A method and system for improving the response dynamic range of SiPM photoelectric sensor

Abstract

The present application discloses a method and system for improving the linear response dynamic range of a SiPM photoelectric sensor, comprising: performing beam shaping on a received incident light signal and irradiating the shaped light signal onto a photosensitive surface of a rear-mounted SiPM sensor; the SiPM sensor converting the received light signal into a current signal and transmitting the current signal to a transimpedance amplifier; the transimpedance amplifier converting the received current signal into a voltage signal and transmitting the voltage signal to a nonlinear amplifier; the nonlinear amplifier performing nonlinear correction based on the intensity amplitude of the received voltage signal; the design of this method, on the one hand, improves the linearity of the SiPM's response to strong light by performing nonlinear correction on the response output signal under strong light irradiation; on the other hand, optimizes the linearity of the SiPM's response to weak light by improving the circuit resolution, ultimately increasing the SiPM's linear dynamic response range to 6 orders of magnitude (pW-uW).

Description

Technical Field

[0001] The present application relates to the field of photoelectric detector technology, and more particularly to a method for improving the response dynamic range of a SiPM photoelectric sensor. Furthermore, the present application also relates to a system for improving the response dynamic range of a SiPM photoelectric sensor. Background Art

[0002] A silicon photomultiplier (SiPM) or multi-pixel photo-counter (MPPC) is an emerging photodetector device with a high internal gain (10^5 to 10^6). Compared to traditional photomultiplier tubes (PMTs), SiPMs offer small size, compact structure, excellent product consistency, and strong reliability. They can operate at low bias voltages and exhibit excellent resistance to magnetic field interference and mechanical shock. They also offer high gain, high photon detection efficiency, fast response, excellent temporal resolution, and a wide spectral response range. They are currently widely used in high-energy physics, nuclear medicine, radar ranging, and immunofluorescence detection.

[0003] In terms of its operating principle, a SiPM consists of an array of avalanche photodiodes (APDs) (approximately 10 to 100 μm in size) operating in Geiger mode (or counting mode). Each APD photosensitive cell (or pixel) operates independently in photoelectron counting mode, and the photoelectric response signal pulses of all pixels are connected in parallel to form the final output signal. For any particular photosensitive cell, when a photon signal arrives and is converted into electrons, it undergoes avalanche amplification and generates a photoelectric pulse signal output. To respond to the next incoming photon signal, the bias voltage across the photosensitive cell is quickly cut after the avalanche occurs, allowing it to return to the photon-receiving state. This process is commonly referred to as the recovery time (Tr). During this recovery time, the photosensitive cell does not respond to any incident photons (regardless of the number of photons), meaning that no photoelectric pulse signal is output. This period is also commonly referred to as the dead time. Therefore, when the photon flux density incident on the SiPM surface exceeds a certain level, the number of photoelectric pulses or voltage amplitude output by the SiPM is no longer in a strictly linear response relationship with the actual number of photons incident on it. Especially under strong light irradiation (such as >100nW), the output signal of the SiPM sensor will show an obvious nonlinear response or even saturation.

[0004] In response to the nonlinear problem of SiPM's strong light response, researchers have proposed several different solutions: 1) Use structured illumination to change the photon density distribution actually irradiated on the SiPM pixel by adding different optical elements (such as lenses, prisms, interference films, reflectors, etc.) on the end face of the SiPM incident window to delay the saturation output light intensity of the SiPM. In essence, the nonlinear improvement of its strong light response is achieved by reducing the number of actual received photons. The disadvantage is that it sacrifices the sensitivity of weak light response and does not significantly improve the linearity of SiPM's strong light response output; 2) Partition the light signal according to the intensity distribution on the surface of the SiPM sensor (such as strong light area a and weak light area b), and divide the corresponding area a signal and area b signal into two paths for output and back-transmission respectively. Periodic processing, and then calculate the calibration curve based on the difference between the two signals, and finally perform the final linear correction and signal output through algorithms or software. Its characteristic is that it is necessary to improve the structural design and production process of SiPM from the source of the process, which has certain technical difficulties; 3) Based on the nonlinearity of the SiPM's own response to the optical radiation signal, a multi-stage operational amplifier correction circuit is designed to calibrate the analog signal originally output by the SiPM before outputting it to the subsequent signal processing unit: first, a zero-order correction signal (Offset), a first-order correction signal (proportional amplification), and a second-order correction signal (square amplification) are generated respectively, and then sent to the post-amplifier for summation operation as the final output. Its main disadvantage is that the correction circuit design and debugging process is relatively complicated and time-consuming. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide a method for improving the linear response dynamic range of a SiPM photoelectric sensor. This method is designed to improve the linearity of the SIPM's response to strong light by performing nonlinear correction on the response output signal under strong light illumination. Furthermore, when the input light signal is relatively weak, the voltage amplitude of the response output signal is increased by increasing the circuit gain, thereby improving the linearity of the SIPM's response to weak light. Ultimately, the linear dynamic response range of the SiPM is increased to six orders of magnitude (pW-uW). Furthermore, this application provides a system for improving the response dynamic range of a SiPM photoelectric sensor.

