System and method for testing sensitivity and stability of photon counter

Abstract

The invention provides a photon counter sensitivity and stability test system and test method. The photon counter sensitivity and stability test system comprises a shielding camera obscura, a self-calibration standard light source, a test board, a photon counter, an electronics system and a computer system. The self-calibration standard light source and the photon counters are arranged in a test board in a shielding camera obscura, the test board is provided with a plurality of test stations, and a plurality of groups of photon counters can be tested at the same time each time. And the computer system receives the photon counting measurement value, automatically analyzes the value in a specified time period, automatically uploads an analysis result to the cloud server, and automatically gives an alarm if a result index exceeds a given technical index. Wherein the electronics system is used for driving the light source to carry out self-calibration according to photon counting of a standard photon counter equipped on the self-calibration standard light source and deviation between a counting value and a standard counting value, so as to eliminate standard output light wave deviation caused by position change caused by electric quantity fluctuation of the light source or external factors; and the sensitivity test accuracy of the photon counter is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photomultiplier tubes, in particular to a photon counter technology based on photomultiplier tubes, and specifically to a photon counter sensitivity and stability testing system and testing method. Background Art

[0002] The photon counting detector is a module that integrates a photomultiplier tube, a high-voltage power supply, a voltage divider circuit, and a photon counting circuit. Figure 1 The block diagram of the photon counting detector shown in the figure shows that when the intensity of the incident light is changed, the pulse interval of the photomultiplier tube output signal is narrow and overlaps with each other to form an analog waveform. When the light is weakened, the proportion of the AC component (fluctuation) increases, and finally becomes a discrete pulse state. The method of digitally counting this pulsed discrete signal in binary form is usually called photon counting. After the current pulse output from the photomultiplier tube is amplified by the amplifier, the comparator discriminates the pulse above a certain threshold. The discrimination threshold in the discriminator is set based on the pulse height distribution (PHD) of the photomultiplier tube output signal, which is converted into a standard pulse signal output by a pulse shaper, and the optical signal pulse output by the discriminator is counted by the counter.

[0003] Counting sensitivity refers to the count rate value output by the photon counting detector corresponding to a certain light intensity when a certain wavelength of light is incident. The sensitivity, consistency and stability of PMT photon counting detectors are its key performance indicators, and there is currently no test system to achieve detection. Summary of the invention

[0004] The present invention aims to provide a photon counter sensitivity and stability test system and test method, so as to realize the photon counting sensitivity and stability test of a PMT-based photon counter.

[0005] According to a first aspect of the present invention, a photon counter sensitivity and stability test system is provided, comprising a shielded dark box, a self-calibration standard light source, a test bench, a photon counter, an electronics system and a computer system;

[0006] The shielded dark box is used to provide a dark test environment and shield external light paths and electromagnetic wave interference; the self-calibration standard light source and the photon counter are arranged in a test bench in the shielded dark box, and the computer system and the electronics system are arranged outside the shielded dark box and connected to the shielded dark box through cables to control the start and stop of the photon counter and receive and store real-time counts;

[0007] The test bench adopts an annular test bench and is fixed at the bottom of the shielding dark box. The annular test bench has multiple groups of parallel test stations, and each group of self-calibration standard light sources and photon counters is fixed on a test station;

[0008] The self-calibration standard light source is configured with a standard light source for continuously outputting a stable light wave of a preset power. The self-calibration standard light source is also provided with a standard photon counter and a light source adjustment drive module. The standard light source is mounted on the light source adjustment drive module, and the standard light source is self-calibrated based on the photon count value of the standard photon counter.

[0009] The electronic system is used to control the standard light source to perform self-calibration according to the photon count value of the standard photon counter and the deviation thereof from the standard count value;

[0010] The computer system is configured to receive the counts of the photon counter of each test station on the annular test bench, perform data analysis on the counts, and output the sensitivity and stability test results of the photon counter.

[0011] In a further embodiment, the computer system is further configured to upload the count and photon counter test results to a cloud server;

[0012] The cloud server makes judgments based on preset index standards and issues an alarm for test results that exceed the preset index standards.

[0013] As an optional embodiment, each test station of the annular test bench includes two clamping molds, wherein the first clamping mold is used to clamp the photon counter, and the second clamping mold is used to clamp the self-calibration standard light source, and the photocathode surface of the photon counter is made to face the standard light source of the corresponding self-calibration standard light source.

