Detection system for dynamically switching multiple silicon photomultipliers

Abstract

The invention provides a detection system for dynamically switching multiple silicon photomultipliers. The device is characterized by comprising a silicon photomultiplier array module (1), a light intensity detection module (2), a control module (3), a signal processing module (4), a bias power supply module (5), a high-speed analog switch network (6), a PIN photodiode (7), a trans-impedance amplifier (8), a low-pass filter circuit (9), a single chip microcomputer (10), a drive circuit (11), a pole zero compensation circuit (12), a filter noise reduction circuit (13), a high-speed ADC (14) and a silicon photomultiplier independent parallel unit (15). The invention can be used for solving the technical problems that the silicon photomultiplier is easy to saturate in a wide light intensity environment and the weak light sensitivity is insufficient, and can be widely applied to the fields of laser radar, medical imaging, industrial visual inspection and the like which require wide light intensity range adaptive photon detection.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of multi-silicon photomultiplier dynamic switching detection system, can be used in laser radar, medical imaging, industrial vision detection etc. BACKGROUND

[0002] As a kind of high sensitivity photonic detection device, silicon photomultiplier has become the core device in the field of laser radar, medical imaging, industrial vision detection, particle physics experiment etc. with single-photon level detection capability, fast time response and good integration, which can convert weak optical signal into detectable electrical signal, provide key support for high-precision measurement, target recognition etc. and is the important foundation to realize the high performance index of various photoelectric systems.

[0003] However, the working principle of silicon photomultiplier determines that it is easy to appear saturation in strong light environment: when the incident photon flux exceeds the maximum photon counting rate of silicon photomultiplier, the avalanche effect will occur frequently in the internal micro-pixel unit and cannot recover in time, which leads to the output signal from discrete pulse to continuous high level, signal distortion, dynamic range compression and other problems, which seriously affects the detection accuracy and system reliability; and in weak light environment, in order to ensure the detection sensitivity, the photon capture efficiency needs to be improved as much as possible, and the traditional fixed structure of silicon photomultiplier is difficult to meet the dual requirements of "strong light" and "weak light high sensitivity".

[0004] The existing technologies to deal with the strong light saturation of silicon photomultiplier mainly include two categories: one is to optimize the structure parameters of silicon photomultiplier itself (such as reducing the micro-pixel size, optimizing the quenching resistance), but this way will sacrifice the weak light detection sensitivity, and the performance improvement space is limited; the other is to use signal processing algorithm (such as digital filtering, pulse discrimination) to suppress the saturation influence, but the algorithm complexity is high, time delay is easy to be introduced, and physical saturation caused by excessive photons cannot be fundamentally avoided, in addition, some schemes fix multiple silicon photomultipliers in parallel to expand the detection area, but the total photon receiving amount increases synchronously under strong light, which will exacerbate the saturation problem, and it is difficult to adjust the sensitivity flexibly under weak light.

[0005] At present, in the application scene of wide light intensity range adaptive detection, how to realize the effective suppression of strong light saturation of silicon photomultiplier from the hardware architecture level without relying on complex algorithm or sacrificing weak light performance, while ensuring high sensitivity in weak light environment, is still a technical problem to be solved, especially in the scene of vehicle-mounted laser radar, outdoor industrial detection etc. with strong dynamic change of light intensity, which puts forward higher requirements for the environmental adaptability and performance stability of detection system, and the traditional technology has been difficult to meet the actual application demand. SUMMARY

[0006] The application aims to provide a multi-silicon photomultiplier dynamic switching detection system to solve the technical problems of traditional silicon photomultiplier detection systems, such as poor environmental adaptability and difficulty in giving consideration to high sensitivity of strong light and weak light, and to realize stable and high-precision photon detection in a wide light intensity range.

