Photon counter sensitivity and stability test system and test method

Abstract

The present invention provides a photon counter sensitivity and stability test system and test method, which include a shielded dark box, a self-calibration standard light source, a test bench, a photon counter, an electronic system and a computer system. The self-calibration standard light source and the photon counter are placed in a test bench inside the shielded dark box. The test bench is provided with multiple test stations, and multiple groups of photon counters can be tested simultaneously each time. The computer system receives the photon counting measurement value and automatically analyzes the value of the specified time period, and automatically uploads the analysis result to the cloud server. If the result index exceeds the given technical index, an automatic alarm is issued. The electronic system is used to count the photons of the standard photon counter equipped with the self-calibration standard light source, and drive the light source to perform self-calibration according to the deviation between the count value and the standard count value, thereby eliminating the standard output light wave deviation caused by the position change of the light source due to power fluctuation or external factors, and improving the accuracy of the sensitivity test of the photon counter.

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 more 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 shows that when the incident light intensity changes, the pulse spacing of the photomultiplier tube output signal narrows, causing them to overlap and form an analog waveform. As the light weakens, the AC component (fluctuation) increases, ultimately resulting in discrete pulses. The method of digitally counting this discrete pulse signal in binary form is commonly known as photon counting. The current pulses output by the photomultiplier tube are amplified by an amplifier, and a comparator identifies pulses 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. A pulse shaper converts the signal into a standard pulse output, and a counter counts the optical signal pulses output by the discriminator.

[0003] Counting sensitivity indicates the count rate output by a photon counting detector for a given light intensity when incident light of a specific wavelength is detected. The sensitivity, consistency, and stability of PMT photon counting detectors are key performance indicators, but currently no test system can accurately measure these. 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 testing system is provided, comprising a shielded darkroom, 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 photon counter are arranged in a test bench inside the shielded dark box, and the computer system and electronics system are arranged outside the shielded dark box and connected to the shielded dark box via cables to control the start and stop of the photon counter and receive and store real-time counts;

[0007] The test bench is an annular test bench fixed to the bottom of the shielded 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 to 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 counting value of the standard photon counter and the deviation thereof from the standard counting value;

[0010] The computer system is configured to receive counts from the photon counter of each test station on the annular test bench, perform data analysis on the counts, and output 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 directed toward 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 the shielding dark box to power the 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 drive motor, and the standard light source is installed on the three-dimensional displacement adjustment mechanism. The drive motor configured for each standard light source is used to drive 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 left and right, the overlapping area of ​​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 a 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 forward and backward. 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 controlled to move left and right, 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 comprises a crossbeam arranged along the X direction, a linear slide rail arranged along the longitudinal direction and a slider that can be driven to slide on the linear slide rail, and the standard light source is mounted 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 a time span, analyze the lagged impact of current data on subsequent data;

[0028] (3) If the analysis results of step (2) indicate that the data have 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 results of step (2) indicate that the data have 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] Where 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, 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, so that the retained count data becomes random counts and eliminates 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 step (5), a unit root test is performed 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, including:

[0053] First, perform AR(1) on the data processed in step (4), and let AR(1) equation be 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 various figures 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 4 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 4 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 This is a schematic diagram of the results of photon counting based on an ordinary light source with existing counting.

[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 below with reference to the accompanying drawings.

[0071] Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which a number of 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 herein are not limited to any embodiment. In addition, some aspects of the present disclosure may be used alone or in any appropriate combination with other aspects disclosed herein.

[0072] {Example 1}

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

[0074] Combine Figure 2 As shown, the shielding dark box 100 is used to provide a dark, lightless test environment and shield the external light path and electromagnetic 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 shielded dark box and connected to the inside of the shielded dark box 100 via cables to control the start and stop of the photon counter and receive and store real-time counts.

