A pulse signal measurement circuit and a pulse signal measurement device

Abstract

This invention discloses a pulse signal measurement circuit and a pulse signal measurement device. The pulse signal measurement circuit includes a photoelectric converter, a preamplifier circuit, and a signal processing circuit connected in sequence. The photoelectric converter converts the pulse signal into a current signal. The preamplifier circuit converts the current signal output by the photoelectric converter into a voltage signal. The signal processing circuit amplifies the voltage signal output by the preamplifier circuit and outputs a processed voltage signal. The processed voltage signal reflects the duration and / or energy of the pulse signal. The pulse signal measurement circuit and device of this invention feature fast response, good radiation synchronization, and portability, and can meet the needs of microsecond-level pulse X-ray time measurement in different scenarios.

Description

Technical Field

[0001] This invention relates to the field of radiation measurement technology, and in particular to a pulse signal measurement circuit and a pulse signal measurement device. Background Technology

[0002] According to the International Electrotechnical Commission (IEC) standard document IEC 60846-1:2009 regarding time equivalents, the response time of active radiation dosimeters should not exceed 10 seconds. Ionizing radiation with a duration of less than 10 seconds is generally classified as pulsed radiation. Pulsed radiation has wide applications in industrial flaw detection, medical diagnostics, nuclear accident emergency response, and public safety inspections.

[0003] Pulsed X-rays are characterized by their short duration and high instantaneous dose rate, making radiation dose measurement extremely challenging. Typically, X-ray pulse durations for personnel and object inspection are approximately 1 millisecond (ms), for diagnostic X-rays they range from 1 ms to 10 s, and for radiotherapy they are on the microsecond (μs) scale. Therefore, millisecond to microsecond-scale pulsed X-rays have important applications in diagnostic radiology, radiotherapy, radiographic testing, and personnel and object inspection. Pulse duration, as a crucial parameter in pulsed radiation dose measurement, is of significant importance. For pulsed X-rays, a pulsed X-ray duration measurement device with good synchronization with the radiation field, high time resolution, and good stability is required. Summary of the Invention

[0004] To address the existing technical problems, embodiments of the present invention provide a pulse signal measurement circuit and a pulse signal measurement device.

[0005] To achieve the above objectives, the technical solution of this invention is implemented as follows:

[0006] In a first aspect, embodiments of the present invention provide a pulse signal measurement circuit, comprising a photoelectric converter, a preamplifier circuit, and a signal processing circuit connected in sequence; wherein...

[0007] The photoelectric converter is used to convert pulse signals into current signals;

[0008] The preamplifier circuit is used to convert the current signal output by the photoelectric converter into a voltage signal;

[0009] The signal processing circuit is used to amplify the voltage signal output by the preamplifier circuit and output the processed voltage signal; the processed voltage signal is used to reflect the duration and / or energy of the pulse signal.

[0010] In the above scheme, the signal processing circuit is also used to zero-adjust the offset voltage generated during the amplification process.

[0011] In the above scheme, the signal processing circuit includes a linear amplifier circuit and a zero-adjustment circuit. The linear amplifier circuit is used to amplify the voltage signal output by the preamplifier circuit, and the zero-adjustment circuit is used to provide a zero-adjustment voltage to the linear amplifier circuit. The input terminal of the zero-adjustment circuit is connected to a reference voltage, and its output terminal is connected to the input terminal of the linear amplifier circuit. The input terminal of the linear amplifier circuit is also connected to the output terminal of the preamplifier circuit, and the output terminal of the linear amplifier circuit serves as the output terminal of the signal processing circuit.

[0012] In the above scheme, the linear amplifier circuit includes a first operational amplifier, a first feedback resistor, a first capacitor, a second operational amplifier, a second feedback resistor, and a second capacitor. The non-inverting input of the first operational amplifier is connected to the zero-adjustment circuit, and the inverting input of the first operational amplifier is connected to the output of the preamplifier circuit via the first resistor. The inverting input of the first operational amplifier is also connected to one end of the first feedback resistor, and the other end of the first feedback resistor is connected to the output of the first operational amplifier. The first capacitor is connected across the two ends of the first feedback resistor. The non-inverting input of the second operational amplifier is connected to the zero-adjustment circuit, and the inverting input of the second operational amplifier is connected to the output of the first operational amplifier via the second resistor. The inverting input of the second operational amplifier is also connected to one end of the second feedback resistor, and the other end of the second feedback resistor is connected to the output of the second operational amplifier. The second capacitor is connected across the two ends of the second feedback resistor. The output of the second operational amplifier serves as the output of the linear amplifier circuit.

