Photomultiplier counting signal processing circuit and photomultiplier counting equipment

Abstract

The utility model discloses a photomultiplier counting signal processing circuit and a photomultiplier counting device, and relates to the technical field of photomultipliers, the photomultiplier counting signal processing circuit comprises a first signal input end used for accessing an anode signal; the second signal input end is used for accessing a last-stage dynode signal; the signal amplification circuit is used for carrying out differential amplification on the photomultiplier anode signal and the last-stage dynode signal and then outputting a corresponding differential signal; the comparison shaping circuit is used for respectively accessing the differential signal and the comparison threshold signal, carrying out comparison shaping and then outputting a shaping signal; the counting circuit is used for counting the shaping signals; according to the technical scheme provided by the utility model, the problem of how to avoid the influence of power ripples on counting accuracy in counting signal processing of the photomultiplier is solved.

Description

Technical Field

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

[0002] When traditional photomultiplier tubes sample signals in the counting mode, they usually amplify the anode current and convert it into a voltage signal, and then compare it with a preset threshold voltage to obtain the corresponding photon voltage pulse count. However, this signal processing method is easily affected by the high-voltage power supply of the photomultiplier tube. Because there is power supply ripple in the power supply, the power supply ripple is amplified when sampling the anode signal and is wrongly counted as a photon pulse signal, thus affecting the counting accuracy.

[0003] Therefore, how to avoid the influence of power supply ripple on counting accuracy in the processing of photomultiplier tube counting signals is an urgent problem to be solved at present. Summary of the Utility Model

[0004] The main purpose of the utility model is to propose a photomultiplier tube counting signal processing circuit and a photomultiplier tube counting device, aiming to solve the problem of how to avoid the influence of power supply ripple on counting accuracy in the processing of photomultiplier tube counting signals.

[0005] To achieve the above purpose, the photomultiplier tube counting signal processing circuit 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 an anode and a plurality of dynodes. The photomultiplier tube counting signal processing circuit includes:

[0006] A first signal input terminal for accessing the anode signal of the photomultiplier tube;

[0007] A second signal input terminal for accessing the signal of the last dynode among the plurality of dynodes of the photomultiplier tube;

[0008] A signal amplification circuit, the first input terminal of the signal amplification circuit is connected to the first signal input terminal, and the second input terminal of the signal amplification circuit is connected to the second signal input terminal; the signal amplification circuit is used for differentially amplifying the anode signal and the last dynode signal of the photomultiplier tube and then outputting the corresponding differential signal;

[0009] Comparator shaping circuit, the non-inverting input terminal of the comparator shaping circuit is connected to the first output terminal of the signal amplification circuit, the inverting input terminal of the comparator shaping circuit is connected to the second output terminal of the signal amplification circuit, and the inverting input terminal of the comparator shaping circuit is further configured to receive a comparison threshold signal; the comparator shaping circuit is configured to receive the differential signal and the comparison threshold signal respectively, and output a shaped signal after comparison and shaping;

[0010] Counting circuit, the input terminal of the counting circuit is connected to the output terminal of the comparator shaping circuit; the counting circuit is configured to count the shaped signal.

[0011] In one embodiment, the signal amplification circuit includes:

[0012] Differential amplifier circuit, the first input terminal of the differential amplifier circuit is connected to the first signal input terminal, the second input terminal of the differential amplifier circuit is connected to the second signal input terminal, the first output terminal of the differential amplifier circuit is connected to the non-inverting input terminal of the comparator shaping circuit, and the second output terminal of the differential amplifier circuit is connected to the inverting input terminal of the comparator shaping circuit, and is configured to perform differential amplification on the anode signal and the last-stage dynode signal of the photomultiplier tube, and output a corresponding differential signal to the comparator shaping circuit;

[0013] DC bias circuit, the DC bias circuit includes a DC bias terminal, and the DC bias circuit is configured to perform DC bias on the anode signal and the last-stage dynode signal of the photomultiplier tube to ensure that the anode signal and the last-stage dynode signal of the photomultiplier tube can be correctly amplified;

[0014] Impedance matching circuit, the first end of the impedance matching circuit is interconnected with the first signal input terminal and the first input terminal of the differential amplifier circuit, the second end of the impedance matching circuit is interconnected with the second signal input terminal and the second input terminal of the differential amplifier circuit, and the third end of the impedance matching circuit is connected to the bias terminal of the DC bias circuit. The impedance matching circuit is configured to make the input impedances of the first input terminal and the second input terminal of the signal amplification circuit match the output impedances of the anode and the last-stage dynode of the photomultiplier tube;

[0015] Input protection circuit, the first end of the input protection circuit is interconnected with the first signal input terminal and the first input terminal of the differential amplifier circuit, the second end of the input protection circuit is interconnected with the second signal input terminal and the second input terminal of the differential amplifier circuit, and the third end of the input protection circuit is interconnected with the third end of the impedance matching circuit and the bias terminal of the DC bias circuit. The input protection circuit is configured to limit the voltages of the anode signal and the last-stage dynode signal of the photomultiplier tube, thereby protecting the differential amplifier circuit.

