Photomultiplier voltage division circuit and photomultiplier counting device

Abstract

The utility model discloses a photomultiplier voltage division circuit and a photomultiplier counting device, and relates to the technical field of photomultipliers, and the photomultiplier voltage division circuit comprises a voltage output circuit which comprises a first output end and a second output end and is used for outputting high-frequency AC voltage; the voltage doubling rectification voltage division circuit comprises a first input end, a second input end, a grounding end and N + 2 voltage division ends, the first input end is connected with the first output end, the second input end is connected with the second output end, the grounding end is grounded, the first voltage division end is connected with the focusing electrode, the last voltage division end is connected with the anode, and the other voltage division ends are connected with the N dynodes in a one-to-one correspondence mode; the voltage doubling rectification voltage division circuit is used for carrying out step-by-step voltage doubling rectification on the accessed high-frequency alternating-current voltage and outputting corresponding direct-current voltage to the N dynodes respectively; according to the technical scheme provided by the utility model, the problem of how to enable the photomultiplier to keep high counting rate under the condition of high input photon density is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of photomultiplier tubes, and particularly relates to a voltage dividing circuit for a photomultiplier tube and a photomultiplier tube counting device. Background Art

[0002] In traditional photomultiplier tubes, the voltages of each dynode are divided by a resistor voltage dividing circuit. As the input photon density increases, the working current of the photomultiplier tube will increase accordingly, especially the current increase of the last dynode is more significant. In the context of a constant voltage output from the power supply, the change in the internal current of the photomultiplier tube using a resistor voltage dividing circuit will directly affect its internal voltage distribution. Specifically, as the current increases, the voltage drop between the subsequent dynodes (close to the anode side) will increase, while the voltage drop between the previous dynodes (close to the cathode side) will decrease accordingly. This change in voltage distribution will directly cause the gain characteristics of the photomultiplier tube to change, and the relationship between the input photon number and the output electrical signal count no longer maintains a linear relationship, making it impossible for the photomultiplier tube to achieve a high counting rate output.

[0003] Therefore, how to enable the photomultiplier tube to maintain a high counting rate under high input photon density is an urgent problem to be solved at present. Summary of the Utility Model

[0004] The main object of the utility model is to propose a voltage dividing circuit for a photomultiplier tube and a photomultiplier tube counting device, aiming to solve the problem of how to enable the photomultiplier tube to maintain a high counting rate under high input photon density.

[0005] To achieve the above object, the voltage dividing circuit for a photomultiplier tube proposed by the utility model is applied to a photomultiplier tube counting device. The photomultiplier tube counting device includes a photomultiplier tube, and the photomultiplier tube includes a cathode, a focusing electrode, N dynodes, and an anode. The voltage dividing circuit for a photomultiplier tube includes:

[0006] A voltage output circuit, including a first output terminal and a second output terminal, for outputting a high-frequency alternating voltage;

[0007] A voltage multiplier rectifier voltage dividing circuit, including a first input terminal, a second input terminal, a ground terminal, and N + 2 voltage dividing terminals. The first input terminal is connected to the first output terminal, the second input terminal is connected to the second output terminal, the ground terminal is grounded, the first voltage dividing terminal among the N + 2 voltage dividing terminals is connected to the focusing electrode of the photomultiplier tube, the last-stage voltage dividing terminal among the N + 2 voltage dividing terminals is connected to the anode of the photomultiplier tube, and the remaining voltage dividing terminals among the N + 2 voltage dividing terminals are respectively connected to the N dynodes of the photomultiplier tube in one-to-one correspondence; wherein,

[0008] The voltage-doubling rectifying and voltage-dividing circuit is used to perform step-by-step voltage-doubling rectification on the input high-frequency AC voltage and output corresponding DC voltages to N dynodes of the photomultiplier tube respectively.

[0009] In one embodiment, the voltage-doubling rectifying and voltage-dividing circuit includes N + 2 cascaded voltage-doubling rectifying and voltage-dividing units. The output end of the first voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units is connected to the focusing electrode, the output end of the last voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units is connected to the anode, and the output ends of the remaining voltage-doubling rectifying and voltage-dividing units among the N + 2 voltage-doubling rectifying and voltage-dividing units are connected to the N dynodes of the photomultiplier tube in one-to-one correspondence.

[0010] In one embodiment, the last voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units includes a first capacitor and a first diode, and each of the remaining voltage-doubling rectifying and voltage-dividing units among the N + 2 voltage-doubling rectifying and voltage-dividing units includes a first capacitor, a second capacitor, a first diode and a second diode;

[0011] In the first voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units, the first end of the first capacitor is connected to the positive electrode of the first diode. The first end of the first capacitor is the grounding end of the voltage-doubling rectifying and voltage-dividing circuit. The second end of the first capacitor is connected to the negative electrode of the second diode. The second end of the first capacitor is the output end of the first voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units. The first end of the second capacitor is connected to the negative electrode of the first diode and the positive electrode of the second diode;

[0012] In the last voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units, the first end of the first capacitor is interconnected with the positive electrode of the first diode and the output end of the previous-stage voltage-doubling rectifying and voltage-dividing unit. The second end of the first capacitor is the output end of the last voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units. The negative electrode of the first diode is connected to the second end of the second capacitor of the previous-stage voltage-doubling rectifying and voltage-dividing unit;

[0013] In the remaining voltage-doubling rectifying and voltage-dividing units among the N + 2 voltage-doubling rectifying and voltage-dividing units, the first end of the first capacitor is interconnected with the positive electrode of the first diode and the output end of the previous-stage voltage-doubling rectifying and voltage-dividing unit. The second end of the first capacitor is connected to the negative electrode of the second diode. The second end of the first capacitor is the output end of the voltage-doubling rectifying and voltage-dividing unit. The first end of the second capacitor is interconnected with the negative electrode of the first diode, the positive electrode of the second diode and the second end of the second capacitor of the previous-stage voltage-doubling rectifying and voltage-dividing unit.

