Multi-threshold digitization method and device, reconstruction method and device and computer equipment

Abstract

The invention relates to the technical field of signal processing, and particularly discloses a multi-threshold digitization method, a reconstruction method and device and computer equipment, and the method comprises the steps: outputting a unit step signal when a pulse response signal meets a triggering condition; acquiring a counting step signal based on the unit step signal; and carrying out digital processing on the counting step signal, and outputting a digital sampling signal. The incident photon sequence is sampled and counted by using the multi-threshold digitization method, the incident photon sequence can be directly read in a digital signal form, a digitized sampling signal can be directly output, the original information of the incident photon sequence is stored to the greatest extent, and a complex analog-to-digital conversion process is abandoned, so that the photon detection performance is remarkably improved; moreover, an additional external digitizer is saved, and the effective detection area of photons is enlarged.

Description

Technical Field

[0001] The present invention relates to the field of photon detection technology, and in particular to a multi-threshold digitization method, a reconstruction method and device, and a computer device. Background Art

[0002] Photodetectors are the core basic components of photon detection and are widely used in key fields.

[0003] SiPM (Silicon photomultiplier) is a photodetector based on integrated circuits, which includes an array of several single photon avalanche diodes (Single Photon Avalanche Diode, also known as MicroCell, MC for short) and corresponding auxiliary circuits, where each MC is a photoelectric sensing pixel. SiPM has the advantages of high gain, low bias voltage, insensitivity to magnetic fields, compact structure, and easy arraying. It is widely believed that it can replace PMT (Photomultiplier Tube), break through the physical limits of existing PMT detection performance, and has huge market prospects.

[0004] SiPM uses the method of applying bias voltage to make MC work in Geiger mode. The state of each MC is only 1 or 0, which is essentially a digital signal. However, in actual operation, the binary signals of hundreds to thousands of MCs are accumulated to form an analog signal output. A series of analog signal processing circuits and analog-to-digital conversion circuits are set outside the SiPM to complete the digitization of the final signal. On the one hand, this process lacks efficiency and cannot recover the time series of incident photons from the analog signal, making it difficult to break through the physical limit of SiPM performance; on the other hand, its supporting digital circuit is complicated, and when integrated with SiPM, it occupies a lot of space, not only sacrificing a large amount of photosensitive area, but also greatly increasing power consumption and cost, fundamentally limiting the effective application of SiPM. Summary of the invention

[0005] Based on this, it is necessary to provide a multi-threshold digitization method, reconstruction method and device, and computer equipment to address at least one technical problem existing in the traditional analog SiPM counting scheme.

[0006] According to the first aspect of the present application, a multi-threshold digitization method is provided, including outputting a unit step signal when an impulse response signal meets a trigger condition; acquiring a counting step signal based on the unit step signal; and digitizing the counting step signal to output a digitized sampling signal.

[0007] In one of the embodiments, when the impulse response signal satisfies the trigger condition, outputting the unit step signal includes comparing the impulse response signal with a trigger threshold; in response to the comparison result that the impulse response signal is not less than the trigger threshold, outputting the unit step signal.

[0008] In one of the embodiments, when the single photon avalanche diode unit of the SiPM is not excited, the unit step signal maintains a 0 output state, and when the single photon avalanche diode unit is excited, the amplitude of the unit step signal rises by one unit and maintains the amplitude.

[0009] In one embodiment, the trigger condition includes: presetting a voltage, and when the pulse response signal is greater than the preset voltage, the trigger condition is determined to be met, and a unit step signal is output; or presetting a waveform feature, and when the waveform feature of the pulse response signal meets the preset waveform feature, the trigger condition is determined to be met, and a unit step signal is output.

[0010] In one embodiment, a waveform feature is preset, including: the maximum voltage reaches a preset voltage threshold, the current amplitude reaches a preset current threshold, or the accumulated voltage reaches a preset amplitude.

[0011] In one of the embodiments, acquiring the counting step signal based on the unit step signal includes performing sum processing on the unit step signal to acquire the counting step signal.

[0012] In one embodiment, the unit step signal is summed, including: a plurality of unit step signals are summed through an in-phase proportional adding circuit to output a counting step signal; or the unit step signals outputted in correspondence with rows and columns are summed through an adding circuit to output a counting step signal; or corresponding delays are set for each unit step signal, and then summed to form a counting step signal.

[0013] In one of the embodiments, when the single-photon avalanche diode unit of the SiPM is not excited, the amplitude of the counting step signal remains at 0; when one of the single-photon avalanche diode units is excited, the amplitude of the counting step signal increases by one unit and maintains the amplitude; when n of the single-photon avalanche diode units are excited, the amplitude of the counting step signal increases by n units and maintains the amplitude.

[0014] In one embodiment, the digital sampling signal includes a counting threshold-time pair, and the counting step signal is digitally processed to output a digital sampling signal, including dividing the counting step signal into P sub-signals, where P is an integer greater than zero; presetting P counting thresholds, and the values ​​of the P counting thresholds are different from each other; comparing the i-th sub-signal with the i-th counting threshold, i=1, 2, ..., P; in response to a threshold comparison result that the i-th sub-signal is not less than the i-th counting threshold, obtaining a trigger time of the threshold comparison result, and outputting P groups of counting threshold-time pairs.

[0015] In one embodiment, the counting step signal is digitally processed to output a digital sampling signal, including: setting multiple voltage thresholds at random, outputting the corresponding voltage threshold-time pair when the counting step signal crosses each voltage threshold, converting the amplitude of the unit step signal that is an integer multiple closest to each voltage threshold, and obtaining the original information of the approximately corresponding incident photon sequence based on the counts and trigger times corresponding to the multiple voltage thresholds.

[0016] In one embodiment, the digital sampling signal includes a counting threshold-time pair, and the counting step signal is digitally processed to output a digital sampling signal, including: measuring the number of times the counting step signal amplitude jumps and the time of the jumps, outputting the jump number and jump time data sequence, and directly reading it out in the form of a digital signal.

[0017] In one embodiment, after the counting step signal is digitized and a digitized sampling signal is output, the method further includes outputting a reset signal to clear the pulse response signal.

[0018] According to the second aspect of the present application, a multi-threshold digital reconstruction method is provided, including obtaining a digital sampling signal; reconstructing the digital sampling signal according to prior information to restore a counting step signal; and converting the counting step signal into unit time counting information.

[0019] In one of the embodiments, the reconstructing the digital sampling signal according to the prior information to restore the counting step signal includes: determining a physical model corresponding to the counting step signal; performing signal recovery processing on the digital sampling signal based on the physical model to restore the counting step signal.

[0020] In one embodiment, the physical model includes an exponential function model or a straight line function model.

[0021] In one of the embodiments, converting the counting step signal into unit time counting information includes: obtaining the unit time counting information by deriving a physical model corresponding to the counting step signal.

[0022] According to the third aspect of the present application, a multi-threshold digitization device is provided, comprising N detection modules, for outputting a pulse response signal when a photon is detected, and outputting a unit step signal when the pulse response signal reaches a trigger condition, wherein N is an integer greater than zero; a signal integration module, respectively connected to the N detection modules, for obtaining a counting step signal based on the unit step signal; and a digitization module, connected to the signal integration module, for digitizing the counting step signal based on a counting threshold, and outputting a digitized sampling signal.

[0023] In one embodiment, the detection module includes a photon counting detection unit, which is used to output a pulse response signal when a photon is detected; and a first threshold comparison unit, which is connected to the photon counting detection unit, is used to output a unit step signal when the pulse response signal reaches a trigger condition.

[0024] In one embodiment, the trigger condition includes: presetting a voltage, and when the pulse response signal is greater than the preset voltage, the trigger condition is determined to be met, and a unit step signal is output; or presetting a waveform feature, and when the waveform feature of the pulse response signal meets the preset waveform feature, the trigger condition is determined to be met, and a unit step signal is output.

[0025] In one embodiment, the preset waveform characteristics include: the maximum voltage reaches a preset voltage threshold, the current amplitude reaches a preset current threshold, or the accumulated voltage reaches a preset amplitude.

[0026] In one embodiment, the photon counting detection unit includes: a single-photon avalanche diode, the cathode of which is connected to an external reverse bias voltage; a quenching tube, the drain of which is connected to the anode of the single-photon avalanche diode, the source of which is grounded, and the gate of which is connected to an external DC voltage.

[0027] In one embodiment, the signal integration module includes an in-phase proportional addition circuit, which is respectively connected to the N detection modules and is used to perform sum processing on the unit step signal to obtain the counting step signal.

[0028] In one embodiment, the N detection modules are respectively connected to the signal input end of the in-phase proportional addition circuit through N input resistors, wherein the resistance values ​​of the N input resistors are the same.