[0016] In one embodiment, the differential amplification circuit includes a first differential operational amplifier, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a first inductor;

[0017] The positive input terminal of the first differential operational amplifier is the first input terminal of the differential amplification circuit, the negative input terminal of the first differential operational amplifier is the second input terminal of the differential amplification circuit, the positive output terminal of the first differential operational amplifier is the first output terminal of the differential amplification circuit, the negative output terminal of the first differential operational amplifier is the second output terminal of the differential amplification circuit. The power supply terminal of the first differential operational amplifier is interconnected with the first end of the first capacitor, the first end of the second capacitor, and the first end of the first inductor. The second end of the first capacitor and the second end of the second capacitor are grounded. The second end of the first inductor is interconnected with the first end of the third capacitor, the first end of the fourth capacitor, and the common power supply terminal. The second end of the third capacitor and the second end of the fourth capacitor are grounded.

[0018] In one embodiment, the DC bias circuit includes a first resistor, a second resistor, and a fifth capacitor:

[0019] The first end of the first resistor is connected to the common power supply terminal. The second end of the first resistor is interconnected with the first end of the second resistor and the first end of the fifth capacitor. The second end of the second resistor and the second end of the fifth capacitor are connected and grounded. The second end of the first resistor is the bias terminal of the DC bias circuit.

[0020] In one embodiment, the impedance matching circuit includes a first matching resistor and a second matching resistor:

[0021] The first end of the first matching resistor is the first end of the impedance matching circuit. The second end of the first matching resistor is connected to the first end of the second matching resistor. The second end of the first matching resistor is the third end of the impedance matching circuit. The second end of the second matching resistor is the second end of the impedance matching circuit.

[0022] In one embodiment, the input protection circuit includes a first diode, a second diode, a third diode, and a fourth diode. The anode of the first diode is connected to the cathode of the second diode. The anode of the first diode is the first end of the input protection circuit. The cathode of the first diode is interconnected with the anode of the second diode, the cathode of the third diode, and the anode of the fourth diode. The cathode of the first diode is the third end of the input protection circuit. The anode of the third diode is connected to the cathode of the fourth diode. The anode of the third diode is the second end of the input protection circuit.

[0023] In one embodiment, the comparison shaping circuit includes:

[0024] A comparison circuit, wherein the positive input terminal of the comparison circuit is connected to the first output terminal of the signal amplification circuit, the negative input terminal of the comparison circuit is connected to the second output terminal of the signal amplification circuit, and the comparison circuit is configured to generate a comparison signal according to the differential signal and output the comparison signal at the output terminal;

[0025] A shaping circuit, wherein the input terminal of the shaping circuit is connected to the output terminal of the comparison circuit, the output terminal of the shaping circuit is the output terminal of the comparison shaping circuit, and the shaping circuit is configured to shape the comparison signal and output a shaped signal to the counting circuit.

[0026] In one embodiment, the comparison shaping circuit further includes:

[0027] A comparison threshold adjustment circuit, which is serially arranged between the second output terminal of the signal amplification circuit and the negative input terminal of the comparison circuit, and the comparison threshold adjustment circuit is configured to output a comparison threshold signal to the comparison circuit.

[0028] In one embodiment, the comparison shaping circuit further includes:

[0029] A DC blocking circuit, which is serially arranged between the signal amplification circuit and the comparison circuit, and the DC blocking circuit is configured to isolate the DC voltage in the differential signal.

[0030] The present invention further provides a photomultiplier tube counting device, which includes a photomultiplier tube and the above-mentioned photomultiplier tube counting signal processing circuit.

[0031] The technical solution of the present invention adopts a photomultiplier tube counting signal processing circuit, and accesses the anode signal and the last-stage dynode signal through the first signal input terminal and the second signal input terminal. Compared with the existing anode single-end output scheme, the output from the last-stage dynode signal is added, and a differential signal that is inverted with the anode is obtained. Moreover, the differential signal output, signal amplification, and input to the comparison process are all differentially processed. Compared with the existing anode single-end signal acquisition technology, differential signals are output from both the last-stage dynode and the anode at the same time, and the differential amplifier is used to process the signals, which can effectively extract the effective photon pulse signal from the signal superimposed by the photomultiplier tube photon pulse and the power supply ripple, and reduce the ripple requirement of the high-voltage power supply for the photomultiplier tube. At the same time, the signal transmission interference between the multiplier tube and the signal amplification circuit and the influence of the amplifier's own noise on the signal are reduced, thereby avoiding the influence of power supply ripple and noise during transmission on the accuracy of photon pulse counting. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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 drawings in the following description 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 1 Schematic diagram of the module structure of an embodiment of the photomultiplier tube counting signal processing circuit provided by the present invention;

[0034] Figure 2 Schematic diagram of the module structure of another embodiment of the photomultiplier tube counting signal processing circuit provided by the present invention;

[0035] Figure 3 Schematic diagram of the circuit structure of an embodiment of the photomultiplier tube counting signal processing circuit provided by the present invention;

[0036] Figure 4 Schematic diagram of the module structure of an embodiment of the photomultiplier tube counting signal processing circuit provided by the present invention;

[0037] Figure 5 Schematic diagram of the circuit structure of an embodiment of the photomultiplier tube counting signal processing circuit provided by the present invention.