[0006] To solve the above technical problems, the present application provides a method for improving the linear response dynamic range of a SiPM photoelectric sensor, comprising:

[0007] The received incident light signal is beam-shaped so that the shaped light signal is irradiated onto the photosensitive surface of the rear SiPM photoelectric sensor;

[0008] The SiPM photoelectric sensor converts the received light signal into a current signal and transmits the current signal to a transimpedance amplifier;

[0009] The transimpedance amplifier converts the received current signal into a voltage signal, and transmits the voltage signal to the nonlinear amplifier;

[0010] The nonlinear amplifier performs nonlinear correction according to the intensity amplitude of the received voltage signal;

[0011] The gain amplification factor of the SiPM photoelectric sensor, the gain amplification factor of the transimpedance amplifier, and the gain amplification factor of the nonlinear amplifier are set by a microprocessor;

[0012] The linear dynamic response range of the SiPM photodetector is 6 orders of magnitude from pW to uW.

[0013] In a specific embodiment,

[0014] The “nonlinear amplifier performs nonlinear correction according to the intensity amplitude of the received voltage signal” includes:

[0015] When a weak light signal is input and the transimpedance amplifier operates at a first predetermined gain, the gain amplification factor of the nonlinear amplifier is a fixed multiple; and / or,

[0016] When a strong light signal is input and the transimpedance amplifier operates at a second predetermined gain, the gain amplification factor of the nonlinear amplifier changes nonlinearly with the intensity of the voltage signal output by the transimpedance amplifier.

[0017] In a specific embodiment,

[0018] The “the SiPM photoelectric sensor converts the received light signal into a current signal, and transmits the current signal to a transimpedance amplifier” includes:

[0019] The photoelectric gain of the SiPM photoelectric sensor can be controlled by a microprocessor, which adjusts the sensor gain control signal according to the intensity range of the input light signal to change the reverse bias voltage applied to the photoelectric sensor.

[0020] In a specific embodiment,

[0021] The “transimpedance amplifier converts the received current signal into a voltage signal, and transmits the voltage signal to the nonlinear amplifier” includes:

[0022] By setting different feedback resistor values through a microprocessor, the transimpedance amplifier has different current-to-voltage conversion factors to match incident light signals of different intensity ranges, so that the corresponding output voltage signal falls within the linear response range of the subsequent signal processing circuit.

[0023] In a specific embodiment,

[0024] The “nonlinear amplifier performs nonlinear correction according to the intensity amplitude of the received voltage signal” includes:

[0025] The gain amplification factor of the nonlinear amplifier is adjusted by a microprocessor.

[0026] In a specific embodiment,

[0027] The step of “shaping the received incident light signal so that the shaped light signal is irradiated onto the photosensitive surface of the rear-mounted photoelectric sensor” includes:

[0028] The incident light signal is shaped into a light spot size or shape that matches the photosensitive area of the SiPM photosensor by a beam shaper, so that the collected light signal fills the photosensitive surface of the SiPM photosensor.

[0029] In a specific embodiment,

[0030] The “nonlinear amplifier performs nonlinear correction according to the intensity amplitude of the received voltage signal” includes:

[0031] The adjustment range of the gain amplification factor of the nonlinear amplifier is determined according to the requirements of a theoretical correction curve of the nonlinear response of the photoelectric sensor at different photoelectric gain setting points.

[0032] In a specific embodiment,

[0033] The “adjustment range of the gain amplification factor of the nonlinear amplifier is determined based on the theoretical correction curve requirements of the nonlinear response of the photoelectric sensor at different photoelectric gain setting points” includes:

[0034] First, based on the voltage signal response curve of the output of the transimpedance amplifier, a deviation curve between the voltage signal response curve and the ideal linear response curve is calculated;

[0035] According to the deviation curve, a circuit parameter setting value of the nonlinear amplifier is further calculated as a correction function, and the gain adjustment range or circuit parameter of the nonlinear amplifier is set by a microprocessor.

[0036] In addition, to solve the above technical problems, the present application also provides a system for improving the response dynamic range of a SiPM photoelectric sensor, comprising:

[0037] A beam shaper is used to shape the received incident light signal so that the shaped light signal is irradiated onto the photosensitive surface of the rear photoelectric sensor;

[0038] A photoelectric sensor, configured to convert a received light signal into a current signal and transmit the current signal to a transimpedance amplifier;

[0039] a transimpedance amplifier, configured to convert the received current signal into a voltage signal, and transmit the voltage signal to the nonlinear amplifier;

[0040] A nonlinear amplifier, configured to perform nonlinear correction according to the intensity amplitude of the received voltage signal;

[0041] A microprocessor, wherein the gain amplification factor of the SiPM photosensor, the gain amplification factor of the transimpedance amplifier, and the gain amplification factor of the nonlinear amplifier are set by the microprocessor;

[0042] The linear dynamic response range of the SiPM photodetector is 6 orders of magnitude from pW to uW.

[0043] In a specific embodiment,

[0044] The nonlinear amplifier is configured as follows:

[0045] When a weak light signal is input and the transimpedance amplifier operates at a first predetermined gain, the gain amplification factor of the nonlinear amplifier is a fixed multiple; and / or,

[0046] When a strong light signal is input and the transimpedance amplifier operates at a second predetermined gain, the gain amplification factor of the nonlinear amplifier changes nonlinearly with the intensity of the voltage signal output by the transimpedance amplifier.