[0013] In the above scheme, the zero-adjustment circuit includes a first potentiometer, a first voltage divider resistor, a second potentiometer, and a second voltage divider resistor; wherein, the input terminal of the first potentiometer is connected to a reference voltage, and the output terminal of the first potentiometer is connected to the non-inverting input terminal of the first operational amplifier through the first voltage divider resistor; the input terminal of the second potentiometer is connected to a reference voltage, and the output terminal of the second potentiometer is connected to the non-inverting input terminal of the second operational amplifier through the second voltage divider resistor.

[0014] In the above scheme, the preamplifier circuit includes a third operational amplifier, a third feedback resistor, and a third capacitor; wherein, the non-inverting input terminal of the third operational amplifier is grounded through the third resistor, the inverting input terminal of the third operational amplifier is connected to the output terminal of the photoelectric converter, the inverting input terminal of the third operational amplifier is also connected to one end of the third feedback resistor, and the other end of the third feedback resistor is connected to the output terminal of the third operational amplifier; the third capacitor is connected across the two ends of the third feedback resistor; and the output terminal of the third operational amplifier serves as the output terminal of the preamplifier circuit.

[0015] In the above scheme, the pulse signal measurement circuit further includes a voltage follower circuit connected to the output terminal of the signal processing circuit. The voltage follower circuit is used to output the voltage signal processed by the signal processing circuit at the same value.

[0016] Secondly, embodiments of the present invention provide a pulse signal measuring device, including the pulse signal measuring circuit and measuring unit described in the foregoing embodiments; the measuring unit is connected to the output terminal of the pulse signal measuring circuit and is used to determine the duration and / or energy magnitude of the pulse signal based on the voltage signal output by the pulse signal measuring circuit.

[0017] In the above scheme, the device further includes a power supply circuit connected to a DC power supply, which is used to supply power to the pulse signal measurement circuit.

[0018] In the above scheme, the pulse signal measurement circuit is set in a shielded box, and the preamplifier circuit in the pulse signal measurement circuit and the shielded box are wrapped with a metal film.

[0019] This invention provides a pulse signal measurement circuit and a pulse signal measurement device, which addresses the problem of short pulse X-ray duration and difficulty in measuring millisecond-level pulse X-ray radiation fields. The pulse signal measurement circuit and device, composed of photoelectric conversion devices, preamplifier circuits, and signal processing circuits, features fast response, good radiation synchronization, and portability, and can meet the needs of microsecond-level pulse signal time measurement in different scenarios. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the composition structure of the pulse signal measurement circuit according to an embodiment of the present invention;

[0021] Figure 2 This is an exemplary circuit diagram of a signal processing circuit according to an embodiment of the present invention;

[0022] Figure 3 This is an exemplary circuit diagram of a preamplifier circuit according to an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the composition structure of the pulse signal measuring device according to an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram illustrating the application and structure of the pulse signal measuring device according to an embodiment of the present invention;

[0025] Figure 6 This is an example of the measurement results of pulsed X-rays by the pulse signal measuring device according to an embodiment of the present invention. Figure 1 ;

[0026] Figure 7 This is an example of the measurement results of pulsed X-rays by the pulse signal measuring device according to an embodiment of the present invention. Figure 2 ;

[0027] Figure 8 This is an example of the measurement results of pulsed X-rays by the pulse signal measuring device according to an embodiment of the present invention. Figure 3 . Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the specific technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings of the embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0029] In the description of the embodiments of the present invention, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of the embodiments of the present invention, unless otherwise stated, "a plurality of" means two or more.

[0030] In the description of the embodiments of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0031] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0032] In the description of embodiments of the present invention, the terms "comprising," "including," or any other variations are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0033] In the description of the embodiments of the present invention, the words "exemplary" or "for example" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of the present invention should not be construed as being more preferred or advantageous than other embodiments or design options. Specifically, the use of the words "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0034] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] This invention provides a pulse signal measurement circuit. Figure 1 This is a schematic diagram of the composition structure of the pulse signal measurement circuit according to an embodiment of the present invention, as shown below. Figure 1 As shown, the pulse signal measurement circuit 10 includes a photoelectric converter 11, a preamplifier circuit 12, and a signal processing circuit 13 connected in sequence; wherein,

[0036] The photoelectric converter 11 is used to convert pulse signals into current signals;

[0037] The preamplifier circuit 12 is used to convert the current signal output by the photoelectric converter 11 into a voltage signal;

[0038] The signal processing circuit 13 is used to amplify the voltage signal output by the preamplifier circuit 12 and output the processed voltage signal; the processed voltage signal is used to reflect the duration and / or energy of the pulse signal.

[0039] In one embodiment, the pulse signal may be, for example, a pulsed radiation signal, such as a pulsed X-ray.

[0040] In one embodiment, the photoelectric converter 11 may be, for example, a silicon photodiode. The selection of the photoelectric converter 11 may take into account its spectral response range, photosensitivity, dark current, and other indicators. For example, if a Si-PIN silicon photodiode is used, compared with conventional photoelectric converters, it has a faster response speed, higher photosensitivity, and a wider spectral response range, which can realize a fast response to pulsed radiation signals and meet the photoelectric conversion requirements of microsecond-level pulsed rays.