[0007] The application is achieved as follows:

[0008] The multi-silicon photomultiplier dynamic switching detection system is composed of a silicon photomultiplier array module (1), a light intensity detection module (2), a control module (3), a signal processing module (4), a bias power supply module (5), a high-speed analog switch network (6), a PIN photodiode (7), a transimpedance amplifier (8), a low-pass filter circuit (9), a single-chip microcomputer (10), a driving circuit (11), a pole-zero compensation circuit (12), a filter and noise reduction circuit (13), a high-speed ADC (14), and a silicon photomultiplier independent parallel unit (15). The silicon photomultiplier array module (1) is divided into a plurality of independent parallel units by the high-speed analog switch network (6) and is used for receiving light signals and converting them into electric pulse signals. The light intensity detection module (2) is used for collecting environmental light signals in real time and outputting voltage feedback signals. The control module (3) receives the feedback signals and controls the on-off of the high-speed analog switch network (6) to dynamically adjust the number of working units of the silicon photomultiplier. The signal processing module (4) is used for optimizing the quality of the electric pulse signals. The bias power supply module (5) provides stable working voltage for the silicon photomultiplier array module (1).

[0009] The silicon photomultiplier array module is composed of a plurality of silicon photomultiplier devices with consistent performance and is divided into a plurality of independent parallel units by the high-speed analog switch network. Each parallel unit contains 1-2 silicon photomultiplier devices and is used for receiving light signals and converting them into electric pulse signals.

[0010] The light intensity detection module adopts a PIN photodiode resistant to strong light as a detection core, cooperates with a transimpedance amplifier and a low-pass filter circuit, and is used for collecting environmental light signals in real time and converting them into analog voltage feedback signals proportional to light intensity.

[0011] The control module includes a single-chip microcomputer and a driving circuit. The single-chip microcomputer is built-in with a light intensity grading calibration table and is used for receiving the feedback signals of the light intensity detection module, judging the light intensity grade, and outputting high-low level control signals to the driving circuit. The driving circuit is used for amplifying the control signals to drive the on-off of the analog switch.

[0012] The signal processing module is composed of a pole-zero compensation circuit, a filter and noise reduction circuit, and a high-speed ADC and is used for filtering, shaping, and digitizing the electric pulse signals output by the silicon photomultiplier array to optimize the signal quality.

[0013] The bias power supply module provides a stable Geiger mode operating voltage for the silicon photomultiplier tube array, and the voltage can be dynamically matched according to the number of silicon photomultiplier tube units to ensure the consistent performance of each working unit.

[0014] The high-speed analog switch uses CMOS technology to simulate the switch, avoiding attenuation or distortion of the silicon photomultiplier tube pulse signal caused by the switching action.

[0015] In addition, the light intensity detection module shares the incident light signal with the silicon photomultiplier tube array through a beam splitter, with a beam splitting ratio of 1:9. 10% of the light signal is used for light intensity monitoring and 90% of the light signal is used for effective detection, ensuring the consistency between light intensity detection and actual detection.

[0016] The microcontroller's built-in light intensity grading calibration table pre-stores the number of silicon photomultiplier tube (SMT) working units corresponding to four light intensity levels: weak light level (P<80μW) corresponds to all SMT units working, medium-weak light level (0.4mW≤P<0.8mW) corresponds to 3 SMT units working, medium-strong light level (0.4mW≤P<0.8mW) corresponds to 2 SMT units working, and strong light level (P≥0.8mW) corresponds to 1 SMT unit working.

[0017] This invention also provides a detection method for dynamic switching of multi-silicon photomultiplier tubes, the method comprising the following steps:

[0018] S1: System initialization, the bias power supply module starts and provides the preset operating voltage to the silicon photomultiplier tube array, the microcontroller loads the light intensity classification calibration table, all analog switches are initially in the on state, and all units of the silicon photomultiplier tube array enter the working state.

[0019] S2: The light intensity detection module collects ambient light signals in real time, which are then converted into analog voltage signals after transimpedance amplification and filtering, and transmitted to the ADC interface of the microcontroller for digital sampling.