[0014] Each test station is equipped with a power supply interface for electrically connecting to a voltage-stabilized power supply in a shielded dark box to supply power to a photon counter on each test station.

[0015] As an optional embodiment, the self-calibration standard light source on each test station is installed in a card slot, and the card slot is clamped by a second clamping mold on the test station;

[0016] The card slot is provided with a three-dimensional displacement adjustment mechanism and a driving motor, the standard light source is installed on the three-dimensional displacement adjustment mechanism, and each standard light source is equipped with a driving motor for driving the three-dimensional displacement adjustment mechanism to move in the front-back direction or the left-right direction to drive the standard light source to move accordingly:

[0017] By moving the standard light source forward and backward, the distance between the standard light source and the photocathode surface is controlled;

[0018] By moving the standard light source to the left and right, the overlapping area between the standard light source and the photocathode surface is controlled.

[0019] As an optional embodiment, the electronic system controls the drive motor to move the standard light source in the front-back and left-right directions based on the deviation between the photon count value of the standard photon counter and the preset standard count value, thereby completing the self-calibration process, wherein:

[0020] During the self-calibration process, the standard light source is first controlled to move in the front-to-back direction. When the deviation between the photon count value of the standard photon counter and the standard count value is within 10%, the standard light source is then controlled to move in the left-to-right direction, and finally the photon count value of the standard photon counter reaches the standard count value.

[0021] As an optional embodiment, the three-dimensional displacement adjustment mechanism includes a first moving pair arranged along the XY plane, and a second moving pair arranged in the XZ direction;

[0022] The first moving pair has a crossbeam arranged along the X direction, a linear slide rail along the longitudinal direction and a slider that can be driven to slide on the linear slide rail are arranged on the crossbeam, and the standard light source is installed on the slider and can move synchronously with the slider;

[0023] The crossbeam of the first moving pair is installed on the second moving pair, and the crossbeam is driven by the second moving pair to move in the front-rear direction, so that the linear guide rail, the slider and the standard light source fixed on the slider of the first moving pair move forward and backward as a whole.

[0024] As an optional embodiment, the electronic system is configured to control the self-calibration of the standard light source according to a preset period, for example, it is configured to self-calibrate once every 5 minutes, 10 minutes, 15 minutes, 30 minutes, or every 1 hour.

[0025] As an optional embodiment, the computer system is configured to read the photon counting data output by the photon counter of each test station through a serial port reading protocol, and perform a photon counter sensitivity test according to the following process:

[0026] (1) Determine the time span and analyze the count data within the time span;

[0027] (2) Based on the count data within the time span, analyze the lagged impact of the current data on the subsequent data;

[0028] (3) If the analysis result of step (2) indicates that the data has autocorrelation, then remove the trend and seasonal components of the count data within the time span so that the retained count data becomes random counts and eliminates the correlation;

[0029] (4) performing a sliding average on the random count data obtained in step (3) to eliminate the lag effect of the error term;

[0030] (5) Perform a unit root test on the data processed in step (4). If there is no unit root, it is determined that the stability of the photon counter has passed the test.

[0031] According to a second aspect of the present invention, a photon counter counting test method of a photon counter sensitivity and stability test system is provided. For any photon counter, the test process includes:

[0032] (1) Determine the time span and perform analysis based on the photon counting data within the time span;

[0033] (2) Based on the photon counting data within the time span, analyze the lag effect of the current data on the subsequent data;

[0034] (3) If the analysis result of step (2) indicates that the data has autocorrelation, then remove the trend and seasonal components of the count data within the time span so that the retained count data becomes random counts and eliminates the correlation;

[0035] (4) performing a sliding average on the random count data obtained in step (3) to eliminate the lag effect of the error term;

[0036] (5) Perform a unit root test on the data processed in step (4). If there is no unit root, it is determined that the stability of the photon counter has passed the test.