[0014] In one embodiment, the photomultiplier tube voltage-dividing circuit further includes:

[0015] An anode protection circuit, which is serially disposed between the dynode and the voltage dividing terminal.

[0016] The anode protection circuit includes a first overcurrent protection resistor and a second overcurrent protection resistor. The first overcurrent protection resistor is serially disposed between the second last dynode among the N dynodes and the third last voltage dividing terminal among the N + 2 voltage dividing terminals. The second overcurrent protection resistor is serially disposed between the third last dynode among the N dynodes and the fourth last voltage dividing terminal among the N + 2 voltage dividing terminals.

[0017] In one embodiment, the photomultiplier tube counting device further includes a counting signal processing circuit. The photomultiplier tube voltage dividing circuit further includes:

[0018] A first signal output terminal, which is interconnected with the second last voltage dividing terminal among the N + 2 voltage dividing terminals and the last stage dynode among the N dynodes, and is used for outputting a first electrical signal output by the last stage dynode to the counting signal processing circuit;

[0019] A second signal output terminal, which is interconnected with the last stage voltage dividing terminal among the N + 2 voltage dividing terminals and the anode of the photomultiplier tube, and is used for outputting a second electrical signal output by the anode to the counting signal processing circuit.

[0020] In one embodiment, the photomultiplier tube voltage dividing circuit further includes:

[0021] An impedance matching circuit, which is serially disposed between the dynode, the anode and the voltage dividing terminal. The impedance matching circuit is used for impedance matching between the first signal output terminal and the second signal output terminal and the counting signal processing circuit.

[0022] In one embodiment, the photomultiplier tube voltage dividing circuit further includes:

[0023] An output signal coupling circuit, which is serially disposed between the first signal output terminal and the anode, and between the second signal output terminal and the last stage dynode among the N dynodes respectively. The output signal coupling circuit is used for isolating the DC high voltage output by the anode of the photomultiplier tube and the last stage dynode among the N dynodes, and coupling and outputting the first electrical signal and the second electrical signal to the counting signal processing circuit.

[0024] In one embodiment, the voltage output circuit includes:

[0025] High-frequency boost circuit, the high-frequency boost circuit includes an input terminal, a first output terminal and a second output terminal. The first output terminal of the high-frequency boost circuit is the first output terminal of the voltage output circuit, and the second output terminal of the high-frequency boost circuit is the second output terminal of the voltage output circuit;

[0026] Control circuit, the control circuit includes an output terminal and a feedback terminal, and the output terminal of the control circuit is connected to the input terminal of the high-frequency boost circuit;

[0027] Feedback circuit, the feedback circuit includes an input terminal, an output terminal and a ground terminal. The input terminal of the feedback circuit is interconnected with the second output terminal of the high-frequency boost circuit and the second input terminal of the voltage-doubling rectifying and voltage-dividing circuit. The output terminal of the feedback circuit is connected to the feedback terminal of the control circuit, and the ground terminal of the feedback circuit is grounded; wherein,

[0028] The high-frequency boost circuit is used to convert the output voltage of the control circuit into a high-frequency alternating voltage and output it to the voltage-doubling rectifying and voltage-dividing circuit. The feedback circuit is used to monitor the input voltage of the voltage-doubling rectifying and voltage-dividing circuit and output a feedback voltage to the feedback terminal of the control circuit. The control circuit adjusts and corrects the output voltage according to the feedback voltage.

[0029] The present invention also provides a photomultiplier tube counting device, which includes a photomultiplier tube, a counting signal processing circuit and the photomultiplier tube voltage-dividing circuit as described above.

[0030] In an embodiment, the cathode of the photomultiplier tube is grounded.

[0031] The technical solution of the present invention adopts a voltage-doubling rectifying and voltage-dividing circuit to perform multi-stage voltage-doubling rectification on the high-frequency alternating voltage output by the voltage output circuit, and sequentially output a DC voltage with a gradually increasing arithmetic difference to each dynode of the photomultiplier tube, so that the voltage division ratio between multiple dynodes of the photomultiplier tube does not change due to the magnitude of the current in the photomultiplier tube, thereby making the gain characteristic of the photomultiplier tube not change with the increase of the input photon density, and enabling the photomultiplier tube to still maintain a high counting rate output under the condition of high input photon density. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0033] Figure 1Schematic diagram of the module structure of an embodiment of the voltage dividing circuit of the photomultiplier tube provided by the present utility model;

[0034] Figure 2 Schematic diagram of the module structure of another embodiment of the voltage dividing circuit of the photomultiplier tube provided by the present utility model;

[0035] Figure 3 Schematic diagram of the circuit structure of an embodiment of the voltage dividing circuit of the photomultiplier tube provided by the present utility model;

[0036] Figure 4 Schematic diagram of the circuit structure of an embodiment of the voltage dividing circuit of the photomultiplier tube provided by the present utility model;

[0037] Figure 5 Schematic diagram of the circuit structure of an embodiment of the voltage dividing circuit of the photomultiplier tube provided by the present utility model;