[0038] Explanation of the reference numerals in the drawings:

[0039] 10. Signal amplification circuit; 11. Differential amplification circuit; U1. First differential operational amplifier; C1. First capacitor; C2. Second capacitor; C3. Third capacitor; C4. Fourth capacitor; L1. First inductor; 12. DC bias circuit; C5. Fifth capacitor; R1. First resistor; R2. Second resistor; 13. Impedance matching circuit; R3. First matching resistor; R4. Second matching resistor; 14. Input protection circuit; D1. First diode; D2. Second diode; D3. Third diode; D4. Fourth diode; 20. Comparison and shaping circuit; 21. Comparison circuit; U2. First comparator; C6. Sixth capacitor; 22. Shaping circuit; U3-A. First flip-flop; U3-B. Second flip-flop; C7. Seventh capacitor; C8. Eighth capacitor; R5. Third resistor; R6. Fourth resistor; D5. Fifth diode; 23. Comparison threshold adjustment circuit; VR1. First potentiometer; R7. Fifth resistor; R8. Sixth resistor; C9. Ninth capacitor; 24. DC blocking circuit; C10. First DC blocking capacitor; C11. Second DC blocking capacitor; R9. Seventh resistor; R10. Eighth resistor; 30. Counting circuit.

[0040] The realization, functional features, and advantages of the present utility model will be further described in conjunction with embodiments and with reference to the accompanying drawings. Specific embodiments

[0041] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with 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 the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

[0042] 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, then such directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If this specific posture changes, then the directional indications will also change accordingly.

[0043] In addition, if there are descriptions such as "first", "second", etc. involved in the embodiments of the present utility model, then such 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 of such features. 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, or 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 fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0044] When traditional photomultiplier tubes sample signals in counting mode, usually the anode current is amplified and converted into a voltage signal, and then compared with a preset threshold voltage to obtain the corresponding photon voltage pulse count. However, this signal processing method is easily affected by the high-voltage power supply of the photomultiplier tube because there is power supply ripple in the power supply. The power supply ripple is amplified when sampling the anode signal and is wrongly counted as a photon pulse signal, thus affecting the counting accuracy.

[0045] Therefore, how to avoid the influence of power supply ripple on counting accuracy in the signal processing of photomultiplier tubes is an urgent problem to be solved at present.

[0046] Based on this, the present utility model proposes a photomultiplier tube counting signal processing circuit, which is applied to a photomultiplier tube counting device. The photomultiplier tube counting device includes a photomultiplier tube, and the photomultiplier tube includes an anode and a plurality of dynodes.

[0047] The photomultiplier tube counting device can be a counting device that includes a photomultiplier tube and can perform signal processing on the photon voltage pulse signal emitted by the photomultiplier tube and can count the processed pulse signal. It should be noted that a photomultiplier tube is an electronic device that converts a weak optical signal into an electrical signal. The last dynode of the photomultiplier tube is adjacent to the anode, and the interference and power supply ripple received by the two electrodes are almost the same. When the anode receives the secondary electrons after multiplication, the last dynode just loses electrons at this time. Therefore, when performing photon pulse conversion, the signal waveforms of the last dynode and the anode are differential signals with opposite polarities.

[0048] Please refer to Figure 1 , in an embodiment of the present utility model, the photomultiplier tube counting device includes a photomultiplier tube, the photomultiplier tube includes an anode and a plurality of dynodes, and the photomultiplier tube counting signal processing circuit includes:

[0049] A first signal input terminal for accessing the anode signal of the photomultiplier tube;

[0050] A second signal input terminal for accessing the signal of the last dynode among the plurality of dynodes of the photomultiplier tube;

[0051] A signal amplification circuit 10, a first input terminal of the signal amplification circuit 10 is connected to the first signal input terminal, and a second input terminal of the signal amplification circuit 10 is connected to the second signal input terminal; the signal amplification circuit 10 is used to differentially amplify the anode signal and the last dynode signal of the photomultiplier tube and output a corresponding differential signal;

[0052] A comparison and shaping circuit 20, a non-inverting input terminal of the comparison and shaping circuit 20 is connected to a first output terminal of the signal amplification circuit 10, an inverting input terminal of the comparison and shaping circuit 20 is connected to a second output terminal of the signal amplification circuit 10, and the inverting input terminal of the comparison and shaping circuit 20 is further used to access a comparison threshold signal; the comparison and shaping circuit 20 is used to respectively access the differential signal and the comparison threshold signal, and output a shaped signal after comparison and shaping;

[0053] A counting circuit 30, an input terminal of the counting circuit 30 is connected to an output terminal of the comparison and shaping circuit 20; the counting circuit 30 is used to count the shaped signal.

[0054] It can be understood that, different from the prior art, the first signal input terminal and the second signal input terminal of this embodiment access a set of differential signals with opposite waveforms and affected by the same power supply ripple from the anode and the last-stage dynode of the photomultiplier tube, and output them to the subsequent signal processing circuit, so that the subsequent signal processing circuit can offset the influence of the power supply ripple through the processing of the differential signals output from the first signal input terminal and the second signal input terminal.

