Fluorescent signal acquisition circuit and fluorescent temperature measuring device

Abstract

The application relates to a fluorescent signal acquisition circuit and a fluorescent temperature measuring device. The fluorescent signal acquisition circuit comprises: an anode of a photodiode for grounding, the photodiode being used for receiving a fluorescent signal and converting the fluorescent signal into a photoelectric current; a first transimpedance amplification module being coupled with the photodiode to receive the photoelectric current; a first power supply end and a second power supply end of a first operational amplifier of the first transimpedance amplification module being connected to a positive voltage end and a negative voltage end of a power supply module through a power supply filtering module to input positive voltage and negative voltage; the first operational amplifier being configured to: based on the negative voltage, clamp a reverse input end of the first operational amplifier to zero potential, so that a potential difference between two ends of the photodiode is zero; and a second transimpedance amplification module being coupled with an output end of the first transimpedance amplification module through an inter-stage filtering module. The application can improve the precision of fluorescent signal acquisition and the accuracy of temperature measurement.

Description

Technical Field

[0001] This application relates to the field of fluorescence thermometry technology, and in particular to a fluorescence signal acquisition circuit and a fluorescence thermometry device. Background Technology

[0002] Fluorescent temperature sensing technology is based on the principle of photoluminescence. It determines the temperature of the measurement point by measuring the exponential decay time of the fluorescence after the excitation light disappears. It has the advantages of being non-contact, having a fast response speed, high spatial resolution, being unaffected by electromagnetic field interference, being safe and reliable, and having strong adaptability. It can be widely used in various industrial environments and has significant advantages over traditional contact temperature sensing technologies (such as liquid thermometers, thermocouples, and resistance temperature detectors).

[0003] In fluorescence temperature measurement systems of related technologies, photodiodes are typically used to convert fluorescence signals into photocurrents, which are then amplified by a transimpedance amplifier to a voltage signal. Fluorescence lifetime is calculated using methods such as exponential fitting, ultimately achieving temperature measurement.

[0004] However, in related technologies, there is usually a certain potential difference between the two ends of the photodiode during operation, which generates dark current and reduces the accuracy of fluorescence temperature measurement. Summary of the Invention

[0005] Therefore, it is necessary to provide a fluorescence signal acquisition circuit and fluorescence temperature measurement device that can improve the accuracy of fluorescence temperature measurement, in order to address the above-mentioned technical problems.

[0006] In a first aspect, embodiments of this application provide a fluorescence signal acquisition circuit, which includes: a photodiode, a power supply module, a first transimpedance amplifier module, a second transimpedance amplifier module, a power supply filter module, and an interstage filter module;

[0007] The anode of the photodiode is grounded, and the photodiode is used to receive fluorescent signals and convert them into photocurrent. The first transimpedance amplifier module is coupled to a photodiode to receive photocurrent; The first transimpedance amplifier module includes a first operational amplifier and a first feedback module; The first power supply terminal and the second power supply terminal of the first operational amplifier are connected to the positive voltage terminal and the negative voltage terminal of the power supply module respectively through the power supply filter module, and are used to connect positive voltage and negative voltage respectively. The first operational amplifier is configured to clamp the inverting input terminal of the first operational amplifier to zero potential based on a negative voltage, so that the potential difference across the photodiode is zero, and work together with the first feedback module to convert the photocurrent into a first voltage signal with a first gain. The second transimpedance amplifier module is coupled to the output of the first transimpedance amplifier module through an interstage filtering module; it is used to convert the first voltage signal into a second voltage signal with a second gain.

[0008] In one embodiment, the negative voltage provided by the power supply module is a preset micro-negative voltage value, the absolute value of which is less than the positive voltage, so that the output swing of the first operational amplifier covers zero level under asymmetrical dual power supply.

[0009] In one embodiment, the power module includes a first voltage conversion unit and a second voltage conversion unit, the first voltage conversion unit being used to generate a positive voltage and the second voltage conversion unit being used to generate a negative voltage.

[0010] In one embodiment, the power filtering module includes: The first LC filter unit is connected between the positive voltage terminal of the power supply module and the first power supply terminal of the first operational amplifier, and is used to perform low-pass filtering on the positive voltage. The second LC filter unit is connected between the negative voltage terminal of the power supply module and the second power supply terminal of the first operational amplifier, and is used to perform low-pass filtering on the negative voltage.

[0011] In one embodiment, the first feedback module includes: The first feedback resistor is connected between the output terminal and the inverting input terminal of the first operational amplifier and is used to set the first gain. The first phase compensation capacitor is connected in parallel with the first feedback resistor to provide phase compensation for the first voltage signal.

[0012] In one embodiment, the second transimpedance amplifier module includes: a second operational amplifier and a second feedback module; The second operational amplifier is configured to work in conjunction with the second feedback module to convert the first voltage signal into a second voltage signal with a second gain to match the input range of the connected analog-to-digital converter.

[0013] In one embodiment, the second feedback module includes: The second feedback resistor is connected between the output terminal of the second operational amplifier and the inverting input terminal of the second operational amplifier. The ground resistor is connected between the inverting input of the second operational amplifier and ground. The ratio of the second feedback resistor to the resistance to ground is used to set the second gain. The second phase compensation capacitor, connected in parallel with the second feedback resistor, is used to provide phase compensation for the second voltage signal; the second feedback resistor and the second phase compensation capacitor are also used to form a low-pass filter.

[0014] In one embodiment, the interstage filtering module includes: The first filter resistor is connected between the output terminal of the first transimpedance amplifier module and the non-inverting input terminal of the second transimpedance amplifier module. The second filter resistor has one end for connecting a positive voltage and the other end connected to the connection point between the first filter resistor and the non-inverting input terminal of the second transimpedance amplifier module. The first filter capacitor has one end connected to the connection point between the first filter resistor and the non-inverting input terminal of the second transimpedance amplifier module, and the other end is used for grounding.

[0015] In one embodiment, the fluorescence signal acquisition circuit further includes an anti-aliasing filter module, which includes: The third filter resistor is connected between the output of the second transimpedance amplifier module and the input of the analog-to-digital converter. The second filter capacitor has one end connected between the third filter resistor and the input terminal of the analog-to-digital converter, and the other end is used for grounding.

[0016] Secondly, this application also provides a fluorescence temperature measurement device, including: a main controller, a pulse excitation light source, a light-emitting device, optical components, and a fluorescence signal acquisition circuit as described above; The main controller is connected to the input terminal of the pulse excitation light source and the output terminal of the fluorescence signal acquisition circuit, respectively, and the light-emitting device is connected to the output terminal of the pulse excitation light source; The optical components are connected to the input terminal of the fluorescence signal acquisition circuit and the light-emitting device, respectively. The main controller calculates the corresponding temperature value based on the digital voltage data acquired by the fluorescence signal acquisition circuit, using the fluorescence decay model and the relationship between fluorescence lifetime and temperature.