[0029] In one embodiment, the in-phase proportional addition circuit includes an operational amplifier, a feedback resistor and a grounding resistor, wherein the output ends of the N detection modules are connected to the input resistor one by one and connected to the positive input end of the operational amplifier, one end of the feedback resistor is connected to the positive input end of the operational amplifier, the other end of the feedback resistor is connected to the output end of the operational amplifier, and the negative input end of the operational amplifier is grounded through the grounding resistor.

[0030] In one embodiment, the digitization module includes a power divider, which is used to divide the counting step signal into P sub-signals, where P is an integer greater than zero; P second threshold comparison units, which are respectively connected to the P output ends of the power divider, and the i-th second threshold comparison unit is used to compare the i-th sub-signal with the i-th counting threshold, i=1, 2, ..., P, and in response to the threshold comparison result that the i-th sub-signal is greater than or equal to the i-th counting threshold, obtain the trigger time of the threshold comparison result; a FIFO memory, which is respectively connected to the P second threshold comparison units, and is used to output P groups of counting threshold-time pairs according to the threshold comparison results and the trigger time output by the P second threshold comparison units.

[0031] In one embodiment, the second threshold comparison unit includes a comparator, a first input terminal of the comparator is connected to the i-th output terminal of the power divider, and a second input terminal of the comparator is connected to a digital-to-analog converter; a digital-to-analog converter, used to output the i-th counting threshold to the second input terminal of the i-th comparator; the comparator is used to compare the i-th sub-signal with the i-th counting threshold, i=1, 2, ..., P, and in response to the threshold comparison result that the i-th sub-signal is not less than the i-th counting threshold, the comparator outputs a trigger signal; a time-to-digital converter, connected to the comparator, used to obtain the trigger time of the comparison result according to the trigger signal.

[0032] In one of the embodiments, the multi-threshold digitization device further includes a reset module for outputting a reset signal to clear the impulse response signal.

[0033] According to the fourth aspect of the present application, a multi-threshold digital reconstruction device is provided, including a transmission module for acquiring a digital sampling signal; a data reconstruction module, connected to the transmission module, for reconstructing the digital sampling signal according to prior information, restoring the counting step signal, and converting the counting step signal into unit time counting information.

[0034] In one embodiment, the data reconstruction module includes: a modeling unit, used to determine the physical model corresponding to the counting step signal; a signal processing unit, connected to the modeling unit, used to perform signal recovery processing on the digitized sampling signal based on the physical model to restore the counting step signal.

[0035] In one embodiment, the physical model includes an exponential function model or a straight line function model.

[0036] In one of the embodiments, the data reconstruction module further includes a signal conversion unit connected to the signal processing unit and configured to convert the counting step signal into unit time counting information.

[0037] According to a fifth aspect of the present application, a computer device is provided, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the multi-threshold digitization method described in any one of the above embodiments are implemented, or the steps of the multi-threshold digital reconstruction method described in any one of the above embodiments are implemented.

[0038] According to the sixth aspect of the present application, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the multi-threshold digitization method described in any one of the above embodiments are implemented, or the steps of the multi-threshold digital reconstruction method described in any one of the above embodiments are implemented.

[0039] According to the seventh aspect of the present application, a computer program product is provided, comprising a computer program or instructions, characterized in that when the computer program or instructions are executed by a processor, the steps of the multi-threshold digitization method described in any one of the above embodiments are implemented, or the steps of the multi-threshold digital reconstruction method described in any one of the above embodiments are implemented.

[0040] The above multi-threshold digitization method outputs a unit step signal when the pulse response signal meets the trigger condition. By digitally processing the counting step signal obtained based on the unit step signal, a digital sampling signal can be output. By counting photons using the above multi-threshold digitization method, a digital sampling signal can be directly output, which preserves the original information of the incident photon sequence to the greatest extent, abandons the complex analog-to-digital conversion process, and directly realizes the digitization of the photon signal, which not only significantly improves the performance of photon detection, but also removes additional external digitization devices, expands the effective detection area of ​​photons, and makes the application prospects of SiPM broader. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the implementation methods of this specification or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 This is a schematic diagram of a flow chart of a multi-threshold digitization method in one embodiment of the present application; Figure 2 This is a schematic diagram of a process of outputting a unit step signal in one of the embodiments of the present application; Figure 3 This is a schematic diagram of a counting step signal in one embodiment of the present application; Figure 4 This is a schematic diagram of a process of outputting a digital sampling signal in one embodiment of the present application; Figure 5 This is a flow chart of a multi-threshold digitization method in another embodiment of the present application; Figure 6 This is a flow chart of a multi-threshold digital reconstruction method in one of the embodiments of the present application; Figure 7 This is a flow chart of a multi-threshold digital reconstruction method in another embodiment of the present application; Figure 8 This is a schematic diagram of the structure of a multi-threshold digitization device in one of the embodiments of the present application; Fig. 9 This is a schematic diagram of the structure of a detection module in one of the embodiments of the present application; Fig.10 This is a schematic diagram of the structure of a signal integration module in one of the embodiments of the present application; Fig.11 This is a schematic diagram of the structure of a signal integration module in one of the embodiments of the present application; Fig.12 This is a schematic diagram of the structure of a multi-threshold digital reconstruction device in one of the embodiments of the present application; Fig.13 This is a schematic diagram of the structure of a multi-threshold digital reconstruction device in another embodiment of the present application; Fig.14 This is a schematic diagram of a sampling system for implementing a multi-threshold digitization method in one embodiment of the present application; Fig.15 This is a diagram of the internal structure of a computer device in one of the embodiments of the present application. DETAILED DESCRIPTION

[0043] In order to make the above-mentioned purposes, features and advantages of the present application more understandable, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0044] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly fixed to the other element or there may be an element in the middle. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an element in the middle at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "and / or" or "and / or" used herein include any and all combinations of one or more related listed items.

[0046] Traditional SiPM generally adds up the MC signals and directly outputs them (referred to as SiPM signals), and then the devices / instruments outside the SiPM, such as ADC sampling circuits and multiple voltage threshold (MVT) acquisition cards, digitize and reconstruct the SiPM signals, thereby extracting the charge and arrival time information of the original SiPM signals, and then inferring the total number and arrival time of the incident photons. However, the traditional counting method essentially treats the already digital MC signals (MC has only two states, 0 and 1) as analog signals, adds them up, and then digitizes them. The digital-analog-digital conversion process will cause the original information of the incident photon sequence to be lost, and the incident photon time series cannot be recovered from the analog SiPM signal. In addition, the binary signals of hundreds to thousands of MCs are accumulated to form an analog signal output, resulting in the need for a series of analog signal processing circuits and analog-to-digital conversion circuits outside the SiPM to complete the digitization and reconstruction of the final signal. The complexity of the circuit makes it difficult to further reduce power consumption and volume, and also leads to performance limitations of the SiPM.

[0047] In response to the technical problems existing in the traditional SiPM counting scheme, the present application proposes a multi-threshold digitization method that can realize SiPM digital readout without losing the photon detection efficiency.

[0048] In some embodiments, the multi-threshold digitization method can be performed by a multi-threshold digitization device. For example, the multi-threshold digitization method can be stored in a storage device (such as a built-in storage unit of the detection device or an external storage device) in the form of a program or instruction, and the program or instruction can implement the multi-threshold digitization method when executed. The multi-threshold digitization device disclosed in the present application can be a device with a large amount of computing resources (for example, a computer, a server, cloud computing, etc.), or a device with limited computing resources (for example, a hardware circuit such as an FPGA chip board, an ASIC chip board, etc.).

[0049] Some preferred embodiments of the present application are described below with reference to the accompanying drawings. It should be noted that the following description is for illustrative purposes and is not intended to limit the scope of protection of the present application.

[0050] Figure 1 This is a flowchart of a multi-threshold digitization method in one of the embodiments of the present application. In one of the embodiments, the multi-threshold digitization method may include the following steps S100 to S300.

[0051] Step S100: when the impulse response signal meets the trigger condition, a unit step signal is output.

[0052] SiPM includes an array of several single photon avalanche diodes (MC) and corresponding auxiliary circuits. In the absence of incident photons, dark counts are not considered, and the MC units in the MC array are in an unexcited state (equivalent to 0 in binary). When a photon sequence is incident on the SiPM, some of the MC units will be excited (equivalent to 1 in binary) and generate a pulse response signal. In this embodiment, a trigger condition is set to assist in determining whether the MC unit has received a photon. When the pulse response signal meets the trigger condition, it is determined that the MC unit has received a photon and outputs a unit step signal. By pre-setting the trigger condition, the problem of erroneous readings of the MC unit due to noise interference and other situations can be reduced.

[0053] In some specific embodiments, the trigger condition can be set according to different application scenarios. For example, a preset voltage can be set corresponding to the MC unit, and the photon reacts with the MC unit to generate a pulse response signal after the photon is incident. When the pulse response signal is greater than the preset voltage, the trigger condition is determined to be met and a unit step signal is output; or the trigger condition can be determined to be met when the waveform of the pulse response signal meets the preset characteristics, such as the maximum voltage reaches the preset voltage threshold, the current amplitude reaches the preset current threshold, or the accumulated voltage reaches a certain amplitude.