[0055] The signal amplification circuit 10 is a circuit for amplifying signals composed of operational amplifiers. It can be a differential amplifier with differential input and differential output, or a circuit composed of two independent amplifiers for separately amplifying differential signals, or a differential amplifier with differential input and single-ended output. This embodiment does not make specific limitations on this. The signal amplification circuit 10 receives the anode signal and the last-stage dynode signal of the photomultiplier tube through the first signal input terminal and the second signal input terminal, amplifies the anode signal and the last-stage dynode signal, raises the amplitudes of these signals to an easily processable level, and increases the ratio of the signal to the noise, thereby making the signal clearer. Moreover, through differential amplification processing, both the anode signal and the last-stage dynode signal are affected by the same noise during the processing of the operational amplifier and can be offset in the subsequent processing, reducing the noise influence of the signal amplification circuit 10 itself on the signal.

[0056] The comparison and shaping circuit 20 can be a combination of a comparator and a trigger. It receives the differential signal output from the signal amplification circuit 10 and the comparison threshold signal, superimposes the amplified last-stage dynode signal and the comparison threshold signal, and compares it with the amplified anode signal to generate a comparison signal, that is, when the amplitude difference between the two signals is greater than the set threshold, a comparison signal is generated. If the amplitude difference is less than the set threshold, it is regarded as an invalid signal. Through the comparison processing of the differential signal by the comparator, the influence of the power supply ripple and the noise of the signal amplification circuit 10 itself on the counting signal can be offset, and then the comparison signal is edge-shaped by the trigger to output a shaped signal. Here, the shaped signal is also the photon pulse signal.

[0057] The counting circuit 30 can be a counter capable of counting the number of pulses of the pulse signal. The counting circuit 30 counts the number of pulses of the shaped signal. It can be understood that the shaped signal is a pulse signal reflecting the photon quantization information. The counting circuit 30 can obtain the quantization data of the optical signal received by the photomultiplier tube by counting the number of pulses of the shaped signal.

[0058] The technical solution of the present utility model adopts a photomultiplier tube counting signal processing circuit, which accesses the anode signal and the last-stage dynode signal through the first signal input terminal and the second signal input terminal. Compared with the existing scheme of single-ended anode output, the output from the last-stage dynode signal is added, and a differential signal that is inverted with respect to the anode is obtained. Moreover, the differential signal output, signal amplification, and input to the comparison process are all differentially processed. Compared with the existing technology of single-ended anode signal acquisition, differential signals are output simultaneously from the last-stage dynode and the anode, and a differential amplifier is used to process the signals, which can effectively extract the effective photon pulse signal from the superposition signal of the photomultiplier tube photon pulse and the power supply ripple, and reduce the ripple requirement of the photomultiplier tube for the high-voltage power supply. At the same time, the signal transmission interference between the multiplier tube and the signal amplification circuit 10 and the influence of the amplifier's own noise on the signal are reduced, thereby avoiding the influence of power supply ripple and noise during transmission on the accuracy of photon pulse counting.

[0059] Please refer to Figure 2 , in an embodiment of the present utility model, the signal amplification circuit 10 includes:

[0060] A differential amplification circuit 11, the first input terminal of the differential amplification circuit 11 is connected to the first signal input terminal, the second input terminal of the differential amplification circuit 11 is connected to the second signal input terminal, the first output terminal of the differential amplification circuit 11 is connected to the positive input terminal of the comparison and shaping circuit 20, and the second output terminal of the differential amplification circuit 11 is connected to the negative input terminal of the comparison and shaping circuit 20, which is used to differentially amplify the anode signal and the last-stage dynode signal of the photomultiplier tube and output the corresponding differential signal to the comparison and shaping circuit 20;

[0061] A DC bias circuit 12, the DC bias circuit 12 includes a DC bias terminal, and the DC bias circuit 12 is used to perform DC biasing on the anode signal and the last-stage dynode signal of the photomultiplier tube to ensure that the anode signal and the last-stage dynode signal of the photomultiplier tube can be correctly amplified;

[0062] An impedance matching circuit 13, the first end of the impedance matching circuit 13 is interconnected with the first signal input terminal and the first input terminal of the differential amplification circuit 11, the second end of the impedance matching circuit 13 is interconnected with the second signal input terminal and the second input terminal of the differential amplification circuit 11, and the third end of the impedance matching circuit 13 is connected to the bias terminal of the DC bias circuit 12. The impedance matching circuit 13 is used to match the input impedance of the first input terminal and the second input terminal of the signal amplification circuit 10 with the output impedance of the anode and the last-stage dynode of the photomultiplier tube;

[0063] Input protection circuit 14, the first end of the input protection circuit 14 is interconnected with the first input end of the differential amplification circuit 11 and the first signal input end, the second end of the input protection circuit 14 is interconnected with the second input end of the differential amplification circuit 11 and the second signal input end, and the third end of the input protection circuit 14 is interconnected with the third end of the impedance matching circuit 13 and the bias end of the DC bias circuit 12. The input protection circuit 14 is used to limit the voltages of the anode signal and the last-stage dynode signal of the photomultiplier tube, thereby protecting the differential amplification circuit 11.