[0017] The fluorescence signal acquisition circuit and fluorescence temperature measurement device provided in this application, by introducing a negative voltage into the first operational amplifier and combining it with a circuit topology where the anode of the photodiode is grounded and the cathode is connected to the inverting input terminal of the first operational amplifier, utilizes the virtual short characteristic of the operational amplifier to precisely clamp the potential of the inverting input terminal of the first operational amplifier to zero. Since the anode of the photodiode is grounded, its cathode potential is clamped to zero, thus making the potential difference across the photodiode strictly zero, forcing the photodiode to operate in photovoltaic mode, i.e., zero-bias mode. In this zero-bias mode, there is no electric field established by the bias voltage inside the photodiode, and the dark current of the photodiode is physically eliminated. Therefore, in the weak fluorescence signal stage, especially in the tail region of the fluorescence decay curve, the baseline rise and signal distortion problems caused by the superposition of dark current and effective photocurrent can be solved. The first voltage signal output by the first transimpedance amplification module can more realistically reflect the decay characteristics of the fluorescence signal, providing high-fidelity raw data for subsequent fluorescence lifetime fitting and temperature calculation, thereby improving the accuracy of fluorescence signal acquisition and temperature measurement. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a fluorescence signal acquisition circuit provided in an embodiment of this application; Figure 2 A specific circuit structure diagram of a fluorescence signal acquisition circuit provided in an embodiment of this application; Figure 3 A schematic diagram of an asymmetric dual-power supply architecture provided for an embodiment of this application; Figure 4 This is a schematic diagram of the connection structure between an anti-aliasing filter module and an analog-to-digital converter provided in an embodiment of this application; Figure 5 This is a schematic diagram of the system architecture of a fluorescence temperature measuring device provided in an embodiment of this application.

[0020] Figure label: 10. Fluorescent signal acquisition circuit; 110. Photodiode; 120. Power supply module; 121. First voltage conversion unit; 122. Second voltage conversion unit; 130. First transimpedance amplifier module; 131. First feedback module; 132. First operational amplifier; 140. Second transimpedance amplifier module; 141. Second operational amplifier; 142. Second feedback module; 150. Power supply filtering module; 151. First LC filter unit; 152. Second LC filter unit; 160. Interstage filtering module; 170. Anti-aliasing filter module; 180. Analog-to-digital converter; 20. Main controller; 30. Pulse excitation light source; 40. Light-emitting device; 50. Optical components. Detailed Implementation

[0021] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0023] It is understood that the terms "first," "second," etc., used in this application may be used herein to describe various components, but these components are not limited by these terms. These terms are only used to distinguish one component from another. For example, without departing from the scope of this application, a first filter resistor may be referred to as a second filter resistor, and similarly, a second filter resistor may be referred to as a first filter resistor. Both the first filter resistor and the second filter resistor are resistors, but they are not the same resistor.

[0024] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0025] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0026] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0027] Fluorescence thermometry is a non-contact temperature measurement technology based on the physical phenomenon of photoluminescence. Compared with traditional contact temperature sensing technologies (such as liquid thermometers, thermocouples, and resistance temperature detectors), fluorescence thermometry has advantages such as no contact required, fast response speed, high spatial resolution, immunity to electromagnetic interference, high safety, and ease of remote operation. Fluorescence thermometry is insensitive to changes in light intensity, unaffected by electromagnetic interference, highly reliable, and highly adaptable, making it widely applicable to various industrial environments. Theoretically, after the excitation light disappears, the intensity of the fluorescence afterglow decays exponentially over time; by measuring the fluorescence decay time, the temperature at the measurement point can be determined.

[0028] In existing fluorescence temperature measurement systems, a potential difference typically exists across the photodiode during the process of receiving fluorescence signals and converting them into electrical signals, causing the photodiode to operate in reverse bias mode. In this reverse bias mode, even without light illumination, a dark current is generated within the photodiode due to the bias voltage. This dark current superimposes on the effective photocurrent during the weak fluorescence signal phase, especially at the tail end of the fluorescence decay curve. Since the fluorescence signal itself has decayed to an extremely low level, the proportion of the dark current in the total output current increases significantly, causing the output current baseline to rise and resulting in offset errors. Because fluorescence lifetime calculations are highly sensitive to data at the tail end of the decay curve, the presence of dark current directly affects the accuracy of exponential fitting, widening the error range of the converted voltage data and limiting further improvements in the temperature measurement accuracy of the fluorescence temperature measurement system.

[0029] Furthermore, under the condition that the transimpedance amplifier amplifies the output current of the photodiode with high gain, the equivalent input error introduced by the dark current is also amplified by the transimpedance amplifier with high gain. Even if the subsequent analog-to-digital converter has a high resolution, it is still difficult to eliminate the systematic bias caused by the dark current.

[0030] Therefore, how to solve the impact of the dark current of the photodiode on the detection signal has become a key technical problem for improving the sampling accuracy of fluorescence decay signal and the accuracy of temperature measurement.

[0031] Based on this, embodiments of this application provide a fluorescence signal acquisition circuit and a fluorescence temperature measurement device that can improve the accuracy of fluorescence temperature measurement.

[0032] In one exemplary embodiment, Figure 1 This is a schematic diagram of the structure of a fluorescence signal acquisition circuit 10 provided in an embodiment of this application, as shown below. Figure 1 As shown, the fluorescence signal acquisition circuit 10 includes: a photodiode 110, a power supply module 120, a first transimpedance amplifier module 130, a second transimpedance amplifier module 140, a power supply filter module 150, and an interstage filter module 160.

[0033] The anode of photodiode 110 is grounded, and photodiode 110 is used to receive fluorescent signals and convert them into photocurrent.

[0034] In this application, photodiode 110 refers to a photodetector that converts a received light signal into a current signal. In this application, it refers to a photoelectric sensor used to receive the fluorescence signal emitted by a fluorescent material in a fluorescence thermometry system. It can be a PN junction photodiode 110 or a PIN photodiode 110. Photocurrent refers to the weak current signal generated by photodiode 110 after receiving fluorescence signal irradiation, which is proportional to the intensity of the incident light. In this application, it refers to the microampere or nanoampere level response current output by photodiode 110 at its cathode after receiving the fluorescence signal emitted by the fluorescent material upon pulse excitation.

[0035] The first transimpedance amplifier module 130 is coupled to the photodiode 110 to receive photocurrent.

[0036] The first transimpedance amplifier module 130 can refer to a circuit unit that performs the first-stage signal conversion in the fluorescence signal acquisition circuit. In this application, it refers to a transimpedance amplifier circuit that directly converts the weak photocurrent output by the photodiode 110 into a first voltage signal with a first gain.

[0037] The first transimpedance amplifier module 130 includes a first operational amplifier 132 and a first feedback module 131.

[0038] The first operational amplifier 132 can refer to the active device in the first transimpedance amplifier module 130. In this application, it refers to a low-noise operational amplifier chip that constitutes the main amplification stage of the transimpedance amplifier. Its non-inverting input terminal can be grounded through a resistor network, and its inverting input terminal is used to connect to the cathode of the photodiode 110. Based on the virtual short characteristic of the operational amplifier input terminal, it can clamp the potential of the inverting input terminal to the same zero potential as the non-inverting input terminal. The first feedback module 131 can refer to a passive network connected between the output terminal and the inverting input terminal of the first operational amplifier 132 for setting the transimpedance gain and providing phase compensation. In this application, it refers to a RC feedback network composed of a high-resistance feedback resistor and a small phase compensation capacitor connected in parallel, used to convert the photocurrent into a first voltage signal and ensure the stability of the negative feedback loop.