[0054] More specifically, the MC unit can be connected to a comparison unit, and the preset voltage of the comparison unit is provided by a digital-to-analog converter integrated on the MC unit chip. When the MC unit detects a photon, it outputs an impulse response signal, which is transmitted to the comparison unit. When the amplitude of the impulse response signal reaches the preset voltage, the comparison unit outputs a unit step signal.

[0055] The unit step signal has the following characteristics: when the MC unit is not activated, it always maintains a 0 voltage output state; when an MC unit is activated, the amplitude of the unit step signal increases by one unit and maintains the amplitude, for example, the voltage amplitude increases by one unit to 3mV.

[0056] Step S200: obtaining a counting step signal based on the unit step signal.

[0057] Usually, SiPM includes an m×n (m, n are both non-zero natural numbers) MC array and corresponding auxiliary circuits. Each MC unit will generate a corresponding pulse response signal after detecting a photon, and a unit step signal will be output when the pulse response signal meets the trigger condition. Therefore, the MC array can output multiple unit step signals during detection. After multiple unit step signals are output in a certain form, a counting step signal is formed. For example, the unit step signals output by each MC unit are summed up by an in-phase proportional addition circuit to output a counting step signal; or the unit step signals output by the MC units corresponding to a row or a column are summed up by an addition circuit to output a counting step signal; or the unit step signals output by each MC unit are directly summed up by an in-phase proportional addition circuit to form a counting step signal; or the unit step signals output by each MC unit are first set with a corresponding delay, and then directly summed up to form a counting step signal. For how to output a counting step signal through an addition circuit, please refer to the device embodiment of this article, which will not be repeated here.

[0058] The counting step signal has the following characteristics: when the MC unit is not excited, it always maintains a 0 voltage output state; when an MC unit is excited, the amplitude of the counting step signal increases by one unit and maintains the amplitude. For example, the voltage amplitude increases by one unit, which is 3mV. At this time, the amplitude of the counting step signal is equal to the amplitude of the unit step signal; when n MC units are excited, the amplitude of the counting step signal increases by n units and maintains the amplitude. In other words, at a certain time t, the total amplitude of the counting step signal divided by the unit amplitude represents the total number of MC units excited in the SiPM as of time t.

[0059] In this embodiment, the counting step signal includes the quantity information of the received unit step signal, and different statistical methods can be used to obtain the counting step signal based on the unit step signal. For example, a counter can be used to count the received counting step signal to obtain the number of unit step signals, or the amplitude of the received counting step signal can be converted to obtain the number of unit step signals.

[0060] Step S300: digitally process the count step signal and output a digital sampling signal.

[0061] Since the counting step signal contains the quantity information of the received unit step signals, the digital processing method can be used to realize the direct digitization of the SiPM incident photon sequence.

[0062] The above-mentioned digital processing method can be a multi-counting threshold digital sampling method, which samples the incident photon sequence through the counting threshold and reads it directly in the form of a digital signal. How to digitize the counting step signal through the multi-threshold digitization method will be further combined with Figure 4 The method can directly digitize the output signal, save additional external digitization devices, and preserve the original information of the incident photon sequence to the greatest extent. The external computer can combine the prior information of the incident photon sequence and the digitized sampling signal to accurately reconstruct the time series of the incident photons through an algorithm.

[0063] The above-mentioned digital processing method can be a multi-voltage threshold digital sampling method, which samples the incident photon sequence through the voltage threshold and reads it out directly in the form of a digital signal. For example, if multiple voltage thresholds are set arbitrarily, when the counting step signal crosses each voltage threshold, a voltage-time pair can be output. Although these voltage thresholds are not integer multiples of the amplitude of the unit step signal, the amplitude of the integer multiple unit step signal closest to each voltage threshold can be converted through an algorithm. For example, the amplitude of the unit step signal is 3mV, and the voltage threshold is 0.1V. Since the cumulative amplitude of 33 unit step signals is 0.099V, it can be considered that when the counting step signal crosses 0.1V, a total of 34 MC units are triggered, thereby obtaining the original information of the incident photon sequence that approximately corresponds to the counts and trigger times corresponding to the multiple voltage thresholds.

[0064] The above-mentioned digital processing method can also be a coded digital sampling method. For example, since the amplitude of the unit step signal is fixed, by measuring the number of times the amplitude of the step signal jumps and the time of the jump, the jump number and jump time data sequence are output and directly read out in the form of a digital signal. The information of the incident photon can be further restored through a computer and prior information of the photon sequence. This is something that a technician in this field can easily think of based on the multi-threshold digitization method of the present application and will not be elaborated here.

[0065] Figure 2 This is a flow chart of outputting a unit step signal in one of the embodiments of the present application. In one of the embodiments, when the pulse response signal meets the trigger condition, outputting the unit step signal may include the following steps S110 to S120.

[0066] Step S110: Compare the impulse response signal with the trigger threshold.

[0067] In this embodiment, a trigger threshold can be set, and the trigger threshold can be compared with the size of the pulse response signal to assist in determining whether the MC unit has received a valid photon. For example, when applied to gamma photon detection, the amplitude of the pulse response signal generated by a single gamma photon is often the same. The trigger threshold can be set to be slightly lower than the amplitude through a digital-to-analog converter, and the pulse response signal output by the MC unit is input into the comparison unit and compared with the trigger threshold preset in the comparison unit.

[0068] Step S120: In response to the comparison result that the impulse response signal is not less than the trigger threshold, output a unit step signal.

[0069] When the pulse response signal is greater than or equal to the trigger threshold, it can be determined that the pulse response signal meets the trigger condition, that is, in this embodiment, the comparison result that the pulse response signal is greater than or equal to the trigger threshold can be defined as the trigger condition. In response to the comparison result that the pulse response signal is greater than or equal to the trigger threshold, a unit step signal can be output. Specifically, when any MC unit detects a photon, a pulse response signal is output. The trigger threshold can be a trigger voltage Vt in a specific implementation. The pulse response signal is transmitted to the first threshold comparison unit, and when the amplitude of the pulse response signal reaches the trigger voltage Vt, the first threshold comparison unit outputs a unit step signal.

[0070] In one embodiment, the step of acquiring the counting step signal based on the unit step signal may specifically include performing sum processing on the unit step signal to acquire the counting step signal.

[0071] In a specific implementation, each unit step signal can be transmitted to an in-phase proportional adding circuit for addition processing to form a counting step signal. For example, five MC units are triggered at 1ns, 2ns, 3ns, 4ns and 5ns, respectively. The adding circuit outputs a signal with a unit amplitude of A0 at 1ns and then maintains it. At 2ns, a signal triggered by another MC unit is added, and the output amplitude is 2A0. At 3ns, a signal triggered by the third MC unit is added, and the output amplitude is 3A0. At 4ns, a signal triggered by the fourth MC unit is added, and the output amplitude is 4A0. At 5ns, a signal triggered by the fifth MC unit is added, and the output amplitude is 5A0. In this way, a step-shaped counting step signal is formed.

[0072] Figure 3 This is a schematic diagram of a counting step signal in one of the embodiments of the present application. Since there is actually an array formed by a large number of MC units, the number of MC units actually triggered is large, and the signals triggered by several MC units are normalized. The counting step signal formed by the in-phase proportional addition circuit has the following characteristics: at the initial stage of detection, the counting step signal output by the SiPM is 0. At time t1, Q1 number of MC units are excited, for example, 100 MC units are excited, and after the unit step signals output by these number of MC units are added, the counting step signal output by the SiPM rises by Q1A0 level heights (i.e., a cumulative Q1 unit level A0), and the amplitude remains at Q1A0 until time t2, when the number of excited MC units reaches Q2, for example, 200, and the counting step signal output by the SiPM rises to Q2A0, that is, the level amplitude of the counting step signal at this time is Q2A0; and so on, the following is formed. Figure 3 As shown in FIG. 1 , the amplitude of the counting step signal at any time t0 is divided by A0, and the resulting value is the number of MC units in the SiPM that are activated up to time t0.

[0073] Figure 4 This is a flow chart of outputting a digital sampling signal in one embodiment of the present application. In one embodiment, the digital sampling signal may include a counting threshold-time pair. Digital processing of the counting step signal and outputting the digital sampling signal may include the following steps S310 to S340.

[0074] Step S310: Divide the counting step signal into P path signals; P is an integer greater than zero.

[0075] Step S320: Preset P counting thresholds, and the values ​​of the P counting thresholds are different from each other.

[0076] Step S330: Compare the i-th path sub-signal with the i-th counting threshold, i=1, 2, ..., P.

[0077] Step S340: in response to the threshold comparison result that the i-th path sub-signal is not less than the i-th counting threshold, obtaining the trigger time of the threshold comparison result, and outputting P groups of counting threshold-time pairs.