[0037] As an optional embodiment, in step (2), analyzing the hysteresis effect of current data on subsequent data includes:

[0038] (2-1) Based on the original data (x_1, x_2, x_3,,, x_t) obtained within the time span, the autoregressive model is established as follows:

[0039]

[0040] In the formula, p is the order of autoregression, c is the constant term, is the coefficient, e t is the random error value with mean set to 0 and standard deviation σ;

[0041] (2-2) After establishing the autoregressive model, the residual between the actual value of the photon counter and the model predicted value is calculated, that is, ∈ t , and further residual analysis is performed. Uncorrelated data indicates that there is no statistical correlation between the residuals:

[0042] First, let the correlation equation of each residual be ∈ t =ρε t-1 +v t , where ∈ t and ε t-1Represent the residual at time t and the residual at time t-1, respectively, v t represents the random error term, T represents the time span;

[0043] In the DW test process, the null hypothesis ρ = 0, the alternative hypothesis ρ ≠ 0, and the statistic of the correlation test is d, then:

[0044]

[0045] Then, we make a judgment based on the statistic d of the correlation test:

[0046] If d is between 1 and 3, it indicates that there is no autocorrelation in the residuals and no lag effect on subsequent data;

[0047] If d is less than 1, it means that there is autocorrelation in the residuals.

[0048] As an optional embodiment, in step (3), removing the trend and seasonal components of the count data within the time span, making the retained count data into random counts, and eliminating correlation, includes:

[0049] Perform d-order difference processing on the count data within the time span, including:

[0050]

[0051] Thus, the trend and seasonal components of the data within the time span are removed.

[0052] As an optional embodiment, in the step (5), a unit root test is performed on the data processed in the step (4). If there is no unit root, it is determined that the stability of the photon counter has passed the test, including:

[0053] First, the data processed in step (4) is subjected to the AR(1) process, and the AR(1) equation is y t =py t-1 +α+βt+ε t , where y t refers to the data at time t, y T It refers to the data at time T, p, α, and β are coefficients respectively;

[0054] Then calculate the unit root test statistic, and record the unit root test statistic as t:

[0055]

[0056] Remember the matrix y=(y2,…,y T )',but:

[0057]

[0058] Where α′, p′, β′ are the statistical values ​​of α, p, β respectively, and X′ is the transpose of matrix X;

[0059] Further we can get:

[0060]

[0061] in, y′ i = p′y′ i-1 +α′+β′i,i=1,2,…,T-1;

[0062] After the above calculations, if t < 0.01, it is determined that the time series has no unit root, and then it is determined that the photon counter count is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The accompanying drawings are not intended to be drawn to scale. In the accompanying drawings, each identical or nearly identical component shown in each figure may be represented by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings.

[0064] Figure 1 This is the principle block diagram of the photon counting detector.

[0065] Figure 2 is a schematic diagram of a photon counter sensitivity and stability testing system according to an embodiment of the present invention.

[0066] Figure 3 Schematic diagram of a card slot used in a photon counter sensitivity and stability testing system according to an embodiment of the present invention.

[0067] Figure 4 1 is a schematic diagram of photon counting results of a photon counter sensitivity and stability testing system according to an embodiment of the present invention.

[0068] Figure 5 It is a schematic diagram of the results of photon counting based on the existing counting of ordinary light sources.

[0069] Figure 6 3 is a stability test comparison diagram of a photon counter sensitivity and stability test system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0070] In order to better understand the technical content of the present invention, specific embodiments are given and described as follows in conjunction with the accompanying drawings.

[0071] Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily intended to include all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed by the present invention are not limited to any implementation. In addition, some aspects disclosed by the present invention can be used alone or in any appropriate combination with other aspects disclosed by the present invention.

[0072] {Example 1}

[0073] Combination Figure 2 As shown, the photon counter sensitivity and stability testing system according to an embodiment of the present invention includes a shielding dark box 100 , a self-calibration standard light source 101 , a photon counter 102 , a computer system 110 and an electronics system 120 .

[0074] Combination Figure 2 As shown, the shielding dark box 100 is used to provide a dark and lightless test environment and shield external light path and electromagnetic wave interference.

[0075] The self-calibration standard light source 101 and the photon counter 102 are both arranged inside the shielding dark box 100 .

[0076] The computer system 110 and the electronics system 120 are arranged outside the shielding dark box and connected to the inside of the shielding dark box 100 through cables to control the start and stop of the photon counter and receive and store real-time counts.

[0077] A test bench is arranged inside the shielding dark box 100 , and in particular, a ring-shaped test bench is adopted and fixed at the bottom inside the shielding dark box.

