A high-precision anti-interference photoelectric feedback circuit for a laser

Abstract

The application provides a high-precision anti-interference photoelectric feedback circuit for a laser, relates to the technical field of laser detection and control, and comprises a signal conditioning and filtering module including TLV9064IRUCR and TLV9061IDCKR operational amplifiers, which are used for multi-stage amplification and band-pass filtering processing of a received voltage signal and output of the processed analog signal to a microcontroller processing module; the microcontroller processing module includes a microcontroller, an ADC input end of which is connected to an output end of the signal conditioning and filtering module, is used for collecting an analog voltage signal and performing digital processing, and outputs a laser control signal and an analog switch control signal according to a processing result. The application can realize omnibearing coverage detection of the whole soot distribution of a climbing tube section and eliminate the detection blind area existing in the single-point detection of the prior art.

Description

Technical Field

[0001] This invention relates to the field of laser detection and control technology, and in particular to a high-precision, anti-interference photoelectric feedback circuit for lasers. Background Technology

[0002] In laser target identification, laser ranging, and photoelectric detection systems, photoelectric sensors are typically used to receive laser signals reflected or scattered by the target and convert them into electrical signals for further processing to achieve target identification, localization, or tracking. Existing photoelectric feedback control circuits typically include photodetectors, preamplifier circuits, signal filtering circuits, and control units.

[0003] However, existing technologies have the following shortcomings when applied to complex electromagnetic environments (such as vehicle platforms, industrial environments, or near high-power electronic devices): In existing circuit structures, high-frequency switching noise in the digital control section can easily couple to the analog signal processing front end through power supply or ground loops, causing distortion or false triggering of weak photoelectric detection signals. For weak laser signals reflected back from the target, existing preamplifier circuits have high noise and lack targeted multi-stage filtering structures, making it difficult to accurately extract the target modulation signal in strong ambient light. Traditional circuits typically use fixed gain and fixed signal paths, making it difficult to flexibly switch between different operating modes (such as normal detection and background calibration) and unable to effectively suppress baseline drift caused by changes in ambient light.

[0004] When a signal change is detected, the closed-loop feedback response of the existing circuit is slow and is prone to oscillation due to improper loop gain design, which affects the stable control of laser emission power.

[0005] Therefore, there is an urgent need for a high-precision, anti-interference photoelectric feedback control circuit that can effectively isolate power supply noise, has multi-level bandpass filtering capability, and can achieve dynamic signal path switching. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a high-precision anti-interference photoelectric feedback circuit for lasers, which avoids system oscillation caused by environmental changes or signal fluctuations, and improves the overall stability and response speed of the photoelectric feedback control system.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A high-precision, anti-interference photoelectric feedback circuit for lasers, comprising: The system includes a power supply regulation and anti-interference module, a photoelectric detection module, a transimpedance amplifier module, an analog switch control module, a signal conditioning and filtering module, and a microcontroller processing module. The power supply regulation and anti-interference module includes a low dropout linear regulator, which is used to provide stable VCC3V3 and AVCC3V3 power supplies for the transimpedance amplifier module, the signal conditioning and filtering module, and the microcontroller processing module. The photoelectric detection module includes at least one VEMD5510C photodiode for receiving the laser signal reflected by the target and converting it into a photocurrent signal. Its output terminal is connected to the input terminal of the transimpedance amplifier module. The transimpedance amplification module includes an operational amplifier, which is used to convert the received photocurrent signal into a voltage signal and perform preliminary amplification. The analog switch control module includes an analog switch, whose input terminal is connected to the output terminal of the transimpedance amplifier module, whose output terminal is connected to the input terminal of the signal conditioning and filtering module, and whose control terminal is connected to the microcontroller processing module. The signal conditioning and filtering module includes TLV9064IRUCR and TLV9061IDCKR operational amplifiers, which are used to amplify and bandpass filter the received voltage signal in multiple stages, and output the processed analog signal to the microcontroller processing module. The microcontroller processing module includes a microcontroller whose ADC input is connected to the output of the signal conditioning and filtering module. It is used to acquire analog voltage signals and perform digital processing, and output laser control signals and analog switch control signals according to the processing results.