[0047] In a specific embodiment,

[0048] The SiPM photoelectric sensor is configured as follows:

[0049] The photoelectric gain of the SiPM photoelectric sensor can be controlled by a microprocessor, which adjusts the sensor gain control signal according to the intensity range of the input light signal to change the reverse bias voltage applied to the photoelectric sensor.

[0050] In a specific embodiment,

[0051] The transimpedance amplifier is configured as follows:

[0052] By setting different feedback resistor values through a microprocessor, the transimpedance amplifier has different current-to-voltage conversion factors to match incident light signals of different intensity ranges, so that the corresponding output voltage signal falls within the linear response range of the subsequent signal processing circuit.

[0053] In a specific embodiment,

[0054] The gain amplification factor of the nonlinear amplifier is adjusted by a microprocessor.

[0055] In a specific embodiment,

[0056] The beam shaper is configured as follows:

[0057] The incident light signal is shaped into a light spot size or shape that matches the photosensitive area of the SiPM photosensor by a beam shaper, so that the collected light signal fills the photosensitive surface of the SiPM photosensor.

[0058] In a specific embodiment,

[0059] The nonlinear amplifier is configured as follows:

[0060] The adjustment range of the gain amplification factor of the nonlinear amplifier is determined according to the requirements of a theoretical correction curve of the nonlinear response of the photoelectric sensor at different photoelectric gain setting points.

[0061] In a specific embodiment,

[0062] The nonlinear amplifier is configured as follows:

[0063] First, based on the voltage signal response curve of the output of the transimpedance amplifier, the deviation curve between the voltage signal response curve and the ideal linear curve response is calculated;

[0064] According to the deviation curve, a circuit parameter setting value of the nonlinear amplifier is further calculated as a correction function, and a gain adjustment range of the nonlinear amplifier is set by a microprocessor.

[0065] The following describes the technical effects of the embodiments of the present application:

[0066] In one embodiment, the present application provides a method for improving the linear response dynamic range of a SiPM photoelectric sensor, comprising: performing beam shaping on a received incident light signal so that the shaped light signal is irradiated onto a photosensitive surface of a rear-mounted SiPM photoelectric sensor; the SiPM photoelectric sensor converts the received light signal into a current signal and transmits the current signal to a transimpedance amplifier; the transimpedance amplifier converts the received current signal into a voltage signal and transmits the voltage signal to a nonlinear amplifier; the nonlinear amplifier performs nonlinear correction based on the intensity amplitude of the received voltage signal; the gain amplification factor of the SiPM photoelectric sensor, the gain amplification factor of the transimpedance amplifier, and the gain amplification factor of the nonlinear amplifier are set by a microprocessor; the linear dynamic response range of the SiPM photodetector is 6 orders of magnitude of pW-uW.

[0067] In summary, the design of this method can, on the one hand, improve the linearity of the SiPM's response to strong light by performing nonlinear correction on the response output signal under strong light irradiation; on the other hand, when the input light signal is relatively weak, the voltage amplitude of the response output signal is increased by increasing the circuit gain, thereby improving the linearity of the SiPM's response to weak light. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0069] Figure 1 This is a flow chart of a method for improving the response dynamic range of a SiPM photosensor in one embodiment of the present application;

[0070] FIG2( a ) is a functional block diagram of a circuit configuration for a method for improving the response dynamic range of a SiPM photoelectric sensor under weak light response in one embodiment of the present application:

[0071] FIG2( b ) is a functional block diagram of a circuit configuration for a method for improving the response dynamic range of a SiPM photoelectric sensor under strong light response in one embodiment of the present application:

[0072] Figure 3 for Figure 1 A schematic diagram of a method for improving the response dynamic range of SiPM photosensors during beam shaping;

[0073] Figure 4 for Figure 1 A method for improving the response dynamic range of SiPM photosensors under weak light conditions;

[0074] Figure 5 for Figure 1 A method for improving the response dynamic range of SiPM photosensors is shown in the photoelectric response output curve under strong light conditions. DETAILED DESCRIPTION

[0075] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0076] In some of the processes described in the specification and claims of this application and the above-mentioned figures, multiple operations that appear in a specific order are included, but it should be clearly understood that these operations may not be executed in the order in which they appear in this document or may be executed in parallel. The serial numbers of the operations, such as 101, 102, etc., are only used to distinguish between different operations, and the serial numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations may be executed in sequence or in parallel. It should be noted that the descriptions of "first", "second", etc. in this document are used to distinguish different messages, devices, modules, etc., and do not represent a sequential order, nor do they limit "first" and "second" to being different types.

[0077] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0078] Please refer to Figure 1 , Figure 2(a), Figure 2(b) and Figure 3 , Figure 1 FIG2 is a flow chart of a method for improving the response dynamic range of a SiPM photoelectric sensor in one embodiment of the present application; FIG2(a) is a functional block diagram of a circuit configuration of a method for improving the response dynamic range of a SiPM photoelectric sensor in one embodiment of the present application under weak light response; FIG2(b) is a functional block diagram of a circuit configuration of a method for improving the response dynamic range of a SiPM photoelectric sensor in one embodiment of the present application under strong light response;

[0079] Figure 3 for Figure 1 Schematic diagram of a method for improving the response dynamic range of SiPM photosensors during beam shaping.