[0039] The first power supply terminal and the second power supply terminal of the first operational amplifier 132 are connected to the positive voltage terminal and the negative voltage terminal of the power supply module 120 respectively through the power supply filter module 150, and are used to connect positive voltage and negative voltage respectively.

[0040] The power module 120 can refer to a power supply unit that provides the required operating voltage for each functional unit in the circuit. In this application, it refers to an asymmetrical dual power supply device that can simultaneously output positive and negative voltages, and can be composed of circuits such as DC-DC converters, low dropout linear regulators, or charge pumps.

[0041] The first operational amplifier 132 is configured to clamp the inverting input terminal of the first operational amplifier 132 to zero potential based on a negative voltage, so that the potential difference across the photodiode 110 is zero, and work together with the first feedback module 131 to convert the photocurrent into a first voltage signal with a first gain.

[0042] The first gain can refer to the conversion ratio of the input photocurrent to the first voltage signal by the first transimpedance amplification module 130. In this application, it can be the transimpedance amplification factor determined by the resistance value of the first feedback resistor in the first feedback module 131. The specific value of the first gain can be selected according to the intensity range of the photocurrent output by the photodiode 110 and the amplitude requirements of the input voltage signal in the subsequent circuit. For example, when the first feedback resistor is set to 20MΩ, the transimpedance gain is 20MΩ, which is equivalent to 20V / μA, that is, 1μA of photocurrent will be converted into a 20V voltage signal. The first voltage signal can refer to the voltage output signal obtained after the photocurrent is converted by the first transimpedance amplification module 130. In this application, it can refer to an analog voltage signal carrying fluorescence attenuation information, the amplitude of which is proportional to the magnitude of the photocurrent and the first gain set by the first feedback module 131. The potential difference between the two ends can refer to the DC voltage difference applied between the anode and cathode terminals of the photodiode 110. In this application, it can refer to the voltage difference between the ground potential connected to the anode of the photodiode 110 and the potential of the inverting input terminal of the first operational amplifier 132 connected to the cathode. When the voltage difference is zero, the photodiode 110 operates in zero bias mode and does not generate dark current.

[0043] The second transimpedance amplifier module 140 is coupled to the output terminal of the first transimpedance amplifier module 130 through the interstage filter module 160; it is used to convert the first voltage signal into a second voltage signal with a second gain.

[0044] The second transimpedance amplifier module 140 can refer to a unit that performs the second stage of signal amplification in the fluorescence signal acquisition circuit. In this application, it refers to a post-amplifier circuit that further amplifies the first voltage signal output by the first transimpedance amplifier module 130 into a second voltage signal with a second gain.

[0045] The second gain can refer to the voltage amplification ratio of the second transimpedance amplifier module 140 in converting the first voltage signal into a second voltage signal. In this application, it refers to the in-phase voltage amplification factor determined by the resistance ratio of the second feedback resistor to the ground resistor in the second feedback module 142. The specific value of the second gain can be designed to match the amplitude range of the first voltage signal and the full-scale input range of the analog-to-digital converter 180.

[0046] In this context, coupling refers to the connection method that enables signal transmission between two functional modules in a circuit. In this application, it refers to the signal transmission relationship between the photodiode 110 and the first transimpedance amplifier module 130, and between the first transimpedance amplifier module 130 and the second transimpedance amplifier module 140, which are directly or indirectly connected through electrical lines. Coupling can be DC coupling, meaning there is a DC path in the signal path; or it can be AC ​​coupling, meaning that AC signal components are transmitted through DC blocking components such as capacitors.

[0047] The power supply filtering module 150 can refer to a passive network that suppresses noise and filters ripple from the output voltage of the power supply module 120. In this application, it can specifically refer to an inductor-capacitor filtering network connected between the power supply module 120 and the power supply terminals of each operational amplifier, which can be an LC low-pass filter circuit or a π-type filter circuit. The interstage filtering module 160 can refer to a signal conditioning network disposed between the first transimpedance amplifier module 130 and the second transimpedance amplifier module 140. In this application, it refers to a passive filter used to filter out high-frequency noise in the output signal of the preceding stage, which can be a resistor-capacitor low-pass filter circuit.

[0048] For example, photodiode 110, power supply module 120, first transimpedance amplifier module 130, second transimpedance amplifier module 140, power supply filter module 150, and interstage filter module 160 can be connected by electrical wiring. The anode of photodiode 110 can be connected to reference ground, and the cathode of photodiode 110 can be connected to the inverting input of first operational amplifier 132 via an electrical node. The positive voltage terminal of power supply module 120 can be connected to the first power supply terminal of first operational amplifier 132 via first LC filter unit 151, and the negative voltage terminal of power supply module 120 can be connected to the second power supply terminal of first operational amplifier 132 via second LC filter unit 152. First feedback module 131 can be connected in parallel between the output terminal and the inverting input terminal of first operational amplifier 132. Interstage filter module 160 can be connected in series between the output terminal of first operational amplifier 132 and the non-inverting input terminal of second transimpedance amplifier module 140. The output terminal of second transimpedance amplifier module 140 can be connected to the input terminal of subsequent analog-to-digital converter 180 via anti-aliasing filter module 170.

[0049] Specifically, through the aforementioned connection structure, the fluorescence signal acquisition circuit can perform high-precision conversion from photocurrent to digital quantity in a fluorescence temperature measurement system. The photodiode 110 receives the fluorescence signal emitted by the fluorescent material and converts it into photocurrent. The power supply module 120 outputs positive and negative voltages respectively. After high-frequency noise is filtered out by the power supply filter module 150, these voltages are supplied to the first and second power supply terminals of the first operational amplifier 132, respectively. Based on the applied negative voltage, the first operational amplifier 132 utilizes the virtual short characteristic of its input terminal to actively clamp the potential of its inverting input terminal to the same zero potential as its non-inverting input terminal, thereby making the potential difference across the photodiode 110 zero. In the zero-bias state, the photodiode 110 does not generate dark current; the photocurrent is simply the pure fluorescence signal response current. The feedback resistor in the first feedback module 131 converts the photocurrent into a first voltage signal with a first gain. The interstage filter module 160 performs a low-pass filter on this first voltage signal, which is then converted into a second voltage signal with a second gain by the second transimpedance amplifier module 140 to match the input range of the subsequent analog-to-digital converter 180.

[0050] As an example, Figure 2 A specific circuit structure diagram of a fluorescence signal acquisition circuit provided in the embodiments of this application is shown below. Figure 2 As shown, this fluorescence signal acquisition circuit can be a high-precision photoelectric signal acquisition circuit for fluorescence temperature measurement. The power module 120, serving as the system's main power supply, generates two power rails—one positive and one slightly negative—through an LC low-pass filter circuit composed of inductors L1 and L2 and capacitor networks C6, C7, and C1, providing a low-noise power supply environment for the first operational amplifier 132. The cathode of the photodiode 110 is connected to the inverting input terminal of the first operational amplifier 132. Since the non-inverting input terminal of the first operational amplifier 132 is grounded through a resistor network, and based on the virtual short characteristic of the operational amplifier, the potential at the inverting input terminal is clamped at 0V. Therefore, the potential difference across the photodiode 110 is maintained close to 0V, allowing the photodiode 110 to operate in a near-zero bias photovoltaic mode. In the first feedback module 131, a 20MΩ feedback resistor R1 can be set to convert the weak photocurrent into a first voltage signal. The parallel capacitor C5 can be set to a 1.5pF small capacitor to compensate for the phase delay caused by the parasitic junction capacitance of the photodiode 110 and the input capacitance of the first operational amplifier 132, providing advanced phase compensation and ensuring the absolute stability of the negative feedback loop.