[0064] It should be noted that the differential amplification circuit 11 is a circuit that amplifies signals composed of operational amplifiers. It can be a differential amplifier with differential input and differential output, or a circuit composed of two independent amplifiers that respectively amplify differential signals, or a differential amplifier with differential input and single-ended output. This embodiment does not make specific limitations on this. The anode signal and the last-stage dynode signal of the photomultiplier tube are received through the first signal input end and the second signal input end, and the anode signal and the last-stage dynode signal are amplified to increase the amplitudes of these signals to an easily processable level and increase the ratio of the signal to the noise, thereby making the signal clearer. Moreover, through differential amplification processing, both the anode signal and the last-stage dynode signal are affected by the same noise during the processing of the operational amplifier and can be cancelled out in subsequent processing, reducing the noise influence of the signal amplification circuit 10 itself on the signal.

[0065] The DC bias circuit 12 can be a DC bias circuit 12 composed of a voltage-dividing resistor and a capacitor, which is used to perform DC biasing on the input differential signal through the voltage-dividing resistor. In this embodiment, the DC bias circuit 12 can provide a stable DC operating point to prevent the circuit from operating in the non-linear regions of saturation or cut-off, thereby improving the linearity and efficiency of the differential amplification circuit 11.

[0066] The impedance matching circuit 13 can be an impedance matching circuit 13 composed of matching resistors. The resistance value of the matching resistor should be set to be consistent with the input impedance of the photomultiplier tube. This embodiment does not make specific limitations on this. In this embodiment, through the impedance matching circuit 13, the input impedances of the first input end and the second input end of the signal amplification circuit 10 are matched with the output impedances of the anode and the last-stage dynode of the photomultiplier tube, reducing reflections and distortions during signal transmission and effectively improving the transmission quality of the photomultiplier tube technology signal.

[0067] The input protection circuit 14 can be a series-parallel network circuit composed of diodes, which serves as the input protection for the differential amplifier circuit 11. When the input voltage exceeds the tolerance range of the circuit or components, the diodes can conduct and shunt the excess voltage, thereby protecting the subsequent circuit from damage. In this embodiment, the input protection circuit 14 can prevent damage to the input protection circuit 14 caused by excessive input signal strength.

[0068] Please refer to Figure 3 , further, in an embodiment of the present invention, the differential amplifier circuit 11 includes a first differential operational amplifier U1, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a first inductor;

[0069] The positive input terminal of the first differential operational amplifier U1 is the first input terminal of the differential amplifier circuit 11, the negative input terminal of the first differential operational amplifier U1 is the second input terminal of the differential amplifier circuit 11, the positive output terminal of the first differential operational amplifier U1 is the first output terminal of the differential amplifier circuit 11, the negative output terminal of the first differential operational amplifier U1 is the second output terminal of the differential amplifier circuit 11. The power supply terminal of the first differential operational amplifier U1 is interconnected with the first terminal of the first capacitor C1, the first terminal of the second capacitor C2, and the first terminal of the first inductor. The second terminal of the first capacitor C1 and the second terminal of the second capacitor C2 are grounded. The second terminal of the first inductor, the second terminal of the first inductor L1 are interconnected with the first terminal of the third capacitor C3, the first terminal of the fourth capacitor C4, and the common power supply terminal. The second terminal of the third capacitor C3 and the second terminal of the fourth capacitor C4 are grounded.

[0070] It should be noted that the voltage of the common power supply terminal can be set to an appropriate voltage value according to the circuit design, and this embodiment does not limit this. The first differential operational amplifier U1 of this embodiment accesses the anode signal through the positive input terminal and accesses the last-stage dynode signal through the negative input terminal, and amplifies both of them at the same time, and outputs the corresponding differential signal to the comparison shaping circuit 20 through the positive output terminal and the negative output terminal. During the signal amplification process, filtering is performed by grounding the first capacitor C1 to the fourth capacitor C4 to reduce noise interference, and a first inductor is connected in series between the first differential operational amplifier U1 and the common power supply terminal to reduce the noise interference of the common power supply on signal amplification.

[0071] In this embodiment, the first differential operational amplifier U1 is used to differentially amplify the anode signal and the signal of the last dynode, increasing the amplitude of these signals to an easily processable level and increasing the signal-to-noise ratio, thereby making the signal clearer. Moreover, through differential amplification processing, both the anode signal and the signal of the last dynode are affected by the same noise during the operational amplifier processing, which can be cancelled out during subsequent processing, reducing the noise impact of the signal amplification circuit 10 itself on the signal.

[0072] In another implementation manner of this embodiment, the differential amplification circuit 11 may be composed of two independent operational amplifiers, and this embodiment does not make specific limitations thereon. In this implementation manner, the two independent operational amplifiers respectively amplify the anode signal and the signal of the last dynode and output the corresponding differential signals to the comparison and shaping circuit 20.

[0073] In yet another implementation manner of this embodiment, the differential amplification circuit 11 may also be composed of a differential amplifier with differential input and single-ended output, and this embodiment does not make specific limitations thereon. In this implementation manner, the differential amplifier amplifies the difference between the anode signal and the signal of the last dynode, and outputs the corresponding difference amplified signal at the output end to the positive input end of the comparison and shaping circuit 20, and the comparison and shaping circuit 20 compares the difference amplified signal with the threshold adjustment signal.