[0077] A test bench is provided inside the shielding dark box 100 , and in particular, a ring-shaped test bench is fixed to 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 configured to continuously output a stable light wave of a preset power. Furthermore, the self-calibration standard light source 101 is provided with a standard photon counter 101b and a light source adjustment and driving module 101c. The standard light source 101a is connected to and mounted on the light source adjustment and driving module 101c. The self-calibration standard light source 101 performs self-calibration of the standard light source based on the photon count values ​​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 values ​​to the computer system and / or electronics system according to a preset period, for example, reporting at a period of 0.5 seconds or 1 second.

[0080] Combine Figure 2 As shown, the electronic system 120 controls the aforementioned standard light source to perform self-calibration based on the photon count value of the standard photon counter 101b and the deviation thereof from the standard count value. In an embodiment of the present invention, the standard photon count value corresponding to the standard light source is set to 45,000, that is, the aforementioned standard count value is set to 45,000.

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

[0082] In a further embodiment, in combination Figure 2 As shown, computer system 110 is further configured to upload the count and photon counter sensitivity test results to a cloud server. The cloud server makes judgments based on preset indicators and issues an alarm for test results that exceed the preset indicators. For example, based on user-preset indicators, the cloud server notifies the user's terminal of test results that exceed the specified indicators. 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 directed toward 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 regulated power supply in the shielding darkbox to supply power to the 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 drive module 101c is provided within the card slot to drive the movement of the standard light source to achieve self-calibration. As an example, the light source adjustment drive module 101c is implemented using a three-dimensional displacement adjustment mechanism and a drive motor to form a light source adjustment drive module for light source self-calibration operation.

[0087] As an example, the standard light source 101a is mounted on a three-dimensional displacement adjustment mechanism. 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 left and right.

[0089] Combine 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 forward and backward. 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 controlled to move left and right, 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 movable pair arranged along the XY plane, and a second movable pair arranged in the XZ direction. The first movable pair has a crossbeam arranged along the X direction, on which are arranged a linear slide along the longitudinal direction and a slider that can be driven to slide on the linear slide. The standard light source is mounted on the slider and can move synchronously with the slider. The crossbeam of the first movable pair is mounted on the second movable pair, and the crossbeam is driven to move in the front-to-back direction by the second movable pair, so that the linear slide, slider, and standard light source fixed to the slider of the first movable pair move back and forth 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 forward and backward (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 teachings of the present invention, other appropriate methods and drives can also be used, including but not limited to linear motor drive, rack and pinion 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 on 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 a time span, analyze the lagged impact of current data on subsequent data;

[0098] (3) If the analysis results of step (2) indicate that the data have 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, with the minimum unit being 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 further 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 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 results of step (2) indicate that the data have 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] Where 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, 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, a value between 1 and 3 indicates no problem, and a value less than 1 indicates that there is autocorrelation in the residuals.

[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, so that the retained count data becomes random counts and eliminates 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 step (5), a unit root test is performed 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, including:

[0128] First, perform AR(1) on the data processed in step (4), and let AR(1) equation be y t =py t-1 +ɑ+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′, β′ are the statistical values ​​of α, p, β respectively, and X′ is the transpose of 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 t of the unit root test is less than 0.01, it is determined that the time series has no unit root, and then it is determined that the photon counter count is stationary.

[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, in this embodiment, we further illustrate the advantages of implementing the present invention in combination with the test results and comparison.

[0140] Combine Figure 4 , which shows the photon counting results of the photon counter sensitivity and stability test system according to an embodiment of the present invention. Figure 5 The figure shows the results of photon counting using an existing conventional light source (designed to produce a standard count value of 45,000 and capable of continuous, stable light emission). The test system of the present invention uses a self-calibrating stable light source, wherein the stable light source is connected to a standard photon counter. The standard photon counter transmits the current photon count to the electronic system 120 (which can be implemented using a single-chip microcomputer) every second. The electronic system 120 controls the self-calibration operation in a 5-minute cycle. If the photon count is not the standard value of 45,000, the drive motor is controlled based on the deviation between the current photon count and 45,000. The positional relationship between the standard light source and the photocathode surface is adjusted, for example, by lateral translation, moving the light source away from or closer to the photocathode surface of the photon counter, thereby completing the self-calibration of the standard light source.

