong, and it is suitable for fast scanning or low-sensitivity detectors.

[0064] As an optional embodiment, the number of microchannel plates in the microchannel plate assembly 6 under test is any one of one, two, or three; when the number is two, the two microchannel plates are assembled in a "V" cascade; when the number is three, the three microchannel plates are assembled in a "Z" cascade.

[0065] As an optional embodiment, the processing electronics 10 includes a charge-sensitive preamplifier, a shaping amplifier, a pole-zero cancellation circuit, and a data acquisition section. The processing electronics 10 is used to filter, amplify, shape, and acquire the amplitude of the current pulse output from the collecting anode 7.

[0066] Figure 2 This is a schematic diagram of a processing electronics 10 provided in an embodiment of the present invention.

[0067] like Figure 2 As shown, the processing electronics 10 includes a charge-sensitive preamplifier, a shaping amplifier, a pole-zero cancellation circuit, and a data acquisition section.

[0068] Specifically, the charge-sensitive preamplifier is used to convert the transient current pulse collected at the anode into a voltage signal and integrate the charge; the shaping amplifier is used to filter and shape the slowly varying signal output by the preamplifier, improve the signal-to-noise ratio (SNR) and standardize the pulse shape; the pole-zero cancellation circuit is used to eliminate the exponential decay tail of the preamplifier output signal; the data acquisition section is used to capture the maximum amplitude of the pulse, convert the analog amplitude into a digital quantity, record the pulse arrival time, and output the digitized pulse amplitude (corresponding to MCP gain) and timestamp for subsequent imaging or energy spectrum analysis.

[0069] As an optional embodiment, the distance between the photocathode 3 and the microchannel plate assembly 6 under test is 0.5-2 mm, and the distance between the microchannel plate assembly 6 under test and the collecting anode 7 is 1-10 mm.

[0070] The distance between the photocathode 3 and the microchannel plate assembly 6 under test is 0.5-2mm, which can maximize the photoelectron collection efficiency, ensure that as many electrons emitted by the photocathode 3 as possible enter the MCP channel, and avoid electron diffusion leading to a decrease in resolution.

[0071] The distance between the microchannel plate assembly 6 under test and the collecting anode 7 is 1-10mm, which ensures that the multiplying electrons output by the MCP are completely transmitted to the anode, avoiding edge loss, and is compatible with position-sensitive anode decoding.

[0072] As an optional embodiment, the collecting anode 7 is located at the output end of the microchannel plate assembly 6 under test, and the collecting anode 7 and the processing electronics 10 are connected through a vacuum system trans-chamber connector 9; an SMA connector is soldered onto the collecting anode 7, and the SMA connector is used to lead out the signal output by the collecting anode 7.

[0073] In this embodiment of the invention, the collecting anode 7 is located directly at the output end of the MCP component under test, close to the MCP but not in contact with it (spacing 1–10 mm, as described above), to ensure efficient collection of the multiplied electron cloud.

[0074] The vacuum chamber needs to maintain a high vacuum, while the processing electronics 10 is located outside the vacuum chamber. The through-chamber connector can achieve leakage-free transmission of electrical signals and electromagnetic shielding to prevent external interference from coupling to sensitive signal lines through the connector.

[0075] The SMA (SubMiniature version Aconnector) connector is used to extract the signal from the anode 7. It features high-frequency characteristics, supports DC–18GHz bandwidth, matches the fast rising edge of the MCP pulse, and has an impedance of 50Ω to reduce signal reflection.

[0076] In summary, the microchannel plate gain uniformity testing device provided in this embodiment of the invention includes: an incident light source, a pinhole template located on the optical path of the incident light source, a photocathode, a microchannel plate assembly under test, and a collecting anode, as well as processing electronics and a data processing system electrically connected to the collecting anode; the incident light source is monochromatic parallel light, the central axis of the pinhole template is perpendicular to the plane of the photocathode and perpendicular to the input surface of the microchannel plate assembly under test; the photocathode, the microchannel plate assembly under test, and the collecting anode are connected to a high-voltage power supply and are sequentially fixed on an electric displacement platform, the electric displacement platform being used to adjust the position of the photocathode, the microchannel plate assembly under test, and the collecting anode; the pinhole template, the photocathode, the microchannel plate assembly under test, the collecting anode, and the electric displacement platform are assembled in a vacuum chamber; the processing electronics and the data processing system are located outside the vacuum chamber. This method can accurately obtain the gain magnitude and difference in different regions of the microchannel plate assembly, especially the gain characteristics and differences in saturated operating mode, and can accurately calculate the gain uniformity performance of the microchannel plate assembly under test throughout the entire effective area.