[0051] In this embodiment, by setting the power supply module 120 to provide a negative voltage, the first operational amplifier 132 can clamp its inverting input terminal to zero potential based on the negative voltage, thereby making the potential difference across the photodiode 110 zero. This can fundamentally eliminate the dark current generated by the photodiode 110 under the bias voltage, avoid baseline shift and signal distortion caused by the superposition of dark current and weak fluorescence signal, and thus improve the accuracy of fluorescence signal acquisition and temperature measurement.

[0052] In one exemplary embodiment, such as Figure 2 As shown, the negative voltage provided by the power module 120 is a preset micro negative voltage value. The absolute value of the micro negative voltage value is less than the positive voltage, so that the output swing of the first operational amplifier 132 covers zero level under asymmetrical dual power supply.

[0053] Here, "micro-negative voltage value" refers to a negative voltage parameter whose absolute value is much smaller than the positive voltage. It refers to a tiny negative voltage value set to allow the output of the first operational amplifier 132 to cross the zero level, such as a few tenths of a volt, which could be a specific value like -0.232 volts or -0.1 volts. "Asymmetrical dual power supply" refers to a power supply method where the absolute values ​​of the positive and negative power supply voltages are not equal, such as... Figure 2 As shown, in this application, "output swing" can refer to a dual-supply configuration with a significant difference in the absolute values ​​of the positive and negative power rails, where the positive voltage is +3.3 volts and the negative voltage is -0.232 volts. "Output swing" can refer to the effective range that the output voltage of an operational amplifier can reach under given power supply conditions; in this application, it refers to the linear operating range of the first operational amplifier 132's output voltage from near the negative power rail to near the positive power rail. "Zero level" can refer to the reference ground potential in the circuit, or the potential of the ground reference plane connected to the non-inverting input terminal of the first operational amplifier 132.

[0054] For example, the power supply module 120 may include a positive voltage output terminal and a negative voltage output terminal. The positive voltage output terminal outputs a positive voltage value, and the negative voltage output terminal outputs a slight negative voltage value, the absolute value of which is less than the positive voltage value. The slight negative voltage value output by the power supply module 120 can be provided to the second power supply terminal of the first operational amplifier 132 through the power supply filter module 150, and the positive voltage value can be provided to the first power supply terminal of the first operational amplifier 132 through the power supply filter module 150. The output terminal of the first operational amplifier 132 can be connected to a subsequent stage circuit, and the non-inverting input terminal of the first operational amplifier 132 can be connected to ground through a resistor network.

[0055] As an example, power module 120 can generate two power rails: a positive voltage and a slightly negative voltage. This slightly negative voltage serves as the negative power supply for the first operational amplifier 132, constructing an asymmetric dual-power supply structure. This allows the output swing of the first operational amplifier 132 to truly cover the region near zero volts. Even with near-zero input fluorescence signals, the first operational amplifier 132 still maintains good conversion integrity and measurement accuracy, avoiding the output "dead zone" problem that occurs when a single-supply operational amplifier is near zero level.

[0056] In this embodiment, by setting the negative voltage to a slightly negative voltage value whose absolute value is less than the positive voltage, an asymmetric dual power supply structure is constructed. This allows the output of the first operational amplifier 132 to completely cover the zero-level region without nonlinear distortion. Furthermore, by using a slightly negative voltage with a small absolute value, the inverting input terminal can be clamped to a true 0V more precisely, achieving zero bias more accurately. This ensures that linear current-voltage conversion characteristics can still be maintained in the region near the zero input corresponding to weak fluorescence signals, thereby further improving the accuracy of fluorescence signal acquisition and temperature measurement.

[0057] In one exemplary embodiment, Figure 3 This application provides a schematic diagram of an asymmetric dual-power supply architecture, combined with... Figure 1 ,like Figure 3 As shown, the power module 120 includes a first voltage conversion unit 121 and a second voltage conversion unit 122. The first voltage conversion unit 121 is used to generate a positive voltage, and the second voltage conversion unit 122 is used to generate a negative voltage.

[0058] The first voltage conversion unit 121 may refer to the voltage conversion circuit in the power module 120 responsible for outputting a positive voltage. In this application, it refers to a DC-DC converter or low-dropout linear regulator and its peripheral circuits that converts the system input power supply into a positive voltage. The second voltage conversion unit 122 may refer to the voltage conversion circuit in the power module 120 responsible for outputting a negative voltage. In this application, it refers to a charge pump, DC-DC converter, or reverse regulator and its peripheral circuits that converts the system input power supply into a slightly negative voltage value.

[0059] For example, the input terminal of the first voltage conversion unit 121 can be connected to the system input power supply, and the output terminal of the first voltage conversion unit 121 can serve as the positive voltage terminal of the power module 120. The input terminal of the second voltage conversion unit 122 can also be connected to the system input power supply, and the output terminal of the second voltage conversion unit 122 can serve as the negative voltage terminal of the power module 120. The first voltage conversion unit 121 and the second voltage conversion unit 122 can operate independently, each outputting a positive voltage and a negative voltage that are isolated from each other or share a common ground.

[0060] As an example, the system's main power supply generates a positive voltage via the first voltage conversion unit 121 and a slightly negative voltage via the second voltage conversion unit 122. The two voltage outputs are respectively connected to an inductor and capacitor network to form a power supply filter module 150, providing a low-noise dual-power supply environment for the subsequent operational amplifier.

[0061] In this embodiment, by setting independent first voltage conversion unit 121 and second voltage conversion unit 122 to generate positive and negative voltages respectively, independent adjustment and optimization of the two power supplies can be achieved, ensuring the stability and accuracy of the positive and negative voltages, providing a stable operating voltage for the first operational amplifier 132 that meets the requirements of asymmetric dual power supplies, thereby ensuring the accuracy of the zero bias state of the photodiode 110, improving the accuracy of fluorescence signal acquisition and temperature measurement.

[0062] In one exemplary embodiment, such as Figure 3 As shown, the power filtering module 150 includes: The first LC filter unit 151 is connected between the positive voltage terminal of the power supply module 120 and the first power supply terminal of the first operational amplifier 132, and is used to perform low-pass filtering on the positive voltage. The second LC filter unit 152 is connected between the negative voltage terminal of the power supply module 120 and the second power supply terminal of the first operational amplifier 132, and is used to perform low-pass filtering on the negative voltage.

[0063] The first LC filter unit 151 can be a passive filter circuit used to filter out high-frequency ripple and noise in the positive voltage, and can be connected in series in the positive voltage power supply circuit. The second LC filter unit 152 can be a passive filter circuit used to filter out high-frequency ripple and noise in the negative voltage, and can be connected in series in the negative voltage power supply circuit. High-frequency ripple can refer to periodic voltage fluctuations higher than the fundamental frequency generated during power conversion, or switching noise introduced by the switching action of the DC-DC converter. Switching noise can refer to electromagnetic interference signals generated by sudden current changes during the switching of the switching devices in the power module 120.