[0078] The annular test bench is provided with multiple groups of parallel test stations, and each group of self-calibration standard light source 101 and photon counter 102 is fixed on a test station.

[0079] In an embodiment of the present invention, the self-calibration standard light source 101 is configured with a standard light source 101a, which is used to continuously output a stable light wave of a preset power. In addition, the self-calibration standard light source 101 is also provided with a standard photon counter 101b and a light source adjustment drive module 101c, and the standard light source 101a is connected to and installed on the light source adjustment drive module 101c. The self-calibration standard light source 101 performs self-calibration on the standard light source based on the photon count value of the standard photon counter 101b. It should be understood that the standard photon counter 101b corresponds to the standard light source 101a, and uploads the photon count value to the computer system and / or the electronics system according to a preset period, for example, reporting according to a period of 0.5s or 1s.

[0080] Combination Figure 2 As shown, the electronic system 120 controls the aforementioned standard light source to perform self-calibration according to the photon count value of the standard photon counter 101b and the deviation thereof from the standard count value. In the embodiment of the present invention, the standard photon count value corresponding to the standard light source is set to 45000, that is, the aforementioned standard count value is set to 45000.

[0081] In an embodiment of the present invention, the computer system 110 is configured to receive the counts of the photon counter of each test station on the ring test bench, perform data analysis on the counts, and output the test results of the photon counter.

[0082] In a further embodiment, in combination Figure 2 As shown, the computer system 110 is also configured to upload the count and photon counter sensitivity test results to the cloud server. The cloud server makes a judgment based on the preset index standard and issues an alarm for the test results that exceed the preset index standard. For example, according to the index standard preset by the user, the test result that exceeds the specified index is notified to the user's terminal, and the alarm method includes SMS notification, app online notification and other appropriate methods.

[0083] As an optional embodiment, each test station of the aforementioned annular test bench includes two clamping molds, wherein the first clamping mold is used to clamp the photon counter 102, and the second clamping mold is used to clamp the self-calibration standard light source 101, and the photocathode surface of the photon counter (PMT-based photon counter) is made to face the standard light source of the corresponding self-calibration standard light source.

[0084] In an embodiment of the present invention, each test station is equipped with a power supply interface for electrically connecting to a voltage-stabilized power supply in a shielding dark box to supply power to a photon counter on each test station.

[0085] As an optional embodiment, the self-calibration standard light source 101 on each test station is installed in a card slot, and the card slot is clamped by the second clamping mold on the test station, such as Figure 3 As shown, the structure of the card slot is exemplarily shown to be U-shaped.

[0086] As an optional embodiment, a light source adjustment driving module 101c is provided in the card slot to drive the movement of the standard light source to achieve self-calibration. As an example, the light source adjustment driving module 101c is implemented by a three-dimensional displacement adjustment mechanism and a drive motor to form a light source adjustment driving module for self-calibration operation of the light source.

[0087] As an example, the standard light source 101a is installed on the three-dimensional displacement adjustment mechanism, and each standard light source is equipped with a driving motor for driving the three-dimensional displacement adjustment mechanism to move in the front-to-back direction or the left-to-right direction to drive the standard light source to move accordingly.

[0088] Thus, the distance between the standard light source and the photocathode surface is controlled by moving the standard light source forward and backward; and the overlapping area between the standard light source and the photocathode surface is controlled by moving the standard light source leftward and rightward.

[0089] Combination Figure 2 As shown, the electronic system 120 controls the driving motor to move the standard light source 101a in the front-back and left-right directions based on the photon count value reported by the standard photon counter 101b and the deviation thereof from the preset standard count value (such as the aforementioned preset value 45000), thereby completing the self-calibration process, wherein:

[0090] During the self-calibration process, the standard light source is first controlled to move in the front-to-back direction. When the deviation between the photon count value of the standard photon counter and the standard count value is within 10%, the standard light source is then controlled to move in the left-to-right direction, and finally the photon count value of the standard photon counter reaches the standard count value.

[0091] In an optional embodiment, the electronic system 120 is configured to perform self-calibration operations on the standard light source according to a preset periodic control, for example, self-calibration is performed every 5 minutes, 10 minutes, 15 minutes, 30 minutes, or every 1 hour, and self-calibration control is performed according to the photon count value of the standard photon counter 101a.