[0074] Please refer to Figure 3 , further, in an embodiment of the present invention, the DC bias circuit 12 includes a first resistor R1, a second resistor R2, and a fifth capacitor C5:

[0075] The first end of the first resistor R1 is connected to the common power supply terminal, the second end of the first resistor R1 is interconnected with the first end of the second resistor R2 and the first end of the fifth capacitor C5, the second end of the second resistor R2 and the second end of the fifth capacitor C5 are connected and grounded, and the second end of the first resistor R1 is the bias terminal of the DC bias circuit 12.

[0076] The DC bias circuit 12 in this embodiment uses a circuit combining a voltage-dividing resistor and a common power supply to divide the output voltage of the common power supply terminal through the first resistor R1 and the second resistor R2, thereby performing a DC bias on the input differential signal, and can provide a stable DC operating point, avoiding the differential amplification circuit 11 from operating in the non-linear regions of saturation or cut-off, thereby improving the linearity and efficiency of the differential amplification circuit 11.

[0077] Please refer to Figure 3 , further, in an embodiment of the present invention, the impedance matching circuit 13 includes a first matching resistor and a second matching resistor:

[0078] The first end of the first matching resistor is the first end of the impedance matching circuit 13, the second end of the first matching resistor is connected to the first end of the second matching resistor, the second end of the first matching resistor is the third end of the impedance matching circuit 13, and the second end of the second matching resistor is the second end of the impedance matching circuit 13.

[0079] It should be noted that the resistance setting of the first matching resistor and the second matching resistor should be consistent with the resistance value of the resistor connected in series between the anode of the photomultiplier tube and the final dynode, which is not specifically limited in this embodiment.

[0080] In this embodiment, by setting the first matching resistor and the second matching resistor in the signal amplifying circuit 10, the input impedance of the signal amplifying circuit 10 is matched with the output impedance of the anode of the photomultiplier tube and the final multiplier electrode, thereby reducing reflection and distortion during signal transmission and effectively improving the transmission quality of the photomultiplier tube technology signal.

[0081] See also Figure 3 Further, in an embodiment of the present utility model, the input protection circuit 14 includes a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4, the anode of the first diode is connected to the cathode of the second diode D2, the anode of the first diode D1 is the first end of the input protection circuit 14, the cathode of the first diode D1 is interconnected with the anode of the second diode D2, the cathode of the third diode D3 and the anode of the fourth diode D4, the cathode of the first diode D1 is the third end of the input protection circuit 14, the anode of the third diode D3 is connected to the cathode of the fourth diode D4, and the anode of the third diode D3 is the second end of the input protection circuit 14.

[0082] In this embodiment, the input of the differential amplifier circuit 11 is protected by a series-parallel network formed by the first diode D1, the second diode D2, the third diode D3 and the fourth diode D4. When the voltage of the input signal exceeds the tolerance range of the differential amplifier circuit 11, the first diode D1, the second diode D2, the third diode D3 and the fourth diode D4 can be turned on and the excess voltage is shunted, thereby protecting the differential amplifier circuit 11 from damage.

[0083] See also Figure 4 In one embodiment of the present utility model, the comparison shaping circuit comprises:

[0084] A comparison circuit 21, the positive input terminal of the comparison circuit 21 is connected to the first output terminal of the signal amplification circuit 10, the negative input terminal of the comparison circuit 21 is connected to the second output terminal of the signal amplification circuit 10, and the comparison circuit 21 is used to generate a comparison signal according to the differential signal and output it at the output terminal;

[0085] A shaping circuit 22, the input terminal of the shaping circuit 22 is connected to the output terminal of the comparison circuit 21, the output terminal of the shaping circuit 22 is the output terminal of the comparison and shaping circuit 20, and the shaping circuit 22 is used to shape the comparison signal and output a shaped signal to the counting circuit 30.

[0086] It should be noted that the comparison circuit 21 can be a circuit composed of comparators. It receives the anode signal amplified by the signal amplification circuit 10 at the positive input terminal, receives the last-stage dynode signal amplified by the signal amplification circuit 10 at the negative input terminal, and receives a threshold adjustment signal at the negative input terminal. The threshold adjustment signal is superimposed and input with the last-stage dynode signal so that the comparator can compare differential signals with opposite amplitudes. By comparing the input signals at the positive input terminal and the negative input terminal, a comparison signal is generated. That is, when the amplitude difference between the two signals is greater than the set threshold, a comparison signal is generated. If the amplitude difference is less than the set threshold, it is regarded as an invalid signal, and the generated comparison signal is output to the shaping circuit 22.

[0087] The shaping circuit 22 can be a shaping circuit 22 composed of flip-flops. When receiving the comparison signal output by the comparison circuit 21, it performs amplitude and edge shaping on the comparison signal, converts it into a shaped signal. The shaped signal is a pulse signal representing the photon quantization characteristics, and the shaped signal is output to the counting circuit 30. The counting circuit 30 counts the number of pulses in the shaped signal to obtain the quantization data of the optical signal received by the photomultiplier tube.