[0038] Figure 6 Schematic diagram of the circuit structure of an embodiment of the voltage dividing circuit of the photomultiplier tube provided by the present utility model;

[0039] Figure 7 Schematic diagram of the circuit structure of an embodiment of the voltage dividing circuit of the photomultiplier tube provided by the present utility model;

[0040] Figure 8 Schematic diagram of the circuit structure of the voltage output circuit provided by an embodiment of the voltage dividing circuit of the photomultiplier tube provided by the present utility model;

[0041] Explanation of the reference numerals in the drawings:

[0042] 10. Voltage output circuit; 11. Control circuit; 12. High-frequency boost circuit; 13. Feedback circuit; R5. First feedback resistor; R6. Second feedback resistor; 20. Voltage doubling rectifying and voltage dividing circuit; 30. Anode protection circuit; R1. First overcurrent protection resistor; R2. Second overcurrent protection resistor; 40. Impedance matching circuit; R3. First matching resistor; R4. Second matching resistor; 50. Output signal coupling circuit; C1. First DC blocking capacitor; C2. Second DC blocking capacitor.

[0043] The realization, functional features and advantages of the object of the present utility model will be further described in conjunction with the embodiments with reference to the accompanying drawings. Detailed implementation manners

[0044] The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without making creative efforts shall fall within the protection scope of the present utility model.

[0045] It should be noted that if there are directional indications (such as up, down, left, right, front, back,...) involved in the embodiments of the present utility model, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0046] In addition, if there are descriptions such as "first", "second", etc. involved in the embodiments of the present utility model, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present utility model.

[0047] In the traditional photomultiplier tube, the voltages of each dynode are supplied by a resistor voltage division circuit. As the input photon density increases, the working current of the photomultiplier tube will increase accordingly, especially the current increase of the last dynode is more significant. In the context of a constant voltage output from the power supply, the change in the internal current of the photomultiplier tube using a resistor voltage division circuit will directly affect its internal voltage distribution. Specifically, as the current increases, the voltage drop between the subsequent dynodes (close to the anode side) will increase, while the voltage drop between the previous dynodes (close to the cathode side) will decrease accordingly. This change in voltage distribution will directly cause the gain characteristics of the photomultiplier tube to change, and the relationship between the input photon number and the output electrical signal count no longer maintains a linear relationship, making it impossible for the photomultiplier tube to achieve a high counting rate output.

[0048] Therefore, how to enable the photomultiplier tube to maintain a high counting rate under high input photon density is an urgent problem to be solved at present.

[0049] Based on this, the present utility model proposes a voltage division circuit for a photomultiplier tube.

[0050] Please refer to Figure 1 , in an embodiment of the present utility model, it is applied to a photomultiplier tube counting device. The photomultiplier tube counting device includes a photomultiplier tube, and the photomultiplier tube includes a cathode, a focusing electrode, N dynodes, and an anode. The voltage dividing circuit of the photomultiplier tube includes:

[0051] A voltage output circuit 10, including a first output terminal and a second output terminal, for outputting a high-frequency alternating voltage;

[0052] A voltage multiplier rectifier voltage dividing circuit 20, including a first input terminal, a second input terminal, a ground terminal, and N + 2 voltage dividing terminals. The first input terminal is connected to the first output terminal, the second input terminal is connected to the second output terminal, the ground terminal is grounded, the first voltage dividing terminal among the N + 2 voltage dividing terminals is connected to the focusing electrode of the photomultiplier tube, the last-stage voltage dividing terminal among the N + 2 voltage dividing terminals is connected to the anode of the photomultiplier tube, and the remaining voltage dividing terminals among the N + 2 voltage dividing terminals are respectively connected to the N dynodes of the photomultiplier tube in one-to-one correspondence; wherein,

[0053] The voltage multiplier rectifier voltage dividing circuit 20 is used to perform step-by-step voltage multiplication rectification on the input high-frequency alternating voltage and output corresponding DC voltages to the N dynodes of the photomultiplier tube respectively.

[0054] It should be noted that a photomultiplier tube is an electronic device that converts a weak optical signal into an electrical signal. Photons are received at the cathode, and electrons are emitted when the cathode receives the input photons, forming a current. After being re-emitted by the focusing electrode and multiple dynodes, it is multiplied and amplified. The anode receives the amplified current and outputs an electrical signal, and the electrical signal is counted by the subsequent signal processing circuit, so as to count the optical signal received by the photomultiplier tube. During this process, it is necessary to ensure that the voltage division ratio between each dynode meets the requirements. If the voltage division ratio is in the non-linear region, the relationship between the input photons and the electrical signal will no longer be linear, resulting in the subsequent technical signal processing circuit being unable to accurately count the optical signal by counting the electrical signal, thereby reducing the counting rate. Therefore, it is necessary to ensure that the voltage division between each dynode meets the requirements.

[0055] The voltage output circuit 10 can be a combination of a high-frequency transformer, a PWM controller, and a DC power supply. This embodiment does not make specific limitations on this. The voltage output circuit 10 converts the DC voltage into a high-frequency alternating voltage through inversion and boosting and outputs it to the voltage multiplier rectifier voltage dividing circuit 20, so that the voltage multiplier rectifier voltage dividing circuit 20 can perform voltage multiplication rectification on the input alternating voltage to achieve the DC voltage division output of the voltage multiplier rectifier voltage dividing circuit.

