High-speed single-photon detection system and method

Abstract

The present invention discloses a high-speed single-photon detection system and method. The system includes: a microchannel plate for converting incident high-speed single photons into electron clouds; an anode for dividing the electron clouds into multiple paths, generating short current pulses from the charge collected in each path and transmitting them to a signal processing path for the corresponding path; the signal processing path for converting the short current pulses into digital pulses, selecting a corresponding target shaping filter based on the time interval between adjacent digital pulses in the same path for adaptive shaping filtering, calculating the relative two-dimensional coordinate value of the high-speed single photon based on the shaped digital pulses, and transmitting the relative two-dimensional coordinate value to a terminal for imaging display. The signal processing path includes multiple shaping filters with different filtering parameters, each corresponding to a preset time interval range. By adaptively selecting the shaping filter based on the dynamic change of the pulse time interval, the present invention improves the actual count rate and spatial resolution during detection.

Description

Technical Field

[0001] The present application relates to the field of particle detection technology, and in particular to a high-speed single-photon detection system and method. Background Art

[0002] The microchannel plate (MCP) is a two-dimensional continuous electron multiplication electro-vacuum device that can be used to directly detect particles such as photons, electrons, ions, alpha particles, gamma rays, and cosmic rays. If the MCP uses a position-sensitive anode (such as a wedge-shaped anode, a delay line anode, or a cross-shaped anode) as a readout method, two-dimensional imaging with single-photon sensitivity can be achieved, which is called a position-sensitive anode photon counting imaging detector. Position-sensitive anode photon counting imaging detectors are widely used in space science (such as space astronomy, space plasma physics, and deep space exploration). Among the many position-sensitive anodes, the cross-shaped anode can achieve high spatial resolution at low gain. The MCP can achieve a higher upper limit on the count rate and maintain a longer life at low gain, which is very important for expensive equipment such as space cameras that are difficult to replace.

[0003] Existing electronic systems for cross-strip anode signal processing typically use a charge amplifier to convert the short current pulses output by the anode into an amplified voltage signal, and then use a shaping amplifier to further amplify and shape the signal to improve the signal-to-noise ratio. Alternatively, the charge amplifier and shaping amplifier can be integrated into a preamplifier with shaping capabilities. However, this processing method has a fixed shaping time. In scenarios where the photon count rate changes dynamically, a shaping amplifier with a fixed shaping time cannot adapt to pulse signals with dynamically changing time intervals. Shaping amplifiers with long shaping times can reduce electronic noise at low count rates, but they can cause severe signal overlap at high count rates. Shaping amplifiers with short shaping times can reduce overlap at high count rates, but they can also cause higher electronic noise at low count rates. Summary of the Invention

[0004] In view of this, the present application provides a high-speed single-photon detection system and method to solve the problem of low performance of analog filtering under dynamically changing count rates.

[0005] In order to solve the above technical problems, a technical solution adopted in this application is: to provide a high-speed single-photon detection system, which includes: a microchannel plate, an anode, and multiple parallel signal processing paths; the microchannel plate is used to convert the incident high-speed single photon into an electron cloud; the anode is used to divide the electron cloud into multiple paths, and then generate a short current pulse from the charge collected in each path and transmit it to the signal processing path of the corresponding path; the signal processing path is used to convert the short current pulse into a digital pulse, and then select the corresponding target shaping filter for adaptive shaping filtering according to the time interval between adjacent digital pulses in the same path, and then calculate the two-dimensional coordinate relative value of the high-speed single photon based on the shaped digital pulse, and then transmit the two-dimensional coordinate relative value to the terminal for imaging display. The signal processing path includes multiple shaping filters with different filtering parameters, and each shaping filter corresponds to a preset time interval range.

[0006] As a further improvement of the present application, the signal processing path includes a preamplifier circuit, an analog-to-digital conversion module, a microprocessor and a data transmission module; the preamplifier circuit is used to convert short current pulses into analog pulse voltage signals; the analog-to-digital conversion module is used to convert analog pulse voltage signals into digital pulses; the microprocessor is used to select the corresponding target shaping filter for adaptive shaping filtering based on the time interval between adjacent digital pulses in the same path, and then calculate the two-dimensional coordinate relative value of the high-speed single photon based on the shaped digital pulse; the data transmission module is used to transmit the two-dimensional coordinate relative value to the terminal for imaging display.

[0007] As a further improvement of the present application, the microprocessor includes an input buffer module, a digital filtering module, a peak extraction module, a centroid calculation module, an output buffer module and a data transmission control module; the input buffer module is used to cache digital pulses; the digital filtering module is used to select the corresponding target shaping filter for adaptive shaping filtering according to the time interval between adjacent digital pulses in the same channel; the peak extraction module is used to extract the waveform peak of the digital pulse after shaping filtering based on a preset method; the centroid calculation module is used to calculate according to the waveform peak of each channel to obtain a centroid result array, and use the centroid result array as a two-dimensional coordinate relative value; the output buffer module is used to cache the two-dimensional coordinate relative values; the data transmission control module is used to package all the two-dimensional coordinate relative values and send them to the terminal through the control data transmission module when the storage area of the output buffer module is full of data.