[0008] The above-described solution of the present invention has at least the following beneficial effects: By setting up a power supply regulation and anti-interference module that includes a low-dropout linear regulator (TPS7A2033PDQNR) and an LC isolation network, the digital power supply VCC3V3 and the analog power supply AVCC3V3 can be physically isolated. This effectively suppresses the high-frequency switching noise generated by digital circuits such as microcontrollers from being coupled to the transimpedance amplifier module and signal conditioning module through the power supply loop, thereby reducing the system noise floor and improving the signal-to-noise ratio for weak signal detection.

[0009] The transimpedance amplifier module (TLV9064IRUCR) converts the microampere photocurrent generated by the photodiode into a voltage signal. Combined with a multi-stage signal conditioning and filtering module composed of TLV9064IRUCR and TLV9061IDCKR, through multi-stage amplification and bandpass filtering network, only the frequency components of the target laser modulation signal are allowed to pass through, effectively suppressing DC and low-frequency interference from ambient light (such as sunlight and lighting), and significantly improving the detection accuracy of weak signals.

[0010] By incorporating an analog switch control module (TS5A4597DCKR) in the signal path, and directly controlling its on / off state via the GPIO pins of a microcontroller (STM32U535CCU6), dynamic selection of the detection signal channel is achieved. This system can flexibly switch between normal operating mode and calibration / self-test mode. For example, in the off state, it can acquire ambient background noise for dynamic threshold calibration, thereby further improving the system's anti-interference capability and recognition reliability in complex environments.

[0011] The microcontroller processing module acquires the conditioned analog voltage signal through its built-in ADC, performs digital processing, calculates the feedback error, and then outputs the laser control signal through the DAC_OUT pin, realizing closed-loop feedback regulation of the laser emission module. This structure ensures the dynamic stability of the laser output intensity, avoids system oscillations caused by environmental changes or signal fluctuations, and improves the overall stability and response speed of the photoelectric feedback control system. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a high-precision anti-interference photoelectric feedback circuit for lasers provided by an embodiment of the present invention.

[0013] Figure 2 This is a circuit diagram of a power supply regulation and anti-interference module provided in an embodiment of the present invention.

[0014] Figure 3 This is a circuit diagram of the photoelectric detection module provided in an embodiment of the present invention.

[0015] Figure 4 This is a circuit diagram of a transimpedance amplifier module provided in an embodiment of the present invention.

[0016] Figure 5 This is a circuit diagram of an analog switch control module provided in an embodiment of the present invention.

[0017] Figure 6 This is a circuit diagram of the signal conditioning and filtering module provided in an embodiment of the present invention.

[0018] Figure 7 This is a circuit diagram of a microcontroller processing module provided in an embodiment of the present invention.

[0019] Figure 8 This is a PCB 3D drawing provided in an embodiment of the present invention. Detailed Implementation

[0020] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0021] This embodiment provides a high-precision, anti-interference photoelectric feedback control circuit for lasers. This circuit is specifically designed for laser target recognition systems and aims to address the problems of poor anti-interference capability, low accuracy in weak signal detection, and insufficient feedback control stability in existing technologies under complex electromagnetic environments. The following describes... Figures 1 to 8 The circuit configuration, specific connection relationships, and workflow of this embodiment will be described in detail.

[0022] like Figure 1 As shown in the circuit block diagram, this embodiment provides a high-precision, anti-interference photoelectric feedback control circuit for lasers, mainly composed of six functional modules: a power supply regulation and anti-interference module, a photoelectric detection module, a transimpedance amplification module, an analog switch control module, a signal conditioning and filtering module, and a microcontroller processing module. These modules are connected via signal lines to form a complete closed-loop photoelectric feedback control system.