[0078] According to the above embodiment, the counted step signal includes time information and the count information of the unit step signal, so the number of MCs excited in the SiPM can be converted and determined according to the voltage amplitude of the counted step signal at different times. Considering the large number of MCs in the SiPM, in this embodiment, by setting P different counting thresholds, counting statistics are implemented in stages, simplifying the digital sampling process.

[0079] The counting step signal is divided into P path signals, and at the same time, P counting thresholds with different values ​​are selected according to prior information, and the P path signals can be compared with the P counting thresholds respectively. In a preferred embodiment, the counting step signal can be equally divided into P path signals, that is, the counting step signals in each path are the same. Wherein, P is a non-zero natural number.

[0080] Taking the counting threshold as voltage as an example, suppose the P counting thresholds are Q1A0, Q2A0, ..., Q i A0, ..., Q p A0, compares the P-path signal with the P counting thresholds one by one. When the amplitude of the counting step signal reaches Q i When A0, the i-th counting threshold is triggered, that is, when the threshold comparison result between the i-th sub-signal and the i-th counting threshold is that the i-th sub-signal is greater than or equal to the i-th counting threshold, the time T when the i-th counting threshold is triggered is obtained. i , we can obtain the count threshold-time pair (Q i A0,T i ); and so on, P counting threshold-time pairs can be obtained. Since the counting step signal obeys a specific physical model, its shape can usually be represented by an exponential model, such as C(t)=N 2 (1-e [a(t-t0)] ), after obtaining the counting threshold-time pair information, the counting step signal can be restored from the counting threshold-time pair information through fitting, neural network and other methods. It can be seen that the counting threshold-time pair (Q i A0,T i ) contains counting information and time information. After eliminating A0 based on the counting threshold-time pair, the total number of MC units excited in SiPM is Q i Time T i .

[0081] In practical applications, a suitable value can be selected as the value of P by comprehensively considering prior information and implementation cost. Preferably, when P=4, a better sampling and counting effect is achieved. For example, when P=4 and a total of 500 MC units are triggered in the SiPM, the counting step signal will be a signal with a maximum amplitude of 500A0=500×3mV=1.5V, then the four counting thresholds can be set to 100A0 (0.3V), 200A0 (0.6V), 300A0 (0.9V), and 400A0 (1.2V), respectively. Compare the first sub-signal with the first counting threshold 0.3V, and when the first sub-signal crosses the first counting threshold 0.3V, obtain the time T1 when the first counting threshold is triggered, thereby obtaining the first counting threshold-time pair (0.3V, T1); compare the second sub-signal with the second counting threshold 0.6V, and when the second sub-signal crosses the second counting threshold 0.6V, obtain the time T2 when the second counting threshold is triggered, thereby obtaining the second counting threshold-time pair (0.6V, T2); and so on, 4 counting threshold-time pairs are obtained, and further computer processing of these counting threshold-time pairs can restore the waveform of the counting step signal.

[0082] Figure 5 This is a flow chart of a multi-threshold digitization method in another embodiment of the present application. In one of the embodiments, after the counting step signal is digitized and the digitized sampling signal is output, the multi-threshold digitization method may further include the following step S400.

[0083] Step S400: output a reset signal to clear the pulse response signal.

[0084] After the current SiPM detection process is completed, a reset signal is output to clear all MC counts to zero and wait for the next detection.

[0085] The above multi-threshold digitization method samples the incident photon sequence by setting the counting threshold, and records the time when the number of incident photons reaches a set of preset and programmable counting thresholds to realize the direct digitization of the SiPM incident photon sequence. The counting threshold and the time of triggering the counting threshold constitute a counting threshold-time pair, which can be directly read out in the form of a digital signal, thereby saving additional external digitization devices and preserving the original information of the incident photon sequence to the greatest extent. The external device can accurately restore the incident photon time series based on the digitized sampling signal.

[0086] This application also proposes a multi-threshold digital reconstruction method that can accurately restore the time series of incident photons. Figure 6This is a flow chart of a multi-threshold digital reconstruction method in one of the embodiments of the present application. In one of the embodiments, the multi-threshold digital reconstruction method may include the following steps S10 to S30.

[0087] Step S10: Acquire a digital sampling signal.

[0088] Step S20: reconstructing the digital sampling signal according to the prior information to restore the counting step signal.

[0089] Step S30: converting the counting step signal into unit time counting information.

[0090] The digitized sampling signal may refer to the digitized sampling signal obtained by the multi-threshold digitization method in the above-mentioned embodiment. In this embodiment, the signal characteristics of the counting step signal can be analyzed by preliminary experiments to determine the relevant prior information, so as to reconstruct the digitized signal according to the prior information and restore the counting step signal. For example, according to the function or shape model that the counting step signal conforms to, the digitized sampling signal is reconstructed and the counting step signal is restored. Furthermore, the counting step signal is transformed to obtain the unit time counting information.

[0091] The above-mentioned multi-threshold digital reconstruction method reconstructs the digital sampling signal according to prior information, preserves the original information of the incident photon sequence to the greatest extent, can accurately restore the incident photon time series, and realizes the digital readout and reconstruction of SiPM without losing the photon detection efficiency. The system detection performance and efficiency are greatly improved compared with the existing technology, and can save system costs at the same time.

[0092] Figure 7 This is a flow chart of a multi-threshold digital reconstruction method in another embodiment of the present application. In one embodiment, reconstructing the digital sampling signal according to prior information and obtaining the counting step signal may include the following steps S21 and S23.

[0093] Step S21: Determine the physical model corresponding to the counting step signal.

[0094] Step S23: performing signal recovery processing on the digital sampling signal based on the physical model to restore the counting step signal.

[0095] According to the embodiment of the multi-threshold digitization method, the counting step signal obeys the physical model, and the voltage threshold of the counting step signal is the number of counts × A0. For the scintillation pulse corresponding to the gamma photon, its step-shaped waveform characteristics can usually be represented by an exponential model, for example, C(t)=N 2 (1-e [a(t-t0)]). Therefore, the external device can recover the count step signal from the count-time pair of the digital sampling signal through signal processing methods such as fitting algorithm and neural network algorithm.

[0096] In one embodiment, after determining the physical model corresponding to the counting step signal, the unit time counting information can be determined based on the physical model corresponding to the counting step signal. Specifically, the model corresponding to the counting step signal can be derived to obtain the unit time counting information. For example, when the exponential model corresponding to the counting step signal is C(t)=N 2 (1-e [a(t-t0)] ), we can derive C(t) to get the unit time counting information.

[0097] In addition, for other types of high-energy photons or visible photons, the waveform of the corresponding pulse signal may be other shapes. For example, for visible light with basically the same light intensity and frequency, the physical model obeyed by the counting step signal can be approximately represented by a linear function model, and the voltage threshold of the counting step signal is the number of counts × A0, for example, C(t) = at + b, where a and b are constants. Therefore, the external device can recover the counting step signal from the count-time pair of the digitized sampling signal through signal processing methods such as fitting algorithms. Furthermore, the unit time counting information can be determined based on the physical model corresponding to the counting step signal. Specifically, the model corresponding to the counting step signal can be derived to obtain the unit time counting information, which is easy to implement based on the inspiration of the present application and will not be repeated here.

[0098] It should be understood that, although the steps in the flowcharts of the accompanying drawings of the specification are displayed in sequence as indicated by the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts of the accompanying drawings of the specification may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0099] Based on the description of the above-mentioned multi-threshold digitization method embodiment, the present application also provides a fast, accurate and stable multi-threshold digitization device. The device may include a device (including a distributed system), software (application), module, component, server, client, etc. using the method described in the embodiment of this specification and a device combined with necessary implementation hardware. Based on the same innovative concept, the device in one or more embodiments provided in the embodiment of the present application is as described in the following embodiments. Since the implementation scheme and method of the device to solve the problem are similar, the implementation of the specific device in the embodiment of this specification can refer to the implementation of the aforementioned method, and the repetitions will not be repeated. As used below, the term "module" or "module" can implement a combination of software and / or hardware for a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0100] The existing counting scheme for realizing full digitization of SiPM usually uses TDC (Time-to-Digit Converter) array to digitize and read out the signals of each MC. Although this realizes full digitization of SiPM, it is necessary to design a large number of electronic devices on the chip to read out the time information of the rising edge and the falling edge respectively. The large number of electronic devices on the chip occupy the photosensitive area of ​​MC, resulting in a significant reduction in the filling rate of SiPM (that is, the ratio of the photosensitive area to the chip area). The reduction in the filling rate leads to a reduction in the efficiency of photon detection, which in turn reduces the signal-to-noise ratio of the signal. Moreover, it also leads to excessive cost and power consumption.

[0101] The present invention provides a multi-threshold digitization device which realizes full digitization of SiPM and reduces the loss of photosensitive area as much as possible. Figure 8 This is a schematic diagram of the structure of a multi-threshold digitization device in one of the embodiments of the present application. In one of the embodiments, the multi-threshold digitization device may include N detection modules 100, a signal integration module 200 and a digitization module 300.