[0008] As a further improvement of the present application, the microprocessor also includes a pulse recognition module, which is used to determine whether the signal processing path in which it is located receives a short current pulse, and to control the signal processing path in which it is located to stop running when the signal processing path in which it is located does not receive a short current pulse.

[0009] As a further improvement of the present application, the preamplifier circuit includes a charge amplifier and a pole-zero cancellation circuit. The charge amplifier is used to convert short current pulses into analog pulse voltage signals, and the pole-zero cancellation circuit is used to reduce the tail length of the analog pulse voltage signals.

[0010] As a further improvement of the present application, the anode includes one of a cross-strip anode, a wedge-strip anode, a vernier anode, and a multi-pixel anode.

[0011] In order to solve the above technical problems, another technical solution adopted in this application is: to provide a high-speed single-photon detection method, which is applied to one of the above-mentioned high-speed single-photon detection systems, the high-speed single-photon detection system includes a microchannel plate, an anode, and a multi-path parallel signal processing path; the method includes: the microchannel plate receives high-speed single photons, and converts the high-speed single photons into electron clouds and transmits them to the anode; the anode divides the electron cloud into multiple paths, and then generates short current pulses from the charges collected in each path and transmits them to the signal processing path of the corresponding path; the signal processing path converts the short current pulses into digital pulses, and then selects the corresponding target shaping filter for adaptive shaping filtering according to the time interval between adjacent digital pulses in the same path, and then calculates the two-dimensional coordinate relative value of the high-speed single photon based on the shaped digital pulse, and then transmits the two-dimensional coordinate relative value to the terminal for imaging display, and the signal processing path includes multiple shaping filters with different filtering parameters, and each shaping filter corresponds to a preset time interval range.

[0012] As a further improvement of the present application, the signal processing path includes a preamplifier circuit, an analog-to-digital conversion module, a microprocessor and a data transmission module; the signal processing path converts the short current pulse into a digital pulse, and then selects the corresponding target shaping filter for adaptive shaping filtering according to the time interval between adjacent digital pulses in the same path, and then calculates the two-dimensional coordinate relative value of the high-speed single photon based on the shaped digital pulse, and then transmits the two-dimensional coordinate relative value to the terminal for imaging display, including: the preamplifier circuit converts the short current pulse into an analog pulse voltage signal; the analog-to-digital conversion module converts the analog pulse voltage signal into a digital pulse; the microprocessor selects the corresponding target shaping filter for adaptive shaping filtering according to the time interval between adjacent digital pulses in the same path, and then calculates the two-dimensional coordinate relative value of the high-speed single photon based on the shaped digital pulse; the data transmission module transmits the two-dimensional coordinate relative value to the terminal for imaging display.

[0013] As a further improvement of the present application, the microprocessor includes an input buffer module, a digital filtering module, a peak extraction module, a centroid calculation module, an output buffer module and a data transmission control module; the microprocessor selects a corresponding target shaping filter according to the time interval between adjacent digital pulses in the same path for adaptive shaping filtering, and then calculates the two-dimensional coordinate relative value of the high-speed single photon according to the shaped digital pulse, including: the input buffer module caches the digital pulse; the digital filtering module selects the corresponding target shaping filter according to the time interval between adjacent digital pulses in the same path for adaptive shaping filtering; the peak extraction module extracts the waveform peak of the digital pulse after shaping filtering based on a preset method; the centroid calculation module calculates according to the waveform peak of each path to obtain a centroid result array, and uses the centroid result array as the two-dimensional coordinate relative value; the output buffer module caches the two-dimensional coordinate relative value; when the storage area of the output buffer module is full of data, the data transmission control module packages all the two-dimensional coordinate relative values and sends them to the terminal through the control data transmission module.

[0014] As a further improvement of the present application, the microprocessor also includes a pulse recognition module; after the step of the input buffer area module caching the digital pulse, it also includes: the pulse recognition module is used to determine whether the signal processing path in which it is located receives a short current pulse, and control the signal processing path in which it is located to stop running when the signal processing path in which it is located does not receive a short current pulse.

[0015] The beneficial effect of the present application is: the high-speed single-photon detection system of the present application pre-sets multiple shaping filters with different filtering in the signal processing path. After the single photon is converted into a multi-channel current short pulse through the microchannel plate and the anode, the multi-channel current short pulse is converted into a multi-channel digital pulse using the signal processing path, and then the most suitable shaping filter is automatically selected according to the time interval between adjacent digital pulses of the same path to realize shaping filtering, thereby solving the problem that the analog filter cannot adapt to the pulse signal with dynamically changing time intervals due to fixed filtering parameters, thereby resulting in a lower actual counting rate and a lower spatial resolution. The filter performance is fully utilized, the noise is effectively filtered out, and high spatial resolution is maintained under dynamically changing counting rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a schematic structural diagram of a high-speed single-photon detection system according to an embodiment of the present invention;

[0017] Figure 2 1 is a schematic diagram of the structure of the signal processing path of the high-speed single-photon detection system according to an embodiment of the present invention;

[0018] Figure 3 It is a schematic diagram of the existing photon detector signal processing flow;