[0092] As an optional embodiment, the aforementioned three-dimensional displacement adjustment mechanism includes a first moving pair arranged along the XY plane, and a second moving pair arranged in the XZ direction. The first moving pair has a crossbeam arranged along the X direction, on which a linear slide rail along the longitudinal direction and a slider that can be driven to slide on the linear slide rail are arranged, and the standard light source is installed on the slider and can move synchronously with the slider. The crossbeam of the first moving pair is installed on the second moving pair, and the crossbeam is driven by the second moving pair to move in the front-rear direction, so that the linear slide rail of the first moving pair, the slider, and the standard light source fixed on the slider move forward and backward as a whole.

[0093] The three-dimensional displacement adjustment mechanism in the above example is only an example. Its purpose and function is to realize the front and back (depth direction) and left and right movement (left and right displacement in the plane) of the standard light source 101a in the card slot to achieve position adjustment, so as to adjust its relative distance and overlapping area relative to the photocathode surface of the photon counter. Under the guidance of the present invention, other appropriate methods and drives can also be used, including but not limited to linear motor drive, gear rack mechanism drive, worm gear mechanism drive, hydraulic telescopic mechanism drive, pneumatic telescopic mechanism drive, etc.

[0094] As an optional embodiment, the aforementioned computer system 110 is configured to read the photon counting data output by the photon counter of each test station through a serial port reading protocol, and perform a test of the photon counter according to the following process.

[0095] For any photon counter on a test station, the test process includes:

[0096] (1) Determine the time span and analyze the count data within the time span;

[0097] (2) Based on the count data within the time span, analyze the lagged impact of the current data on the subsequent data;

[0098] (3) If the analysis result of step (2) indicates that the data has autocorrelation, then remove the trend and seasonal components of the count data within the time span so that the retained count data becomes random counts and eliminates the correlation;

[0099] (4) performing a sliding average on the random count data obtained in step (3) to eliminate the lag effect of the error term;

[0100] (5) Perform a unit root test on the data processed in step (4). If there is no unit root, it is determined that the stability of the photon counter has passed the test.

[0101] It should be understood that the aforementioned time span is usually designed to be defined according to the user's requirements for stability, and the minimum unit is seconds (s). In the embodiment of the present invention, 30 seconds is taken as an example.

[0102] In an optional embodiment, the test system is also provided with a low-power DTU module as a communication unit. With the help of the DTU of the wireless cellular network, the traditional serial port device is connected to the Internet through the wireless cellular network to achieve remote communication and data transmission and reception.

[0103] {Example 2}

[0104] In combination with the test system structure of the above embodiment, the test method for testing the sensitivity and stability of a photon counter is implemented. For any photon counter, the test process includes:

[0105] (1) Determine the time span and perform analysis based on the photon counting data within the time span;

[0106] (2) Based on the photon counting data within the time span, analyze the lag effect of the current data on the subsequent data;

[0107] (3) If the analysis result of step (2) indicates that the data has autocorrelation, then remove the trend and seasonal components of the count data within the time span so that the retained count data becomes random counts and eliminates the correlation;

[0108] (4) performing a sliding average on the random count data obtained in step (3) to eliminate the lag effect of the error term;

[0109] (5) Perform a unit root test on the data processed in step (4). If there is no unit root, it is determined that the stability of the photon counter has passed the test.

[0110] As an optional embodiment, in step (2), analyzing the hysteresis effect of current data on subsequent data includes:

[0111] (2-1) Based on the original data (x_1, x_2, x_3,,, x_t) obtained within the time span, the autoregressive model is established as follows:

[0112]

[0113] In the formula, p is the order of autoregression, c is the constant term, is the coefficient, e t is the random error value with mean set to 0 and standard deviation σ;

[0114] (2-2) After establishing the autoregressive model, the residual between the actual value of the photon counter and the model predicted value is calculated, that is, ∈ t , and further residual analysis is performed. Uncorrelated data indicates that there is no statistical correlation between the residuals:

[0115] First, let the correlation equation of each residual be ∈ t =ρε t-1 +v t , where ∈ t and ε t-1 Represent the residual at time t and the residual at time t-1, respectively, v t represents the random error term, T represents the time span;

[0116] In the DW test process, the null hypothesis ρ = 0, the alternative hypothesis ρ ≠ 0, and the statistic of the correlation test is d, then:

[0117]

[0118] Then, we make a judgment based on the statistic d of the correlation test:

[0119] If d is between 1 and 3, it indicates that there is no autocorrelation in the residuals and no lag effect on subsequent data;

[0120] If d is less than 1, it means that there is autocorrelation in the residuals.