[0077] Figure 3 This is a flowchart illustrating the steps of a microchannel plate gain uniformity testing method provided in an embodiment of the present invention. Figure 3 As shown, this method is applied to Figure 1The apparatus and method include the following steps:

[0078] Step 101: Evacuate the vacuum chamber to make the vacuum level of the vacuum chamber greater than or equal to the preset vacuum level.

[0079] First, the photocathode, the MCP component under test, and the collecting anode are assembled, placed on the motorized displacement platform, and reliably fixed. The initial position ensures that the pinhole template and the assembled MCP component under test are coaxial. Then, the high-voltage line is reliably connected to the photocathode, the MCP component under test, and the collecting anode, while a coaxial cable is used to reliably connect the collecting anode to the processing electronics.

[0080] After connection, turn on the vacuum pump system to begin evacuating the vacuum chamber, ensuring the vacuum level is higher than the preset vacuum level. The preset vacuum level can be set to 2 × 10⁻⁶. -4 Pa.

[0081] Step 102: Turn on the incident light source, and after the incident light source stabilizes, turn on the high voltage power supply of the photocathode, the microchannel plate assembly under test, and the collecting anode.

[0082] Turn on the power switch of the ultraviolet light source (deuterium lamp or xenon lamp) and allow the light source to stabilize for 30 minutes. At this time, the input window aperture of the incident light source is closed.

[0083] Turn on the high-voltage power supply to power the photocathode, the MCP component under test, and the collecting anode, and turn on the power supply to the collecting anode.

[0084] Step 103: Open the input window aperture of the incident light source so that the incident light emitted by the incident light source passes through the pinhole template and is perpendicularly incident on the surface of the photocathode.

[0085] Open the system input window aperture, and the ultraviolet light source passes through the pinhole template and is vertically incident on the photocathode surface.

[0086] Step 104: The photocathode converts the incident light into photoelectrons, the microchannel plate assembly under test amplifies the photoelectrons and outputs an electron cloud, and the collecting anode converts the collected electron cloud into a current pulse.

[0087] A single incident particle (such as a photon or electron) from the photocathode strikes the inner wall of the MCP channel, generating initial secondary electrons. Under high voltage, these electrons collide multiple times within the channel, exciting even more secondary electrons, resulting in an exponential multiplication. The final output electron cloud is collected by the collecting anode and converted into a current pulse. The charge of the current pulse (i.e., the pulse height) is directly related to the gain.

[0088] Step 105: The processing electronics acquire the current pulse, convert the current pulse into processable pulse data, and upload the pulse data to the computer.

[0089] The output signal of the incident photons after being amplified by processing electronics is collected at the collecting anode. The threshold is set to 0V during collection to ensure that all output pulse amplitudes are collected as much as possible.

[0090] The processing electronics acquire current pulses. After accumulating data for 5 minutes, the processing electronics convert the current pulses into processable pulse data. The pulse data is then uploaded to a computer, which processes the pulse data to obtain pulse height information.

[0091] Step 106: Adjust the position of the photocathode by moving the electric displacement platform so that the entire surface of the photocathode is irradiated and covered by the incident light, and the microchannel plate assembly under test covers the entire effective area of ​​the photocathode; the collecting anode converts the electron cloud output from each position of the microchannel plate assembly under test into current pulses.

[0092] By continuously moving the position of the electric displacement platform, steps 104-105 are repeated sequentially to ensure that the MCP component under test covers the entire effective area of ​​the photocathode, thereby obtaining pulse height information at each position of the microchannel plate component.

[0093] Figure 4 This is a pulse height distribution curve at a certain location of a microchannel plate provided in an embodiment of the present invention.

[0094] like Figure 4 As shown, in the Pulse Height Distribution (PHD) curve, the horizontal axis represents the amplitude information at a certain position on the MCP surface, reflecting the gain magnitude, while the vertical axis represents the number of pulses, which is the statistical count of that amplitude range. The PHD distribution is a quasi-Gaussian distribution.

[0095] Figure 5 This is a schematic diagram of various positions of the microchannel plate assembly under test provided in an embodiment of the present invention.

[0096] like Figure 5 As shown, by continuously moving the position of the electric displacement platform, the entire surface of the photocathode is irradiated and covered by incident light, and the microchannel plate assembly under test covers the entire effective area of ​​the photocathode, thereby obtaining the pulse height information at various positions of the microchannel plate, such as positions A1, A2, A3...A9 of the microchannel plate assembly.