[0019] Figure 4 1 is a schematic diagram of a signal processing flow of a high-speed single-photon detection system according to an embodiment of the present invention;

[0020] Figure 5 2 is a schematic diagram of the structure of a microprocessor of a high-speed single-photon detection system according to an embodiment of the present invention;

[0021] Figure 6 1 is a flow chart of a high-speed single-photon detection method according to an embodiment of the present invention;

[0022] Figure 7 yes Figure 6 Specific flow diagram of step S3;

[0023] Figure 8 yes Figure 7 Specific flow diagram of step S33 in FIG. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0025] The terms "first," "second," and "third" in this application are used only for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of such features. In the description of this application, "multiple" means at least two, for example, two, three, etc., unless otherwise specifically defined. All directional indications in the embodiments of this application (such as up, down, left, right, front, back...) are only used to explain the relative positional relationship, movement, etc. between the components under a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications also change accordingly. In addition, the terms "including" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products, or devices.

[0026] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0027] Figure 1 FIG is a schematic diagram of the structure of a high-speed single-photon detection system according to an embodiment of the present invention. Figure 1 As shown, the high-speed single-photon detection system includes a microchannel plate 1, an anode 2, and a multi-path parallel signal processing path 3.

[0028] Among them, the microchannel plate 1 (Microchannel Plate, hereinafter referred to as MCP) can be used to detect various particles and high-energy electromagnetic waves such as electrons, ions, high-energy particles, neutrons, ultraviolet rays, X-rays, etc. The microchannel plate 1 is a sheet-like structure composed of a large number of hollow capillaries (microchannels) arranged in two dimensions. The inner wall of the microchannel is treated so that secondary electrons can be generated when particles bombard it. A voltage is applied to both ends of the microchannel plate 1, forming an electric field inside the microchannel. The secondary electrons generated by the particle bombardment are accelerated by the electric field and bombard the microchannel again to generate more secondary electrons. This process is repeated many times in the same microchannel, and finally a large number of electrons (i.e., electron cloud) are output at the outlet end. In this embodiment, the microchannel plate 1 is a V-shaped structure with two microchannel plates stacked or a Z-shaped structure with three microchannel plates stacked. The incident end of the microchannel plate 1 receives the incident high-speed single photons, which are continuously multiplied inside the microchannel stack, forming an electron cloud containing 106-107 electrons at the outlet end of the microchannel plate 1, thereby realizing the conversion of high-speed single photons into electron clouds. In addition, an electric field is provided between the microchannel plate 1 and the anode 2 , and the electron cloud flies toward the anode 2 under the action of the electric field.

[0029] The anode 2 is used to divide the electron cloud into multiple paths, and then generate a short current pulse from the charge collected in each path and transmit it to the signal processing path 3 of the corresponding path. It should be noted that the anode 2 includes one of a cross-strip anode, a wedge-strip anode, a vernier anode, and a multi-pixel anode. In this embodiment, the cross-strip anode is taken as an example. The cross-strip anode is composed of a double layer of orthogonal metal strips, usually including 2n channels. After receiving the electron cloud, the anode 2 divides the electron cloud into multiple channels, and generates a short current pulse from the charge collected in each channel. The amount of electricity contained in the short current pulse is the amount of charge in the channel collected by the anode.

[0030] The signal processing path 3 is used to convert short current pulses into digital pulses, and then select the corresponding target shaping filter for adaptive shaping filtering based on the time interval between adjacent digital pulses in the same channel. The relative two-dimensional coordinate value of the high-speed single photon is calculated based on the shaped digital pulse, and the relative two-dimensional coordinate value is then transmitted to the terminal for imaging display. It should be understood that the anode 2 converts the electron cloud into multiple short current pulses. Therefore, a corresponding signal processing path 3 needs to be set for each channel of the anode 2. All signal processing paths 3 can process the short current pulses transmitted by each channel of the anode 2 in parallel. In addition, all signal processing paths 3 adopt a fully parallel structure, so that the signal of each path can be processed and transmitted in a timely manner.

[0031] In this embodiment, signal processing path 3 includes multiple shaping filters with different filtering parameters, each corresponding to a preset time interval range. Shaping filters with different filtering parameters have different denoising effects on digital pulses within different time interval ranges. Preliminary experiments determine the optimal time interval ranges corresponding to shaping filters with different filtering parameters, and the corresponding shaping filters are used to achieve the optimal denoising effect on the digital pulses.

[0032] Specifically, after receiving the short current pulse transmitted by the anode 2, the short current pulse is transmitted to the corresponding signal processing pathway 3 for processing according to the signal processing pathway 3 corresponding to each channel of the anode 2. After receiving the short current pulse, the signal processing pathway 3 converts the short current pulse into a digital pulse. Then, based on the time interval between adjacent digital pulses in the same channel, the corresponding target shaping filter is selected for adaptive shaping filtering. The relative two-dimensional coordinate value of the high-speed single photon is calculated based on the shaped digital pulse, and the relative two-dimensional coordinate value is then transmitted to the terminal for imaging display.

[0033] Furthermore, the high-speed single-photon detection system of this embodiment also includes an incident window 4 and a photocathode. The photocathode is attached to the incident port of the microchannel plate 1. After the photon passes through the incident window 4, it is processed by the photocathode at the incident port of the microchannel plate 1 and converted into a photoelectron.