[0023] In this system, the main signal processing path is as follows: the optical signal is converted into photocurrent by the photoelectric detection module, the photocurrent is converted into voltage signal by the transimpedance amplification module, the voltage signal is selected by the analog switch control module, and then enters the signal conditioning and filtering module for multi-stage amplification and bandpass filtering. Finally, it is acquired by the built-in ADC of the microcontroller processing module. The system control path is as follows: based on the acquired and processed signal, the microcontroller processing module outputs a control signal to the analog switch control module to switch the signal path, and outputs a control signal to the external laser emission module to adjust the laser emission intensity. The system's anti-interference path is constructed by the power isolation and low-noise power supply implemented by the power supply regulation and anti-interference module, the analog bandpass filtering implemented by the signal conditioning and filtering module, and the synchronous control strategy implemented by the microcontroller.

[0024] The circuit diagram of the power supply regulation and anti-interference module is as follows: Figure 2 As shown, this module provides a stable, low-noise power supply for the entire photoelectric feedback control circuit, which is fundamental to achieving high-precision detection in the system. It receives a single VCC 5V power supply from an external source and internally processes it into multiple isolated power rails to power both the digital and analog circuits.

[0025] Specifically, the VCC5V power supply directly powers the digital circuitry of the system. VCC5V is connected to the input of the first low-dropout linear regulator U7, specifically the TPS7A2033PDQNR, which outputs a stable 3.3V digital power supply, VCC3V3. To filter out high-frequency noise, U7's output is equipped with parallel-to-ground filter capacitors C33 (1uF) and C35 (1uF). This VCC3V3 power supply is dedicated to providing power to the digital core and I / O of the microcontroller U5 (STM32U535CCU6) in the microcontroller processing module. VCC5V is also connected to the input of the second low-dropout linear regulator U6, which is also a TPS7A2033PDQNR. U6's output generates a stable 3.3V analog power supply, AVCC3V3. U6's output also has parallel-to-ground filter capacitors C32 (1uF) and C25 (1uF). The AVCC3V3 power supply is primarily used to provide low-noise analog power to the operational amplifiers in the signal conditioning and filtering module. The four-channel VCC5V also passes through an LC isolation network consisting of inductor L1 (10uH) and capacitors C26 (100nF), C30 (10uF), C27 (100nF), and C31 (10uF), converting it into an independent analog power supply, AVCC5V, isolated from the digital VCC5V. This AVCC5V power supply is mainly used to power analog circuits that are extremely sensitive to noise, such as the transimpedance amplifier module and the photoelectric detection front-end circuit.

[0026] Through the above-mentioned two-stage voltage regulation (VCC5V to VCC3V3 / AVCC3V3) and LC isolation (VCC5V to AVCC5V) design, this module physically isolates the switching noise of the digital circuit from the power supply of the analog weak signal processing circuit. It also greatly suppresses the power supply ripple through the low-noise LDO and decoupling capacitor network, thereby reducing the noise floor of the entire system and creating conditions for subsequent weak signal detection.

[0027] The circuit diagram of the photoelectric detection module is as follows: Figure 3 As shown, this is used to convert laser signals into electrical signals. In this embodiment, to increase the effective photosensitive area and improve detection sensitivity, a photoelectric detection array consisting of eight VEMD5510C photodiodes connected in parallel is used. These eight photodiodes are numbered D1 to D8.

[0028] In terms of connectivity, the anodes of all photodiodes (D1-D8) are connected to system ground (GND); the cathodes of all photodiodes are connected to the same node, named Port. The Port node is the output terminal of this photoelectric detection module and is connected to the input terminal of the next-stage transimpedance amplifier module. This module uses a low-side drive connection method, which helps improve anti-interference capabilities. During operation, the laser signal reflected from the target illuminates the photodiode array, generating a photoelectric effect within each diode, forming a weak photocurrent proportional to the incident light intensity. The current signal is output through the Port node.