[0056] The voltage-doubling rectifying voltage-dividing circuit 20 can be a circuit with voltage-doubling rectifying function composed of capacitors and diodes. During the positive and negative half-cycles of the high-frequency alternating voltage, the capacitors are continuously charged through the unidirectional conduction characteristic of the diodes, so that the voltage on the capacitors accumulates continuously, enabling the voltage at each voltage-dividing end to reach the required voltage, and the DC voltages increasing arithmetically are respectively output from the first voltage-dividing end to the (N + 1)-th voltage-dividing end to the focusing electrode and N dynodes of the photomultiplier tube, making the voltage difference between adjacent dynodes of the photomultiplier tube equal. The (N + 2)-th voltage-dividing end is connected to the anode, and the anode is not voltage-doubled.

[0057] Through the adoption of the voltage-doubling rectifying voltage-dividing circuit 20, the technical solution of the present utility model performs multi-stage voltage-doubling rectification on the output high-frequency alternating voltage of the voltage output circuit 10, and respectively outputs DC voltages increasing arithmetically to the dynodes of the photomultiplier tube, so that the voltage division ratio between multiple dynodes of the photomultiplier tube does not change due to the magnitude of the current in the photomultiplier tube. Thus, the gain characteristic of the photomultiplier tube does not change with the increase of the input photon density, and it can still maintain a high counting rate output under the condition of high input photon density. Moreover, the voltage-dividing circuit of the photomultiplier tube in this embodiment has extremely low static power consumption, can effectively reduce the power and volume, and realizes the miniaturization of the module.

[0058] Please refer to Figure 2 , in an embodiment of the present utility model, the voltage-doubling rectifying voltage-dividing circuit 20 includes N + 2 voltage-doubling rectifying voltage-dividing units cascaded in sequence. The output end of the first voltage-doubling rectifying voltage-dividing unit among the N + 2 voltage-doubling rectifying voltage-dividing units is connected to the focusing electrode, the output end of the last voltage-doubling rectifying voltage-dividing unit among the N + 2 voltage-doubling rectifying voltage-dividing units is connected to the anode, and the output ends of the remaining voltage-doubling rectifying voltage-dividing units among the N + 2 voltage-doubling rectifying voltage-dividing units are respectively connected to the N dynodes of the photomultiplier tube in one-to-one correspondence.

[0059] It should be noted that the voltage-doubling rectifying voltage-dividing unit can be a circuit with voltage-doubling rectifying function composed of capacitors and diodes. During the positive and negative half-cycles of the high-frequency alternating voltage, the capacitors are continuously charged through the unidirectional conduction characteristic of the diodes, so that the voltage on the capacitors accumulates continuously to reach the required output voltage. From the output end of the first voltage-doubling rectifying voltage-dividing unit to the output end of the (N + 1)-th voltage-doubling rectifying voltage-dividing unit of the voltage-doubling rectifying voltage-dividing circuit 20, the voltage difference between the output ends of two adjacent voltage-doubling rectifying voltage-dividing units is equal, so that the voltage difference between adjacent dynodes of the photomultiplier tube is equal.

[0060] In this embodiment, the voltage-doubling rectifying and voltage-dividing circuit 20 uses a voltage-dividing loop composed of capacitors and diodes to replace the original resistor voltage division, reducing the impedance of the voltage-dividing loop, so that the voltage division ratio between multiple dynodes of the photomultiplier tube does not change due to the magnitude of the current in the photomultiplier tube. As a result, the gain characteristic of the photomultiplier tube does not change with the increase in the input photon density, enabling the photomultiplier tube to still maintain a high counting rate output under the condition of high input photon density. Moreover, the voltage-dividing circuit of the photomultiplier tube in this embodiment has extremely low static power consumption, can effectively reduce the power and volume, and realizes the miniaturization of the module.

[0061] In an embodiment of the present invention, the last-stage voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units includes a first capacitor and a first diode, and each of the remaining N + 2 voltage-doubling rectifying and voltage-dividing units includes a first capacitor, a second capacitor, a first diode, and a second diode;

[0062] In the first-stage voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units, the first end of the first capacitor is connected to the positive electrode of the first diode. The first end of the first capacitor is the grounding end of the voltage-doubling rectifying and voltage-dividing circuit 20. The second end of the first capacitor is connected to the negative electrode of the second diode. The second end of the first capacitor is the output end of the first-stage voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units. The first end of the second capacitor is connected to the negative electrode of the first diode and the positive electrode of the second diode;

[0063] In the last-stage voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units, the first end of the first capacitor is interconnected with the positive electrode of the first diode and the output end of the previous-stage voltage-doubling rectifying and voltage-dividing unit. The second end of the first capacitor is the output end of the last-stage voltage-doubling rectifying and voltage-dividing unit among the N + 2 voltage-doubling rectifying and voltage-dividing units. The negative electrode of the first diode is connected to the second end of the second capacitor of the previous-stage voltage-doubling rectifying and voltage-dividing unit;

[0064] In the remaining voltage-doubling rectifying and voltage-dividing units among the N + 2 voltage-doubling rectifying and voltage-dividing units, the first end of the first capacitor is interconnected with the positive electrode of the first diode and the output end of the previous-stage voltage-doubling rectifying and voltage-dividing unit. The second end of the first capacitor is connected to the negative electrode of the second diode. The second end of the first capacitor is the output end of the voltage-doubling rectifying and voltage-dividing unit. The first end of the second capacitor is interconnected with the negative electrode of the first diode, the positive electrode of the second diode, and the second end of the second capacitor of the previous-stage voltage-doubling rectifying and voltage-dividing unit.