[0080] In one embodiment, if Figure 1 As shown, in one embodiment provided by the present application, a method for improving the response dynamic range of a SiPM photoelectric sensor includes the following steps:

[0081] Step S101: performing beam shaping on the received incident light signal so that the shaped light signal is irradiated onto the photosensitive surface of the rear-mounted photoelectric sensor;

[0082] Step S102: The SiPM photoelectric sensor converts the received light signal into a current signal, and transmits the current signal to a transimpedance amplifier;

[0083] Step S103: the transimpedance amplifier converts the received current signal into a voltage signal, and transmits the voltage signal to the nonlinear amplifier;

[0084] Step S104: The nonlinear amplifier performs nonlinear correction according to the intensity amplitude of the received voltage signal.

[0085] The gain amplification factor of the SiPM photoelectric sensor, the gain amplification factor of the transimpedance amplifier, and the gain amplification factor of the nonlinear amplifier are set by a microprocessor;

[0086] The linear dynamic response range of the SiPM photodetector is 6 orders of magnitude from pW to uW.

[0087] Further improvements can be made based on the above embodiment. For example, the step of “shaping the received incident light signal and irradiating the shaped light signal onto the photosensitive surface of the rear-mounted photoelectric sensor” includes:

[0088] The incident light signal is shaped into a light spot size or shape that matches the photosensitive area of the SiPM photosensor by a beam shaper, so that the collected light signal fills the photosensitive surface of the SiPM photosensor.

[0089] That is, the beam shaper is used to shape the incident light signal into a spot size or shape that matches the photosensitive area of the subsequent photoelectric sensor device, so that the collected light signal can eventually fill the entire photosensitive area.

[0090] The beam shaper can use a single lens or a combination of multiple lenses. Its working distance to the surface of the photoelectric sensor can be fixed or freely adjusted according to the size of the incident light spot and the photosensitive area of the rear photoelectric sensor to meet the detection requirements of different optical input signals.

[0091] The beam shaper primarily collects the energy of the beam emitted by the object being detected and adjusts its energy distribution and spot size to ensure that the sensor receives the maximum energy beam while also ensuring that the focused spot covers the entire photosensitive surface of the SiPM sensor. In practical applications, the design can be optimized based on the energy of the incident beam and the photosensitive area of the subsequent SiPM photoelectric sensor. The optimal design is to ensure a uniform distribution of the light spot across the sensor's photosensitive surface.

[0092] In some embodiments, further designs may be made. For example, the “the SiPM photoelectric sensor converts the received light signal into a current signal and transmits the current signal to a transimpedance amplifier” may include:

[0093] The photoelectric gain of the SiPM photoelectric sensor can be adjusted by a sensor gain control signal of a microprocessor to change the reverse bias voltage applied to the SiPM photoelectric sensor.

[0094] Specifically, a SiPM photoelectric sensor converts received optical signals into electrical signals. It can be a single SiPM sensor with varying areas and pixel sizes, or a SiPM array consisting of multiple sensors. The photoelectric gain of the SiPM photoelectric sensor can be adjusted based on the input optical signal intensity range to achieve an optimal response signal-to-noise ratio. In this embodiment, the optical signal intensity is primarily adjusted by a microprocessor adjusting the sensor gain control signal to change the reverse bias voltage applied to the SiPM.

[0095] The photoelectric sensor's gain can be set based on the actual intensity range of the input light signal to ensure that the photocurrent signal output by the SiPM, after subsequent TIA amplification, meets the required output voltage range of the TIA op amp. The optimal photoelectric gain setting is: 1) When detecting strong light signals, reduce the reverse bias voltage so that the maximum photoelectric response current is less than or equal to (1 / 2 the saturation current); 2) When detecting weak light signals, increase the reverse bias voltage so that the minimum photocurrent is greater than or equal to (10x the dark output current noise).

[0096] In some embodiments, further designs may be made. For example, the “transimpedance amplifier converts the received current signal into a voltage signal and transmits the voltage signal to the nonlinear amplifier” may include:

[0097] By setting different feedback resistor values through a microprocessor, the transimpedance amplifier has different current-to-voltage conversion factors to match incident light signals of different intensity ranges, so that the corresponding output voltage signal falls within the linear input / output range of the subsequent signal processing circuit.

[0098] In this embodiment, the transimpedance amplifier TIA can convert the current signal output by the photoelectric sensor into a voltage signal, and its gain amplification factor is mainly determined by the resistance value of the feedback resistor added thereto.

[0099] As shown in Figures 2(a) and 2(b), the feedback resistor Rf of the transimpedance amplifier (TIA) does not have a fixed resistance value, but has at least two or more resistance values to choose from. By setting different Rf values through a microcontroller, the transimpedance amplifier can have different current-to-voltage conversion factors to match the input of optical signals in different intensity ranges, so that its corresponding output voltage signal falls within the linear response range of the subsequent signal processing circuit.

[0100] To address the sensor's nonlinear response to weak light input, the transimpedance amplifier in this invention employs a variable gain switching design (e.g., a single-pole, double-ended switch). A higher TIA gain can be selected for weak light signals, further reducing the impact of dark output noise. Switching to a lower gain for strong light signals mitigates circuit saturation (note: the output signal may exhibit nonlinear response). Furthermore, the SiPM photoelectric gain and the TIA transimpedance amplifier gain can be adjusted jointly, extending the sensor's input light intensity detection range.