[0020] S3: The microcontroller compares the sampled light intensity digital signal with the threshold in the calibration table to determine the current light intensity level and the corresponding number of target working units for the silicon photomultiplier tube.

[0021] S4: The microcontroller outputs corresponding high and low level control signals, which control the analog switch to turn on and off through the drive circuit, so that the excess silicon photomultiplier tube units are disconnected from the power supply and stop working, and only the target number of units are retained to participate in the detection, thereby realizing the dynamic adjustment of the detection area.

[0022] S5: The working unit of the silicon photomultiplier tube array converts the received optical signal into an electrical pulse signal, which is then filtered, shaped, and digitized by the signal processing module.

[0023] S6: The light intensity detection module continuously monitors changes in light intensity. If the light intensity level changes, repeat steps S3 to S5 to achieve real-time dynamic adjustment of the number of silicon photomultiplier tube units. After ensuring that the system is always in a non-saturated, highly sensitive working state, the data is output to the subsequent data processing unit.

[0024] Meanwhile, in step S4, during the switching process of the silicon photomultiplier tube unit, the bias power supply module dynamically adjusts the output current according to the number of working units to ensure that the operating voltage fluctuation of a single silicon photomultiplier tube unit is ≤0.01V, thus maintaining the consistency of detection performance.

[0025] This invention, through a collaborative design of modular grouping of multi-silicon photomultiplier tubes, feedback from a strong light detector, and dynamic switching by a microcontroller, effectively solves the problem of strong light saturation of silicon photomultiplier tubes while ensuring high sensitivity detection in low-light environments, and significantly improves the system's wide light intensity adaptability and detection stability. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a multi-silicon photomultiplier tube dynamic switching detection system, which consists of a silicon photomultiplier tube array module (1), a light intensity detection module (2), a control module (3), a signal processing module (4), a bias power supply module (5), a high-speed analog switch network (6), a PIN photodiode (7), a transimpedance amplifier (8), a low-pass filter circuit (9), a microcontroller (10), a drive circuit (11), a pole-zero compensation circuit (12), a filter noise reduction circuit (13), a high-speed ADC (14), and an independent parallel unit of silicon photomultiplier tubes (15).

[0027] Figure 2 This is a schematic diagram of the topology of each module of the dynamic switching detection system for multi-silicon photomultiplier tubes of the present invention.

[0028] Figure 3 This is the operational amplifier circuit diagram of the silicon photomultiplier tube driving circuit of the present invention.

[0029] Figure 4 This is a schematic diagram of the circuit principle of the light intensity detection module of the present invention. Detailed Implementation

[0030] The present invention will be further illustrated below with reference to specific embodiments.

[0031] System overall architecture implementation details.

[0032] like Figure 1As shown, the multi-silicon photomultiplier tube dynamic switching detection system of the present invention consists of a silicon photomultiplier tube array module (1), a light intensity detection module (2), a control module (3), a signal processing module (4), a bias power supply module (5), a high-speed analog switch network (6), a PIN photodiode (7), a transimpedance amplifier (8), a low-pass filter circuit (9), a microcontroller (10), a drive circuit (11), a pole-zero compensation circuit (12), a filtering and noise reduction circuit (13), a high-speed ADC (14), and a silicon photomultiplier tube independent parallel unit (15). Each module is connected via high-speed... The high-speed signal line and control line work together to form a complete photoelectric detection closed loop; among them, the silicon photomultiplier tube array module (1) is connected to the signal processing module (4) through the high-speed analog switch network (6), the signal output terminal of the light intensity detection module (2) is connected to the signal input terminal of the control module (3), the control output terminal of the control module (3) is connected to the high-speed analog switch network (6) through the drive circuit (11), and the voltage output terminal of the bias power supply module (5) is connected to the power supply interface of the silicon photomultiplier tube array module (1) and each functional module respectively to ensure the stable operation of the system.