[0088] As an example, please refer to Figure 5 , the comparison circuit 21 includes a first comparator and a sixth capacitor C6; the shaping circuit 22 includes a first flip-flop U3-A, a second flip-flop U3-B, a seventh capacitor C7, an eighth capacitor C8, a third resistor R5, a fourth resistor R6, and a fifth diode D5; the counting circuit 30 includes a counting unit. When the signal difference received by the first comparator at the positive input terminal and the negative input terminal exceeds the set threshold, it outputs a comparison signal to the first flip-flop U3-A. The output terminal of the first flip-flop U3-A is connected to the input terminal of the second flip-flop U3-B. Through the shaping of the comparison signal by the first flip-flop U3-A and the second flip-flop U3-B, a shaped signal is output to the counting unit, and the counting unit counts the number of pulses in the shaped signal to obtain the quantization data of the optical signal received by the photomultiplier tube.

[0089] Please refer toFigure 4 , further, in an embodiment of the present utility model, the comparison shaping circuit 20 further includes:

[0090] A comparison threshold adjustment circuit 23, which is serially arranged between the second output terminal of the signal amplification circuit 10 and the inverting input terminal of the comparison circuit 21, and the comparison threshold adjustment circuit 23 is used to output a comparison threshold signal to the comparison circuit 21.

[0091] It should be noted that the comparison threshold adjustment circuit 23 can be a voltage division circuit composed of a potentiometer, a resistor, and a capacitor, or a circuit composed of a PWM controller or a DAC as a voltage division adjustment device. The comparison threshold adjustment circuit 23 can perform threshold adjustment settings for the comparator, and this embodiment does not make specific limitations on this.

[0092] As an example, please refer to Figure 5 , the comparison threshold adjustment circuit 23 includes a first potentiometer VR1, a fifth resistor R7, a sixth resistor R8, and a ninth capacitor C9. By adjusting the resistance value of the first potentiometer VR1 to change the voltage division, the comparison threshold signal is adjusted.

[0093] Please refer to Figure 4 , further, in an embodiment of the present utility model, the comparison shaping circuit 20 further includes:

[0094] A DC blocking circuit 24, which is serially arranged between the signal amplification circuit 10 and the comparison circuit 21, and the DC blocking circuit 24 is used to isolate the DC voltage in the differential signal.

[0095] It should be noted that the DC blocking circuit 24 can be a DC blocking and coupling circuit composed of capacitors. The DC blocking capacitors are arranged between the signal amplification circuit 10 and the comparison circuit 21. By coupling the differential signal through the DC blocking capacitors in the DC blocking circuit 24, the DC voltage in the differential signal amplified by the signal amplification circuit 10 can be effectively isolated, reducing the noise interference in the signal. Further, the DC blocking circuit 24 also includes a grounded resistor to further filter out the noise in the signal, improve the signal transmission quality, and enhance the signal-to-noise ratio.

[0096] As an example, please refer to Figure 5 , the DC blocking circuit 24 includes a seventh resistor R9, an eighth resistor R10, a first DC blocking capacitor C10, and a second DC blocking capacitor C11. The first DC blocking capacitor C10 and the second DC blocking capacitor C11 respectively couple the amplified anode signal and the last-stage dynode signal, filter out the DC voltage in the signal, and couple the AC part of the differential signal to output to the comparison circuit 21.

[0097] The present utility model also provides a photomultiplier tube counting device. The power supply system includes a photomultiplier tube and the photomultiplier tube counting signal processing circuit as described in the above embodiments. The specific structure of the photomultiplier tube counting device may refer to the above embodiments. Since the photomultiplier tube counting device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated herein one by one.

[0098] 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 photomultiplier tube counting signal processing circuit, characterized in that Applied to a photomultiplier tube counting device, the photomultiplier tube counting device includes a photomultiplier tube, and the photomultiplier tube includes an anode and a plurality of dynodes. The photomultiplier tube counting signal processing circuit includes: A first signal input terminal for accessing the anode signal of the photomultiplier tube; A second signal input terminal for accessing the signal of the last dynode among the plurality of dynodes of the photomultiplier tube; A signal amplification circuit, a first input terminal of the signal amplification circuit is connected to the first signal input terminal, and a second input terminal of the signal amplification circuit is connected to the second signal input terminal; the signal amplification circuit is used for differentially amplifying the anode signal and the last dynode signal of the photomultiplier tube and then outputting a corresponding differential signal; A comparison and shaping circuit, a non-inverting input terminal of the comparison and shaping circuit is connected to a first output terminal of the signal amplification circuit, an inverting input terminal of the comparison and shaping circuit is connected to a second output terminal of the signal amplification circuit, and the inverting input terminal of the comparison and shaping circuit is further used for accessing a comparison threshold signal; the comparison and shaping circuit is used for respectively accessing the differential signal and the comparison threshold signal, and outputting a shaped signal after comparison and shaping; A counting circuit, an input terminal of the counting circuit is connected to an output terminal of the comparison and shaping circuit; the counting circuit is used for counting the shaped signal.