[0065] It should be noted that each of the first voltage-doubling rectifier unit to the N+1th voltage-doubling rectifier unit includes two capacitors and two diodes. Taking the output voltage of the voltage output circuit 10 as the first AC voltage, during the positive and negative half-cycles of the first AC voltage output by the voltage output circuit 10, the peak voltage of the first AC voltage (√2 times the first AC voltage) is stored in the two capacitors respectively according to the conduction and cutoff directions of the two diodes, and is accumulated at the output end of the voltage-doubling rectifier unit (i.e., the voltage-dividing end of the voltage-doubling rectifier voltage-dividing circuit 20), so that the first DC voltage (2√2 times the first AC voltage) is rectified and output at the first voltage-dividing end, and the output voltage of the subsequent voltage-dividing end is the voltage of the previous voltage-dividing end plus the first DC voltage.

[0066] Please refer to Figure 3 , taking N = 10 as an example, the voltage-doubling rectifier voltage-dividing circuit 20 includes twelve voltage-dividing ends. Taking the ground terminal node as A, the first voltage-dividing end node as B, the second voltage-dividing end node as C,... the twelfth voltage-dividing end node as M, the cathode of the photomultiplier tube corresponds to the ground terminal node A, the focusing electrode corresponds to the connection of the first voltage-dividing end node B, the first dynode to the tenth dynode respectively correspond to the connection of the second voltage-dividing end node C to the eleventh voltage-dividing end node L, and the anode corresponds to the connection of the twelfth voltage-dividing end node M. In this embodiment, the voltages of nodes A to L and the voltage differences between adjacent nodes are shown in the following table, and u is the first DC voltage:

[0067]

[0068]

[0069] Referring to this table, it can be seen that in this embodiment, the voltages of the voltage-dividing ends of the voltage-doubling rectifier voltage-dividing circuit 20 increase step by step in an arithmetic progression and are output to the dynodes of the photomultiplier tube. Compared with the traditional resistor voltage division, the internal resistance of the voltage-dividing circuit is greatly reduced. When the current of the photomultiplier tube increases when the photomultiplier tube is under high photon input density, the voltage division ratio between the dynodes can remain the same, so that the gain characteristic of the photomultiplier tube is maintained in the linear region, and the high counting rate output of the photomultiplier tube is realized.

[0070] Moreover, the voltage-doubling rectifier voltage-dividing circuit 20 of this embodiment uses capacitors and diodes to double-rectify the input voltage, and has extremely low static power consumption, which can effectively reduce the power output of the power supply, reduce the product volume, and contribute to the miniaturization of the product module.

[0071] In another implementation manner of this embodiment, for the voltage division characteristics of different dynodes of the photomultiplier tube, the series connection level of the voltage-doubling rectifier unit can be increased between the dynodes to realize different voltage distribution ratios of the dynodes, which increases the versatility of the voltage-dividing circuit of the photomultiplier tube in this embodiment and can be flexibly applied to different types of photomultiplier tubes.

[0072] In an embodiment of the present utility model, there is an anode protection circuit 30. The anode protection circuit 30 is serially arranged between the dynode and the voltage dividing end. The anode protection circuit 30 is used to make the anode current of the photomultiplier tube lower than a preset current threshold value;

[0073] As an example, the anode protection circuit 30 includes a first overcurrent protection resistor R1 and a second overcurrent protection resistor R2. The first overcurrent protection resistor R1 is serially arranged between the penultimate dynode among the N dynodes and the third last voltage dividing end among the N + 2 voltage dividing ends. The second overcurrent protection resistor R2 is serially arranged between the third last dynode among the N dynodes and the fourth last voltage dividing end among the N + 2 voltage dividing ends.

[0074] It should be noted that a photomultiplier tube amplifies photoelectron signals through multiple amplification stages. When photons hit the cathode, electrons are generated. These electrons are accelerated in each amplification stage and strike the next amplification stage, generating more electrons through collisions, and finally reaching the anode to form a measurable current. As the electrons are continuously amplified in the amplification stages, the current reaching the anode may exceed the preset current threshold value (the preset current threshold value is the maximum current value at which the anode can maintain safe operation). Due to the excessive current, the anode may overheat and may damage the anode and the dynode, affecting the performance and service life of the photomultiplier tube; the large current may also cause an increase in the noise of the photomultiplier tube and reduce the signal-to-noise ratio. By connecting resistors in series to the penultimate and third last dynodes of the photomultiplier tube, the current passing through the penultimate and third last dynodes can be restricted, thereby reducing the current reaching the anode, so that the anode operates within the preset current threshold value.

[0075] In this embodiment, the resistance values of the first overcurrent protection resistor R1 and the second overcurrent protection resistor R2 need to be determined based on the technical specifications of the photomultiplier tube and the voltage and current limitations required by the serially connected dynodes. This embodiment does not make specific limitations in this regard. Taking N = 10 as an example, please refer to Figure 4 , the first overcurrent protection resistor R1 and the second overcurrent protection resistor R2 are respectively serially connected to the eighth dynode and the ninth dynode. The serially connected overcurrent resistors will restrict the current passing through the eighth dynode and the ninth dynode, thereby avoiding excessive anode current. The overcurrent protection of the anode of the photomultiplier tube is realized, and the performance and service life of the photomultiplier tube are guaranteed.