[0121] It should be understood that in the embodiment of the present invention, the closer the test statistic d is to 2, the better. Generally, if it is between 1 and 3, it means there is no problem. If it is less than 1, it means that there is autocorrelation in the residual.

[0122] After the DW test, if it is proved that there is no autocorrelation in the residuals, indicating that the current data has no lagged effect on the subsequent data, the unit root test in the above step (5) can be directly performed.

[0123] As an optional embodiment, in step (3), removing the trend and seasonal components of the count data within the time span, making the retained count data into random counts, and eliminating correlation, includes:

[0124] Perform d-order difference processing on the count data within the time span, including:

[0125]

[0126] Thus, the trend and seasonal components of the data within the time span are removed.

[0127] As an optional embodiment, in the step (5), a unit root test is performed on the data processed in the step (4). If there is no unit root, it is determined that the stability of the photon counter has passed the test, including:

[0128] First, the data processed in step (4) is subjected to the AR(1) process, and the AR(1) equation is y t =py t-1 +α+βt+ε t , where y t refers to the data at time t, y T It refers to the data at time T, p, α, and β are coefficients respectively;

[0129] Then calculate the unit root test statistic, and record the test statistic of the unit root test as t:

[0130]

[0131] Remember the matrix y=(y2,…,y T )',but:

[0132]

[0133] Where α′, p′, i′ are the statistical values ​​of α, p, i respectively, and X′ is the transpose of the matrix X;

[0134] Further we can get:

[0135]

[0136] in, y′ i = p′y′ i-1 +α′+β′i,i=1,2,…,T-1.

[0137] After the above calculations, if the test statistic of the unit root test is t<0.01, it is determined that the time series has no unit root, and then it is determined that the photon counter count is stable.

[0138] {Example 3}

[0139] In combination with the design of the photon counter sensitivity and stability test system and the process of the test method in the above embodiment, we further illustrate the advantages of implementing the present invention in this embodiment in combination with the test results and comparison.

[0140] Combination Figure 4 FIG. 4 shows the result of photon counting by the photon counter sensitivity and stability test system according to an embodiment of the present invention. Figure 5 The figure shows the result of photon counting using an existing ordinary light source for counting (designed according to the standard count value of 45,000, which can emit light stably and continuously). The self-calibrated stable light source used in the test system of the present invention is connected to a standard photon counter, which sends the current photon number to the electronic system 120 (which can be implemented by a single-chip microcomputer) once every second. The electronic system 120 controls the self-calibration operation according to a 5-minute cycle. If the photon number is not the standard value of 45,000, the operation of the drive motor is controlled according to the deviation between the current photon number and 45,000, and the position relationship between the standard light source and the photocathode surface is adjusted, such as horizontal translation, away from or close to the photocathode surface of the photon counter, thereby completing the self-calibration of the standard light source.

[0141] The common light source used in the existing test device is based on a single-wavelength LED design, which contains a light source module and a light source control circuit, which can drive it to output light of a stable wavelength. The output wavelength is optional, and the power includes strong and weak gears, which can accurately output photons with a power of 1pw. The light source is powered by a battery. When the battery power decreases or the relative position of the light source and the photon counter changes due to external factors, the light wave output by the standard light source has an error, which will cause a deviation in the sensitivity test of the photon counter.

[0142] Combination Figure 4 , 5 As shown in the figure, the photon count values ​​of the self-calibration standard light source and the ordinary standard light source within 10 minutes are shown. It can be seen that the luminous stability of the self-calibration standard light source designed by the present invention is better, and its maximum fluctuation range is less than 0.022%, ensuring that the test and calibration of the photon counter are accurate. The luminous stability of the ordinary standard light source has a larger fluctuation range, and the fluctuation range is higher than 4.5%.