[0041] In one embodiment, the preamplifier circuit 12 can be, for example, a trans-impedance amplifier (TIA) circuit. The TIA circuit may include a transimpedance amplifier and a feedback resistor. The current signal obtained by the photoelectric converter 11 can be converted into a voltage signal across the feedback resistor. In this embodiment, the transimpedance amplifier needs to have low current noise and low voltage noise, and a wide gain-bandwidth product (GBP) and a higher slew rate to support high feedback gain. This satisfies the wide feedback gain bandwidth requirement and faster conversion rate corresponding to weak pulse current signals, quickly converting the weak pulse signal into a larger voltage signal, achieving initial signal amplification, and improving the signal-to-noise ratio. It should be noted that the feedback resistor of the TIA circuit determines the circuit's amplification gain and needs to have a large resistance value and sufficiently high precision. For example, a metal film resistor can be used, and the resistance value can be selected according to actual needs. When a higher response speed is required, the resistance value of the feedback resistor can be appropriately reduced.

[0042] In one embodiment, the signal processing circuit 13 may include at least a linear filter amplifier circuit, which may include a single-stage or multi-stage amplifier circuit composed of one or more high-speed operational amplifiers. The high-speed operational amplifiers may have a high slew rate and unity-gain bandwidth product to achieve a faster integration rate and a higher measurement upper limit, while ensuring linear signal amplification without distortion.

[0043] The pulse signal measurement circuit of this invention first converts the pulse signal into a current signal through a photoelectric converter 11, and then converts it into a voltage signal through a preamplifier circuit 12. At this time, the signal can be initially amplified by the feedback resistor in the preamplifier circuit 12 to improve the signal-to-noise ratio. Then, the voltage signal output by the preamplifier circuit 12 is amplified by the signal processing circuit 13, which can amplify the weak voltage signal and output a pulse voltage signal with a certain amplitude. This can reflect the duration and / or energy of the original pulse signal, realize pulse signal measurement, and has the characteristics of fast response and good radiation synchronization.

[0044] In an optional embodiment of the present invention, the signal processing circuit 13 can also be used to zero-adjust the offset voltage generated during the amplification process.

[0045] As an optional implementation, the signal processing circuit 13 may include a linear amplifier circuit and a zero-adjustment circuit. The linear amplifier circuit is used to amplify the voltage signal output by the preamplifier circuit, and the zero-adjustment circuit is used to provide a zero-adjustment voltage to the linear amplifier circuit. The input terminal of the zero-adjustment circuit is connected to a reference voltage, and its output terminal is connected to the input terminal of the linear amplifier circuit. The input terminal of the linear amplifier circuit is also connected to the output terminal of the preamplifier circuit, and the output terminal of the linear amplifier circuit serves as the output terminal of the signal processing circuit.

[0046] Figure 2 This is an exemplary circuit diagram of a signal processing circuit according to an embodiment of the present invention. Please refer to... Figure 2 The linear amplifier circuit may include a first operational amplifier U1, a first feedback resistor Rf1, a first capacitor C1, a second operational amplifier U2, a second feedback resistor Rf2, and a second capacitor C2; wherein, the non-inverting input terminal of the first operational amplifier U1 is connected to a zero-adjustment circuit, and the inverting input terminal of the first operational amplifier U1 is connected to the output terminal of the preamplifier circuit (i.e., ...) through the first resistor R1. Figure 2 Medium voltage signal V i(Output from the preamplifier circuit), the inverting input of the first operational amplifier U1 is also connected to one end of the first feedback resistor Rf1, and the other end of the first feedback resistor Rf1 is connected to the output of the first operational amplifier U1. The first capacitor C1 is connected across the two ends of the first feedback resistor Rf1. The non-inverting input of the second operational amplifier U2 is connected to the zero-adjustment circuit. The inverting input of the second operational amplifier U2 is connected to the output of the first operational amplifier U1 through the second resistor R2. The inverting input of the second operational amplifier U2 is also connected to one end of the second feedback resistor Rf2, and the other end of the second feedback resistor Rf2 is connected to the output of the second operational amplifier U2. The second capacitor C2 is connected across the two ends of the second feedback resistor Rf2. The output of the second operational amplifier U2 serves as the output of the linear amplifier circuit, i.e. Figure 2 Medium voltage signal V o The output voltage signal of the linear amplifier circuit is denoted as .

[0047] In this embodiment, the first capacitor C1 and the second capacitor C2 are used to prevent signal oscillation caused by high-gain amplification in the linear amplifier circuit.