[0101] In some embodiments, further improvements can be made. For example, the nonlinear amplifier performs nonlinear correction according to the intensity amplitude of the received voltage signal, including:

[0102] The gain amplification factor of the nonlinear amplifier is configured and adjusted by a microprocessor. In this technical solution, the nonlinear amplifier is used to correct the voltage signal output by the TIA. The gain amplification factor / curve of the nonlinear amplifier is also controlled and adjusted by the microprocessor. To address the nonlinear response output of SiPM photoelectric sensors to strong light input, the present invention introduces a nonlinear amplifier circuit correction unit. By appropriately correcting the photovoltage signal output by the TIA, the linearity of the SiPM sensor's response to strong light is further improved.

[0103] In some specific embodiments, “the nonlinear amplifier performs nonlinear correction according to the intensity amplitude of the received voltage signal” includes:

[0104] When a weak light signal is input and the transimpedance amplifier operates at a first predetermined gain, the gain amplification factor of the nonlinear amplifier is a fixed multiple; or, when a strong light signal is input and the transimpedance amplifier operates at a second predetermined gain, the gain amplification factor of the nonlinear amplifier changes nonlinearly with the intensity of the voltage signal output by the transimpedance amplifier.

[0105] Specifically, the nonlinear amplifier has a gain amplification factor of a constant value Rc in one case (for example, when a weak light signal is input and the TIA circuit of the SiPM sensor operates at high gain), and does not change with the intensity of the TIA output signal. In other cases (for example, when a strong light signal is input and the TIA circuit of the SiPM sensor operates at low gain), the gain amplification factor of the nonlinear amplifier changes nonlinearly with the intensity of the TIA output signal. In this case, the corresponding variable gain amplification factor can be recorded as Rv.

[0106] To address the nonlinear response output problem of SiPM sensors under strong light input, the present invention introduces a nonlinear amplifier circuit correction unit. By appropriately correcting the photovoltage signal output by the TIA, the linearity of the SiPM sensor's response to strong light is further improved.

[0107] Furthermore, because the nonlinearity of the SiPM sensor's intense light response varies under different photoelectric gain settings, the required theoretical correction curves (i.e., the corresponding nonlinear correction circuit parameters) are also different. To address this issue, the present invention employs an adjustable-gain nonlinear amplifier circuit design. The circuit parameters are configured by a microprocessor to match the SiPM's photoelectric gain control voltage, achieving a linear output in the intense light response under different photoelectric gain settings.

[0108] In some embodiments, the “nonlinear amplifier performing nonlinear correction according to the intensity amplitude of the received voltage signal” includes:

[0109] The adjustment range of the gain amplification factor of the nonlinear amplifier is determined according to the requirements of a theoretical correction curve of the nonlinear response of the photoelectric sensor at different photoelectric gain setting points.

[0110] The “adjustment range of the gain amplification factor of the nonlinear amplifier is determined based on the theoretical correction curve requirements of the nonlinear response of the photoelectric sensor at different photoelectric gain setting points” includes:

[0111] First, based on the voltage signal response curve of the output of the transimpedance amplifier, the deviation curve between the voltage signal response curve and the ideal linear curve response is calculated;

[0112] According to the deviation curve, a circuit parameter setting value of the nonlinear amplifier is further calculated as a correction function, and a gain adjustment range of the nonlinear amplifier is set by a microprocessor.

[0113] In the above technical solution, the gain adjustment range of the nonlinear amplifier can be set by optimizing the peripheral circuit parameters. In application, it is necessary to match the actual photoelectric gain value (or reverse bias operating point) set by the SiPM to achieve the theoretical correction requirements for different nonlinear responses of the SiPM.

[0114] The gain adjustment range (VGA circuit parameters) of the nonlinear amplifier (such as a variable gain amplifier (VGA)) is determined based on the theoretical correction curve of the nonlinear response of the SiPM at different photoelectric gain settings. In application, the deviation from the ideal linear response curve is calculated based on the TIA's direct output signal response curve. This is used as a correction function to further calculate the relevant circuit parameter settings for the nonlinear amplifier. Ultimately, the microprocessor flexibly sets the gain adjustment range.

[0115] Please refer to Figure 4 and Figure 5 , Figure 4 for Figure 1 A method for improving the response dynamic range of SiPM photosensors under weak light conditions; Figure 5 for Figure 1 A method for improving the response dynamic range of SiPM photosensors is shown in the photoelectric response output curve under strong light conditions.

[0116] Specifically, Figure 4 The photoelectric response output curve of the SiPM sensor under weak light illumination at different TIA circuit gains is shown in Figure 2. Figure 5 Comparison of the response output curves of SiPM under strong light irradiation, directly output through TIA and after VGA correction.