[0143] Therefore, according to the test system design proposed in the present invention, the light source is driven to self-calibrate through the deviation between the real-time photon count of the light source and the standard count value to achieve stable output of the self-calibrated light source, eliminate the deviation of the standard output light wave caused by the position change of the light source due to power fluctuations or external factors, and improve the accuracy of the sensitivity test of the photon counter.

[0144] Combined with the design of the photon counter sensitivity and stability test system of the above embodiment, combined with Figure 4 The test results shown represent sensitivity test results, indicating the photon counts obtained by operating the photon counter in a completely lightless environment under no light illumination, that is, the count rate (dark count rate).

[0145] In a further embodiment, the average dark count rate may also be calculated by recording the photon count values ​​within a time span.

[0146] Combination Figure 6 As shown, a stability test comparison diagram of the photon counter sensitivity and stability test system according to an embodiment of the present invention is shown. Since the existing test device data processing only uses the simplest cv calculation, the algorithm cannot eliminate the influence of random factors, resulting in a large autocorrelation of the test data, which is not random. The test method proposed in the present invention eliminates the influence of the trend and seasonality of the data and the error components, making the test results of the photon counter more accurate. As shown in the figure, blue is the photon count within 20 minutes before the traditional method performs trend and seasonal processing, and orange is the processed data. By comparison, it can be seen that the method proposed in the present invention eliminates the influence of the trend and seasonal components of the data, ensures that the data is random, and improves the objectivity and accuracy of the test results of the photon counter.

[0147] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A photon counter sensitivity and stability test system, characterized in that: Including shielded dark box, self-calibration standard light source, test bench, photon counter, electronics system and computer system; The shielded dark box is used to provide a dark test environment and shield external light paths and electromagnetic wave interference; the self-calibration standard light source and the photon counter are arranged in the shielded dark box, and the computer system and the electronics system are arranged outside the shielded dark box and connected to the shielded dark box through cables to control the start and stop of the photon counter and receive and store real-time counts; The test bench adopts an annular test bench and is fixed at the bottom of the shielding dark box. The annular test bench has multiple groups of parallel test stations, and each group of self-calibration standard light sources and photon counters is fixed on a test station; The self-calibration standard light source is configured with a standard light source for continuously outputting a stable light wave of a preset power. The self-calibration standard light source is also provided with a standard photon counter and a light source adjustment drive module. The standard light source is mounted on the light source adjustment drive module, and the standard light source is self-calibrated based on the photon count value of the standard photon counter. The electronic system is used to control the standard light source to perform self-calibration according to the deviation between the photon count value of the standard photon counter and the standard count value; The computer system is configured to receive the counts of the photon counter of each test station on the annular test bench, perform data analysis on the counts, and output the sensitivity and stability test results of the photon counter.

2. The photon counter sensitivity and stability testing system according to claim 1, characterized in that: Each test station of the annular test bench includes two clamping molds, wherein the first clamping mold is used to clamp the photon counter, and the second clamping mold is used to clamp the self-calibration standard light source, and the photocathode surface of the photon counter is directed toward the corresponding self-calibration standard light source; Each test station is equipped with a power supply interface for electrically connecting to a voltage-stabilized power supply in the shielding dark box to supply power to the photon counter on each test station.

3. The photon counter sensitivity and stability testing system according to claim 2, characterized in that: The self-calibration standard light source on each test station is installed in a card slot, and the card slot is clamped by the second clamping mold on the test station; The card slot is provided with a three-dimensional displacement adjustment mechanism and a driving motor, the standard light source is installed on the three-dimensional displacement adjustment mechanism, and each standard light source is equipped with a driving motor for driving the three-dimensional displacement adjustment mechanism to move in the front-back direction or the left-right direction to drive the standard light source to move accordingly: By moving the standard light source forward and backward, the distance between the standard light source and the photocathode surface is controlled; By moving the standard light source to the left and right, the overlapping area between the standard light source and the photocathode surface is controlled.

4. The photon counter sensitivity and stability testing system according to claim 3, characterized in that: The electronic system controls the driving motor to move the standard light source in the front-back and left-right directions based on the deviation between the photon count value of the standard photon counter and the preset standard count value, thereby completing the self-calibration process, wherein: During the self-calibration process, the standard light source is first controlled to move in the front-to-back direction. When the deviation between the photon count value of the standard photon counter and the standard count value is within 10%, the standard light source is then controlled to move in the left-to-right direction, and finally the photon count value of the standard photon counter reaches the standard count value.