[0064] For example, the input terminal of the first LC filter unit 151 can be connected to the positive voltage terminal of the power supply module 120, and the output terminal of the first LC filter unit 151 can be connected to the first power supply terminal of the first operational amplifier 132. The input terminal of the second LC filter unit 152 can be connected to the negative voltage terminal of the power supply module 120, and the output terminal of the second LC filter unit 152 can be connected to the second power supply terminal of the first operational amplifier 132. The first and second power supply terminals of the first operational amplifier 132 receive the filtered positive and negative voltages, respectively.

[0065] As an example, the system's main power supply uses an LC low-pass filter circuit composed of an inductor and capacitor network to generate two power rails with positive and slightly negative voltage values, providing a low-noise power supply environment for the first operational amplifier 132. The combination of inductors and capacitors can effectively suppress high-frequency ripple and switching noise in the power bus, reducing their interference to the high-gain analog link and ensuring the stability and signal-to-noise ratio of weak signal detection.

[0066] In this embodiment, by setting the first LC filter unit 151 and the second LC filter unit 152 in the power supply circuits with positive and negative voltages respectively, high-frequency ripple and switching noise on the power rail can be effectively filtered out, and power supply noise can be prevented from being coupled to the signal link through the operational amplifier and amplified by high gain, thereby reducing the system noise floor, ensuring the stability and signal-to-noise ratio of weak fluorescence signal detection, and further improving the accuracy of fluorescence signal acquisition and temperature measurement.

[0067] In one exemplary embodiment, such as Figure 2 As shown, the first feedback module 131 includes: The first feedback resistor R1 is connected between the output terminal and the inverting input terminal of the first operational amplifier 132 and is used to set the first gain; The first phase compensation capacitor C5 is connected in parallel with the first feedback resistor R1 to provide phase compensation for the first voltage signal.

[0068] The first feedback resistor R1 can be a resistor connected between the output terminal and the inverting input terminal of the first operational amplifier 132 to determine the transimpedance gain. In this application, it can be a high-value precision resistor with a resistance of 20MΩ, used to convert microampere-level or nanoampere-level photocurrent into a volt-level voltage signal. The first phase compensation capacitor C5 can be a capacitor connected in parallel with the first feedback resistor R1 to compensate for the loop phase margin. In this application, it can be a small ceramic capacitor or film capacitor with a capacitance of 1.5pF. Phase compensation refers to a stability design technique that introduces a leading phase in the negative feedback amplification loop to offset the phase lag caused by parasitic capacitance, thereby preventing the circuit from generating high-frequency self-oscillations.

[0069] For example, the first feedback resistor R1 may have a first terminal and a second terminal. The first terminal of the first feedback resistor R1 may be connected to the inverting input terminal of the first operational amplifier 132, and the second terminal of the first feedback resistor R1 may be connected to the output terminal of the first operational amplifier 132. The first phase compensation capacitor C5 may have a first terminal and a second terminal. The first terminal of the first phase compensation capacitor C5 may be connected to the inverting input terminal of the first operational amplifier 132, and the second terminal of the first phase compensation capacitor C5 may be connected to the output terminal of the first operational amplifier 132. The first feedback resistor R1 and the first phase compensation capacitor C5 may be connected in parallel, together between the output terminal and the inverting input terminal of the first operational amplifier 132. The first feedback module 131 cooperates with the first operational amplifier 132 to convert the photocurrent across the impedance into a first voltage signal.

[0070] As an example, a 20MΩ first feedback resistor R1 is set in the first transimpedance amplifier module 130 to convert the weak photocurrent into a first voltage signal. The 1.5pF small capacitor connected in parallel with the first feedback resistor R1 serves as the first phase compensation capacitor C5, which is used to compensate for the phase delay caused by the parasitic junction capacitance of the photodiode 110 and the input capacitance of the first operational amplifier 132, providing advanced phase compensation, ensuring the absolute stability of the negative feedback loop, and preventing high-frequency self-oscillation.

[0071] In this embodiment, by setting a first feedback resistor and a first phase compensation capacitor in parallel in the first feedback module 131, the high-resistance first feedback resistor can achieve high-gain conversion of weak photocurrent, and the first phase compensation capacitor can compensate the loop phase, ensuring the stability of the transimpedance amplifier and avoiding signal distortion caused by high-frequency oscillations due to parasitic parameters, thereby improving the accuracy of fluorescence signal acquisition and temperature measurement.

[0072] In one exemplary embodiment, such as Figure 2 As shown, the second transimpedance amplifier module 140 includes: a second operational amplifier 141 and a second feedback module 142; The second operational amplifier 141 is configured to work in conjunction with the second feedback module 142 to convert the first voltage signal into a second voltage signal with a second gain to match the input range of the connected analog-to-digital converter 180.

[0073] The second operational amplifier 141 can refer to an operational amplifier device used for second-stage signal amplification in a fluorescence signal acquisition circuit, and in this application, it can be a low-noise operational amplifier chip constituting a non-inverting amplifier circuit. The input range of the analog-to-digital converter 180 can refer to the input voltage amplitude range in which the analog-to-digital converter 180 can perform linear quantization conversion, and in this application, it can be the full-scale input range of the analog-to-digital converter 180, such as the range from zero volts to a reference voltage.

[0074] For example, the non-inverting input of the second operational amplifier 141 can be connected to the output of the first transimpedance amplifier module 130 via the interstage filter module 160. The connection node of the inverting input of the second operational amplifier 141 can be connected to a reference ground and to its output via the second feedback module 142. The second feedback module 142 may include a feedback resistor and a resistor to ground, and the value of the second gain is set by configuring the ratio of the two resistors. The output of the second operational amplifier 141 can be connected to the input of the subsequent analog-to-digital converter 180.

[0075] As an example, the second operational amplifier 141 can form a non-inverting amplifier circuit. The feedback network in the second feedback module 142 consists of a 4.99KΩ feedback resistor and a 665Ω resistor to ground. The second operational amplifier 141 provides a fixed voltage gain, with the gain formula being: 1 + R 反 / R 对 , where R 反 For the feedback resistor, R 对 The resistor to ground amplifies the first voltage signal to match the full-scale input range of the analog-to-digital converter 180, thereby maximizing the sampling resolution of the analog-to-digital converter 180.

[0076] In this embodiment, by setting the second transimpedance amplifier module 140 to amplify the first voltage signal in the second stage, the first voltage signal output from the previous stage can be further amplified to an amplitude that matches the input range of the analog-to-digital converter 180, so that the analog-to-digital converter 180 can sample within its optimal quantization range, maximizing the utilization of the resolution of the analog-to-digital converter 180, thereby improving the accuracy of fluorescence signal acquisition and temperature measurement.

[0077] In one exemplary embodiment, such as Figure 2 As shown, the second feedback module 142 includes: The second feedback resistor R6 is connected between the output terminal of the second operational amplifier 141 and the inverting input terminal of the second operational amplifier 141. The ground resistor RA2 is connected between the inverting input terminal of the second operational amplifier 141 and ground; The ratio of the second feedback resistor R6 to the ground resistor RA2 is used to set the second gain. The second phase compensation capacitor C10 is connected in parallel with the second feedback resistor R6 to provide phase compensation for the second voltage signal; the second feedback resistor R6 and the second phase compensation capacitor C10 are also used to form a low-pass filter.