[0048] Please refer to Figure 2 The zero-adjustment circuit may include a first potentiometer Rs1, a first voltage divider resistor, a second potentiometer Rs2, and a second voltage divider resistor; wherein, the input terminal of the first potentiometer Rs1 is connected to a reference voltage (i.e., Figure 2 (+VCC and -VCC are the positive and negative terminals of the reference voltage, respectively). The output terminal of the first potentiometer Rs1 is connected to the non-inverting input terminal of the first operational amplifier U1 through the first voltage divider resistor. The input terminal of the second potentiometer Rs2 is connected to the reference voltage, and the output terminal of the second potentiometer Rs2 is connected to the non-inverting input terminal of the second operational amplifier U2 through the second voltage divider resistor.

[0049] The pulse signal measurement circuit of this invention includes a zero-adjustment circuit. Positive and negative voltages are applied across the zero-adjustment potentiometer. Positive and negative zero-adjustment voltages can be generated by adjusting the potentiometer. The zero-adjustment voltage is reduced by the voltage divider resistor and then input to the non-inverting input of the operational amplifier of the linear amplifier circuit to match the offset voltage input to the inverting input, thereby achieving the purpose of zero adjustment.

[0050] In one embodiment, the reference voltage may be provided by a power supply circuit.

[0051] In one embodiment, the first voltage divider resistor and the second voltage divider resistor can be obtained by connecting multiple resistors in series and / or in parallel, please refer to... Figure 2The first voltage divider resistor can be formed by connecting the fifth resistor R5 and the sixth resistor R6 in series. One end of the fifth resistor R5 is connected to the output terminal of the first potentiometer Rs1, and the other end is connected to the non-inverting input terminal of the first operational amplifier U1 and one end of the sixth resistor R6. The other end of the sixth resistor R6 is grounded. The second voltage divider resistor can be formed by connecting the seventh resistor R7 and the eighth resistor R8 in series. One end of the seventh resistor R7 is connected to the output terminal of the second potentiometer Rs2, and the other end is connected to the non-inverting input terminal of the second operational amplifier U2 and one end of the eighth resistor R8. The other end of the eighth resistor R8 is grounded.

[0052] In the pulse signal measurement circuit of this embodiment, for the linear filter amplifier circuit composed of operational amplifiers, the offset voltage introduced by the performance of the operational amplifier itself will be amplified at a higher gain. When the pulse signal energy is low, the influence of the offset voltage generated by the signal processing circuit 13 when operating the amplifier will not be ignored. This embodiment can reduce the input offset voltage of the operational amplifier by using the offset voltage zeroing circuit, effectively avoiding the influence of the offset voltage introduced by the performance of the operational amplifier itself on the small pulse signal amplitude, and improving the measurement accuracy.

[0053] Figure 3 This is an exemplary circuit diagram of a preamplifier circuit according to an embodiment of the present invention. Please refer to... Figure 3 The preamplifier circuit 12 may include a third operational amplifier U3, a third feedback resistor Rf3, and a third capacitor C3; wherein, the non-inverting input terminal of the third operational amplifier U3 can be grounded through the third resistor R3, and the inverting input terminal of the third operational amplifier U3 is connected to the output terminal of the photoelectric converter 11 (i.e., Figure 3 Medium current signal I i (Output from photoelectric converter 11), the inverting input terminal of the third operational amplifier U3 is also connected to one end of the third feedback resistor Rf3, and the other end of the third feedback resistor Rf3 is connected to the output terminal of the third operational amplifier U3; the third capacitor C3 is connected across the two ends of the third feedback resistor Rf3; the output terminal of the third operational amplifier U3 serves as the output terminal of the preamplifier circuit 12, i.e. Figure 3 Medium voltage signal V o This is the output voltage signal of the preamplifier circuit 12. The third capacitor C3 is used to prevent signal oscillation caused by high-gain amplification in the preamplifier circuit.

[0054] In one embodiment, the inverting input terminal of the third operational amplifier U3 can also be grounded through a fourth capacitor C4, such as... Figure 3 As shown.

[0055] In one embodiment, the inverting input of the third operational amplifier U3 can be connected to the output of the photoelectric converter 11 via a fourth resistor.

[0056] In an optional embodiment of the present invention, the pulse signal measurement circuit 10 may further include a voltage follower circuit connected to the output terminal of the signal processing circuit 13, the voltage follower circuit being used to output the voltage signal processed by the signal processing circuit at an equivalent value.

[0057] In one embodiment, the voltage follower circuit may include a fourth operational amplifier and a fourth feedback resistor. The non-inverting input of the fourth operational amplifier is connected to the output of the signal processing circuit 13, and the inverting input of the fourth operational amplifier is connected to one end of the fourth feedback resistor. The other end of the fourth feedback resistor is connected to the output of the fourth operational amplifier. The output of the fourth operational amplifier serves as the output of the voltage follower circuit, which is also the output of the pulse signal measurement circuit 10. In this embodiment, the voltage pulse signal output from the preamplifier circuit is input to the non-inverting input of the fourth operational amplifier. According to the principle of "virtual short" and "virtual open," the input voltage is output from the inverting input, with a feedback coefficient of 1. This isolates the influence of the distributed capacitance of the downstream signal transmission line on the preamplifier circuit and outputs the voltage signal processed by the signal processing circuit as an equivalent value, ensuring the measurement accuracy of the pulse signal.