[0141] The standard light source used in existing test equipment is based on a single-wavelength LED design. It contains a light source module and light source control circuitry, which drives it to output light at a stable wavelength. The output wavelength is selectable, and the power level is adjusted to high or low, accurately outputting photons with a power of 1 pW. This battery-powered light source can cause errors in the light wave output of the standard light source if the battery level drops or if external factors cause the relative position of the light source and the photon counter to change. This can lead to deviations in the sensitivity test of the photon counter.

[0142] Combine Figure 4 、 5 The following figures show the photon counts of the self-calibration standard light source and a standard light source over a 10-minute period. This shows that the self-calibration standard light source designed by the present invention has superior luminous stability, with a maximum fluctuation range of less than 0.022%, ensuring accurate testing and calibration of the photon counter. In contrast, the luminous stability of the standard light source is more volatile, with a fluctuation range of more than 4.5%.

[0143] Therefore, according to the test system design proposed in the present invention, the light source is driven to self-calibrate by 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 standard output light wave deviation 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 dark environment under no light illumination, that is, the count rate (dark count rate).

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

[0146] Combine Figure 6 The figure shows a stability test comparison of a photon counter sensitivity and stability test system according to an embodiment of the present invention. Because existing test devices process data using only the simplest CV calculation, this algorithm cannot eliminate the influence of random factors, resulting in large autocorrelations in the test data and non-randomness. The test method proposed in the present invention eliminates the influence of data trends, seasonality, and errors, making the photon counter test results more accurate. As shown in the figure, blue represents the photon count within 20 minutes before trend and seasonality processing using the traditional method, and orange represents the processed data. A comparison shows that the method proposed in the present invention eliminates the influence of data trends and seasonality, ensuring that the data is random, and improving the objectivity and accuracy of the photon counter test results.

[0147] While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by 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 testing environment and shield external light paths and electromagnetic wave interference; the self-calibration standard light source and photon counter are arranged in the shielded dark box, and the computer system and electronics system are arranged outside the shielded dark box and connected to the shielded dark box via cables to control the start and stop of the photon counter and receive and store real-time counts; The test bench is an annular test bench fixed to the bottom of the shielded 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 to 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 counts from the photon counter of each test station on the annular test bench, perform data analysis on the counts, and output 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 regulated 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 drive motor, and the standard light source is installed on the three-dimensional displacement adjustment mechanism. The drive motor configured for each standard light source is used to drive 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 left and right, the overlapping area of ​​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 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 a 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 forward and backward. 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 controlled to move left and right, 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 comprises a crossbeam arranged along the X direction, a linear slide rail arranged along the longitudinal direction and a slider that can be driven to slide on the linear slide rail, and the standard light source is mounted 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 testing 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 a time span, analyze the lagged impact of current data on subsequent data; (3) If the analysis results of step (2) indicate that the data have 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, wherein: In step (2), analyzing the hysteresis effect of current data on 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: Where 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 prediction value is calculated, that is, ∈t, and further residual analysis is performed. Uncorrelated data means 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, v t represents the random error term; 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 7, wherein: In step (3), the trend and seasonal components of the count data within the time span are removed to convert the retained count data into random counts and eliminate correlation, 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 8, wherein: In step (4), the random count data obtained in step (3) is subjected to a sliding average to eliminate the lag effect of the error term, specifically comprising: The count data retained after processing in step (3) is further subjected to sliding average. The process of sliding average processing is as follows: Therefore, after processing in steps (3) and (4), the influence of autocorrelation, seasonal components, and error lag factors are eliminated.

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