[0078] The second feedback resistor R6 can be a resistor connected between the output and inverting input of the second operational amplifier 141 to set the closed-loop gain. In this application, it can be a precision resistor with a resistance of 4.99KΩ. The ground resistor RA2 can be a gain setting resistor connected between the inverting input of the second operational amplifier 141 and ground. In this application, it can be a resistor with a resistance of 665Ω, which, together with the second feedback resistor R6, determines the voltage gain of the non-inverting amplifier. The low-pass filter refers to the frequency selectivity characteristic that allows signals below the cutoff frequency to pass while attenuating signals above the cutoff frequency. In this application, it can be the first-order low-pass frequency response presented by the feedback network formed by the second feedback resistor R6 and the second phase compensation capacitor C10 connected in parallel, used to limit the closed-loop bandwidth of the amplifier and filter out high-frequency noise.

[0079] For example, one end of the second feedback resistor R6 can be connected to the inverting input of the second operational amplifier 141, and the other end of the second feedback resistor R6 can be connected to the output of the second operational amplifier 141. One end of the ground resistor RA2 can be connected to the inverting input of the second operational amplifier 141, and the other end of the ground resistor RA2 can be connected to reference ground. One end of the second phase compensation capacitor C10 can be connected to the inverting input of the second operational amplifier 141, and the other end of the second phase compensation capacitor C10 can be connected to the output of the second operational amplifier 141. The second feedback resistor R6 and the second phase compensation capacitor C10 can be connected in parallel.

[0080] As an example, the second operational amplifier 141 can function as a non-inverting amplifier circuit, and the feedback network can include a 4.99KΩ second feedback resistor R6 and a 665Ω resistor to ground RA2. Furthermore, the feedback capacitor and the second feedback resistor R6 together form an active low-pass filter, which not only limits the closed-loop bandwidth of the second-stage amplification but also acts as an anti-aliasing filter before sampling by the analog-to-digital converter 180, suppressing out-of-band noise and assisting in anti-aliasing sampling, further optimizing the overall noise and bandwidth performance.

[0081] In this embodiment, by setting the second phase compensation capacitor and the second feedback resistor in parallel in the second feedback module 142, an active low-pass filter frequency response can be constructed by utilizing the characteristic that the capacitive reactance of the capacitor decreases as the frequency increases while providing a fixed voltage gain. This limits the closed-loop bandwidth of the second-stage amplifier and suppresses high-frequency noise, preventing high-frequency interference from entering the subsequent analog-to-digital converter 180 and causing aliasing errors. This further improves the accuracy of fluorescence signal acquisition and temperature measurement.

[0082] In one exemplary embodiment, such as Figure 2 As shown, the interstage filtering module 160 includes: The first filter resistor RA1 is connected between the output terminal of the first transimpedance amplifier module 130 and the non-inverting input terminal of the second transimpedance amplifier module 140. The second filter resistor R2 has one end for connecting a positive voltage, and the other end of the second filter resistor R2 is connected to the connection point between the first filter resistor RA1 and the non-inverting input terminal of the second transimpedance amplifier module 140. The first filter capacitor CA1 has one end connected to the connection point between the first filter resistor RA1 and the non-inverting input terminal of the second transimpedance amplifier module 140, and the other end is used for grounding.

[0083] The first filter resistor RA1 can be a resistor connected in series between the output terminal of the first transimpedance amplifier module 130 and the non-inverting input terminal of the second transimpedance amplifier module 140. In this application, it can be a current-limiting resistor or filter resistor that, together with the first filter capacitor CA1, forms a passive low-pass filter network, and its resistance value can be 4.99KΩ. The second filter resistor R2 can be a bias resistor connected between the positive voltage and the non-inverting input terminal of the second transimpedance amplifier module 140. In this application, it can be a pull-up resistor that provides the DC operating point for the non-inverting input terminal of the second operational amplifier 141. The first filter capacitor CA1 can be a filter capacitor connected between the non-inverting input terminal of the second transimpedance amplifier module 140 and ground. In this application, it can be a grounding capacitor that, together with the first filter resistor RA1, forms a resistor-capacitor low-pass filter, and its capacitance can be 2.2nF.

[0084] For example, one end of the first filter resistor RA1 can be connected to the output terminal of the first transimpedance amplifier module 130, and the other end of the first filter resistor RA1 can be connected to the non-inverting input terminal of the second transimpedance amplifier module 140. One end of the second filter resistor R2 can be connected to a positive voltage, and the other end of the second filter resistor R2 can be connected to the connection node between the other end of the first filter resistor RA1 and the non-inverting input terminal of the second transimpedance amplifier module 140. One end of the first filter capacitor CA1 can be connected to the connection node between the other end of the first filter resistor RA1 and the non-inverting input terminal of the second transimpedance amplifier module 140, and the other end of the first filter capacitor CA1 can be connected to reference ground.

[0085] As an example, the interstage filtering module 160 can be positioned between the output of the first-stage operational amplifier and the non-inverting input of the second-stage operational amplifier, forming a passive resistor-capacitor low-pass filter composed of a series-connected first filter resistor RA1 and a grounded first filter capacitor CA1. While performing extremely high-gain amplification, the first transimpedance amplifier module 130 inevitably introduces and amplifies circuit thermal noise and environmental electromagnetic interference. The low-pass filter formed by the first filter resistor RA1 and the second filter capacitor can filter out high-frequency noise outside the useful fluorescent signal frequency band, improving signal purity and preventing high-frequency noise from being further amplified in subsequent stages.

[0086] In this embodiment, by setting an interstage filtering module 160 composed of a first filter resistor, a second filter resistor, and a first filter capacitor between the first transimpedance amplification module 130 and the second transimpedance amplification module 140, the voltage signal after the first stage amplification can be low-pass filtered, effectively filtering out high-frequency noise and electromagnetic interference introduced by the first transimpedance amplification module 130 under high-gain operating conditions, improving the purity of the signal entering the second transimpedance amplification module 140, and preventing noise from being further amplified by subsequent stages, thereby further improving the accuracy of fluorescence signal acquisition and temperature measurement.

[0087] In one exemplary embodiment, Figure 4 This application provides a schematic diagram of the connection structure between an anti-aliasing filter module and an analog-to-digital converter, as shown in the embodiment. Figure 4 As shown, the fluorescence signal acquisition circuit also includes an anti-aliasing filter module 170, which includes: The third filter resistor R7 is connected between the output terminal of the second transimpedance amplifier module 140 and the input terminal of the analog-to-digital converter 180; The second filter capacitor C4 has one end connected between the third filter resistor R7 and the input terminal of the analog-to-digital converter 180, and the other end is used for grounding.

[0088] The anti-aliasing filter module 170 can refer to a low-pass filter circuit located at the end of the analog signal chain and before the input of the analog-to-digital converter 180. In this application, it can be a resistor-capacitor filter network used to limit the signal bandwidth to less than half the sampling frequency of the analog-to-digital converter 180, preventing high-frequency noise from folding into the baseband due to undersampling and causing aliasing errors. The third filter resistor R7 can refer to a resistor connected in series between the output of the second transimpedance amplifier module 140 and the input of the analog-to-digital converter 180. In this application, it can be a current-limiting resistor that, together with the second filter capacitor C4, forms an anti-aliasing filter. The second filter capacitor C4 can refer to a filter capacitor connected between the input of the analog-to-digital converter 180 and ground. In this application, it can be a grounding capacitor that, together with the third filter resistor R7, forms a first-order resistor-capacitor low-pass filter.