[0034] The high-speed single-photon detection system of an embodiment of the present invention pre-sets multiple shaping filters with different filtering in the signal processing path. After the single photon is converted into a multi-channel current short pulse through the microchannel plate 1 and the anode 2, the multi-channel current short pulse is converted into a multi-channel digital pulse using the signal processing path 3, and then the most suitable shaping filter is automatically selected according to the time interval between adjacent digital pulses of the same path to implement shaping filtering, thereby solving the problem that the analog filter cannot adapt to the pulse signal with dynamically changing time intervals due to fixed filtering parameters, thereby resulting in a decrease in actual counting rate and a decrease in spatial resolution. The filter performance is fully utilized, noise is effectively filtered out, and high spatial resolution is maintained under dynamically changing counting rates.

[0035] Further, such as Figure 2 As shown, the signal processing path 3 includes a preamplifier circuit 31 , an analog-to-digital conversion module 32 , a microprocessor 33 and a data transmission module 34 .

[0036] The preamplifier circuit 31 converts short current pulses into analog pulse voltage signals. The analog-to-digital conversion module 32 converts the analog pulse voltage signals into digital pulses. The microprocessor 33 selects the corresponding target shaping filter based on the time interval between adjacent digital pulses in the same channel for adaptive shaping filtering. The microprocessor then calculates the relative two-dimensional coordinate value of the high-speed single photon based on the shaped digital pulses. The data transmission module 34 transmits the relative two-dimensional coordinate value to the terminal for imaging display.

[0037] In this embodiment, the preamplifier circuit 31 includes a charge amplifier 311 and a pole-zero cancellation circuit 312. The charge amplifier 311 is used to convert short current pulses into analog pulse voltage signals, and the pole-zero cancellation circuit 312 is used to reduce the tail length of the analog pulse voltage signal. Specifically, the charge amplifier 311 converts the short current pulses into analog pulse voltage signals with long tails, and the pole-zero cancellation circuit 312 is then used to reduce the tail length of the analog pulse voltage signal. Ultimately, the output of the preamplifier circuit 31 is a negative exponential analog pulse voltage signal with a pulse width of approximately 200ns. The analog-to-digital conversion module 32 is composed of an analog-to-digital converter with a sampling accuracy of 12-14 bits and a sampling rate of 65-140MSPS. It is used to convert the analog pulse voltage signal into digital pulses and input them into the microprocessor 33. The microprocessor 33 is a field programmable gate array (FPGA) that selects the corresponding target shaping filter based on the time interval between adjacent digital pulses in the same channel for adaptive shaping filtering. The relative two-dimensional coordinate value of the high-speed single photon is calculated based on the shaped digital pulses. The data transmission module 34 is used to transmit the two-dimensional coordinate relative values obtained by the microprocessor 33 to the terminal for imaging display.

[0038] Specifically, see Figure 3 , Figure 3 The figure shows the signal processing flow of existing photon detectors, including the signal processing modules of existing photon detectors and the output signals corresponding to each processing module. Figure 3 As shown, after the photon is incident on the existing photon detector, the anode generates a short current pulse (such as Figure 3 (A1), where the horizontal axis represents time and the vertical axis represents charge), and then the charge amplifier converts the short current pulse into a negative exponential analog pulse voltage signal (such as Figure 3 (B1), where the horizontal axis represents time and the vertical axis represents amplitude); then, the analog pulse voltage signal is input into the shaping amplifier and shaped into a nearly Gaussian shape (such as Figure 3 (C1), where the horizontal axis represents time and the vertical axis represents amplitude), the shaped analog pulse voltage signal is converted to digital, and then the peak value is extracted in the microprocessor (such as Figure 3 (D1), where the horizontal axis represents time and the vertical axis represents amplitude). Compared to existing photon detectors, the signal processing path of this embodiment does not require a shaping amplifier to perform analog shaping on the signal. For details, please refer to Figure 4 , Figure 4 The figure shows the signal processing flow diagram of the high-speed single-photon detection system of this embodiment, which includes the signal processing modules of the high-speed single-photon detection system of this embodiment and the output signals corresponding to each processing module. Figure 4 As shown, after the photon is incident on the high-speed single-photon detection system, the anode 2 generates a short current pulse (such as Figure 4 (A2), where the horizontal axis represents time and the vertical axis represents power), and then the preamplifier circuit 31 converts the short current pulse into a negative exponential analog pulse voltage signal (such as Figure 4 (B2), where the horizontal axis represents time and the vertical axis represents amplitude); then, the analog pulse voltage signal is converted into a digital pulse (such as Figure 4 (C2), where the horizontal axis represents time and the vertical axis represents amplitude, and the digital filtering and peak value extraction (such as Figure 4 (D2), where the horizontal axis represents time and the vertical axis represents amplitude).

[0039] Compared with existing photon detectors, the signal processing path 3 of this embodiment does not require a shaping amplifier to perform analog shaping on the signal. The preamplifier circuit 31 converts the short current pulse into an analog pulse voltage signal and directly transmits it to the analog-to-digital conversion module 32 for analog-to-digital conversion. Its structural design is more streamlined than that of existing photon detectors, thereby reducing the overall cost.