[0076] Please refer to Figure 5 , in an embodiment of the present utility model, the photomultiplier tube counting device further includes a counting signal processing circuit. The photomultiplier tube voltage dividing circuit further includes:

[0077] The first signal output terminal is interconnected with the penultimate voltage dividing terminal among the N + 2 voltage dividing terminals and the last dynode among the N dynodes, and is used to output the first electrical signal output by the last dynode to the counting signal processing circuit;

[0078] The second signal output terminal is interconnected with the last voltage dividing terminal among the N + 2 voltage dividing terminals and the anode of the photomultiplier tube, and is used to output the second electrical signal output by the anode to the counting signal processing circuit.

[0079] In an embodiment of the present invention, the photomultiplier tube voltage dividing circuit further includes: an impedance matching circuit 40, the impedance matching circuit 40 is serially arranged between the dynode, the anode and the voltage dividing terminal, and the impedance matching circuit 40 is used to impedance-match the first signal output terminal and the second signal output terminal with the counting signal processing circuit;

[0080] As an example, the impedance matching circuit 40 includes a first matching resistor R3 and a second matching resistor R4, the first matching resistor R3 is serially arranged between the last dynode among the N dynodes and the penultimate voltage dividing terminal among the N + 2 voltage dividing terminals, and the second matching resistor R4 is serially arranged between the anode and the last voltage dividing terminal among the N + 2 voltage dividing terminals.

[0081] It should be noted that the first signal output terminal and the second signal output terminal need to be impedance-matched with the subsequent counting signal processing circuit to ensure that the signal can be efficiently transmitted during the transmission process, reducing signal reflection and distortion. The resistance values of the first matching resistor R3 and the second matching resistor R4 should be matched with the input impedance of the counting signal processing circuit, and this embodiment does not make specific limitations in this regard. Additionally, if the distance from the photomultiplier tube to the counting signal processing is relatively long and coaxial cable transmission is used (the characteristic impedance of the coaxial cable is usually 50 ohms or 75 ohms), then the resistance values of the first matching resistor R3 and the second matching resistor R4 here should be set to be the same as the characteristic impedance of the coaxial cable.

[0082] In this embodiment, please refer to Figure 6 , taking N = 10 as an example, by respectively connecting the first matching resistor R3 and the second matching resistor R4 in series between the tenth dynode and the anode to the voltage doubling rectifying voltage dividing circuit 20 for impedance matching with the subsequent counting signal processing circuit, the transmission quality of the photomultiplier tube technical signal is effectively improved, signal reflection and distortion are reduced, thereby improving the counting rate of the circuit.

[0083] In an embodiment of the present utility model, there is an output signal coupling circuit 50. The output signal coupling circuit 50 is respectively serially disposed between the first signal output terminal and the anode, and between the second signal output terminal and the last dynode among the N dynodes. The output signal coupling circuit 50 is used to isolate the DC high voltage output by the anode of the photomultiplier tube and the last dynode among the N dynodes, and couple and output the first electrical signal and the second electrical signal to the counting signal processing circuit;

[0084] As an example, please refer to Figure 7 , the output signal coupling circuit 50 includes a first DC-blocking capacitor C1 and a second DC-blocking capacitor C2. The first DC-blocking capacitor C1 is serially disposed between the first signal output terminal and the anode, and the second DC-blocking capacitor C2 is serially disposed between the second signal output terminal and the last dynode among the N dynodes.

[0085] It should be noted that since the voltage dividing circuit of the photomultiplier tube in this embodiment adopts a positive bias method with the cathode grounded, the DC potentials of the last dynode and the anode will reach 1 kilovolt or even higher. Directly sending the signal to the backend circuit may damage the circuit.

[0086] The first DC-blocking capacitor C1 and the second DC-blocking capacitor C2 are high-voltage capacitors, which can operate normally under the DC high voltage output by the anode of the photomultiplier tube and the last dynode. The first DC-blocking capacitor C1 and the second DC-blocking capacitor C2 should be specifically selected according to the influence of the capacitance value on the signal and the withstand voltage level of the capacitor. This embodiment does not make specific limitations in this regard.

[0087] In this embodiment, by connecting the first DC-blocking capacitor C1 and the second DC-blocking capacitor C2 in series between the first signal output terminal and the second signal output terminal and the last dynode and the anode of the photomultiplier tube, the DC high voltage is isolated, ensuring that only the AC signal (i.e., the changing signal generated by the photoelectron flow) is coupled and transmitted to the counting signal processing circuit, effectively isolating the DC high voltage, protecting the backend signal processing circuit from damage, and ensuring the integrity of the signal and improving the signal quality.

[0088] In an embodiment of the present utility model, the voltage output circuit 10 includes:

[0089] A high-frequency boost circuit 12. The high-frequency boost circuit 12 includes an input terminal, a first output terminal, and a second output terminal. The first output terminal of the high-frequency boost circuit 12 is the first output terminal of the voltage output circuit 10, and the second output terminal of the high-frequency boost circuit 12 is the second output terminal of the voltage output circuit 10;

[0090] A control circuit 11, the control circuit 11 includes an output terminal and a feedback terminal, and the output terminal of the control circuit 11 is connected to the input terminal of the high-frequency boost circuit 12;

[0091] A feedback circuit 13, the feedback circuit 13 includes an input terminal, an output terminal and a ground terminal. The input terminal of the feedback circuit 13 is interconnected with the second output terminal of the high-frequency boost circuit 12 and the second input terminal of the voltage multiplier rectifier voltage dividing circuit 20. The output terminal of the feedback circuit 13 is connected to the feedback terminal of the control circuit 11, and the ground terminal of the feedback circuit 13 is grounded; wherein,

[0092] The high-frequency boost circuit 12 is used to convert the output voltage of the control circuit 11 into a high-frequency AC voltage and output it to the voltage multiplier rectifier voltage dividing circuit 20. The feedback circuit 13 is used to monitor the input voltage of the voltage multiplier rectifier voltage dividing circuit 20 and output a feedback voltage to the feedback terminal of the control circuit 11. The control circuit 11 adjusts and corrects the output voltage according to the feedback voltage.