[0089] For example, one end of the third filter resistor R7 can be connected to the output terminal of the second transimpedance amplifier module 140, and the other end of the third filter resistor R7 can be connected to the input terminal of the analog-to-digital converter 180. One end of the second filter capacitor C4 can be connected to the connection node between the other end of the third filter resistor R7 and the input terminal of the analog-to-digital converter 180, and the other end of the second filter capacitor C4 can be connected to reference ground. The input terminal of the analog-to-digital converter 180 can receive the filtered second voltage signal through the anti-aliasing filter module 170 to prevent spectral aliasing from occurring during sampling by the subsequent analog-to-digital converter 180.

[0090] As an example, such as Figure 4 As shown, the analog signal AIN_Dout output by the second transimpedance amplifier module 140 passes through an RC anti-aliasing filter network composed of resistor R7 and capacitor C4, and is then input to the non-inverting input AINP of the analog-to-digital converter chip U3. The inverting input AINN of the analog-to-digital converter chip U3 is connected to analog ground to form a single-ended sampling structure. The analog-to-digital converter chip U3 has high resolution and low drift characteristics, enabling high-fidelity sampling of microvolt-level signals. Its fastest sampling rate of 1μs can accurately capture transient fluorescence characteristics, improving the stability and sensitivity of temperature measurement in complex electromagnetic environments.

[0091] In this embodiment, by setting an anti-aliasing filter module 170 composed of a third filter resistor and a second filter capacitor between the output terminal of the second transimpedance amplifier module 140 and the input terminal of the analog-to-digital converter 180, the signal bandwidth entering the analog-to-digital converter 180 can be limited, preventing high-frequency noise higher than the Nyquist frequency of the analog-to-digital converter 180 from being converted into low-frequency pseudo-signals due to sampling aliasing. This ensures that the digital signal after analog-to-digital conversion truly reflects the fluorescence attenuation waveform, thereby further improving the accuracy of fluorescence signal acquisition and temperature measurement.

[0092] In some exemplary embodiments, the fluorescence signal acquisition circuit may further include a beam splitter, a condenser, and an optical fiber coupler. A pulsed excitation source sends a pulsed excitation signal to the light-emitting device, causing the device to emit pulsed light. This pulsed emission signal is transmitted through the beam splitter to the condenser, where it is focused and coupled by the optical fiber coupler to the fluorescent material within the optical fiber probe. The fluorescent material, excited by the pulsed emission signal, generates a corresponding fluorescence signal. This fluorescence signal is transmitted back to the condenser through the optical fiber coupler, completing the initial collection and focusing of the light signal. After passing through the condenser, the fluorescence signal is reflected by the beam splitter to a photodetector, which converts the fluorescence signal into the electrical signal to be acquired.

[0093] In some exemplary embodiments, the analog signal output from the photoelectric conversion unit passes through an anti-aliasing filter network and is then input to the non-inverting input of the analog-to-digital converter (ADC). The inverting input of the ADC is connected to analog ground to form a single-ended sampling structure. The ADC features high resolution and low drift characteristics, enabling high-fidelity sampling of microvolt-level signals. The fastest sampling rate of the ADC can be set to 1 μs to accurately capture transient fluorescence characteristics and improve temperature measurement stability and sensitivity in complex electromagnetic environments.

[0094] In one exemplary embodiment, this application also provides a fluorescence thermometer, comprising: Such as the fluorescence signal acquisition circuit described above; An analog-to-digital converter is used to receive the second voltage signal output from the fluorescence signal acquisition circuit.

[0095] Among them, the fluorescence temperature measuring device refers to a device that uses the photoluminescence properties of fluorescent materials to measure temperature, and can be an industrial temperature measuring instrument that performs non-contact temperature measurement based on the fluorescence decay time method, applicable to environments such as semiconductor manufacturing and power equipment monitoring. The analog-to-digital converter refers to an electronic device that converts continuously changing analog voltage signals into discrete digital quantities. In this application, it can be a high-resolution analog-to-digital converter chip used to quantize and sample the second voltage signal output from the fluorescence signal acquisition circuit, with a resolution of 16 bits or 24 bits.

[0096] For example, the fluorescence temperature measurement device may include the fluorescence signal acquisition circuit, analog-to-digital converter, and main controller described in the above embodiments. The input terminal of the fluorescence signal acquisition circuit may be coupled to a photodiode for receiving fluorescence signals. The output terminal of the fluorescence signal acquisition circuit may be connected to the input terminal of the analog-to-digital converter via an anti-aliasing filter module. The digital output terminal of the analog-to-digital converter may be connected to the main controller via a communication interface for transmitting digitized voltage data to the main controller for fluorescence lifetime calculation and temperature conversion.

[0097] As an example, such as Figures 1 to 4As shown, the fluorescence signal acquisition circuit may further include an analog-to-digital converter 180. The main controller sends a pulse excitation signal to the light-emitting device via a pulse excitation source, causing the device to emit pulsed light. This pulsed emission signal is transmitted through a beam splitter to a condenser lens, where it is focused and coupled by an optical fiber coupler before being transmitted to the fluorescent material within the optical fiber probe. The fluorescent material, excited by the pulsed emission signal, generates a corresponding fluorescence signal, which is transmitted back to the condenser lens via the optical fiber coupler, completing the initial collection and focusing of the light signal. The fluorescence signal, after passing through the condenser lens, is reflected by the beam splitter to a photodetector, which converts the fluorescence signal into an electrical signal to be acquired. The fluorescence signal acquisition circuit converts the fluorescence signal into a second voltage signal, which is then sampled by the analog-to-digital converter 180.

[0098] In this embodiment, by integrating the fluorescence signal acquisition circuit of the above embodiment into the fluorescence temperature measurement device, the fluorescence signal acquisition circuit can eliminate the dark current of the photodiode 110 and reduce system noise, providing a high-precision second voltage signal for the analog-to-digital converter 180. This allows subsequent fluorescence lifetime fitting and temperature conversion to be based on more accurate raw data, thereby improving the accuracy of fluorescence signal acquisition and temperature measurement.

[0099] In some exemplary embodiments, Figure 5 This is a schematic diagram of the system architecture of a fluorescence thermometer provided in an embodiment of this application, as shown below. Figure 5 As shown, the fluorescence temperature measurement device includes: a main controller 20, a pulsed excitation light source 30, a light-emitting device 40, an optical component 50, and a fluorescence signal acquisition circuit 10 as described in any of the above embodiments. The main controller 20 is connected to the input terminal of the pulsed excitation light source 30 and the output terminal of the fluorescence signal acquisition circuit 10, respectively. The light-emitting device 40 is connected to the output terminal of the pulsed excitation light source 30. The optical component 50 is connected to the input terminal of the fluorescence signal acquisition circuit 10 and the light-emitting device 40, respectively. Based on the digital voltage data acquired by the fluorescence signal acquisition circuit 10, the main controller 20 calculates the corresponding temperature value through a fluorescence decay model and the dependence of fluorescence lifetime on temperature. This fluorescence temperature measurement device integrates a high-performance fluorescence signal acquisition circuit 10, which can accurately and quickly acquire the raw data of the fluorescence decay process, providing high-quality input for the algorithm processing of the main controller 20, thereby realizing high-precision and high-stability non-contact temperature measurement.