[0040] Further, such as Figure 5 As shown, the microprocessor 33 includes an input buffer module 331 , a digital filtering module 332 , a peak extraction module 333 , a centroid calculation module 334 , an output buffer module 335 and a data transmission control module 336 .

[0041] The input buffer module 331 is used to buffer digital pulses.

[0042] The digital filtering module 332 is used to select a corresponding target shaping filter to perform adaptive shaping filtering according to the time interval between adjacent digital pulses in the same channel.

[0043] Peak extraction module 333 is used to extract the peak value of the digital pulse waveform after shaping and filtering based on a preset method. Specifically, peak extraction module 333 extracts the peak value of the output waveform, which is proportional to the charge in that path of anode 2. For the output waveform of a Gaussian filter, a point-by-point comparison method is used to select the peak value. For a trapezoidal filter, the peak value is selected as a single peak point or the average of multiple peak points based on the width and slope of the flat top of the waveform.

[0044] The centroid calculation module 334 is used to calculate the centroid result array based on the waveform peak value of each channel, and use the centroid result array as the relative value of the two-dimensional coordinates. Specifically, the centroid algorithm can use a Gaussian fitting algorithm or a center of gravity algorithm. The output centroid result array (X, Y) represents the relative value of the two-dimensional coordinates of the incident photon.

[0045] The output buffer module 335 is used to buffer the relative values of the two-dimensional coordinates.

[0046] The data transmission control module 336 is used to package all the two-dimensional coordinate relative values and send them to the terminal through the control data transmission module 34 when the storage area of the output buffer module 335 is full of data.

[0047] Furthermore, it should be understood that for a single photon event, its electron cloud may only be divided into a small number of channels in the anode 2, generating a short current pulse. Therefore, to improve data processing efficiency and reduce resource usage, in this embodiment, the microprocessor 33 also includes a pulse recognition module 337. The pulse recognition module 337 is used to determine whether the signal processing path 3 in which it is located has received a short current pulse, and to control the signal processing path 3 in which it is located to stop operating if the signal processing path 3 in which it is located has not received a short current pulse.

[0048] Specifically, each signal processing path 3 corresponds to a channel in the anode 2. When there is no segmented electron cloud in the channel, the channel will not generate a short current pulse. Therefore, the channel will not send a short current pulse to the corresponding signal processing path 3. That is, the signal processing path 3 that has not received the short current pulse does not need to process the pulse signal. The signal processing path 3 can be controlled to stop running to save computing resources. Only the signal processing path 3 that receives the pulse signal needs to perform calculations, thereby improving the running speed.

[0049] Furthermore, the high-speed single-photon detection system of this embodiment can also be used to detect other high-energy particles.

[0050] Figure 6 It is a flow chart of a high-speed single photon detection method according to an embodiment of the present invention. It should be noted that the method of the present invention is not limited to the method of the embodiment of the present invention if the results are substantially the same. Figure 6 The process sequence shown is limited. Figure 6As shown, the high-speed single-photon detection method is applied to the high-speed single-photon detection system described in the above embodiment. The high-speed single-photon detection system includes a microchannel plate, an anode, and a multi-path parallel signal processing path. The high-speed single-photon detection method includes the following steps:

[0051] Step S1: The microchannel plate receives a high-speed single photon, converts the high-speed single photon into an electron cloud, and transmits the electron cloud to the anode.

[0052] Specifically, microchannel plate (Microchannel Plate, hereinafter referred to as MCP) can be used to detect various particles such as electrons, ions, high-energy particles, neutrons, ultraviolet rays, X-rays and electromagnetic waves with higher energy. The microchannel plate is a sheet structure formed by a large number of hollow capillaries (microchannels) arranged in two dimensions. The inner wall of the microchannel is processed so that secondary electrons can be generated when particles bombard. Voltage is applied to both ends of the microchannel plate to form an electric field inside the microchannel. The secondary electrons generated by the particle bombardment are accelerated by the electric field and bombard the microchannel again to produce more secondary electrons. This process is repeated many times in the same microchannel, and a large amount of electrons (i.e., electron cloud) are finally output at the outlet end. In the present embodiment, the microchannel plate is a V-shaped structure with two microchannel plates superimposed or a Z-shaped structure with three microchannel plates superimposed. The incident end of the microchannel plate receives the incident high-speed single photons, which are continuously multiplied inside the microchannel stack, forming an electron cloud containing 106-107 electrons at the outlet end of the microchannel plate, thereby achieving the conversion of high-speed single photons into electron clouds. In addition, an electric field is set between the microchannel plate and the anode, and the electron cloud flies toward the anode under the action of the electric field.

[0053] Step S2: The anode divides the electron cloud into multiple paths, and then generates a short current pulse from the charge collected in each path and transmits it to the signal processing path of the corresponding path.