[0029] The circuit diagram of the transimpedance amplifier module is as follows: Figure 4 As shown, this module converts and initially amplifies the microampere or even nanoampere level photocurrent signal output from the photodiode into a voltage signal. The core of this module is an operational amplifier connected to the low side of the photodiode, specifically a TLV9064IRUCR. This module uses one operational amplifier from this chip, namely U2C. The inverting input of operational amplifier U2C, pin 8 of the chip, is directly connected to the output node Port of the photodiode; the non-inverting input of operational amplifier U2C, pin 9 of the chip, is connected to the bias voltage provided by the system. The output of the operational amplifier U2C, i.e., pin 7 of the chip, forms a new node, Port1, which is the output of this module. The key to the transimpedance amplification function is the feedback network connected between the output (pin 7) and the inverting input (pin 8). This network consists of a feedback resistor R13 (1MΩ) and a compensation capacitor C10 (22pF) connected in parallel.

[0030] Its working principle follows the volt-ampere characteristic of a transimpedance amplifier, and the output voltage... This linearly converts the input photocurrent into a voltage signal. The parallel feedback compensation capacitor C10 is crucial; it, together with R13, forms a pole to limit the amplifier's high-frequency bandwidth, effectively preventing circuit self-oscillation caused by parasitic parameters such as the photodiode junction capacitance, and ensuring the stability of the weak signal amplification process.

[0031] The circuit diagram of the analog switch control module is as follows: Figure 5 As shown, this is used to achieve dynamic selection of signal paths and switching of system gain modes. Its core component is a single-channel single-pole single-throw analog switch, specifically model TS5A4597DCKR. Figure 5 The U3 in the diagram features low on-resistance and low leakage current, making it suitable for controlling precision signal paths.

[0032] In the specific connection relationship, the signal terminal COM (pin 4) of U3 is connected to the output node Port1 of the transimpedance amplifier module; its signal output terminal NO (pin 3) is floating and not connected; its other signal terminal IN (pin 2) is connected to the input terminal of the signal conditioning and filtering module. The positive power supply terminal VCC (pin 5) of U3 is connected to the analog power supply AVCC5V generated by the power supply module, and the negative power supply terminal GND (pin 3, note that the sub-diagram labels may overlap, but it is a logical connection) is connected to the system ground GND. The control terminal CTRL (pin 1) of U3 is connected to a GPIO pin of the microcontroller U5 in the microcontroller processing module. This control signal is named GAIN-CTRL. In addition, the module also integrates a bias current control circuit with Q1 (2SA1162-Y) PNP transistor and U2D as the core. The collector of Q1 is connected to the signal path of U3 through R7 (220Ω), and the base is connected to the bias voltage driven by the microcontroller U2D through R10 (10kΩ).

[0033] In terms of operation, when the microcontroller U5 outputs a low level to pin 1 (CTRL), the analog switch U3 closes, the signal path is open, and the signal from the Port1 node enters the subsequent conditioning circuit through U3, and the system is in normal signal detection mode. When the microcontroller outputs a high level, U3 opens, the signal path is cut off, and the system can be used to collect background noise or ambient light signals, perform system self-tests, or perform dynamic threshold calibration.

[0034] The circuit diagram of the signal conditioning and filtering module is as follows: Figure 6 As shown, this module is used for fine conditioning of the voltage signal generated by the transimpedance amplifier module, including multi-stage amplification and narrowband filtering, to extract the weak laser modulation signal submerged in noise and ambient light interference. The module consists of one quad op-amp TLV9064IRUCR and one single op-amp TLV9061IDCKR, both featuring rail-to-rail, low-noise characteristics.

[0035] The signal conditioning and filtering module contains a four-stage amplification network, but the main signal conditioning consists of a three-stage AC-coupled bandpass amplification stage and a buffered output stage.