2. The photomultiplier tube counting signal processing circuit according to claim 1, wherein The signal amplification circuit includes: A differential amplification circuit, a first input terminal of the differential amplification circuit is connected to the first signal input terminal, a second input terminal of the differential amplification circuit is connected to the second signal input terminal, a first output terminal of the differential amplification circuit is connected to the non-inverting input terminal of the comparison and shaping circuit, and a second output terminal of the differential amplification circuit is connected to the inverting input terminal of the comparison and shaping circuit, and is used for differentially amplifying the anode signal and the last dynode signal of the photomultiplier tube and then outputting a corresponding differential signal to the comparison and shaping circuit; A DC bias circuit, the DC bias circuit includes a DC bias terminal, and the DC bias circuit is used for DC biasing the anode signal and the last dynode signal of the photomultiplier tube to ensure that the anode signal and the last dynode signal of the photomultiplier tube can be correctly amplified; An impedance matching circuit, a first end of the impedance matching circuit is interconnected with the first signal input terminal and the first input terminal of the differential amplification circuit, a second end of the impedance matching circuit is interconnected with the second signal input terminal and the second input terminal of the differential amplification circuit, and a third end of the impedance matching circuit is connected to the bias terminal of the DC bias circuit. The impedance matching circuit is used for matching the input impedances of the first input terminal and the second input terminal of the signal amplification circuit with the output impedances of the anode and the last dynode of the photomultiplier tube; Input protection circuit, the first end of the input protection circuit is interconnected with the first input end of the differential amplification circuit and the first signal input end, the second end of the input protection circuit is interconnected with the second input end of the differential amplification circuit and the second signal input end, the third end of the input protection circuit is interconnected with the third end of the impedance matching circuit and the bias end of the DC bias circuit, and the input protection circuit is used to limit the voltages of the anode signal and the last-stage dynode signal of the photomultiplier tube, thereby protecting the differential amplification circuit.

3. The photomultiplier tube counting signal processing circuit according to claim 2, wherein, The differential amplification circuit includes a first differential operational amplifier, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a first inductor; The positive input end of the first differential operational amplifier is the first input end of the differential amplification circuit, the negative input end of the first differential operational amplifier is the second input end of the differential amplification circuit, the positive output end of the first differential operational amplifier is the first output end of the differential amplification circuit, the negative output end of the first differential operational amplifier is the second output end of the differential amplification circuit, the power supply end of the first differential operational amplifier is interconnected with the first end of the first capacitor, the first end of the second capacitor, and the first end of the first inductor, the second end of the first capacitor and the second end of the second capacitor are grounded, the second end of the first inductor is interconnected with the first end of the third capacitor, the first end of the fourth capacitor, and the common power supply end, and the second end of the third capacitor and the second end of the fourth capacitor are grounded.

4. The photomultiplier tube counting signal processing circuit according to claim 3, characterized in that, The DC bias circuit includes a first resistor, a second resistor, and a fifth capacitor; The first end of the first resistor is connected to the common power supply end, the second end of the first resistor is interconnected with the first end of the second resistor and the first end of the fifth capacitor, the second end of the second resistor and the second end of the fifth capacitor are connected and grounded, and the second end of the first resistor is the bias end of the DC bias circuit.

5. The photomultiplier tube counting signal processing circuit according to claim 2, characterized in that, The impedance matching circuit includes a first matching resistor and a second matching resistor; The first end of the first matching resistor is the first end of the impedance matching circuit, the second end of the first matching resistor is connected to the first end of the second matching resistor, the second end of the first matching resistor is the third end of the impedance matching circuit, and the second end of the second matching resistor is the second end of the impedance matching circuit.

6. The photomultiplier tube counting signal processing circuit according to claim 2, characterized in that, The input protection circuit includes a first diode, a second diode, a third diode, and a fourth diode; The positive electrode of the first diode is connected to the negative electrode of the second diode, the positive electrode of the first diode is the first end of the input protection circuit, the negative electrode of the first diode is interconnected with the positive electrode of the second diode, the negative electrode of the third diode, and the positive electrode of the fourth diode, the negative electrode of the first diode is the third end of the input protection circuit, the positive electrode of the third diode is connected to the negative electrode of the fourth diode, and the positive electrode of the third diode is the second end of the input protection circuit.

7. The photomultiplier tube counting signal processing circuit according to claim 1, characterized in that The comparison and shaping circuit includes: A comparison circuit, the positive input terminal of the comparison circuit is connected to the first output terminal of the signal amplification circuit, the negative input terminal of the comparison circuit is connected to the second output terminal of the signal amplification circuit, and the comparison circuit is configured to generate a comparison signal according to the differential signal and output it at the output terminal; A shaping circuit, the input terminal of the shaping circuit is connected to the output terminal of the comparison circuit, the output terminal of the shaping circuit is the output terminal of the comparison and shaping circuit, and the shaping circuit is configured to shape the comparison signal and output a shaped signal to the counting circuit.

8. The photomultiplier tube counting signal processing circuit according to claim 7, characterized in that, The comparison and shaping circuit further includes: A comparison threshold adjustment circuit, the comparison threshold adjustment circuit is serially arranged between the second output terminal of the signal amplification circuit and the negative input terminal of the comparison circuit, and the comparison threshold adjustment circuit is configured to output a comparison threshold signal to the comparison circuit.

9. The photomultiplier tube counting signal processing circuit according to claim 7, characterized in that, The comparison and shaping circuit further includes: A DC isolation circuit, the DC isolation circuit is serially arranged between the signal amplification circuit and the comparison circuit, and the DC isolation circuit is configured to isolate the DC voltage in the differential signal.

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

Images