5. The photon counter sensitivity and stability testing system according to claim 3, characterized in that: The three-dimensional displacement adjustment mechanism includes a first moving pair arranged along the XY plane, and a second moving pair arranged in the XZ direction; The first moving pair has a crossbeam arranged along the X direction, a linear slide rail along the longitudinal direction and a slider that can be driven to slide on the linear slide rail are arranged on the crossbeam, and the standard light source is installed on the slider and can move synchronously with the slider; The crossbeam of the first moving pair is installed on the second moving pair, and the crossbeam is driven by the second moving pair to move in the front-rear direction, so that the linear guide rail, the slider and the standard light source fixed on the slider of the first moving pair move forward and backward as a whole.

6. The photon counter testing method of the photon counter sensitivity and stability testing system according to any one of claims 1 to 5, characterized in that: For any photon counter, the test process includes: (1) Determine the time span and perform analysis based on the photon counting data within the time span; (2) Based on the count data within the time span, analyze the lagged impact of the current data on the subsequent data; (3) If the analysis result of step (2) indicates that the data has autocorrelation, then remove the trend and seasonal components of the count data within the time span so that the retained count data becomes random counts and eliminates the correlation; (4) performing a sliding average on the random count data obtained in step (3) to eliminate the lag effect of the error term; (5) Perform a unit root test on the data processed in step (4). If there is no unit root, it is determined that the stability of the photon counter has passed the test.

7. The method for testing the sensitivity and stability of a photon counter according to claim 6, characterized in that: In the step (2), analyzing the hysteresis effect of the current data on the subsequent data includes: (2-1) Based on the original data (x_1, x_2, x_3,,, x_t) obtained within the time span, the autoregressive model is established as follows: In the formula, p is the order of autoregression, c is the constant term, is the coefficient, e t is the random error value with mean set to 0 and standard deviation σ; (2-2) After establishing the autoregressive model, the residual between the actual value of the photon counter and the model predicted value is calculated, that is, ∈ t , and further residual analysis is performed. Uncorrelated data indicates that there is no statistical correlation between the residuals: First, let the correlation equation of each residual be ∈ t =ρε t-1 +v t , where ∈ t and ε t-1 Represent the residual at time t and the residual at time t-1, respectively, v t represents the random error term, T represents the time span; In the DW test process, the null hypothesis ρ = 0, the alternative hypothesis ρ ≠ 0, and the statistic of the correlation test is d, then: Then, we make a judgment based on the statistic d of the correlation test: If d is between 1 and 3, it indicates that there is no autocorrelation in the residuals and no lag effect on subsequent data; If d is less than 1, it means that there is autocorrelation in the residuals.

8. The method for testing the sensitivity and stability of a photon counter according to claim 6, characterized in that: In the step (3), the trend and seasonal components of the count data within the time span are removed so that the retained count data becomes random counts and correlation is eliminated, including: Perform d-order difference processing on the count data within the time span, including: Thus, the trend and seasonal components of the data within the time span are removed.

9. The method for testing the sensitivity and stability of a photon counter according to claim 6, characterized in that: In step (5), after the trend and seasonal component removal process in step (3), the count data is further processed by moving average to eliminate the lag effect of the error term, as shown below: The data processed by steps (3) and (4) are free from the influence of autocorrelation, seasonal components and error lag factors.

10. The method for testing the sensitivity and stability of a photon counter according to claim 8, characterized in that: In the step (5), a unit root test is performed on the data processed in the step (4). If there is no unit root, it is determined that the stability of the photon counter has passed the test, including: First, the data processed in step (4) is subjected to the AR(1) process, and the AR(1) equation is y t =py t-1 +α+β t +ε t , where y t refers to the data at time t, y T It refers to the data at time T, p, α, and β are coefficients respectively; Then calculate the unit root test statistic, and record the unit root test statistic as t: Remember the matrix y=(y2,…,y T )',but: Where α′, p′, β′ are the statistical values ​​of α, p, β respectively, and X′ is the transpose of matrix X; Further we can get: Among them, u′ i =p′y′ i-1 +α′+β′i,i=1,2,…,T-1; After the above calculations, if t < 0.01, it is determined that the time series has no unit root, and then it is determined that the photon counter count is stable.

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