[0097] Step 107: The computer analyzes and processes the pulse data to obtain the gain distribution uniformity of the microchannel plate assembly under test.

[0098] After plotting the pulse heights at all locations, the gain distribution at each location can be obtained. Based on the effective area of ​​the MCP component under test, the test points can be appropriately distributed to test and evaluate the gain performance differences across the entire effective area.

[0099] As an optional embodiment, step 107 includes:

[0100] Step 1071: Calculate the amplitude information of all current pulses in the pulse data, and count the number of pulses corresponding to each amplitude information.

[0101] Step 1072: Using the amplitude information as the horizontal axis and the number of pulses corresponding to the amplitude information as the vertical axis, plot the pulse height distribution curve corresponding to each amplitude information.

[0102] Step 1073: Obtain the peak pulse height information corresponding to each amplitude information according to the pulse height distribution curve, and determine the variation range of the peak information corresponding to each amplitude information;

[0103] Step 1074: Determine the uniformity of gain distribution of the microchannel plate assembly under test based on the size of the variation range.

[0104] In steps 1071-1074, the amplitude information of all pulse light output signals acquired is statistically analyzed, and the amplitude information and number of all pulses are statistically distributed and plotted.

[0105] Specifically, the MCP surface is divided into a grid, such as a 10×10 matrix, with each grid corresponding to a test point. For all pulse amplitudes within each grid, the MPG or median is taken, and the gain value of each region is represented by a heatmap or contour map to obtain a pulse distribution height curve.

[0106] Figure 6 The overall pulse height distribution curve of the microchannel plate provided in the embodiment of the present invention.

[0107] like Figure 6 As shown, the horizontal axis of the pulse height distribution curve (PHD) represents the amplitude information at various positions on the MCP surface, reflecting the gain magnitude, while the vertical axis represents the number of pulses, which is the statistical count of a certain amplitude range.

[0108] Depend on Figure 6 It can be seen that for various amplitude information, the number of pulses is concentrated between 4.0K and 6.0K.

[0109] Since the PHD distribution of the MCP output in photon counting mode is quasi-Gaussian, the peak position of the PHD distribution can be used as the gain of the MCP component. By judging the change of PHD peak at different positions, the uniformity of the gain distribution of the MCP component under test can be obtained.

[0110] Uniformity is specifically calculated through global non-uniformity, and the formula for global non-uniformity is:

[0111]

[0112] Where, σ <g>This represents the standard deviation of the gain across all grid cells. <g>This represents the average gain of all grid cells.

[0113] For example, the MCP area is 40mm × 40mm, divided into a 1mm × 1mm grid (1600 points). 1000 pulses are collected at each point, and the PHD peak value is statistically analyzed. σ <g> ＝800， <g>If the value is 10000, then the non-uniformity is 8%.

[0114] Figure 4 The figure shows the gain performance of the MCP component under test at 9 test points in the embodiment. The results show that the overall uniformity is consistent and the gain non-uniformity of the MCP component under test is less than 10% within the effective area.

[0115] In summary, the microchannel plate gain uniformity testing method provided by this invention includes: evacuating a vacuum chamber to a vacuum level greater than or equal to a preset vacuum level; turning on an incident light source, and after the incident light source stabilizes, turning on the high-voltage power supplies of the photocathode, the microchannel plate assembly under test, and the collecting anode; opening the input window aperture of the incident light source, allowing the incident light emitted by the incident light source to pass through a pinhole template and be perpendicularly incident on the surface of the photocathode; the photocathode converts the incident light into photoelectrons, the microchannel plate assembly under test amplifies the photoelectrons, outputting an electron cloud, and the collecting anode collects the electrons... The electron cloud is converted into current pulses; the position of the photocathode is adjusted by moving an electric displacement platform so that the entire surface of the photocathode is irradiated and covered by the incident light, and the microchannel plate assembly under test covers the entire effective area of ​​the photocathode; the collecting anode converts the electron cloud output from various positions of the microchannel plate assembly under test into current pulses; the processing electronics collect the current pulses, convert them into processable pulse data, and upload the pulse data to a computer; the computer analyzes and processes the pulse data to obtain the gain distribution uniformity of the microchannel plate assembly under test. This scheme can accurately obtain the gain magnitude and difference in different regions of the microchannel plate assembly, especially the gain characteristics and differences in saturated operating mode, and can accurately calculate the gain uniformity performance of the microchannel plate assembly under test over the entire effective area.