[0058] This invention also provides a pulse signal measuring device. Figure 4 This is a schematic diagram of the composition structure of the pulse signal measuring device according to an embodiment of the present invention, as shown below. Figure 4 As shown, the pulse signal measuring device 20 includes the pulse signal measuring circuit 21 and measuring unit 22 described in the foregoing embodiments;

[0059] The measuring unit 22 is connected to the output terminal of the pulse signal measuring circuit and is used to determine the duration and / or energy of the pulse signal based on the voltage signal output by the pulse signal measuring circuit.

[0060] For a detailed description of the pulse signal measurement circuit 21 in this embodiment, please refer to the detailed description of the pulse signal measurement circuit 10 in the previous embodiment. To save space, it will not be repeated here.

[0061] In one embodiment, the measurement unit 22 may be, for example, an oscilloscope. In this embodiment, the pulse signal measurement circuit 21 outputs a pulse voltage signal of a certain amplitude, which can be captured by the oscilloscope to achieve accurate measurement of the duration and / or energy of the pulse signal.

[0062] In an optional embodiment of the present invention, the pulse signal measuring device 20 further includes a power supply circuit connected to a DC power supply, the power supply circuit being used to supply power to the pulse signal measuring circuit.

[0063] In one embodiment, the power supply circuit includes a voltage inverter and a linear regulator. The DC power supply voltage generates a positive operating voltage through the linear regulator and a negative operating voltage through the voltage inverter and the linear regulator, providing an operating voltage (or reference voltage) for the pulse signal measurement circuit 21.

[0064] In one embodiment, the DC power supply may be, for example, a removable battery, which increases the portability of the pulse signal measuring device.

[0065] In an optional embodiment of the present invention, the pulse signal measurement circuit 21 may be housed in a shielded box, and the preamplifier circuit in the pulse signal measurement circuit 21 and the shielded box are wrapped with a metal film. The photoelectric converter in the pulse signal measurement circuit is a photosensitive device and requires necessary noise reduction measures. In this embodiment, the pulse signal measurement circuit is placed in a shielded box, and the preamplifier circuit and the entire shielded box are wrapped with a metal film to further reduce noise and block light.

[0066] Optionally, the shielding box is a metal shielding box, such as an aluminum alloy shielding box, and the metal film may be, for example, aluminum foil.

[0067] The pulse signal measuring device of this invention will be described below in conjunction with specific application scenarios.

[0068] Figure 5 This is a schematic diagram illustrating the application and structure of the pulse signal measuring device according to an embodiment of the present invention. This example uses the measurement of the duration of a pulsed X-ray as an example. Figure 5 As shown, the pulse signal measuring device in this example includes a pulse X-ray time measuring circuit (i.e., the pulse signal measuring circuit in the aforementioned embodiment) and a power supply circuit ( Figure 5 (not shown in the image) and a pulse signal acquisition system (i.e., the measurement unit in the aforementioned embodiments), wherein the pulse X-ray time measurement circuit includes a photoelectric converter (e.g., a Si-PIN silicon photodiode), a transimpedance preamplifier (TIA), a signal processing circuit, and a voltage follower circuit. In this example, the pulse signal acquisition system uses an oscilloscope.

[0069] Please refer to Figure 5 The basic principle of the pulse signal measuring device is as follows: pulsed X-rays can be converted into pulsed current signals I by a photoelectric converter (Si-PIN). i And the pulse current signal I iThe duration of the pulsed X-ray is positively correlated with the exposure time of the pulsed X-ray; the pulsed current signal is converted into a pulsed voltage signal V across the third feedback resistor Rf3 by a transimpedance preamplifier circuit. o At this point, the signal is initially amplified by the feedback resistor, improving the signal-to-noise ratio. The gain of the transimpedance preamplifier circuit is limited by the feedback resistor, so the output voltage signal magnitude depends entirely on the energy of the pulsed X-ray at the measurement point. This results in different voltage signal magnitudes generated by pulsed X-rays of different energies. Weaker pulse signals will be difficult or impossible for the back-end circuit to identify and acquire. After processing by the linear filtering and amplification circuit in the signal processing circuit, the weaker pulse signals can be linearly amplified. However, at the same time, the offset voltage introduced by the operational amplifier itself under higher gain will also be amplified, possibly reaching tens of millivolts (mV). When the pulsed X-ray energy is low, the impact of the operational amplifier offset voltage will not be ignored. Therefore, the signal processing circuit in this example also includes a zero-adjustment circuit, which can zero the offset voltage of the operational amplifier. Finally, the pulse voltage signal with a certain amplitude is output to the oscilloscope through the voltage follower circuit. The oscilloscope captures the trigger signal, which can realize the accurate measurement of the pulse duration of the pulsed X-ray. The voltage follower circuit can effectively avoid the influence of the distributed capacitance of long signal lines on the front-end signal.