[0117] The following is an overall introduction to the technical solution of this application in combination with specific application scenarios:

[0118] As shown in Figures 2(a) and 2(b), in this embodiment, a single spherical lens is used as the beam shaper, and the SiPM sensor has a 3x3mm photosensitive area (11,000 total pixels). The gain parameters of the TIA and VGA circuits are both controlled by a single-pole double-set switch (SPDS) controlled by the MCU. The TIA circuit uses a gain factor of 1*Rf and n*Rf (where n is an integer greater than 1), respectively. In the following example, n=64. Regarding the VGA circuit correction unit: For weak light signals, the SiPM's response output is linear and requires no correction, so the VGA has a fixed gain factor Rc. For strong light signals that require correction, the TIA output voltage undergoes nonlinear VGA correction before being output to the subsequent signal processing system. In this case, the VGA gain factor is a variable variable, Rv (Rv>=Rc), which increases with the actual TIA output signal strength.

[0119] The working distance of the spherical lens used to collect the light beam can be adjusted according to the actual strength of the input light signal. The specific adjustment method is as follows: Figure 3For relatively weak light signals (such as pW~uW), the signal spot collected by the lens should just fill the SiPM photosensitive surface to obtain the maximum signal-to-noise ratio, as shown in Figure 3 As shown in the upper middle figure; for very strong light signals (such as >1uW), the lens can be moved backward to make the signal spot larger than the SiPM photosensitive surface, so that only part of the light signal is detected and the SiPM is not saturated, as shown in the upper middle figure. Figure 3 As shown in the figure below.

[0120] Improvement of weak light signal response linearity:

[0121] As shown in Figure 2(a), when a weak light signal (pW to nW) illuminates the SiPM's photosensitive surface, the TIA circuit needs to be set to its default high gain setting (64*Rf) to achieve a higher output voltage amplitude. This setting improves the resolution of subsequent signal processing circuits and enhances weak signal detection sensitivity. Because the SiPM's response is linear under weak light conditions (e.g., <~50nW), no correction is required. In this case, the TIA voltage output signal is linearly amplified by the VGA circuit and then directly output, meaning that the VGA has a fixed gain. Figure 4 The photoelectric response curves of the SiPM sensor are shown when only the TIA circuit gain is changed, while other parameters (such as photoelectric gain, AD acquisition accuracy, and signal processing algorithm) remain unchanged. Linear fitting analysis shows that the SiPM's minimum detection sensitivity is 3 pW at high TIA gain and 10 pW at low TIA gain. This minimum sensitivity is improved by approximately 3.3 times through TIA optimization.

[0122] However, the problem faced by high TIA gain is the circuit saturation in response to strong light signals (nW-uW), such as Figure 4 As shown in the light-colored curve, when the input light is greater than 20nW, the output of the SiPM sensor module no longer increases with the increase in signal strength. At this time, the TIA gain can be switched from the default high gain state (64*Rf) to the low gain state (1*Rf). The corresponding response output curve is shown in Figure 4 As shown in the darker curve, the circuit saturation issue has been significantly improved. TIA gain switching can be manually controlled or automatically by the MCU after sampling and analyzing the output voltage. Linear fitting analysis of the response curve at 1*Rf reveals that when the optical signal exceeds ~50nW, the SiPM's output response begins to deviate from linearity, and this deviation becomes increasingly pronounced as the optical signal intensity increases. The specific degree of linearity deviation is determined by the SiPM sensor's performance, such as the number of pixels, recovery time, photoelectric conversion efficiency, and photoelectric gain setpoint. Therefore, linearity compensation is required for the photoelectric signal output of the TIA at this time.

[0123] Improvement of the linearity of strong light signal response:

[0124] As shown in Figure 2(b), this embodiment utilizes a nonlinear amplifier circuit to compensate for the nonlinearity of the SiPM sensor's strong light response. This linear correction is then applied to the strong light response signal before it is used as the final output voltage signal. Specifically, the VGA gain operating point is controlled and adjusted by a microprocessor. In the default operating state, the microprocessor sets the SiPM sensor's TIA circuit to a high gain state (64*Rf) and the VGA circuit to a fixed gain state (Rc). The VGA output signal is then collected and analyzed in real time. When the threshold voltage exceeds a preset threshold (e.g., 1 / 2 the maximum output voltage), the microprocessor automatically switches the TIA circuit to a low gain state (1*Rf) and simultaneously switches the VGA circuit's gain switch to a variable gain state (Rv), as shown in Figure 2(b). Furthermore, the microprocessor can configure VGA circuit parameters to match the SiPM's actual photoelectric gain control bias voltage. Figure 5 This is the correction effect of SiPM under a specific photoelectric gain setting (~5x10^5). The dark color is the photoelectric response output curve without VGA correction, and the light color is the photoelectric response curve after VGA nonlinear correction. By comparison, the linear output range of SiPM's strong light response has increased from 50nW to 500nW, an increase of about 10 times. For the weak light signal part (<100pW), since the VGA circuit introduces additional gain noise, and the TIA amplifier operates in low gain mode at this time, the overall noise level of SiPM becomes higher, causing the weak light response to deviate from linearity. Therefore, in the application of the present invention, it is necessary to configure the circuit parameters for weak light signals and strong light signals separately to achieve the purpose of improving the linear dynamic response range of SiPM.