[0036] The first-stage amplifier consists of U2B (a TLV9064IRUCR). The signal from the analog switch U3 after it is turned on enters the inverting input of U2B through an AC coupling network composed of DC blocking capacitor C11 (1nF) and input resistor R12 (47kΩ). Its feedback network consists of R11 (470kΩ) and C8 (100pF) connected in parallel. The gain of this stage is approximately... The parallel C8 limits the high-frequency gain.

[0037] The second-stage amplifier consists of U2A (a TLV9064IRUCR). The output of the preamplifier U2B enters the inverting input of U2A through coupling capacitor C12 (100nF) and input resistor R14 (100kΩ). Its feedback network consists of R9 (10MΩ) and C7 (1nF) connected in parallel. The gain of this stage is approximately... The C7 further limits high-frequency noise.

[0038] The third amplification stage consists of U4 (model TLV9061IDCKR). The output of the preamplifier U2A enters the inverting input of U4 via coupling capacitor C13 (1nF) and input resistor R15 (47kΩ). Its feedback network consists of R8 (470kΩ) and C6 (100pF) connected in parallel. The gain of this stage is approximately... times.

[0039] After the signal is amplified through the above three cascaded stages, the overall gain is extremely high. More importantly, the DC blocking capacitors (C11, C12, C13) connected in series at the input of each stage, together with the input resistor of the subsequent stage, form a series high-pass filter to block the DC component of ambient light and low-frequency interference; while the capacitors (C8, C7, C6) connected in parallel in each feedback loop, together with the feedback resistor, form a parallel low-pass filter to limit high-frequency noise. By cascading these high-pass and low-pass filtering characteristics, the entire signal conditioning module effectively forms a steep active bandpass filter, making it only effective for a specific frequency (the laser modulation signal frequency targeted in this invention). The signal near the band is amplified with high gain, while the out-of-band ambient light and electromagnetic interference are greatly suppressed, and finally a high signal-to-noise ratio analog voltage signal Signal is formed at the output.

[0040] The circuit diagram of the microcontroller processing module is as follows: Figure 7 The diagram shows the system's control and data processing core. Its core component is an ultra-low-power, high-performance microcontroller, specifically the STM32U535CCU6. Figure 7 The U5 microcontroller is based on the ARM Cortex-M33 core and integrates a high-precision analog-to-digital converter and a digital-to-analog converter, which meets the requirements of this system.

[0041] For power supply connections, the digital power domain of U5 (pins 24, 36, 48, etc.) is connected to VCC3V3, and the analog power domain (pins 1, 9, 22, etc.) is connected to AVCC3V3, achieving internal power isolation. Its external clock circuit consists of a 16MHz passive crystal oscillator X1 and two start-up capacitors C17 (12pF) and C18 (12pF), providing a precise clock source for the chip. The key I / O pin connections are as follows: ADC input: Pin 12 of U5, its function is multiplexed as follows: This pin is directly connected to the final output of the signal conditioning and filtering module and is used to acquire the analog voltage signal Signal.

[0042] DAC output: Pin 14 of U5, its function is multiplexed as follows: This pin outputs an analog control voltage after internal DAC conversion. This voltage is smoothed by a low-pass filter network consisting of R20 (510Ω), R21 (510Ω), and C28 (1nF) before being output to an external laser emission module to adjust the laser drive current and thus control the emission power.

[0043] GPIO control: Pin 4 of U5 is configured as a general-purpose output port with the signal name GAIN-CTRL. This pin is directly connected to the control terminal (pin 1) of U3 in the analog switch control module to control the on / off state of the analog switch.

[0044] Debugging communication interface: Pins 30 (DBG-TX) and 31 (DBG-RX) of U5 are connected to an interface circuit consisting of R27 (510Ω), R26 (510Ω) and C36 (1nF) for system debugging and data communication.