[0070] In this example, a Si-PIN photodiode is selected as the photoelectric conversion unit for microsecond-level pulsed X-rays. The selection of the photodiode mainly considers its spectral response range, photosensitivity, and dark current. In this example, the S3590-08 Si-PIN photodiode can be selected, with a spectral response range of 340nm to 110nm, a typical photosensitivity of 0.66 amps per watt (A / W), a maximum dark current of only 6000 picoamperes (pA), and a cutoff frequency of 40 MHz, which can effectively achieve the conversion of optical signals to electrical signals.

[0071] The transimpedance preamplifier circuit in this example uses a transimpedance amplifier and a feedback resistor. Since the input signal is a weak pulsed current signal, a transimpedance amplifier suitable for this application typically needs to have low current noise and voltage noise, and be able to support a wide GBP and higher slew rate under high feedback gain. For example, the transimpedance amplifier could be an OPA657 transimpedance operational amplifier, which features low input current noise of 1.8 femtoamperes per square hertz (fA / rtHz), low input voltage noise of 4.8 nanovolts per square hertz (nV / rtHz), and high GBP. With a 1.6 GHz frequency and a slew rate of 700 V / μs, it can meet the requirements of a wider feedback gain bandwidth and achieve a faster conversion rate, converting weak pulsed X-rays into larger voltage signals more quickly and improving the signal-to-noise ratio. The third feedback resistor Rf3 determines the gain of the preamplifier and should have a large resistance value and high precision. In this example, a metal film resistor is used. The resistance value can be selected according to actual needs. When a higher response speed is required, the resistance value can be appropriately reduced. The typical resistance value used in this example is 470 kΩ, that is, the feedback resistor Rf3 can be 470 kΩ.

[0072] In this example, the signal processing circuit includes a linear amplifier circuit and an offset voltage zero-adjustment circuit. The linear amplifier circuit is constructed using an inverse proportional amplifier composed of high-speed operational amplifiers, such as... Figure 2 and Figure 5 As shown. For example, the linear amplifier circuit can use an AD8066 FET (Field Effect Transistor) input stage high-speed operational amplifier. The op-amp chip employs a dual op-amp design, enabling the construction of a two-stage amplifier circuit to amplify the pulse signal stage by stage, ensuring linear amplification without distortion. Its open-loop gain is 113 dB, input current noise is 0.6 fA / rtHz, input voltage noise is 7 nV / rtHz, slew rate is 180 V / μs, and GBP is 145 MHz. In this example, the high slew rate and unity-gain bandwidth product of the operational amplifier allow for a faster integration rate, i.e., a higher measurement upper limit, meeting the requirements of the linear amplifier circuit. The resistance values ​​of the first feedback resistor Rf1 and the second feedback resistor Rf2 can be selected from 10 kΩ to 50 kΩ. When higher sensitivity is required, higher resistance values ​​can be preferred. In this example, the typical resistance value is 20 kΩ, meaning the resistance values ​​of the first feedback resistor Rf1 and the second feedback resistor Rf2 can be 20 kΩ.

[0073] The offset voltage zeroing circuit is composed of a zeroing potentiometer and voltage divider resistors, such as... Figure 2As shown, the first potentiometer Rs1 and the second potentiometer Rs2 can be 10kΩ zero-adjustment potentiometers. Resistors R5, R6 and R7, R8 form two voltage-group resistors, one end of which is connected to the operational amplifier input and the other end to the zero-adjustment potentiometer. Optionally, 150kΩ and 50Ω resistors can be used to form one voltage-group circuit, for example, with R5 and R7 at 150kΩ and R6 and R8 at 50Ω. This can divide the ±5V zero-adjustment voltage to ±1.67mV, which meets the adjustment range of the AD8066 operational amplifier's maximum 1.5mV input offset voltage. In this example, the minimum adjustable voltage of the zero-adjustment circuit is 333nanovolts (nV).

[0074] A voltage follower can be constructed from an AD8065 operational amplifier and a corresponding feedback resistor. The non-inverting input of the operational amplifier receives the voltage pulse signal output from the preamplifier circuit. Based on the principle of "virtual short" and "virtual open", the input voltage is output from the inverting input. The feedback coefficient is 1, which isolates the influence of the distributed capacitance of the back-end signal transmission line on the preamplifier circuit.