[0125] It should be pointed out that in actual applications, the SiPM may be set under different photoelectric gains, and the theoretical nonlinear correction curves of the corresponding photoelectric response curves are different, so the VGA circuit is required to be able to configure different circuit parameter settings. In theory, for any nonlinear curve of the SiPM photoelectric response, as long as a suitable correction curve can be found, reasonable VGA peripheral circuit parameters can be configured to enable the final voltage response output signal to achieve linear output within a certain range. In actual operation, a mapping relationship can be established between the VGA circuit operating parameters and the SiPM photoelectric gain parameters by looking up a table. While adjusting the SiPM photoelectric gain, the MCU performs synchronous configuration of the VGA circuit parameters Rv (gain adjustment parameters) to improve the timeliness of the correction of the SiPM nonlinear response. Specifically, the theoretical formula for the gain coefficient of the nonlinear amplifier circuit VGA in this embodiment is as follows:

[0126] A(V / V)=A vmax *1 / (1+K1*exp(K2*V i ))

[0127] Among them A vmax Is the maximum gain corresponding to the VGA circuit

[0128] K1, K2 are the theoretical parameters of the VGA circuit

[0129] V i is the voltage signal output by the TIA

[0130] It should be pointed out that the VGA output signal is based on the e-exponential amplification of the input signal, which only corrects the required part of the input signal, rather than the entire range signal.

[0131] In addition, as shown in FIG. 2( a ) and FIG. 2( b ), the present application also provides a system for improving the response dynamic range of a SiPM photoelectric sensor, comprising:

[0132] A beam shaper is used to shape the received incident light signal and make the shaped light signal illuminate the photosensitive surface of the rear photoelectric sensor;

[0133] A photoelectric sensor, configured to convert a received light signal into a current signal and transmit the current signal to a transimpedance amplifier;

[0134] a transimpedance amplifier, configured to convert the received current signal into a voltage signal, and transmit the voltage signal to the nonlinear amplifier;

[0135] The nonlinear amplifier is used for performing nonlinear correction according to the intensity amplitude of the received voltage signal.

[0136] In some embodiments, the beam shaper is configured as follows:

[0137] The incident light signal is shaped into a light spot size or shape that matches the photosensitive area of the SiPM photosensor by a beam shaper, so that the collected light signal fills the photosensitive surface of the SiPM photosensor.

[0138] In some embodiments, the SiPM photoelectric sensor is configured as follows:

[0139] The photoelectric gain of the SiPM photoelectric sensor can be achieved by a microprocessor adjusting the reverse bias voltage applied to the photoelectric sensor by a sensor gain control signal according to the intensity range of the input light signal.

[0140] In some embodiments, the transimpedance amplifier is configured as follows:

[0141] By setting different feedback resistor values through a microprocessor, the transimpedance amplifier has different current-to-voltage conversion factors to match incident light signals of different intensity ranges, so that the corresponding output voltage signal falls within the linear response range of the subsequent signal processing circuit.

[0142] In some embodiments, the nonlinear amplifier is configured as follows:

[0143] The gain amplification factor of the nonlinear amplifier is adjusted by a microprocessor.

[0144] In some embodiments, the nonlinear amplifier is configured as follows:

[0145] When a weak light signal is input and the transimpedance amplifier operates at a first predetermined gain, the gain amplification factor of the nonlinear amplifier is 1;

[0146] Alternatively, when a strong light signal is input and the transimpedance amplifier operates at a second predetermined gain, the gain amplification factor of the nonlinear amplifier changes nonlinearly with the intensity of the voltage signal output by the transimpedance amplifier.

[0147] In some embodiments, the nonlinear amplifier is configured as follows:

[0148] The adjustment range of the gain amplification factor of the nonlinear amplifier is determined according to the requirements of a theoretical correction curve of the nonlinear response of the photoelectric sensor at different photoelectric gain setting points.

[0149] In some embodiments, the nonlinear amplifier is configured as follows:

[0150] First, based on the voltage signal response curve of the output of the transimpedance amplifier, the deviation curve between the voltage signal response curve and the ideal linear curve response is calculated;

[0151] The deviation curve is used as a correction function line to further calculate the circuit parameter setting values of the nonlinear amplifier, and the gain adjustment range of the nonlinear amplifier is set by a microprocessor.

[0152] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0153] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0154] References throughout this specification to "embodiments," "some embodiments," "one embodiment," or "an embodiment" mean that a specific feature, component, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, phrases such as "in embodiments," "in some embodiments," "in at least another embodiment," or "in an embodiment" appearing throughout this specification do not necessarily all refer to the same embodiment. Furthermore, in one or more embodiments, specific features, components, or characteristics may be combined in any suitable manner. Thus, without limitation, specific features, components, or characteristics shown or described in connection with one embodiment may be combined in whole or in part with features, components, or characteristics of one or more other embodiments. Such modifications and variations are intended to be within the scope of this application.

[0155] In addition, it will be understood by those skilled in the art that various aspects of the present application can be illustrated and described by a number of patentable categories or situations, including any new and useful process, machine, product or combination of substances, or any new and useful improvements thereto. Accordingly, various aspects of the present application can be performed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The above hardware or software may all be referred to as "data blocks", "modules", "engines", "terminals", "components" or "systems". In addition, various aspects of the present application may be manifested as a computer product located in one or more computer-readable media, which includes computer-readable program code.