[0033] like Figure 2 As shown, the silicon photomultiplier tube array module (1) consists of 8 silicon photomultiplier tube devices with consistent performance. It is divided into 4 independent parallel units (15) in a 2×4 array layout. Each independent parallel unit (15) contains 2 silicon photomultiplier tube devices. The selected silicon photomultiplier tube devices have a photosensitive area of ​​3mm×3mm, a dark count rate of ≤50kHz, and a peak photon detection efficiency of ≥65% (at a wavelength of 500nm). The cathodes of each independent parallel unit (15) of silicon photomultiplier tubes are connected to the output terminal of the bias power supply module (5). The anodes are connected to the common signal terminal through the isolation resistor and then connected to the signal processing module (4) through the high-speed analog switch network (6). The high-speed analog switch network (6) uses a CMOS process switch chip, which can avoid the attenuation or waveform distortion of the electrical pulse signal output by the silicon photomultiplier tube by the switching action.

[0034] like Figure 3 As shown, the operational amplifier of the silicon photomultiplier tube driving circuit uses an operational amplifier chip with high gain-bandwidth product and low input noise, which is suitable for amplifying weak pulse signals. In the circuit, Rf is the feedback resistor, which determines the transimpedance gain of the first stage amplification. Cf is the compensation capacitor, which is used to suppress circuit self-oscillation and ensure amplification stability. C1 and C2 are power supply filter capacitors, which are connected in parallel between the positive and negative power supply pins of the amplifier chip and ground, respectively, to filter power supply noise. The chip is powered by a ±5V dual power supply. The weak current pulse signal output by the silicon photomultiplier tube array is connected to the inverting input terminal of the operational amplifier chip after passing through the high-speed analog switch network (6). After transimpedance amplification, the measurable voltage signal Vout1 is output. Its transimpedance amplification relationship satisfies the formula: (1)

[0035] in, The silicon photomultiplier tube is the peak value of the weak current pulse signal output by the silicon photomultiplier tube array; Rf is the resistance value of the feedback resistor; Vout1 is the peak value of the operational amplifier output voltage signal.

[0036] The light intensity detection module (2) uses a strong light-resistant PIN photodiode (7) as the detection core. The anode of the PIN photodiode (7) is grounded through a current-limiting resistor, and the cathode is connected to the inverting input of the transimpedance amplifier (8) to convert the photocurrent signal into a voltage signal. The low-pass filter circuit (9) adopts a second-order RC filter structure to filter high-frequency noise in the light intensity signal. The light intensity detection module (2) shares the incident light signal with the silicon photomultiplier tube array module (1) through a beam splitter. The beam splitting ratio is set to 1:9, that is, 10% of the light signal is used for light intensity monitoring and 90% of the light signal is used for effective detection, ensuring that the light intensity detection result is consistent with the actual light intensity received by the silicon photomultiplier tube. The relationship between the output voltage Vdet of the light intensity detection module and the incident light intensity P satisfies the formula: (2)

[0037] in, Sensitivity of the PIN photodiode (unit: A / W). The value of the feedback resistor of the transimpedance amplifier (in Ω). The beam splitter's splitting efficiency (value 0.1). The incident light intensity is expressed in W.

[0038] The control module (3) consists of a microcontroller (10) and a drive circuit (11). The selected microcontroller has a built-in 12-bit ADC module for collecting the voltage feedback signal output by the light intensity detection module (2). The drive circuit (11) amplifies the high and low level control signals output by the microcontroller to drive the on and off of the high-speed analog switch network (6). The microcontroller (10) has a built-in light intensity grading calibration table and pre-stores the number of silicon photomultiplier tube working units corresponding to the four light intensity levels. The specific grading standards are as follows: weak light level (P<80μW) corresponds to all four silicon photomultiplier tube units working, medium weak light level (80μW≤P<0.4mW) corresponds to three silicon photomultiplier tube units working, medium strong light level (0.4mW≤P<0.8mW) corresponds to two silicon photomultiplier tube units working, and strong light level (P≥0.8mW) corresponds to one silicon photomultiplier tube unit working.