[0045] Based on the above hardware circuit, the complete working process and control method of this embodiment are described in detail below: The laser emitter emits a laser signal modulated at a specific frequency toward the target area. This signal, after being reflected or scattered by the target, returns carrying target information. The VEMD5510C photodiode array (D1-D8) in the photoelectric detection module receives this weak light signal and converts it into a microampere-level photocurrent proportional to the light intensity. The photocurrent enters the transimpedance amplifier module through the Port node. The TLV9064 operational amplifier (U2C) and the feedback network (R13, C10) linearly convert the photocurrent into a voltage signal, which is then output at the Port1 node.

[0046] In normal detection mode, pin 4 (GAIN-CTRL) of microcontroller U5 outputs a low level, controlling the analog switch U3 to close. The signal enters the signal conditioning and filtering module from Port1 via U3. This signal then passes through a three-stage bandpass amplification network consisting of U2B, U2A, and U4. The target laser modulation frequency component in the signal is amplified with high gain, while DC interference from ambient light, low-frequency interference, and high-frequency noise are effectively suppressed and filtered out. Finally, the processed high signal-to-noise ratio analog voltage signal... Output from the Signal node and transmitted to pin 12 of microcontroller U5 ( The microcontroller U5, through its internal program, initiates the ADC... Continuous sampling and analog-to-digital conversion are performed to obtain digital signal values.

[0047] The microcontroller U5 collects digital signals. A judgment is made to identify whether a valid target exists. The judgment is based on a dynamic threshold. The judgment condition is: when When the signal is received, it is determined that a valid laser target signal has been received.

[0048] Dynamic threshold The calculation formula is: .in, For environmental background signals, It is a preset safety margin to prevent false triggering caused by noise.

[0049] Environmental background signals The acquisition process embodies the innovative calibration mechanism of this circuit. Microcontroller U5 periodically, or upon receiving a calibration command, enters a self-test / calibration mode. In this mode, pin 4 of microcontroller U5 outputs a high level, controlling analog switch U3 to open, thereby cutting off the signal path from the photodiode to the signal conditioning module. At this time, the signal acquired by the subsequent circuitry of the conditioning module is the sum of the system's background noise and ambient light background noise. U5 samples multiple times through the ADC and averages the results, recording the obtained voltage value as the real-time ambient background signal. After calibration, U5 switches back to normal operating mode (U3 closed) and uses the latest... Value calculation of dynamic threshold Target identification is then performed. This dynamic background subtraction method allows the system to automatically adapt to changes in ambient light, greatly improving detection accuracy and anti-interference capabilities under low-light conditions.

[0050] Once the system detects a valid target, it executes closed-loop feedback control to stabilize the received laser signal intensity, ensuring the system operates at its optimal state. The microcontroller U5 internally presets a reference voltage value. This value represents the desired signal strength. U5 calculates the acquired signal. Compared with reference value Error value between The calculation formula is: .

[0051] The microcontroller is based on the error Perform calculations (e.g., using a PID control algorithm). If the error... A positive value indicates that the currently received laser signal is weak, possibly due to the target being farther away or the reflectivity being reduced. U5 will then use its internal DAC converter to select the signal from pin 14 (…). This outputs a correspondingly increased analog voltage. This voltage, after being low-pass filtered by external resistors R20, R21, and capacitor C28, is sent to the laser emission module's drive circuit, thereby increasing the laser drive current and improving the laser emission intensity. Conversely, if... A negative value indicates an excessively strong signal, in which case U5 reduces the DAC output voltage, decreasing the transmission power. Through this closed-loop control circuit, the system can dynamically and rapidly adjust the laser emission intensity, compensating for signal fluctuations caused by changes in target characteristics or the environment, thus ensuring the high stability and rapid response of the photoelectric feedback control system.