[0054] Specifically, the anode divides the electron cloud into multiple paths, and then generates a short current pulse from the charge collected in each path and transmits it to the signal processing path of the corresponding path. It should be noted that the anode includes one of a cross-strip anode, a wedge-strip anode, a vernier anode, and a multi-pixel anode. In this embodiment, the cross-strip anode is taken as an example. The cross-strip anode is composed of a double layer of orthogonal metal strips, usually including 2n channels. After receiving the electron cloud, the anode divides the electron cloud into multiple channels, and generates a short current pulse from the charge collected in each channel. The amount of electricity contained in the short current pulse is the amount of charge in the channel collected by the anode.

[0055] Step S3: The signal processing pathway converts the short current pulses into digital pulses, and then selects the corresponding target shaping filter for adaptive shaping filtering based on the time interval between adjacent digital pulses in the same path. The two-dimensional coordinate relative value of the high-speed single photon is calculated based on the shaped digital pulse, and the two-dimensional coordinate relative value is then transmitted to the terminal display. The signal processing pathway includes multiple shaping filters with different filtering parameters, and each shaping filter corresponds to a preset time interval range.

[0056] Specifically, the signal processing pathway converts short current pulses into digital pulses, and then selects the corresponding target shaping filter for adaptive shaping filtering based on the time interval between adjacent digital pulses in the same channel. The relative two-dimensional coordinate value of the high-speed single photon is calculated based on the shaped digital pulse, and the relative two-dimensional coordinate value is then transmitted to the terminal for imaging display. It should be understood that the anode converts the electron cloud into multiple short current pulses. Therefore, a corresponding signal processing pathway needs to be set for each channel of the anode, and all signal processing pathways can process the short current pulses transmitted by each channel of the anode in parallel. In addition, all signal processing pathways adopt a fully parallel structure, so that the signal of each channel can be processed and transmitted in a timely manner.

[0057] In this embodiment, the signal processing path includes multiple shaping filters with different filtering parameters, each corresponding to a preset time interval range. These shaping filters with different filtering parameters have different denoising effects on digital pulses within different time interval ranges. Preliminary experiments determine the optimal time interval ranges for the shaping filters with different filtering parameters, and the corresponding shaping filters are used to achieve the optimal denoising effect on the digital pulses.

[0058] Specifically, after receiving a short current pulse transmitted by the anode, the current pulse is transmitted to the corresponding signal processing pathway for processing according to the signal processing pathway corresponding to each anode channel. After receiving the short current pulse, the signal processing pathway converts the short current pulse into a digital pulse. Then, based on the time interval between adjacent digital pulses in the same channel, the corresponding target shaping filter is selected for adaptive shaping filtering. The relative two-dimensional coordinate value of the high-speed single photon is calculated based on the shaped digital pulse, and the relative two-dimensional coordinate value is transmitted to the terminal for imaging display.

[0059] Among them, the high-speed single-photon detection system also includes an incident window and a photocathode. The photocathode is attached to the incident port of the microchannel plate. After the photon passes through the incident window, it is processed by the incident port of the microchannel plate and converted into a photoelectron by the photocathode.

[0060] Furthermore, the signal processing path includes a preamplifier circuit, an analog-to-digital conversion module, a microprocessor and a data transmission module, such as Figure 7 As shown, step S3 specifically includes:

[0061] Step S31: The preamplifier circuit converts the short current pulse into a voltage pulse.

[0062] Step S32: The analog-to-digital conversion module converts the voltage pulse into a digital pulse.

[0063] Step S33: The microprocessor selects a corresponding target shaping filter to perform adaptive shaping filtering according to the time interval between adjacent digital pulses in the same channel, and then calculates the relative value of the two-dimensional coordinate of the high-speed single photon based on the shaped digital pulses.

[0064] Step S34: The data transmission module transmits the two-dimensional coordinate relative value to the terminal for display.

[0065] Specifically, the preamplifier circuit converts short current pulses into analog pulse voltage signals. The analog-to-digital conversion module converts the analog pulse voltage signals into digital pulses. The microprocessor selects the corresponding target shaping filter based on the time interval between adjacent digital pulses in the same channel for adaptive shaping filtering. The two-dimensional coordinate relative value of the high-speed single photon is calculated based on the shaped digital pulses. The data transmission module transmits the two-dimensional coordinate relative value to the terminal for imaging display.

[0066] In this embodiment, the preamplifier circuit includes a charge amplifier and a pole-zero cancellation circuit. The charge amplifier is used to convert short current pulses into analog pulse voltage signals, and the pole-zero cancellation circuit is used to reduce the tail length of the analog pulse voltage signal. Specifically, the charge amplifier converts short current pulses into analog pulse voltage signals with long tails, and then uses the pole-zero cancellation circuit to reduce the tail length of the analog pulse voltage signal. The final output of the preamplifier circuit is a negative exponential analog pulse voltage signal with a pulse width of approximately 200ns. The analog-to-digital conversion module is composed of an analog-to-digital converter with a sampling accuracy of 12-bit to 14-bit and a sampling rate of 65-140MSPS, which is used to convert the analog pulse voltage signal into digital pulses and input them into a microprocessor. The microprocessor is a field programmable gate array (FPGA), which is used to select the corresponding target shaping filter based on the time interval between adjacent digital pulses in the same channel for adaptive shaping filtering, and then calculate the two-dimensional coordinate relative value of the high-speed single photon based on the shaped digital pulses. The data transmission module is used to transmit the two-dimensional coordinate relative value obtained by the microprocessor to the terminal for imaging display.