[0100] In one embodiment, the fluorescent material mentioned above generates a fluorescence afterglow signal after being excited by pulsed light. The fluorescence afterglow signal is transmitted to the photodiode 110 after being reflected sequentially by an optical fiber coupler, a condenser lens, and a beam splitter.

[0101] Among them, the fluorescence temperature measuring device can refer to a device that uses the photoluminescence properties of fluorescent materials to measure temperature, or an industrial temperature measuring instrument that performs non-contact temperature measurement based on the fluorescence decay time method, and can be applied in environments such as semiconductor manufacturing and power equipment monitoring. The analog-to-digital converter 180 can refer to an electronic device that converts continuously changing analog voltage signals into discrete digital quantities. In this application, it can be a high-resolution analog-to-digital converter chip used to quantize and sample the second voltage signal output from the fluorescence signal acquisition circuit, with a resolution of 16 bits or 24 bits.

[0102] For example, the fluorescence temperature measurement device may include the fluorescence signal acquisition circuit of the above embodiment. The input terminal of the fluorescence signal acquisition circuit may be coupled to a photodiode for receiving fluorescence signals. The output terminal of the fluorescence signal acquisition circuit may be connected to the input terminal of the analog-to-digital converter chip U3 through an RC anti-aliasing filter circuit. The digital output terminal of the analog-to-digital converter chip U3 may be connected to the main controller 20 through a communication interface for transmitting digitized voltage data to the main controller for fluorescence lifetime calculation and temperature conversion.

[0103] Similarly, since the fluorescence temperature measuring device uses the fluorescence signal acquisition circuit provided in the above embodiments, the beneficial effects it achieves are the same as those of the fluorescence signal acquisition circuit, and will not be repeated here.

[0104] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0105] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0106] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A fluorescence signal acquisition circuit, characterized in that, The fluorescence signal acquisition circuit includes: a photodiode, a power supply module, a first transimpedance amplifier module, a second transimpedance amplifier module, a power supply filter module, and an interstage filter module; The anode of the photodiode is grounded, and the photodiode is used to receive fluorescence signals and convert them into photocurrent. The first transimpedance amplifier module is coupled to the photodiode to receive the photocurrent; The first transimpedance amplifier module includes a first operational amplifier and a first feedback module; The first power supply terminal and the second power supply terminal of the first operational amplifier are respectively connected to the positive voltage terminal and the negative voltage terminal of the power supply module through the power supply filter module, and are used to receive positive voltage and negative voltage respectively; wherein, the negative voltage is a preset micro negative voltage value, and the absolute value of the micro negative voltage value is less than the positive voltage, so that the output swing of the first operational amplifier covers zero level under asymmetrical dual power supply; The first operational amplifier is configured to clamp the inverting input terminal of the first operational amplifier to zero potential based on the negative voltage, so that the potential difference across the photodiode is zero, and work together with the first feedback module to convert the photocurrent into a first voltage signal with a first gain. The interstage filtering module is an RC low-pass filter used to filter out high-frequency noise; The second transimpedance amplifier module is coupled to the output terminal of the first transimpedance amplifier module through the interstage filtering module, and is used to convert the first voltage signal into a second voltage signal with a second gain; the second transimpedance amplifier module includes a second operational amplifier, and the first voltage signal is input to the non-inverting input terminal of the second operational amplifier after passing through the interstage filtering module.

2. The fluorescence signal acquisition circuit according to claim 1, characterized in that, The power module includes a first voltage conversion unit and a second voltage conversion unit. The first voltage conversion unit is used to generate the positive voltage, and the second voltage conversion unit is used to generate the negative voltage.

3. The fluorescence signal acquisition circuit according to claim 1, characterized in that, The power filtering module includes: The first LC filter unit is connected between the positive voltage terminal of the power supply module and the first power supply terminal of the first operational amplifier, and is used to perform low-pass filtering on the positive voltage. The second LC filter unit is connected between the negative voltage terminal of the power supply module and the second power supply terminal of the first operational amplifier, and is used to perform low-pass filtering on the negative voltage.

4. The fluorescence signal acquisition circuit according to claim 1, characterized in that, The first feedback module includes: The first feedback resistor is connected between the output terminal and the inverting input terminal of the first operational amplifier and is used to set the first gain. The first phase compensation capacitor is connected in parallel with the first feedback resistor to provide phase compensation for the first voltage signal.

5. The fluorescence signal acquisition circuit according to claim 1, characterized in that, The second transimpedance amplifier module includes: a second operational amplifier and a second feedback module; The second operational amplifier is configured to work in conjunction with the second feedback module to convert the first voltage signal into a second voltage signal with a second gain to match the input range of the connected analog-to-digital converter.

6. The fluorescence signal acquisition circuit according to claim 5, characterized in that, The second feedback module includes: The second feedback resistor is connected between the output terminal of the second operational amplifier and the inverting input terminal of the second operational amplifier; A ground resistor is connected between the inverting input of the second operational amplifier and ground. The ratio of the second feedback resistor to the ground resistor is used to set the second gain; The second phase compensation capacitor, connected in parallel with the second feedback resistor, is used to provide phase compensation for the second voltage signal; the second feedback resistor and the second phase compensation capacitor are also used to form a low-pass filter.

7. The fluorescence signal acquisition circuit according to claim 1, characterized in that, The inter-stage filtering module includes: The first filter resistor is connected between the output terminal of the first transimpedance amplifier module and the non-inverting input terminal of the second transimpedance amplifier module; The second filter resistor has one end for connecting a positive voltage and the other end connected to the connection point between the first filter resistor and the non-inverting input terminal of the second transimpedance amplifier module. The first filter capacitor has one end connected to the connection point between the first filter resistor and the non-inverting input terminal of the second transimpedance amplifier module, and the other end is used for grounding.

8. The fluorescence signal acquisition circuit according to claim 1, characterized in that, The fluorescence signal acquisition circuit further includes an anti-aliasing filter module, which includes: The third filter resistor is connected between the output terminal of the second transimpedance amplifier module and the input terminal of the analog-to-digital converter. The second filter capacitor has one end connected between the third filter resistor and the input terminal of the analog-to-digital converter, and the other end is used for grounding.

9. A fluorescence thermometer, characterized in that, include: The main controller, the pulsed excitation light source, the light-emitting device, the optical components, and the fluorescence signal acquisition circuit as described in any one of claims 1-8; The main controller is connected to the input terminal of the pulse excitation light source and the output terminal of the fluorescence signal acquisition circuit, respectively, and the light-emitting device is connected to the output terminal of the pulse excitation light source; The optical components are connected to the input terminal of the fluorescence signal acquisition circuit and the light-emitting device, respectively. The main controller calculates the corresponding temperature value based on the digital voltage data acquired by the fluorescence signal acquisition circuit, using a fluorescence decay model and the relationship between fluorescence lifetime and temperature.

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