[0075] Specifically, please refer to Figure 2 , Figure 3 and Figure 5In this example, the non-inverting input of the transimpedance operational amplifier (i.e., the third operational amplifier U3) can be grounded through the third resistor R3. The inverting input of the transimpedance operational amplifier (U3) is connected to the output of the photoelectric converter through the fourth resistor R4, and also to one end of the third feedback resistor Rf3. The other end of the third feedback resistor Rf3 can be connected to the output of the transimpedance operational amplifier (U3). In the signal processing circuit, the inverting input of the first high-speed operational amplifier (i.e., the first operational amplifier U1) is connected to the output of the transimpedance operational amplifier (U3) through the first resistor R1, and also to one end of the first feedback resistor Rf1. The other end of the first feedback resistor Rf1 is connected to the output of the high-speed operational amplifier (U1). In the signal processing circuit, the inverting input of the second high-speed operational amplifier (i.e., the second operational amplifier U2) is connected to the output of the high-speed operational amplifier (U1) through the second resistor R2, and also to one end of the second feedback resistor Rf2. The other end of f2 is connected to the output of the high-speed operational amplifier (U2). Furthermore, the input of the first potentiometer Rs1 is connected to a reference voltage (provided by the power supply circuit), and its output is connected to the non-inverting input of the high-speed operational amplifier (U1) via resistor R5. The non-inverting input of the high-speed operational amplifier (U1) is also grounded via resistor R6. Resistors R5 and R6 form a voltage divider. The input of the second potentiometer Rs2 is connected to a reference voltage, and its output is connected to the non-inverting input of the high-speed operational amplifier (U2) via resistor R7. The non-inverting input of the high-speed operational amplifier (U2) is also grounded via resistor R8. Resistors R7 and R8 form a voltage divider. The output of the high-speed operational amplifier (U2) is also connected to the non-inverting input of the fourth operational amplifier U4 in the voltage follower circuit. The inverting input of the fourth operational amplifier U4 is connected to one end of the fourth feedback resistor Rf4, and the other end of the fourth feedback resistor Rf4 is connected to the output of the fourth operational amplifier U4. The output of the fourth operational amplifier U4 is connected to an oscilloscope.

[0076] In addition, please refer to Figure 2 The first feedback resistor Rf1 and the second feedback resistor Rf2 can also be connected across the first capacitor C1 and the second capacitor C2 respectively to prevent signal oscillation in the high-gain amplifier circuit. Figure 5 (Not shown in the image) The capacitance value can be 1 picofarad (pF); please refer to [reference needed]. Figure 3 The third feedback resistor Rf3 can also be connected across the third capacitor C3 to prevent signal oscillation in high-gain amplifier circuits.

[0077] In this example, the power supply circuit can be powered by a 9V lithium battery. A negative voltage can be generated using a TP7660H voltage inverter, and the 9V power supply can be converted to a -5V voltage using a TPS723 linear regulator and its matching circuit. Additionally, the 9V power supply can be converted to a +5V voltage using a TPS76050 linear regulator and its matching circuit. The ±5V voltage provides the operating voltage for the operational amplifiers OPA657, AD8066, and AD8065, and provides the zero-adjustment voltage for the input offset voltage zero-adjustment circuit.

[0078] Considering that the excitation signal source of this device is pulsed X-rays, and that the device contains a photoelectric converter which is a photosensitive device, and taking necessary noise reduction measures, this example places the pulsed X-ray time measurement circuit in an aluminum alloy shielding box, and wraps the preamplifier circuit and the entire shielding box with aluminum foil to achieve further noise reduction and light protection.

[0079] In this example, the pulse time capture system is constructed using an oscilloscope. The oscilloscope can be selected in Single-signal trigger mode, with a voltage threshold ranging from 0 to 5V. The time step can be adjusted to the duration of the measured pulsed X-ray in μs to ms. The channel signal parameter measurements can select rise time and fall time. When a pulse signal is generated, the oscilloscope can quickly capture the pulse duration, as well as the pulse rise time and pulse fall time. Figure 6 , Figure 7 and Figure 8 The following are example diagrams showing the measurement results of pulsed X-rays by the pulse signal measuring device according to an embodiment of the present invention. A waveform measurement diagram of a certain pulsed X-ray is shown below. Figure 6 As shown, Figure 6 The rise time is 460 ns and the fall time is 400 ns, both in the nanosecond range. More specifically, the rise and fall responses of the pulsed X-rays were measured, and the rise response waveform is shown below. Figure 7 As shown, the corresponding rise time is 340ns, achieving a nanosecond-level response speed; the fall response waveform is as follows. Figure 8 As shown, the corresponding fall time is 360 ns, which enables the measurement of pulsed X-ray duration in the millisecond to microsecond range.