[0067] Furthermore, the microprocessor includes an input buffer module, a digital filtering module, a peak extraction module, a centroid calculation module, an output buffer module and a data transmission control module, such as Figure 8 As shown, step S33 specifically includes:

[0068] Step S331: The input buffer module buffers the digital pulse.

[0069] Step S332: The digital filtering module selects a corresponding target shaping filter to perform adaptive shaping filtering according to the time interval between adjacent digital pulses in the same channel.

[0070] Step S333: The peak extraction module extracts the peak value of the waveform of the digital pulse after shaping and filtering based on a preset method.

[0071] Specifically, the peak extraction module extracts the peak value of the output waveform, which is proportional to the charge in that path of the anode. For Gaussian filters, a point-by-point comparison method is used to select the peak value. For trapezoidal filters, the peak value is selected based on the width and slope of the waveform's flat top, or the average of multiple peaks.

[0072] Step S334: The centroid calculation module performs calculations based on the waveform peak value of each channel to obtain a centroid result array, and uses the centroid result array as a two-dimensional coordinate relative value.

[0073] Specifically, the centroid algorithm can use a Gaussian fitting algorithm or a center of mass algorithm, and the output centroid result array (X, Y) represents the relative value of the two-dimensional coordinates of the incident photon.

[0074] Step S335: The output buffer module buffers the relative values of the two-dimensional coordinates.

[0075] Step S336: When the storage area of the output buffer module is full of data, the data transmission control module packages all the two-dimensional coordinate relative values and sends them to the terminal through the control data transmission module.

[0076] Furthermore, the microprocessor further includes a pulse recognition module. After step S331, the pulse recognition module is further configured to determine whether the signal processing path in which the microprocessor is located receives a current pulse, and to control the signal processing path in which the microprocessor is located to stop operating if the signal processing path in which the microprocessor is located does not receive a current pulse.

[0077] It should be understood that for a single photon event, its electron cloud may be divided into only a small number of channels in the anode, generating a short current pulse. Therefore, to improve data processing efficiency and reduce resource usage, the microprocessor in this embodiment also includes a pulse recognition module. The pulse recognition module is used to determine whether the signal processing path in which it is located has received a short current pulse and control the signal processing path to stop operation if the signal processing path in which it is located does not receive a short current pulse.

[0078] Specifically, each signal processing path corresponds to a channel in the anode. When there is no split electron cloud in the channel, the channel will not generate a short current pulse. Therefore, the channel will not send a short current pulse to the corresponding signal processing path. That is, the signal processing path that does not receive the short current pulse does not need to process the pulse signal. The signal processing path can be controlled to stop running to save computing resources. Only the signal processing path that receives the pulse signal needs to perform calculations, thereby improving the running speed.

[0079] The high-speed single-photon detection method of an embodiment of the present invention pre-sets multiple shaping filters with different filtering in the signal processing path. After the single photon is converted into a multi-channel current short pulse through the microchannel plate and the anode, the multi-channel current short pulse is converted into a multi-channel digital pulse using the signal processing path, and then the most suitable shaping filter is automatically selected according to the time interval between adjacent digital pulses of the same path to implement shaping filtering. This solves the problem that the analog filter cannot adapt to the pulse signal with dynamically changing time intervals due to fixed filtering parameters, thereby causing the actual counting rate to decrease and the spatial resolution to decrease. The filter performance is fully utilized, the noise is effectively filtered out, and the high spatial resolution is maintained under the dynamically changing counting rate.

[0080] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, 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.

[0081] The above embodiments merely represent preferred embodiments of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A high-speed single-photon detection system, characterized in that: It includes: a microchannel plate, an anode, and multiple parallel signal processing pathways; The microchannel plate is used to convert incident high-speed single photons into electron clouds; The anode is used to split the electron cloud into multiple paths, and then generate short current pulses from the charges collected in each path and transmit them to the signal processing path of the corresponding path; The signal processing path is used to convert the short current pulses into digital pulses, and then select the corresponding target shaping filter for adaptive shaping filtering based on the time interval between adjacent digital pulses in the same path, and then calculate the two-dimensional coordinate relative value of the high-speed single photon based on the shaped digital pulses, and then transmit the two-dimensional coordinate relative value to the terminal for imaging display. The signal processing path includes multiple shaping filters with different filtering parameters, and each shaping filter corresponds to a preset time interval range.

2. The high-speed single-photon detection system according to claim 1, characterized in that: The signal processing path includes a preamplifier circuit, an analog-to-digital conversion module, a microprocessor and a data transmission module; The preamplifier circuit is used to convert the short current pulse into an analog pulse voltage signal; The analog-to-digital conversion module is used to convert the analog pulse voltage signal into a digital pulse; The microprocessor is used to select a corresponding target shaping filter to perform adaptive shaping filtering according to the time interval between adjacent digital pulses in the same channel, and then calculate the relative value of the two-dimensional coordinate of the high-speed single photon based on the shaped digital pulses; The data transmission module is used to transmit the two-dimensional coordinate relative value to the terminal for imaging display.