[0156] It should be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that an article or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0157] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand and implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to be construed in the broadest manner consistent with the principles and novel features disclosed herein.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for improving the linear response dynamic range of a SiPM photoelectric sensor, characterized in that: include: The received incident light signal is beam-shaped so that the shaped light signal is irradiated onto the photosensitive surface of the rear SiPM photoelectric sensor; The SiPM photoelectric sensor converts the received light signal into a current signal and transmits the current signal to a transimpedance amplifier; The transimpedance amplifier converts the received current signal into a voltage signal, and transmits the voltage signal to the nonlinear amplifier; The nonlinear amplifier performs nonlinear correction according to the intensity amplitude of the received voltage signal, wherein the adjustment range of the gain amplification factor of the nonlinear amplifier is determined according to a theoretical correction curve of the nonlinear response of the SiPM photoelectric sensor at different photoelectric gain setting points; The gain amplification factor of the SiPM photoelectric sensor, the gain amplification factor of the transimpedance amplifier and the gain amplification factor of the nonlinear amplifier are set by a microprocessor; The linear dynamic response range of the SiPM photoelectric sensor is 6 orders of magnitude from pW to uW.

2. The method for improving the response dynamic range of a SiPM photoelectric sensor according to claim 1, wherein: The “nonlinear amplifier performs nonlinear correction according to the intensity amplitude of the received voltage signal” includes: When a weak light signal is input and the transimpedance amplifier operates at a first predetermined gain, the gain amplification factor of the nonlinear amplifier is a fixed multiple; and / or, When a strong light signal is input and the transimpedance amplifier operates at a second predetermined gain, the gain amplification factor of the nonlinear amplifier changes nonlinearly with the intensity of the voltage signal output by the transimpedance amplifier.

3. The method for improving the response dynamic range of a SiPM photoelectric sensor according to claim 1, wherein: The “the SiPM photoelectric sensor converts the received light signal into a current signal, and transmits the current signal to a transimpedance amplifier” includes: The photoelectric gain of the SiPM photoelectric sensor is controlled by a microprocessor, which adjusts the sensor gain control signal according to the intensity range of the input light signal to change the reverse bias voltage applied to the photoelectric sensor.

4. The method for improving the response dynamic range of a SiPM photoelectric sensor according to claim 1, wherein: The “transimpedance amplifier converts the received current signal into a voltage signal, and transmits the voltage signal to the nonlinear amplifier” includes: By setting different feedback resistor values through a microprocessor, the transimpedance amplifier has different current-to-voltage conversion factors to match incident light signals of different intensity ranges, so that the corresponding output voltage signal falls within the linear response range of the subsequent signal processing circuit.

5. The method for improving the response dynamic range of a SiPM photoelectric sensor according to claim 1, wherein: The “nonlinear amplifier performs nonlinear correction according to the intensity amplitude of the received voltage signal” includes: The gain amplification factor of the nonlinear amplifier is adjusted by a microprocessor.

6. A system for improving the response dynamic range of a SiPM photoelectric sensor, characterized in that: include: A beam shaper is used to shape the received incident light signal so that the shaped light signal is irradiated onto the photosensitive surface of the rear photoelectric sensor; A photoelectric sensor, configured to convert a received light signal into a current signal and transmit the current signal to a transimpedance amplifier; a transimpedance amplifier, configured to convert the received current signal into a voltage signal, and transmit the voltage signal to the nonlinear amplifier; a nonlinear amplifier configured to perform nonlinear correction based on the intensity amplitude of the received voltage signal, wherein the adjustment range of the gain amplification factor of the nonlinear amplifier is determined based on a theoretical correction curve of the nonlinear response of the SiPM photoelectric sensor at different photoelectric gain setting points; A microprocessor, wherein the gain amplification factor of the SiPM photoelectric sensor, the gain amplification factor of the transimpedance amplifier, and the gain amplification factor of the nonlinear amplifier are set by the microprocessor; The linear dynamic response range of the SiPM photoelectric sensor is 6 orders of magnitude from pW to uW.

7. The system for improving the response dynamic range of a SiPM photoelectric sensor according to claim 6, wherein: The nonlinear amplifier is configured as follows: When a weak light signal is input and the transimpedance amplifier operates at a first predetermined gain, the gain amplification factor of the nonlinear amplifier is a fixed multiple; and / or, When a strong light signal is input and the transimpedance amplifier operates at a second predetermined gain, the gain amplification factor of the nonlinear amplifier changes nonlinearly with the intensity of the voltage signal output by the transimpedance amplifier.

8. The system for improving the response dynamic range of a SiPM photoelectric sensor according to claim 6, wherein: The SiPM photoelectric sensor is configured as follows: The photoelectric gain of the SiPM photoelectric sensor is controlled by a microprocessor, which adjusts the sensor gain control signal according to the intensity range of the input light signal to change the reverse bias voltage applied to the photoelectric sensor.

9. The system for improving the response dynamic range of a SiPM photoelectric sensor according to claim 6, wherein: The transimpedance amplifier is configured as follows: By setting different feedback resistor values through a microprocessor, the transimpedance amplifier has different current-to-voltage conversion factors to match incident light signals of different intensity ranges, so that the corresponding output voltage signal falls within the linear response range of the subsequent signal processing circuit.

10. The system for improving the response dynamic range of a SiPM photoelectric sensor according to claim 6, wherein: The gain amplification factor of the nonlinear amplifier is adjusted by a microprocessor.

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