[0080] The silicon photodiode used in this example has a fast response speed, high photosensitivity, and a wide spectral response range, enabling rapid response to pulsed X-rays. At the same time, the offset voltage zeroing circuit reduces the operational amplifier input offset voltage, effectively avoiding the impact of offset voltage on the amplitude of small pulse signals. The signal processing stage employs a high-speed operational amplifier and a circuit design with a small time constant, achieving rise and fall times in the nanosecond range, enabling synchronous response to microsecond-level pulsed X-rays. In addition, a removable battery can be used as a power source, making it portable.

[0081] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A pulse signal measurement circuit, characterized in that, It includes a photoelectric converter, a preamplifier circuit, and a signal processing circuit connected in sequence; wherein, The photoelectric converter is used to convert pulse signals into current signals; The preamplifier circuit is used to convert the current signal output by the photoelectric converter into a voltage signal. The signal processing circuit is used to amplify the voltage signal output by the preamplifier circuit and output the processed voltage signal; the processed voltage signal is used to reflect the duration and / or energy of the pulse signal. The signal processing circuit includes a linear amplifier circuit and a zero-adjustment circuit. The linear amplifier circuit amplifies the voltage signal output by the preamplifier circuit, and the zero-adjustment circuit provides a zero-adjustment voltage to the linear amplifier circuit. The input terminal of the zero-adjustment circuit is connected to a reference voltage, and its output terminal is connected to the input terminal of the linear amplifier circuit. The input terminal of the linear amplifier circuit is also connected to the output terminal of the preamplifier circuit, and the output terminal of the linear amplifier circuit serves as the output terminal of the signal processing circuit. The linear amplifier circuit includes a first operational amplifier, a first feedback resistor, a first capacitor, a second operational amplifier, a second feedback resistor, and a second capacitor. The non-inverting input of the first operational amplifier is connected to the zero-adjustment circuit. The inverting input of the first operational amplifier is connected to the output of the preamplifier circuit via the first resistor. The inverting input of the first operational amplifier is also connected to one end of the first feedback resistor, and the other end of the first feedback resistor is connected to the output of the first operational amplifier. The first capacitor is connected across the two ends of the first feedback resistor. The non-inverting input of the second operational amplifier is connected to the zero-adjustment circuit. The inverting input of the second operational amplifier is connected to the output of the first operational amplifier via the second resistor. The inverting input of the second operational amplifier is also connected to one end of the second feedback resistor, and the other end of the second feedback resistor is connected to the output of the second operational amplifier. The second capacitor is connected across the two ends of the second feedback resistor. The output of the second operational amplifier serves as the output of the linear amplifier circuit.

2. The pulse signal measurement circuit according to claim 1, characterized in that, The signal processing circuit is also used to zero out the offset voltage generated during the amplification process.

3. The pulse signal measurement circuit according to claim 2, characterized in that, The zero-adjustment circuit includes a first potentiometer, a first voltage-dividing resistor, a second potentiometer, and a second voltage-dividing resistor; wherein... The input terminal of the first potentiometer is connected to a reference voltage, and the output terminal of the first potentiometer is connected to the non-inverting input terminal of the first operational amplifier through the first voltage divider resistor; The input terminal of the second potentiometer is connected to a reference voltage, and the output terminal of the second potentiometer is connected to the non-inverting input terminal of the second operational amplifier through the second voltage divider resistor.

4. The pulse signal measurement circuit according to claim 1, characterized in that, The preamplifier circuit includes a third operational amplifier, a third feedback resistor, and a third capacitor; wherein... The non-inverting input terminal of the third operational amplifier is grounded through a third resistor, the inverting input terminal of the third operational amplifier is connected to the output terminal of the photoelectric converter, the inverting input terminal of the third operational amplifier is also connected to one end of the third feedback resistor, and the other end of the third feedback resistor is connected to the output terminal of the third operational amplifier; the third capacitor is connected across the two ends of the third feedback resistor. The output terminal of the third operational amplifier serves as the output terminal of the preamplifier circuit.

5. The pulse signal measurement circuit according to any one of claims 1 to 4, characterized in that, The pulse signal measurement circuit further includes a voltage follower circuit connected to the output terminal of the signal processing circuit. The voltage follower circuit is used to output the voltage signal processed by the signal processing circuit at the same value.

6. A pulse signal measuring device, characterized in that, Includes the pulse signal measurement circuit and measurement unit as described in any one of claims 1 to 5; The measuring unit is connected to the output terminal of the pulse signal measuring circuit and is used to determine the duration and / or energy of the pulse signal based on the voltage signal output by the pulse signal measuring circuit.

7. The apparatus according to claim 6, characterized in that, The device also includes a power supply circuit connected to a DC power source, which supplies power to the pulse signal measurement circuit.

8. The apparatus according to claim 6, characterized in that, The pulse signal measurement circuit is housed in a shielded box, and the preamplifier circuit in the pulse signal measurement circuit and the shielded box are wrapped with a metal film.

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