[0116] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The above embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.< / g> < / g> < / g> < / g>

Claims

1. A microchannel plate gain uniformity testing device, characterized in that, The device includes: an incident light source, a pinhole template located in the optical path of the incident light source, a photocathode, a microchannel plate assembly to be tested and a collecting anode, and a processing electronics and data processing system electrically connected to the collecting anode; The incident light source is monochromatic parallel light, and the central axis of the pinhole template is perpendicular to the plane of the photocathode and to the input surface of the microchannel plate assembly under test. The photocathode, the microchannel plate assembly under test, and the collecting anode are connected to a high-voltage power supply and are fixed sequentially on an electric displacement platform. The electric displacement platform is used to adjust the position of the photocathode, the microchannel plate assembly under test, and the collecting anode. The pinhole template, the photocathode, the microchannel plate assembly to be tested, the collecting anode, and the electric displacement platform are assembled in a vacuum chamber; the processing electronics and the data processing system are located outside the vacuum chamber.

2. The apparatus according to claim 1, characterized in that, The incident light source is ultraviolet light, which is the ultraviolet band portion of the light wave emitted by a deuterium lamp or xenon lamp, and the wavelength range of the ultraviolet band is 100–300 nm.

3. The apparatus according to claim 2, characterized in that, The photocathode is fabricated on a light-transmitting substrate material, and the substrate material corresponds to the wavelength range of the ultraviolet band.

4. The apparatus according to claim 1, characterized in that, The pinhole template is a light-transmitting hole etched on a metal thin film material, and the diameter of the light-transmitting hole ranges from 0.1 mm to 0.2 mm.

5. The apparatus according to claim 1, characterized in that, The number of microchannel plates in the microchannel plate assembly under test can be any one, two, or three; when the number is two, the two microchannel plates are assembled in a "V" cascade; when the number is three, the three microchannel plates are assembled in a "Z" cascade.

6. The apparatus according to claim 1, characterized in that, The processing electronics include a charge-sensitive preamplifier, a shaping amplifier, a pole-zero cancellation circuit, and a data acquisition section. The processing electronics are used to filter, amplify, shape, and acquire the amplitude of the current pulses output from the anode.

7. The apparatus according to claim 1, characterized in that, The distance between the photocathode and the microchannel plate assembly under test is 0.5-2 mm, and the distance between the microchannel plate assembly under test and the collecting anode is 1-10 mm.

8. The apparatus according to claim 1, characterized in that, The collecting anode is located at the output end of the microchannel plate assembly under test. The collecting anode and the processing electronics are connected through a vacuum system trans-chamber connector. An SMA connector is soldered onto the collecting anode, which is used to extract the signal output by the collecting anode.

9. A method for testing the gain uniformity of a microchannel plate, characterized in that, The method is applied to the apparatus according to any one of claims 1-8, and the method includes: The vacuum chamber is evacuated to a level greater than or equal to a preset vacuum level. Turn on the incident light source, and after the incident light source stabilizes, turn on the high voltage power supply of the photocathode, the microchannel plate assembly under test, and the collecting anode; Open the input window aperture of the incident light source so that the incident light emitted by the incident light source passes through the pinhole template and is perpendicularly incident on the surface of the photocathode. The photocathode converts the incident light into photoelectrons, the microchannel plate assembly under test amplifies the photoelectrons and outputs an electron cloud, and the collecting anode converts the collected electron cloud into a current pulse. The position of the photocathode is adjusted by moving the electric displacement platform so that the entire surface of the photocathode is irradiated and covered by the incident light, and the microchannel plate assembly under test covers the entire effective area of ​​the photocathode; the collecting anode converts the electron cloud output from each position of the microchannel plate assembly under test into current pulses. The processing electronics acquire the current pulse, convert the current pulse into processable pulse data, and upload the pulse data to the computer; The computer analyzes and processes the pulse data to obtain the gain distribution uniformity of the microchannel plate assembly under test.

10. The method according to claim 9, characterized in that, The computer analyzes and processes the pulse data, including: The amplitude information of all current pulses in the pulse data is statistically analyzed, and the number of pulses corresponding to each amplitude information is counted. Using the amplitude information as the horizontal axis and the number of pulses corresponding to the amplitude information as the vertical axis, a pulse height distribution curve corresponding to each amplitude information is plotted. Based on the pulse height distribution curve, obtain the pulse height peak information corresponding to each amplitude information, and determine the variation range of the peak information corresponding to each amplitude information; The uniformity of the gain distribution of the microchannel plate assembly under test is determined based on the size of the variation range.

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