[0039] The signal conditioning module (4) consists of a pole-zero compensation circuit (12), a filter and noise reduction circuit (13), and a high-speed ADC (14). The pole-zero compensation circuit (12) adopts an RC series structure to compress the rising edge of the signal and eliminate pole-zero distortion in the signal. The high-speed ADC (14) converts the analog voltage signal into a digital signal and outputs it to the subsequent data processing unit.

[0040] The bias power supply module (5) enables dynamic voltage adjustment.

[0041] The multi-silicon photomultiplier tube dynamic switching detection method of the present invention specifically includes the following steps:

[0042] System initialization. The bias power supply module (5) outputs an initial voltage, which is then boosted to output a 70V bias voltage V. bias Power is supplied to the silicon photomultiplier tube array module (1); the microcontroller (10) loads the preset light intensity classification calibration table, all high-speed analog switches are initialized to the on state, and all four groups of silicon photomultiplier tube independent parallel units (15) enter the working state; each circuit unit of the signal conditioning module (4) completes the power-on self-test, and the high-speed ADC (14) is started and the sampling rate is set.

[0043] Real-time monitoring of light intensity. The PIN photodiode (7) of the light intensity detection module (2) collects the ambient light signal, converts it into a weak photocurrent, amplifies it into an analog voltage signal through the transimpedance amplifier (8), filters high-frequency noise through the low-pass filter circuit (9), and transmits it to the ADC interface of the microcontroller (10); the microcontroller (10) digitally samples the voltage signal at a frequency of 1kHz to obtain the light intensity digital signal V. det .

[0044] Light intensity level determination. The microcontroller (10) will process the sampled digital light intensity signal V. det Convert the light intensity to the actual light intensity P, and then compare it with the threshold in the light intensity grading calibration table to determine the current light intensity level; if the light intensity change causes the voltage signal change rate to exceed the threshold, the microcontroller (10) triggers the fast switching mode to shorten the control delay and avoid system saturation caused by transient strong light.

[0045] Dynamic switching control. The microcontroller (10) outputs the corresponding high and low level control signals according to the light intensity level judgment result. After being amplified by the drive circuit (11), the corresponding switch tubes in the high-speed analog switch network (6) are turned on and off. When the light intensity level is judged to be strong, the microcontroller outputs the control signal to turn off the 3 sets of switch tubes, and only one set of silicon photomultiplier tube independent parallel unit (15) is retained to participate in the detection. By reducing the effective detection area, the photon reception is reduced, and silicon photomultiplier tube saturation is avoided.

[0046] Signal acquisition and processing. The working unit of the silicon photomultiplier tube array converts the received optical signal into a weak current pulse signal, which is then amplified into a voltage signal V by an operational amplifier transimpedance amplifier. out1 After further polarity compensation and filtering noise reduction by the signal conditioning module (4), a voltage signal with optimized waveform V is obtained. out2 High-speed ADC (14) for V out2 Digital sampling is performed, and the digital signal is output to the subsequent data processing unit (such as FPGA or PC) for counting, amplitude analysis and other operations.

[0047] This invention provides a detection system with dynamic switching of multiple silicon photomultiplier tubes, which can achieve high sensitivity and non-saturated photon detection over a wide range of light intensity. The system separates the detection and monitoring of optical signals through a beam splitter, collects ambient light information in real time by a light intensity detection module, and dynamically adjusts the number of independent parallel units of silicon photomultiplier tubes according to the light intensity level by a control module. In conjunction with a signal conditioning module to optimize signal quality and a bias power supply module to ensure voltage stability, the system effectively solves the technical problem that traditional silicon photomultiplier tubes cannot achieve high sensitivity in both strong and weak light, and significantly improves the system's environmental adaptability and detection stability.