[0102] The N detection modules 100 can output an impulse response signal when detecting a photon, and the detection module 100 can also output a unit step signal when the impulse response signal reaches a trigger condition; N is an integer greater than zero. In the design of practical applications, the N detection modules 100 in the multi-threshold digitization device can be arranged in an n×n array form (N=n×n) or in an m×n array form (N=m×n), where m and n are both non-zero natural numbers.

[0103] In the absence of photon incidence, dark counts are not considered, and the detection module 100 is in an unexcited state (i.e., equivalent to an output of 0 in binary). When a photon sequence is incident on a multi-threshold digitization device, the detection module 100 will be excited (i.e., equivalent to an output of 1 in binary) and generate a pulse response signal. In this embodiment, a trigger condition is set to assist in determining whether the detection module 100 has received a photon. When the pulse response signal meets the trigger condition, it is determined that the detection module 100 has received a photon and outputs a unit step signal. By presetting the trigger condition, the problem of erroneous readings of the detection module 100 due to noise interference and the like can be reduced.

[0104] In some specific embodiments, the trigger condition can be set according to different application scenarios. For example, a preset voltage can be set on the MC unit in the detection module 100, and the photon reacts with the MC unit to generate a pulse response signal after the photon is incident. When the pulse response signal is greater than the preset voltage, the trigger condition is determined to be met, and the detection module outputs a unit step signal; the trigger condition can be determined to be met when the waveform of the pulse response signal meets the preset characteristics, such as the maximum voltage reaches a preset threshold, the current amplitude reaches a preset threshold, or the cumulative voltage reaches a certain amplitude, etc. This is easy for a person skilled in the art to think of based on the enlightenment of this application, and will not be listed here one by one.

[0105] The unit step signal has the following characteristics: when the MC unit is not activated, it always maintains a 0 voltage output state; when an MC unit is activated, the amplitude of the unit step signal increases by one unit and maintains the amplitude, for example, the voltage amplitude increases by one unit to 3mV.

[0106] The signal integration module 200 is connected to the N detection modules 100 respectively. The signal integration module 200 can be used to obtain a counting step signal based on a unit step signal.

[0107] When multiple detection modules 100 detect photons, they respectively output multiple unit step signals. In this embodiment, the signal integration module 200 can obtain a counting step signal based on the unit step signal, and use the counting step signal to count the number of received unit step signals.

[0108] Usually, SiPM includes an m×n (m, n are both non-zero natural numbers) MC array and corresponding auxiliary circuits. Each MC unit will generate a corresponding pulse response signal after detecting a photon, and a unit step signal will be output when the pulse response signal meets the trigger condition. Therefore, the MC array can output multiple unit step signals during detection. After multiple unit step signals are output in a certain form, a counting step signal is formed. For example, the unit step signals output by each MC unit are summed up through an in-phase proportional addition circuit to output a counting step signal; or the unit step signals output by the MC units corresponding to a row or a column are summed up through an addition circuit to output a counting step signal; or the unit step signals output by each MC unit are directly summed up through an in-phase proportional addition circuit to form a counting step signal; or the unit step signals output by each MC unit are first set with a corresponding delay, and then directly summed up to form a counting step signal.

[0109] Different statistical methods can be used to obtain the counting step signal based on the unit step signal. For example, a counter can be used to count the received counting step signal to obtain the number of unit step signals contained therein, or the amplitude of the received counting step signal can be converted to obtain the number of unit step signals.

[0110] The digitization module 300 is connected to the signal integration module 200. The digitization module 300 can be used to digitize the count step signal based on a threshold or encoding, and output a digitized sampling signal. Since the count step signal contains the quantity information of the received unit step signal, the digitization module 300 can use a digital processing method to realize direct digitization of the SiPM incident photon sequence. The above-mentioned digital processing method can be any digital processing method described in the method embodiment part of this application, which will not be repeated here.

[0111] Fig. 9 This is a schematic diagram of the structure of a detection module in one of the embodiments of the present application. In one of the embodiments, the detection module 100 may include a photon counting detection unit 110 and a first threshold comparison unit 120 .

[0112] The photon counting detection unit 110 can be used to output a pulse response signal when a photon is detected. Fig. 9 The photon counting detection unit 110 may include a single photon avalanche diode D1 and a quenching tube Q1. The cathode of the single photon avalanche diode D1 is connected to the reverse bias voltage input externally, the anode of the single photon avalanche diode D1 is connected to the ground via the quenching tube Q1, the drain of the quenching tube Q1 is connected to the anode of the single photon avalanche diode D1, the source of the quenching tube Q1 is grounded, and the gate of the quenching tube Q1 is connected to the external DC voltage V q , DC voltage V qCan be used to control the pulse width of the quench tube.

[0113] The first threshold comparison unit 120 can be connected to the photon counting detection unit 110. The first threshold comparison unit 120 can be used to output a unit step signal when the pulse response signal reaches the trigger condition. Fig. 9 The first threshold comparison unit 120 may include a comparator U1. The output end of the photon counting detection unit 110 may be connected to the positive input end of the comparator U1, and the negative input end of the comparator U1 may be connected to the external input trigger voltage V t .

[0114] When the single-photon avalanche diode D1 detects a photon, it will output a pulse response signal. The pulse response signal is transmitted to the positive input terminal of the comparator U1, and the comparator U1 compares the pulse response signal with the trigger voltage V t When the amplitude of the pulse response signal reaches the trigger voltage V t When , the comparator U1 outputs a unit step signal Vij, where i and j represent the number of rows and columns in the MC array, respectively, and j=1, 2, 3, ..., N. The jth detection module 100 outputs the unit step signal Vij. The trigger voltage V t can be the same, and the trigger voltages V t Both can be provided by a digital-to-analog converter (DAC) integrated on-chip.

[0115] Fig.10 1 is a schematic diagram of the structure of a signal integration module in one embodiment of the present application. In one embodiment, the signal integration module 200 may include an in-phase proportional addition circuit 210 .

[0116] The in-phase proportional adding circuit 210 can be connected to N detection modules 100 respectively. The in-phase proportional adding circuit 210 can be used to perform sum processing on the unit step signal output by any detection module 100 to obtain a counting step signal.

[0117] In one embodiment, the output ends of the N detection modules 100 can be connected to the signal input end of the in-phase proportional addition circuit 210 through N input resistors 211 respectively. Fig.10 The in-phase proportional adding circuit 210 may include an operational amplifier U2, a feedback resistor R f and grounding resistance Rs. The unit step signals output by the N detection modules 100 can be V i1 、V i2 , ..., V iNThe output terminals of the N detection modules 100 are connected to the input resistors 211 (shown as R1, R2, ..., R N ) is connected to the positive input terminal of the operational amplifier U2, and the feedback resistor R f One end is connected to the positive input terminal of the operational amplifier U2, and the feedback resistor R f The other end is connected to the output end of the operational amplifier U2, and the negative input end of the operational amplifier U2 is grounded through the grounding resistor Rs.

[0118] The operational amplifier U2 can perform a sum operation on N unit step signals and output a count step signal Vo. Specifically, the count step signal Vo=R f ×(V i1 / R1+V i2 / R2+V i3 / R3+...V iN / R N ), which is equivalent to multiplying the unit step signal output by each detection module 100 by a ratio and outputting it. Among them, the resistance values ​​of the N input resistors 211 are all the same, so the ratio of the unit step signal output by each detection module 100 is the same, which can ensure that the voltage input to the in-phase proportional addition circuit 210 of each detection module 100 is the same. Due to the difference in the arrival time of the photons, the unit step signal output by each detection module 100 has a time difference, so a counting step signal with an amplitude that changes with time will be generated at the output end of the in-phase proportional addition circuit 210. For example, if two detection modules 100 are triggered at 1ns and 2ns respectively, the in-phase proportional addition circuit 210 outputs a counting step signal with an amplitude of A0 at 1ns and maintains it, and at 2ns, the unit step signal output by the second triggered detection module 100 is added, and the amplitude of the counting step signal output by the in-phase proportional addition circuit 210 at 2ns becomes 2A0, thereby forming a stepped counting step signal.

[0119] In a specific embodiment, the multi-threshold digitization device includes detection modules 100 arranged in a 32×32 square, and the total number of detection modules 100 is 32×32=1024. After each detection module 100 converts the pulse response signal into a unit step signal of a digital logic high level, the 1024 detection modules 100 are connected to the in-phase proportional addition circuit 210, and the unit step signal is converted into a counting step signal by the in-phase proportional addition circuit 210. Usually, the power supply of the in-phase proportional addition circuit 210 is 3.3V, so the voltage range of the in-phase proportional addition circuit 210 output is 0-3.3V. When the number of triggered detection modules 100 ranges from 0 to 1024, A0=3.3V÷1024≈3mV.