[0093] It should be noted that the control circuit 11 can be a combination of a DC power supply and a PWM controller, which converts the DC voltage output of the DC power supply into an AC voltage output, and generates an error signal by comparing the reference voltage with the feedback voltage. According to the error signal, the switching frequency or duty cycle of the PWM controller is adjusted, and finally the purpose of adjusting the output voltage of the voltage output circuit 10 is achieved. The high-frequency boost circuit 12 is a high-frequency transformer, which is used to boost the AC voltage output by the control circuit 11 and output it to the voltage multiplier rectifier voltage dividing circuit 20. The feedback circuit 13 can be a combination of feedback voltage dividing resistors, which is used to detect the actual output voltage and feedback this information to the control circuit 11 for adjusting the output voltage of the voltage output circuit 10.

[0094] As an example, please refer to Figure 8 , the feedback circuit 13 includes a first feedback resistor R5 and a second feedback resistor R6. The first end of the first feedback resistor R5 is interconnected with the second output terminal of the high-frequency boost circuit 12 and the second input terminal of the voltage multiplier rectifier voltage dividing circuit 20. The first end of the first feedback resistor R5 is the input terminal of the feedback circuit 13. The second end of the first feedback resistor R5 is interconnected with the first end of the second feedback resistor R6 and the feedback terminal of the control circuit 11. The second end of the first feedback resistor R5 is the output terminal of the feedback circuit 13. The second end of the second feedback resistor R6 is grounded.

[0095] The present utility model also provides a photomultiplier tube counting device, which includes a photomultiplier tube, a counting signal processing circuit, and the photomultiplier tube voltage dividing circuit as described above. The specific structure of this photomultiplier tube counting device refers to the above embodiments. Since this photomultiplier tube counting device adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated one by one here.

[0096] In an embodiment of the present utility model, the cathode of the photomultiplier tube is grounded.

[0097] It should be noted that the photomultiplier tube includes a metal shell as the electromagnetic shielding layer of the photomultiplier tube, and the metal shell can reduce the influence of external electromagnetic interference on the photomultiplier tube.

[0098] In this embodiment, by grounding the cathode of the photomultiplier tube, the cathode and the metal shell of the photomultiplier tube have equal potentials, and the entire photomultiplier tube becomes a well-shielded system, further reducing the influence of external electromagnetic interference and improving the signal quality and signal-to-noise ratio of the photomultiplier tube.

[0099] The above description is only an exemplary embodiment of the present utility model, and does not limit the patent scope of the present utility model. Any equivalent structural transformation made under the technical concept of the present utility model by using the content of the specification and drawings of the present utility model, or any direct / indirect application in other related technical fields is included in the patent protection scope of the present utility model.

Claims

1. A voltage dividing circuit for a photomultiplier tube, characterized in that, Applied to a photomultiplier tube counting device, the photomultiplier tube counting device includes a photomultiplier tube, and the photomultiplier tube includes a cathode, a focusing electrode, N dynodes, and an anode. The photomultiplier tube voltage dividing circuit includes: A voltage output circuit, including a first output terminal and a second output terminal, for outputting a high-frequency alternating voltage; A voltage multiplier rectifier voltage dividing circuit, including a first input terminal, a second input terminal, a ground terminal, and N + 2 voltage dividing terminals. The first input terminal is connected to the first output terminal, the second input terminal is connected to the second output terminal, the ground terminal is grounded, the first of the N + 2 voltage dividing terminals is connected to the focusing electrode of the photomultiplier tube, the last voltage dividing terminal of the N + 2 voltage dividing terminals is connected to the anode of the photomultiplier tube, and the remaining voltage dividing terminals of the N + 2 voltage dividing terminals are respectively connected to the N dynodes of the photomultiplier tube in one-to-one correspondence; wherein, The voltage multiplier rectifier voltage dividing circuit is used for performing step-by-step voltage multiplication and rectification on the input high-frequency alternating voltage, and respectively outputting corresponding DC voltages to the N dynodes of the photomultiplier tube.

2. The photomultiplier tube voltage dividing circuit according to claim 1, characterized in that The voltage multiplier rectifier voltage dividing circuit includes N + 2 voltage multiplier rectifier voltage dividing units connected in cascade in sequence. The output terminal of the first voltage multiplier rectifier voltage dividing unit among the N + 2 voltage multiplier rectifier voltage dividing units is connected to the focusing electrode, the output terminal of the last voltage multiplier rectifier voltage dividing unit among the N + 2 voltage multiplier rectifier voltage dividing units is connected to the anode, and the output terminals of the remaining voltage multiplier rectifier voltage dividing units among the N + 2 voltage multiplier rectifier voltage dividing units are respectively connected to the N dynodes of the photomultiplier tube in one-to-one correspondence.