Claims

1. A detection system for dynamic switching of multi-silicon photomultiplier tubes, characterized in that: It consists of a silicon photomultiplier tube array module (1), a light intensity detection module (2), a control module (3), a signal processing module (4), a bias power supply module (5), a high-speed analog switch network (6), a PIN photodiode (7), a transimpedance amplifier (8), a low-pass filter circuit (9), a microcontroller (10), a drive circuit (11), a pole-zero compensation circuit (12), a filter noise reduction circuit (13), a high-speed ADC (14), and a silicon photomultiplier tube independent parallel unit (15). In the system, the silicon photomultiplier tube array module (1) is divided into several independent parallel units through the high-speed analog switch network (6) to receive light signals and convert them into electrical pulse signals. The light intensity detection module (2) is used to collect ambient light signals in real time and output voltage feedback signals. The control module (3) receives feedback signals and controls the high-speed analog switch network (6) to turn on and off, dynamically adjusting the number of silicon photomultiplier tube working units. The signal processing module (4) is used to optimize the quality of electrical pulse signals. The bias power supply module (5) provides a stable working voltage for the silicon photomultiplier tube array module (1).

2. The silicon photomultiplier array module (1) used in the detection system for dynamic switching of multiple silicon photomultiplier tubes according to claim 1 is composed of multiple silicon photomultiplier tube devices with consistent performance, characterized in that: Each independent parallel unit contains two silicon photomultiplier tube devices, and each unit is connected to the common signal terminal through an isolation resistor. The high-speed analog switch network (6) adopts CMOS process to simulate switches.

3. The detection system for dynamic switching of multi-silicon photomultiplier tubes according to claim 1, characterized in that: The light intensity detection module (2) uses a strong light resistant PIN photodiode (7) as the detection core, and works with a transimpedance amplifier (8) and a low-pass filter circuit (9). It shares the incident light signal with the silicon photomultiplier tube array module (1) through a beam splitter. The beam splitting ratio is 1:

9. The beam splitter distributes 10% of the light signal to the light intensity detection module (2) and 90% of the light signal to the silicon photomultiplier tube array module (1).

4. The detection system for dynamic switching of multi-silicon photomultiplier tubes according to claim 1, characterized in that: The control module (3) includes a microcontroller (10) and a drive circuit (11). The microcontroller (10) has a built-in light intensity grading calibration table and pre-stores the number of silicon photomultiplier tube working units corresponding to the four light intensity levels. The drive circuit (11) is used to amplify the high and low level control signals output by the microcontroller (10) and drive the analog switch to turn on and off.

5. The detection system for dynamic switching of multi-silicon photomultiplier tubes according to claim 1, characterized in that: The bias power supply module (5) outputs a voltage of +2.5V, which is the breakdown voltage of the silicon photomultiplier tube. It can also dynamically adjust the output current according to the number of working silicon photomultiplier tube units to ensure that the working voltage fluctuation of a single silicon photomultiplier tube unit is ≤0.01V.

6. The detection method for dynamic switching of multi-silicon photomultiplier tubes according to claim 1, characterized in that, A detection signal reference system is established with the common signal terminal of the silicon photomultiplier tube array module (1) as the reference, and a light intensity monitoring coordinate system is established with the detection center of the PIN photodiode (7) of the light intensity detection module as the reference. The coordinate directions of the two are consistent. The incident light signal is distributed to the light intensity detection module (2) and the silicon photomultiplier tube array module (1) at a ratio of 1:9 by the beam splitter. The light intensity detection module (2) converts the collected light signal into an analog voltage signal and processes it digitally. The microcontroller (10) calls the built-in light intensity grading calibration table to determine the light intensity level and outputs high and low level control signals to drive the high-speed analog switch network (6) to switch on and off through the drive circuit (11). The number of independent parallel units of the silicon photomultiplier tube is dynamically adjusted. The silicon photomultiplier tube working unit converts the received light signal into an electrical pulse signal and outputs it after pole-zero compensation, filtering and noise reduction and high-speed digital processing by the signal processing module. At the same time, the bias power supply module (5) dynamically matches the output current according to the number of working units to ensure no saturation in strong light environment and high sensitivity adaptive detection in weak light environment.

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