[0120] Fig.11This is a structural diagram of a digitization module in one of the embodiments of the present application. In one of the embodiments, the digitization module 300 may include a power divider (not shown), P second threshold comparison units 310 and a FIFO (First Input First Output) memory 320.

[0121] In this embodiment, the counting step signal can be compared with the counting thresholds of different values, and the counting threshold-time pair can be obtained by recording the time when the counting step signal triggers the counting threshold. Therefore, the counting step signal can be divided into P path signals by a power divider; P is an integer greater than zero. The P path signals are respectively input into P second threshold comparison units 310, and P can take any value.

[0122] The P second threshold comparison units 310 are respectively connected to the P output terminals of the power divider in one-to-one correspondence. Among them, the i-th second threshold comparison unit 310 can be used to compare the i-th sub-signal with the i-th counting threshold, i=1, 2, ..., P, and the i-th second threshold comparison unit 310 can also obtain the trigger time of the threshold comparison result in response to the threshold comparison result that the i-th sub-signal is greater than or equal to the i-th counting threshold.

[0123] Since the detection module 100 uses the trigger threshold to normalize the output unit step signal, in this embodiment, a counting threshold can be set, and the counting threshold = the number of excited detection modules 100 × A0, to achieve the counting of photon detection. Considering the device output value corresponding to 511keV gamma photons (denoted as E γ ) is affected by the detection efficiency of the device, the properties of the crystal, etc., and is generally not a fixed value. A radiation source experiment must be performed first to determine E γ Therefore, in practical applications, the device output value corresponding to the gamma photon can be determined by preliminary experiments. Usually, more channels will bring greater costs. Therefore, considering the experimental results and cost efficiency, P=4 can usually achieve a better sampling effect. The 4-channel counting threshold can be set to E γ 20%, 40%, 60%, 80% of.

[0124] The FIFO memory 320 can be connected to the P second threshold comparison units 310 respectively, and the FIFO memory 320 can be used to output P groups of counting threshold-time pairs according to the threshold comparison results and the triggering time of the threshold comparison results respectively output by the P second threshold comparison units 310. The FIFO memory 320 can collect the threshold comparison results and the triggering time of the threshold comparison results of the P second threshold comparison units 310, push them into a stack and store them. The FIFO memory 320 is a first-in-first-out dual-port buffer, that is, the first data entering it is the first to be removed, and continuous data streams can be cached to prevent data loss during machine entry and storage operations.

[0125] When P=4, after the counting step signal is input into the digitization module 300, the power divider divides it into 4 sub-signals and enters the input channels of the 4 second threshold comparison units 310 respectively, and the counting threshold (comparator threshold) corresponding to each channel is different. When the sub-signal is higher than the counting threshold corresponding to this channel, the second threshold comparison unit 310 will output a digital pulse signal (such as a unit high-level signal) and measure the trigger time of this digital pulse signal. Each second threshold comparison unit 310 can obtain the counting threshold and timestamp that triggers this comparison threshold, so that the FIFO memory 320 centrally stores the data of the 4 second threshold comparison units 310, and 4 groups of counting threshold-time pairs can be obtained. The subsequent external computer can restore the entire counting pulse through prior information.

[0126] See also Fig.11 In one embodiment, the second threshold comparison unit 310 includes a comparator 311 , a digital-to-analog converter 312 , and a time-to-digital converter 313 .

[0127] The first input terminal of the comparator 311 is connected to the i-th output terminal of the power divider, and the second input terminal of the comparator 311 is connected to the digital-to-analog converter 312. The digital-to-analog converter 312 can be used to output the i-th counting threshold to the second input terminal of the comparator 311. The comparator 311 can be used to compare the i-th sub-signal with the i-th counting threshold, i=1, 2, ..., P, and the comparator 311 can also output a digital pulse signal in response to the threshold comparison result that the i-th sub-signal is greater than or equal to the i-th counting threshold. The time-to-digital converter 313 is connected to the output terminal of the comparator 311, and the time-to-digital converter 313 can be used to obtain the trigger time of the comparison result according to the digital pulse signal.

[0128] The i-th sub-signal is transmitted to the first input terminal of the i-th comparator 311, and the i-th digital-to-analog converter 312 also inputs the i-th counting threshold to the second input terminal of the i-th comparator 311. Among them, the counting thresholds input to the second input terminal of the comparator 311 by each digital-to-analog converter 312 in the P second threshold comparison units 310 are different. When the amplitude of the i-th sub-signal is higher than the i-th counting threshold, the i-th comparator 311 outputs a digital pulse signal. The digital pulse signal is transmitted to the i-th time digital converter 313, and the i-th time digital converter 313 can measure the trigger time of the digital pulse signal. In this embodiment, the i-th time digital converter 313 can measure the timestamp of the digital pulse signal and package it into a Gray code output with a length of about 30 bits, including the timestamp and counting threshold information. That is, each second threshold comparison unit 310 can obtain the counting threshold and timestamp that triggers this path.

[0129] In one embodiment, the multi-threshold digitization device may further include a reset module, which may be used to output a reset signal to clear the pulse response signal. After the time-to-digital converters 313 in the P second threshold comparison units 310 have completed their work and output event frames (each channel outputs a Gray code with a length of about 30 bits), the reset module may output a reset signal to clear all counts of the N detection modules 100 to wait for the next detection work.

[0130] Compared with the traditional sampling device that uses a TDC array to digitally sample the signals of each MC unit, the multi-threshold digitization device provided by the present application only sets P TDCs to realize the sampling and counting of the detector, abandons the complex analog-to-digital conversion process, and directly realizes the digitization of the photon signal, which not only significantly improves the performance of photon detection, but also reduces the number of electronic devices designed on the chip, increases the photosensitive area, increases the fill rate, thereby improving the photon detection efficiency and effectively reducing the cost. The above-mentioned multi-threshold digitization device can realize the digital readout of SiPM with the smallest possible electronic cost without losing the photon detection efficiency.

[0131] Fig.12 This is a schematic diagram of the structure of a multi-threshold digital reconstruction device in one of the embodiments of the present application. In one of the embodiments, the multi-threshold digital reconstruction device may include a transmission module 400 and a data reconstruction module 500.

[0132] The transmission module 400 can be used to obtain the digital sampling signal. The data reconstruction module 500 can be connected to the transmission module 400, and the data reconstruction module 500 can be used to reconstruct the digital sampling signal according to the prior information to obtain the counting step signal; the data reconstruction module 500 can also be used to convert the counting step signal into unit time counting information.

[0133] The digitized sampling signal may refer to the digitized sampling signal obtained by the multi-threshold digitization device in the above-mentioned embodiment. In this embodiment, the multi-threshold digital reconstruction device can read the digitized sampling signal of the multi-threshold digitization device through the transmission module 400. After obtaining the digitized sampling signal, the data reconstruction module 500 can analyze the signal characteristics of the counting step signal through preliminary experiments, determine the relevant prior information, and then reconstruct the digitized signal according to the prior information to restore the counting step signal. For example, according to the function or shape model that the counting step signal conforms to, the digitized sampling signal is reconstructed and the counting step signal is restored. Further, the counting step signal is transformed to obtain the unit time counting information.

[0134] The multi-threshold digital reconstruction device reconstructs the digital sampling signal according to the prior information, preserves the original information of the incident photon sequence to the greatest extent, accurately restores the incident photon time series, and realizes the digital readout and reconstruction of SiPM without losing the photon detection efficiency.

[0135] Fig.13 This is a schematic structural diagram of a multi-threshold digital reconstruction device in another embodiment of the present application. In one embodiment, the data reconstruction module 500 may include a modeling unit 510 and a signal processing unit 520.

[0136] The modeling unit 510 may be used to determine the physical model corresponding to the count step signal. The signal processing unit 520 may be connected to the modeling unit 510 and may be used to perform signal recovery processing on the digitized sampling signal based on the physical model to restore the count step signal.

[0137] According to the embodiment of the multi-threshold digitization device described above, the counting step signal obeys the physical model. The voltage threshold of the counting step signal is the number of counts × A0. The modeling unit 510 can set the corresponding physical model according to the characteristics of the counting step signal. For example, the exponential model C(t)=N 2 (1-e [a(t-t0)] ) or a straight line function model represents the count step signal. Furthermore, the signal processing unit 520 can perform signal recovery processing on the digitized sampled signal based on the physical model determined by the modeling unit 510 by a signal processing method such as a fitting algorithm and a neural network algorithm, and recover the count step signal from the count threshold-time pair of the digitized sampled signal.

[0138] In one embodiment, the data reconstruction module 500 may further include a signal conversion unit 530. The signal conversion unit 530 may be connected to the signal processing unit 520, and the signal conversion unit 530 may be used to convert the counting step signal into unit time counting information. In a specific implementation, the signal conversion unit 530 may derive the model corresponding to the counting step signal to obtain the unit time counting information. For example, when the exponential model corresponding to the counting step signal is C(t)=N 2 (1-e [a(t-t0)] ), C(t) can be differentiated to obtain the unit time counting information, which can be an impulse sequence function.