[0052] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-precision, anti-interference photoelectric feedback circuit for lasers, characterized in that, It includes a power supply regulation and anti-interference module, a photoelectric detection module, a transimpedance amplifier module, an analog switch control module, a signal conditioning and filtering module, and a microcontroller processing module; The power supply regulation and anti-interference module includes a low dropout linear regulator, which is used to provide stable VCC3V3 and AVCC3V3 power supplies for the transimpedance amplifier module, the signal conditioning and filtering module, and the microcontroller processing module. The photoelectric detection module includes at least one VEMD5510C photodiode for receiving the laser signal reflected by the target and converting it into a photocurrent signal. Its output terminal is connected to the input terminal of the transimpedance amplifier module. The transimpedance amplification module includes an operational amplifier, which is used to convert the received photocurrent signal into a voltage signal and perform preliminary amplification. The analog switch control module includes an analog switch, whose input terminal is connected to the output terminal of the transimpedance amplifier module, whose output terminal is connected to the input terminal of the signal conditioning and filtering module, and whose control terminal is connected to the microcontroller processing module. The signal conditioning and filtering module includes TLV9064IRUCR and TLV9061IDCKR operational amplifiers, which are used to amplify and bandpass filter the received voltage signal in multiple stages, and output the processed analog signal to the microcontroller processing module. The microcontroller processing module includes a microcontroller whose ADC input is connected to the output of the signal conditioning and filtering module. It is used to acquire analog voltage signals and perform digital processing, and output laser control signals and analog switch control signals according to the processing results.

2. The anti-interference photoelectric feedback control circuit for a laser according to claim 1, characterized in that, The power supply regulation and anti-interference module includes two TPS7A2033PDQNR low dropout linear regulators; the first low dropout linear regulator U7 has its input terminal connected to VCC5V and its output terminal connected to VCC3V3, and is equipped with filter capacitors C33 and C35, which are used to provide digital power to the microcontroller processing module; the second low dropout linear regulator U6 has its input terminal connected to VCC5V and its output terminal connected to AVCC3V3, and is equipped with filter capacitors C32 and C25, which are used to provide analog power to the signal conditioning and filtering module; it also includes an LC isolation network composed of inductor L1 and capacitors C26, C30, C27, and C31, which is used to convert VCC5V into an independent analog power supply AVCC5V and isolate the coupling of digital switching noise to the analog circuit.

3. The anti-interference photoelectric feedback control circuit for a laser according to claim 2, characterized in that, The photoelectric detection module consists of multiple VEMD5510C photodiodes connected in parallel. The anodes of each photodiode are connected to GND, and the cathodes are connected to the Port node in the transimpedance amplifier module. In the transimpedance amplifier module, the inverting input terminal (pin 8) of the TLV9064IRUCR operational amplifier U2C is connected to the Port node, and the non-inverting input terminal (pin 9) is connected to the bias voltage Vcm. A feedback resistor R13 and a compensation capacitor C10 are connected in parallel between its output terminal (pin 7) and the inverting input terminal (pin 8). The transimpedance amplifier module converts the microampere photocurrent generated by the photodiodes into a voltage signal and uses C10 to limit the high-frequency bandwidth to prevent oscillation.

4. The anti-interference photoelectric feedback control circuit for a laser according to claim 3, characterized in that, The analog switch control module uses a TS5A4597DCKR analog switch U3. Its pin 4, i.e., the COM terminal, is connected to the output terminal Port1 of the transimpedance amplifier module; its pin 2, i.e., the IN terminal, is connected to the input terminal of the signal conditioning and filtering module; its pin 5 is connected to AVCC5V; and its pin 1, i.e., the CTRL terminal, is connected to pin 4, i.e., gain-CTRL, of the microcontroller STM32U535CCU6. The microcontroller controls the conduction or disconnection of U3 by outputting high or low levels, thereby realizing the connection or disconnection of the detection signal channel.