3. The voltage dividing circuit of the photomultiplier tube according to claim 2, characterized in that The last voltage multiplier rectifier voltage dividing unit among the N + 2 voltage multiplier rectifier voltage dividing units includes a first capacitor and a first diode, and each of the remaining voltage multiplier rectifier voltage dividing units among the N + 2 voltage multiplier rectifier voltage dividing units includes a first capacitor, a second capacitor, a first diode, and a second diode; In the first voltage multiplier rectifier voltage dividing unit among the N + 2 voltage multiplier rectifier voltage dividing units, the first end of the first capacitor is connected to the positive electrode of the first diode, the first end of the first capacitor is the ground terminal of the voltage multiplier rectifier voltage dividing circuit, the second end of the first capacitor is connected to the negative electrode of the second diode, the second end of the first capacitor is the output terminal of the first voltage multiplier rectifier voltage dividing unit among the N + 2 voltage multiplier rectifier voltage dividing units, and the first end of the second capacitor is connected to the negative electrode of the first diode and the positive electrode of the second diode; In the last voltage multiplier rectifier voltage dividing unit among the N + 2 voltage multiplier rectifier voltage dividing units, the first end of the first capacitor is interconnected with the positive electrode of the first diode and the output terminal of the previous-stage voltage multiplier rectifier voltage dividing unit, the second end of the first capacitor is the output terminal of the last voltage multiplier rectifier voltage dividing unit among the N + 2 voltage multiplier rectifier voltage dividing units, and the negative electrode of the first diode is connected to the second end of the second capacitor of the previous-stage voltage multiplier rectifier voltage dividing unit; Among the remaining voltage multiplier rectifier voltage dividing units in the N + 2 voltage multiplier rectifier voltage dividing units, the first end of the first capacitor is interconnected with the positive electrode of the first diode and the output end of the previous-stage voltage multiplier rectifier voltage dividing unit. The second end of the first capacitor is connected to the negative electrode of the second diode. The second end of the first capacitor is the output end of the voltage multiplier rectifier voltage dividing unit. The first end of the second capacitor is interconnected with the negative electrode of the first diode, the positive electrode of the second diode, and the second end of the second capacitor of the previous-stage voltage multiplier rectifier voltage dividing unit.

4. The photomultiplier tube voltage dividing circuit according to claim 1, characterized in that, The photomultiplier voltage dividing circuit further includes: An anode protection circuit, which is serially arranged between the dynode and the voltage dividing end.

5. The voltage dividing circuit of the photomultiplier tube according to claim 1, wherein The photomultiplier counting device further includes a counting signal processing circuit. The photomultiplier voltage dividing circuit further includes: A first signal output terminal, which is interconnected with the penultimate voltage dividing terminal among the N + 2 voltage dividing terminals and the final-stage dynode among the N dynodes, and is used to output the first electrical signal output by the final-stage dynode to the counting signal processing circuit; A second signal output terminal, which is interconnected with the final-stage voltage dividing terminal among the N + 2 voltage dividing terminals and the anode of the photomultiplier, and is used to output the second electrical signal output by the anode to the counting signal processing circuit.

6. The photomultiplier tube voltage dividing circuit according to claim 5, characterized in that The photomultiplier voltage dividing circuit further includes: An impedance matching circuit, which is serially arranged between the dynode, the anode, and the voltage dividing end. The impedance matching circuit is used to make the impedance of the first signal output terminal and the second signal output terminal match the impedance of the counting signal processing circuit.

7. The voltage dividing circuit of a photomultiplier tube according to claim 5, characterized in that, The photomultiplier voltage dividing circuit further includes: An output signal coupling circuit, which is respectively serially arranged between the first signal output terminal and the anode, and between the second signal output terminal and the final-stage dynode among the N dynodes. The output signal coupling circuit is used to isolate the DC high voltage output by the anode of the photomultiplier and the final-stage dynode among the N dynodes, and couple and output the first electrical signal and the second electrical signal to the counting signal processing circuit.

8. The voltage dividing circuit of a photomultiplier tube according to claim 1, characterized in that, The voltage output circuit includes: A high-frequency boost circuit, which includes an input terminal, a first output terminal, and a second output terminal. The first output terminal of the high-frequency boost circuit is the first output terminal of the voltage output circuit, and the second output terminal of the high-frequency boost circuit is the second output terminal of the voltage output circuit; A control circuit, which includes an output terminal and a feedback terminal. The output terminal of the control circuit is connected to the input terminal of the high-frequency boost circuit; A feedback circuit, which includes an input terminal, an output terminal, and a ground terminal. The input terminal of the feedback circuit is interconnected with the second output terminal of the high-frequency boost circuit and the second input terminal of the voltage multiplier rectifier voltage dividing circuit. The output terminal of the feedback circuit is connected to the feedback terminal of the control circuit, and the ground terminal of the feedback circuit is grounded. Among them, The high-frequency boost circuit is used to convert the output voltage of the control circuit into a high-frequency AC voltage and output it to the voltage-doubling rectifying and voltage-dividing circuit. The feedback circuit is used to monitor the input voltage of the voltage-doubling rectifying and voltage-dividing circuit and output a feedback voltage to the feedback terminal of the control circuit. The control circuit adjusts and corrects the output voltage according to the feedback voltage.

9. A photomultiplier tube counting device, characterized in that, The photomultiplier tube counting device includes a photomultiplier tube, a counting signal processing circuit, and a photomultiplier tube voltage-dividing circuit according to any one of claims 1 to 8.

10. The photomultiplier tube counting device according to claim 9, characterized in that, The cathode of the photomultiplier tube is grounded.

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