[0139] It should be understood that Figure 8 , Fig.12 and Fig.13 The device and its modules shown can be implemented in various ways. For example, in some embodiments, the device and its modules can be implemented by hardware, software, or a combination of software and hardware. Among them, the hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution device, such as a microprocessor or a dedicated design hardware. Those skilled in the art will understand that the above methods and devices can be implemented using computer executable instructions and / or included in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the device and its modules of this specification. Not only can the hardware circuits such as ultra-large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc. be implemented, they can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above hardware circuits and software (for example, firmware).

[0140] It should be noted that the above description of the modules is only for convenience of description and does not limit this specification to the scope of the embodiments. It is understandable that for those skilled in the art, after understanding the principle of the device, it is possible to arbitrarily combine the modules or form a subsystem to connect with other modules without deviating from this principle. For example, the modules can share a storage module, or each module can have its own storage module. Such variations are all within the scope of protection of this specification.

[0141] Fig.14 This is a schematic diagram of a sampling system for implementing a multi-threshold digitization method in one embodiment of the present application. Fig.14The multi-threshold digitization system S00 may include a processing component S20, which further includes one or more processors, and a memory resource represented by a memory S22 for storing instructions executable by the processor of the processing component S20, such as an application. The application stored in the memory S22 may include one or more instructions, and each module corresponds to a set of instructions. In addition, the processing component S20 is configured to execute instructions to perform the multi-threshold digitization method described above.

[0142] The operations and / or methods implemented by one processor described in the embodiments of this specification may also be implemented jointly or independently by multiple processors. For example, if in this specification, a processor of a processing device executes step 1 and step 2, it should be understood that step 1 and step 2 may also be executed jointly or independently by two different processors of the processing device (for example, the first processor executes step 1, the second processor executes step 2, or the first and second processors execute step 1 and step 2 jointly).

[0143] The multi-threshold digitizing system S00 may also include: a power supply component S24 configured to perform power management of the multi-threshold digitizing system S00; a wired or wireless network interface S26 configured to connect the multi-threshold digitizing system S00 to a network; and an input / output (I / O) interface S28. The multi-threshold digitizing system S00 may operate based on an operating system stored in the memory S22, such as Windows Server, Mac OS X, Unix, Linux, FreeBSD, or the like.

[0144] In an exemplary embodiment, a computer-readable storage medium including instructions is also provided, such as a memory S22 including instructions, and the above instructions can be executed by a processor of the multi-threshold digitization system S00 to complete the above method. The storage medium can be a computer-readable storage medium, for example, the computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0145] In an exemplary embodiment, a computer program product is further provided. The computer program product includes instructions. The instructions can be executed by a processor of the multi-threshold digitization system S00 to implement the above method.

[0146] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Fig.15 As shown, Fig.15This is an internal structure diagram of a computer device in one of the embodiments of the present application. The computer device includes a processor, a memory and a network interface connected via a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data related to users and tasks used in the above-mentioned multi-threshold digitization method. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a multi-threshold digitization method is implemented.

[0147] Those skilled in the art will understand that Fig.15 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0148] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0149] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the hardware + program embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0150] It should be noted that the above-mentioned devices, electronic devices, servers, etc. may also include other implementation methods according to the description of the method embodiments, and the specific implementation methods may refer to the description of the relevant method embodiments. At the same time, the new embodiments composed of the mutual combination of the features between the various methods and device, equipment, and server embodiments still fall within the scope of implementation covered by this application, and will not be described one by one here.

[0151] In the description of this specification, the descriptions with reference to the terms "one embodiment", "an embodiment", and / or "some embodiments", "some embodiments", "other embodiments", "ideal embodiments", etc., mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example, and certain features, structures or characteristics in one or more embodiments of this specification may be appropriately combined.

[0152] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0153] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0154] The basic concepts have been described herein. It is obvious to those skilled in the art that the above detailed disclosure is merely an example and does not constitute a limitation of this specification. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to this specification. Such modifications, improvements and amendments are suggested in this specification, so such modifications, improvements and amendments still fall within the spirit and scope of the exemplary embodiments of this specification.

[0155] In addition, it will be understood by those skilled in the art that various aspects of this specification may be illustrated and described by a number of patentable categories or situations, including any new and useful process, machine, product or combination of substances, or any new and useful improvements thereto. Accordingly, various aspects of this specification may be performed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The above hardware or software may be referred to as "data blocks", "modules", "engines", "modules", "components" or "systems". In addition, various aspects of this specification may be represented as a computer product located in one or more computer-readable media, which includes computer-readable program code.

[0156] A computer storage medium may include a propagated data signal containing computer program code, for example, in baseband or as part of a carrier wave. The propagated signal may be in a variety of forms, including electromagnetic, optical, etc., or a suitable combination. A computer storage medium may be any computer-readable medium other than a computer-readable storage medium, which can be connected to an instruction execution system, device or apparatus to communicate, propagate or transmit the program for use. The program code on the computer storage medium may be transmitted via any suitable medium, including radio, cable, fiber optic cable, RF, or similar media, or any combination of the above media.

[0157] The computer program codes required for the operation of the various parts of this specification can be written in any one or more programming languages, including object-oriented programming languages ​​such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, etc., conventional procedural programming languages ​​such as C language, Visual Basic, Fortran 3003, Perl, COBOL 3002, PHP, ABAP, dynamic programming languages ​​such as Python, Ruby and Groovy, or other programming languages. The program code can be run entirely on the user's computer, or run on the user's computer as a separate software package, or run partly on the user's computer and partly on a remote computer, or run entirely on a remote computer or server. In the latter case, the remote computer can be connected to the user's computer through any network form, such as a local area network (LAN) or a wide area network (WAN), or connected to an external computer (e.g., via the Internet), or in a cloud computing environment, or used as a service such as software as a service (SaaS).

[0158] In addition, unless explicitly stated in the claims, the order of the processing elements and sequences described in this specification, the use of alphanumeric characters, or the use of other names are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some invention embodiments that are currently considered useful through various examples, it should be understood that such details are only for illustrative purposes, and the attached claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the essence and scope of the embodiments of this specification. For example, although the system components described above can be implemented by hardware devices, they can also be implemented only by software solutions, such as installing the described system on an existing server or mobile device.

[0159] Similarly, it should be noted that in order to simplify the description disclosed in this specification and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this specification, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the subject matter of this specification are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0160] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining the digits. Although the numerical domains and parameters used to confirm the breadth of the range in some embodiments of this specification are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0161] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this specification is hereby incorporated by reference in its entirety. Except for application history documents that are inconsistent with or conflicting with the contents of this specification, documents that limit the broadest scope of the claims of this specification (currently or later attached to this specification) are also excluded. It should be noted that if the descriptions, definitions, and / or use of terms in the materials attached to this specification are inconsistent or conflicting with the contents described in this specification, the descriptions, definitions, and / or use of terms in this specification shall prevail.

[0162] Finally, it should be understood that the embodiments described in this specification are only used to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, as an example and not a limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly introduced and described in this specification.

Claims

1. A multi-threshold digitization method, characterized in that: include: When the impulse response signal meets the trigger condition, a unit step signal is output; Acquire a counting step signal based on the unit step signal; The counting step signal is digitized and a digitized sampling signal is output.

2. The multi-threshold digitization method according to claim 1, characterized in that: When the impulse response signal meets the trigger condition, a unit step signal is output, including: comparing the impulse response signal with a trigger threshold; In response to a comparison result that the impulse response signal is not less than the trigger threshold, a unit step signal is output.

3. The multi-threshold digitization method according to claim 2, characterized in that: When the single photon avalanche diode unit of the SiPM is not excited, the unit step signal maintains a 0 output state. When the single photon avalanche diode unit is excited, the amplitude of the unit step signal rises by one unit and maintains the amplitude.

4. The multi-threshold digitization method according to claim 2, characterized in that: The trigger conditions include: A voltage is preset, and when the pulse response signal is greater than the preset voltage, it is determined that the trigger condition is met, and the unit step signal is output; or A waveform feature is preset, and when the waveform feature of the impulse response signal meets the preset waveform feature, it is determined that a trigger condition is met, and the unit step signal is output.

5. The multi-threshold digitization method according to claim 4, characterized in that: The preset waveform features include: The maximum voltage reaches a preset voltage threshold, the current amplitude reaches a preset current threshold, or the accumulated voltage reaches a preset amplitude.

6. The multi-threshold digitization method according to claim 1, characterized in that: The acquiring a counting step signal based on the unit step signal comprises: The unit step signal is summed to obtain the count step signal.

7. The multi-threshold digitization method according to claim 6, characterized in that: The unit step signal is summed up, comprising: A plurality of the unit step signals are added together by an in-phase proportional adding circuit to output the counting step signal; or The unit step signals outputted corresponding to different rows and columns are respectively added up by an adding circuit and then outputted to generate the counting step signal; or A corresponding delay is set for each unit step signal, and then the delays are added together to form the counting step signal.