3. The high-speed single-photon detection system according to claim 2, characterized in that: The microprocessor includes an input buffer module, a digital filtering module, a peak extraction module, a centroid calculation module, an output buffer module and a data transmission control module; The input buffer module is used to buffer the digital pulse; The digital filtering module is used to select a corresponding target shaping filter to perform adaptive shaping filtering according to the time interval between adjacent digital pulses on the same path; The peak extraction module is used to extract the waveform peak of the digital pulse after shaping and filtering based on a preset method; The centroid calculation module is used to calculate according to the waveform peak of each channel to obtain a centroid result array, and use the centroid result array as the two-dimensional coordinate relative value; The output buffer module is used to buffer the relative value of the two-dimensional coordinates; The data transmission control module is used for packaging all the two-dimensional coordinate relative values and sending them to the terminal by controlling the data transmission module when the storage area of the output buffer module is full of data.

4. The high-speed single-photon detection system according to claim 3, characterized in that: The microprocessor also includes a pulse recognition module, which is used to determine whether the signal processing path in which it is located receives the short current pulse, and control the signal processing path in which it is located to stop running when the signal processing path in which it is located does not receive the short current pulse.

5. The high-speed single-photon detection system according to claim 2, characterized in that: The preamplifier circuit includes a charge amplifier and a pole-zero cancellation circuit. The charge amplifier is used to convert the short current pulse into the analog pulse voltage signal, and the pole-zero cancellation circuit is used to reduce the tail length of the analog pulse voltage signal.

6. The high-speed single-photon detection system according to claim 1, characterized in that: The anode includes one of a cross-strip anode, a wedge-strip anode, a vernier anode, and a multi-pixel anode.

7. A high-speed single-photon detection method, characterized in that: The method is applied to the high-speed single-photon detection system according to any one of claims 1 to 6, wherein the high-speed single-photon detection system comprises a microchannel plate, an anode, and multiple parallel signal processing paths; the method comprises: The microchannel plate receives high-speed single photons, converts the high-speed single photons into electron clouds, and transmits the electron clouds to the anode; The anode divides the electron cloud into multiple paths, and then generates a short current pulse from the charge collected in each path and transmits it to the signal processing path of the corresponding path; The signal processing path converts the short current pulses into digital pulses, and then selects the corresponding target shaping filter for adaptive shaping filtering based on the time interval between adjacent digital pulses in the same path. The two-dimensional coordinate relative value of the high-speed single photon is calculated based on the shaped digital pulses, and the two-dimensional coordinate relative value is then transmitted to the terminal for imaging display. The signal processing path includes multiple shaping filters with different filtering parameters, and each shaping filter corresponds to a preset time interval range.

8. The high-speed single-photon detection method according to claim 7, characterized in that: The signal processing path includes a preamplifier circuit, an analog-to-digital conversion module, a microprocessor and a data transmission module; The signal processing path converts the short current pulses into digital pulses, selects a corresponding target shaping filter according to the time interval between adjacent digital pulses in the same path for adaptive shaping filtering, calculates the two-dimensional coordinate relative value of the high-speed single photon based on the shaped digital pulses, and transmits the two-dimensional coordinate relative value to the terminal for imaging display, including the following steps: The preamplifier circuit converts the short current pulse into an analog pulse voltage signal; The analog-to-digital conversion module converts the analog pulse voltage signal into a digital pulse; The microprocessor selects a corresponding target shaping filter to perform adaptive shaping filtering according to the time interval between adjacent digital pulses in the same channel, and then calculates the relative value of the two-dimensional coordinate of the high-speed single photon based on the shaped digital pulses; The data transmission module transmits the two-dimensional coordinate relative value to the terminal for imaging display.

9. The high-speed single-photon detection method according to claim 8, characterized in that: The microprocessor includes an input buffer module, a digital filtering module, a peak extraction module, a centroid calculation module, an output buffer module and a data transmission control module; The microprocessor selects a corresponding target shaping filter to perform adaptive shaping filtering according to the time interval between adjacent digital pulses in the same path, and then calculates the relative value of the two-dimensional coordinate of the high-speed single photon according to the shaped digital pulses, including: The input buffer module buffers the digital pulses; The digital filtering module selects a corresponding target shaping filter to perform adaptive shaping filtering according to the time interval between adjacent digital pulses on the same path; The peak extraction module extracts the waveform peak of the digital pulse after shaping and filtering based on a preset method; The centroid calculation module calculates according to the waveform peak value of each channel to obtain a centroid result array, and uses the centroid result array as the two-dimensional coordinate relative value; The output buffer module buffers the relative value of the two-dimensional coordinates; When the storage area of the output buffer module is full of data, the data transmission control module packages all the two-dimensional coordinate relative values and sends them to the terminal by controlling the data transmission module.

10. The high-speed single-photon detection method according to claim 9, characterized in that: The microprocessor also includes a pulse identification module; After the step of buffering the digital pulse by the input buffer module, the method further comprises: The pulse identification module is used to determine whether the signal processing path in which it is located receives the short current pulse, and to control the signal processing path in which it is located to stop running when the signal processing path in which it is located does not receive the short current pulse.

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