5. The anti-interference photoelectric feedback control circuit for a laser according to claim 4, characterized in that, The signal conditioning and filtering module includes a four-stage amplification network; The first stage of amplification is composed of a TLV9064IRUCR operational amplifier U2B. Its inverting input is connected to the output of U3 in the analog switch control module through R12 and C11. The feedback network is composed of R11 and C8 connected in parallel. The second stage of amplification is composed of a TLV9064IRUCR operational amplifier U2A. The output of the pre-stage is coupled to the inverting input through C12 and R14. The feedback network is composed of R9 and C7 (1nF) in parallel. The third stage of amplification is composed of TLV9061IDCKR operational amplifier U4. The output of the pre-stage is coupled to the inverting input through C13 and R15. The feedback network is composed of R8 and C6 in parallel. A multi-stage amplifier circuit is connected in series to form a bandpass filter, which only allows the frequency components of the target laser modulation signal to pass through.

6. The anti-interference photoelectric feedback control circuit for a laser according to claim 5, characterized in that, Pin 12 of the STM32U535CCU6 microcontroller U5 in the microcontroller processing module is used as the ADC input terminal and is directly connected to the output terminal Signal in the signal conditioning and filtering module. The microcontroller acquires the voltage signal Vsig through its internal ADC and sets a dynamic threshold Vth for signal determination. When the acquired Vsig is greater than the dynamic threshold Vth, it is determined that a valid laser target signal has been received.

7. The anti-interference photoelectric feedback control circuit for a laser according to claim 6, characterized in that, The method by which the microcontroller processing module calculates the dynamic threshold Vth includes: The environmental background signal Vbg is obtained through multiple samplings, and a safety margin ΔV is added to Vbg. The formula for calculating the dynamic threshold is as follows: Vth = Vbg + ΔV; The sampling of the environmental background signal Vbg is achieved by the microcontroller acquiring the voltage value output by the signal conditioning and filtering module when the analog switch control module is off.

8. The anti-interference photoelectric feedback control circuit for a laser according to claim 7, characterized in that, Pin 14 of the STM32U535CCU6 microcontroller U5 in the microcontroller processing module is connected to the external laser emission module via a low-pass filter network composed of resistors R20, R21 and capacitor C28. The microcontroller acquires the voltage signal Vsig output by the signal conditioning module through the ADC, calculates the error value e between it and the preset reference voltage Vref, i.e., e = Vref - Vsig. When the error e is positive, the microcontroller increases the laser driving voltage through DAC_OUT to increase the laser emission intensity, thereby realizing closed-loop feedback control.

9. The anti-interference photoelectric feedback control circuit for a laser according to claim 8, characterized in that, The bandpass filtering characteristics of the signal conditioning and filtering module are implemented through the following structure: The DC blocking capacitors C11, C12, and C13 between stages, together with the input resistor of the subsequent operational amplifier, form a high-pass filter to block DC and low-frequency interference. The feedback parallel RC network of each operational amplifier forms a low-pass filter to limit high-frequency noise; through the cascaded series connection of three high-pass and low-pass networks, a steep band-pass filter is formed to extract the laser modulation signal and suppress ambient stray light.

10. The anti-interference photoelectric feedback control circuit for a laser according to claim 9, characterized in that, The microcontroller processing module controls the operating mode of the analog switch U3 through its pin 4 to achieve system self-testing or calibration. In self-test mode, the microcontroller outputs a high level, causing U3 to disconnect and cutting off the signal path between the transimpedance amplifier module and the signal conditioning and filtering module. The signal acquired by the ADC is the background noise or ambient noise Vbg. In normal operating mode, the microcontroller outputs a low level, closing U3 and opening the signal path. The microcontroller then acquires the laser signal Vsig reflected from the target in real time and uses Vbg obtained during the self-test phase to perform dynamic threshold calculation, thereby improving the detection accuracy of weak signals and the system's anti-interference capability.

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