8. The multi-threshold digitization method according to claim 7, characterized in that: When the single-photon avalanche diode unit of the SiPM is not excited, the amplitude of the counting step signal remains at 0. When one of the single-photon avalanche diode units is excited, the amplitude of the counting step signal increases by one unit and maintains the amplitude. When n of the single-photon avalanche diode units are excited, the amplitude of the counting step signal increases by n units and maintains the amplitude, where n is a non-zero natural number.

9. The multi-threshold digitization method according to claim 1, characterized in that: The digital sampling signal includes a counting threshold-time pair, and the digital processing of the counting step signal to output the digital sampling signal includes: Dividing the counting step signal into P path signals, where P is a non-zero natural number; Preset P counting thresholds, and the values ​​of the P counting thresholds are different from each other; Compare the i-th sub-signal with the i-th counting threshold, i=1, 2, ..., P; In response to the threshold comparison result that the i-th path sub-signal is not less than the i-th counting threshold, the trigger time of the threshold comparison result is obtained, and P groups of the counting threshold-time pairs are output.

10. The multi-threshold digitization method according to claim 1, characterized in that: The step of digitally processing the counting step signal and outputting a digital sampling signal comprises: Arbitrarily set multiple voltage thresholds, when the counting step signal crosses each voltage threshold, output the corresponding voltage threshold-time pair, convert the amplitude of the integer multiple unit step signal closest to each voltage threshold, and obtain the original information of the approximately corresponding incident photon sequence according to the counting and triggering time corresponding to the multiple voltage thresholds.

11. The multi-threshold digitization method according to claim 1, characterized in that: The digital sampling signal includes a counting threshold-time pair, and the digital processing of the counting step signal to output the digital sampling signal includes: By measuring the number of jumps and the time of the amplitude jumps of the counting step signal, a jump number and a jump time data sequence are output and directly read out in the form of a digital signal.

12. The multi-threshold digitization method according to claim 1, characterized in that: After the counting step signal is digitally processed and a digital sampling signal is output, the multi-threshold digitization method further includes: Output a reset signal to clear the pulse response signal.

13. A multi-threshold digital reconstruction method, characterized in that: include: Acquire digital sampling signals; Reconstruct the digital sampling signal according to the prior information to restore the counting step signal; The counting step signal is converted into unit time counting information.

14. The multi-threshold digital reconstruction method according to claim 13, characterized in that: The reconstructing the digital sampling signal according to the prior information to restore the counting step signal includes: Determining a physical model corresponding to the counting step signal; The digital sampling signal is subjected to signal recovery processing based on the physical model to restore the counting step signal.

15. The multi-threshold digital reconstruction method according to claim 14, characterized in that: The physical model includes an exponential function model or a straight line function model.

16. The multi-threshold digital reconstruction method according to claim 15, characterized in that: Converting the counting step signal into unit time counting information includes: The unit time counting information is obtained by deriving the physical model corresponding to the counting step signal.

17. A multi-threshold digitization device, characterized in that: include: N detection modules, used to output an impulse response signal when a photon is detected, and output a unit step signal when the impulse response signal reaches a trigger condition; N is a non-zero natural number; A signal integration module, connected to the N detection modules respectively, and used for acquiring a counting step signal based on the unit step signal; The digitization module is connected to the signal integration module and is used to digitize the counting step signal based on the counting threshold value and output a digitized sampling signal.

18. The multi-threshold digitizing device according to claim 17, characterized in that: The detection module comprises: A photon counting detection unit, configured to output a pulse response signal when a photon is detected; The first threshold comparison unit is connected to the photon counting detection unit, and is used to output the unit step signal when the pulse response signal reaches a trigger condition.

19. The multi-threshold digitizing device according to claim 17, characterized in that: The trigger conditions include: A voltage is preset, and when the pulse response signal is greater than the preset voltage, it is determined that the trigger condition is met, and the unit step signal is output; or A waveform feature is preset, and when the waveform feature of the impulse response signal meets the preset waveform feature, it is determined that the trigger condition is met, and the unit step signal is output.

20. The multi-threshold digitizing device according to claim 19, characterized in that: The preset waveform features include: The maximum voltage reaches a preset voltage threshold, the current amplitude reaches a preset current threshold, or the accumulated voltage reaches a preset amplitude.

21. The multi-threshold digitizing device according to claim 17, characterized in that: The photon counting detection unit comprises: A single-photon avalanche diode, wherein the cathode of the single-photon avalanche diode is connected to an externally input reverse bias voltage; A quenching tube, wherein the drain of the quenching tube is connected to the anode of the single-photon avalanche diode, the source of the quenching tube is grounded, and the gate of the quenching tube is connected to an externally inputted DC voltage.

22. The multi-threshold digitizing device according to claim 17, characterized in that: The signal integration module comprises: The in-phase proportional adding circuit is connected to the N detection modules respectively, and is used for performing sum processing on the unit step signal to obtain the counting step signal.

23. The multi-threshold digitizing device according to claim 22, characterized in that: The N detection modules are respectively connected to the signal input end of the in-phase proportional addition circuit through N input resistors, wherein the resistance values ​​of the N input resistors are the same.

24. The multi-threshold digitizing device according to claim 23, characterized in that: The in-phase proportional addition circuit includes an operational amplifier, a feedback resistor and a grounding resistor, wherein the output ends of the N detection modules are connected to the input resistor one by one and connected to the positive input end of the operational amplifier, one end of the feedback resistor is connected to the positive input end of the operational amplifier, the other end of the feedback resistor is connected to the output end of the operational amplifier, and the negative input end of the operational amplifier is grounded through the grounding resistor.

25. The multi-threshold digitizing device according to claim 17, characterized in that: The digitization module comprises: A power divider, used for dividing the counting step signal into P path signals, where P is a non-zero natural number; P second threshold comparison units are respectively connected to the P output terminals of the power divider, the i-th second threshold comparison unit is used to compare the i-th sub-signal with the i-th counting threshold, i is a non-zero natural number not greater than P, and in response to the threshold comparison result that the i-th sub-signal is not less than the i-th counting threshold, obtain the trigger time of the threshold comparison result; The FIFO memory is connected to the P second threshold comparison units respectively, and is used to output P groups of counting threshold-time pairs according to the threshold comparison results and the trigger time respectively output by the P second threshold comparison units.

26. The multi-threshold digitizing device according to claim 25, characterized in that: The second threshold comparison unit comprises: A comparator, wherein a first input terminal of the comparator is connected to the i-th output terminal of the power divider, and a second input terminal of the comparator is connected to a digital-to-analog converter; a digital-to-analog converter, configured to output the ith counting threshold to the second input terminal of the ith comparator; The comparator is used to compare the i-th sub-signal with the i-th counting threshold, i=1, 2, ..., P, and in response to the threshold comparison result that the i-th sub-signal is not less than the i-th counting threshold, the comparator outputs a trigger signal; A time-to-digital converter is connected to the comparator and is used to obtain a trigger time of the comparison result according to the trigger signal.

27. The multi-threshold digitizing device according to claim 17, characterized in that: The multi-threshold digitization device also includes: The reset module is used to output a reset signal to clear the pulse response signal.

28. A multi-threshold digital reconstruction device, characterized in that: include: A transmission module, used for acquiring a digital sampling signal; The data reconstruction module is connected to the transmission module and is used to reconstruct the digital sampling signal according to the prior information, restore the counting step signal, and convert the counting step signal into unit time counting information.

29. The multi-threshold digital reconstruction device according to claim 28, characterized in that: The data reconstruction module comprises: A modeling unit, used for determining a physical model corresponding to the counting step signal; A signal processing unit is connected to the modeling unit and is used to perform signal recovery processing on the digital sampling signal based on the physical model to restore the counting step signal.

30. The multi-threshold digital reconstruction device according to claim 29, characterized in that: The physical model includes an exponential function model or a straight line function model.

31. The multi-threshold digital reconstruction device according to claim 29, characterized in that: The data reconstruction module also includes: The signal conversion unit is connected to the signal processing unit and is used to convert the counting step signal into unit time counting information.

32. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, it implements the steps of the multi-threshold digitization method described in any one of claims 1 to 12, or implements the steps of the multi-threshold digital reconstruction method described in any one of claims 13 to 16.

33. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the multi-threshold digitization method described in any one of claims 1 to 12 are implemented, or the steps of the multi-threshold digitization reconstruction method described in any one of claims 13 to 16 are implemented.

34. A computer program product, characterized in that It comprises a computer program or an instruction, characterized in that when the computer program or the instruction is executed by a processor, it implements the steps of the multi-threshold digitization method described in any one of claims 1 to 12, or implements the steps of the multi-threshold digital reconstruction method described in any one of claims 13 to 16.

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