Laser brightness control circuit and laser ranging system

Abstract

The invention provides a laser brightness control circuit and a laser ranging system, a photodiode D1 is arranged to monitor and feed back the brightness of a laser light source, a current in direct proportion to the light intensity is generated, the current is converted into a voltage signal through a resistor R1, and then the voltage signal is sent to the inverted input end of an operational amplifier U1. The operational amplifier U1 compares the voltage signal with a reference signal, and controls the on or off of a triode Q0 in the laser emission circuit according to the voltage signal and the reference signal, thereby realizing the negative feedback adjustment of the optical signal emission, enabling a laser diode to continuously and stably work only when the brightness is maintained within a certain range, and improving the reliability of the laser emission circuit. And the distance measuring accuracy of the laser distance measuring sensor caused by temperature drift is improved.

Description

Technical Field

[0001] This application relates to the field of laser ranging technology, and in particular to a laser brightness control circuit and a laser ranging system. Background Technology

[0002] When using a laser rangefinder to measure distance, the sensor may be affected by temperature drift, which can cause changes in the light signal emitted by the laser diode. This can lead to a large deviation in the signal amplitude output by the photodetector, ultimately resulting in a distance measurement error.

[0003] refer to Figure 1 As shown, the traditional method typically uses a constant current source circuit consisting of a voltage source V0, an operational amplifier U0, a transistor Q0, and a resistor R0 to drive the laser diode LD1, thereby controlling the light intensity of the laser diode LD1. However, when temperature drift occurs, even if the current of the constant current source remains unchanged, the light intensity of the laser diode will change, which will cause the signal amplitude generated by the optical receiver to change, ultimately leading to an increase in ranging error. Summary of the Invention

[0004] This application provides a laser brightness control circuit and a laser ranging system that can reduce measurement errors caused by temperature drift.

[0005] A laser brightness control circuit is applied to a laser ranging sensor, the laser ranging sensor including a laser emitting circuit and a laser receiving circuit, the laser brightness control circuit including: The system comprises a photodiode D1, resistors R1, R2, and R3, a capacitor C1, an operational amplifier U1, and a first power supply module. The cathode of photodiode D1 is connected to the power supply, and the anode of photodiode D1 is connected to the first terminal of resistor R1, the inverting input of operational amplifier U1, and the first terminal of capacitor C1. The second terminal of resistor R1 is connected to ground. The first power supply module is connected to the non-inverting input of operational amplifier U1 via resistor R2 to provide a reference signal. The output terminal of operational amplifier U1 is connected to the second terminal of capacitor C1 and the first terminal of resistor R3, and the second terminal of resistor R3 is connected to the base of transistor Q0 in the laser emitting circuit. Photodiode D1 receives the light signal emitted by the laser emitting circuit and generates a detection signal corresponding to the light intensity of the light signal at the inverting input of operational amplifier U1, so that operational amplifier U1 controls the light emission of the laser emitting circuit based on the voltage difference between the reference signal and the detection signal.

[0006] In some embodiments, the laser brightness control circuit further includes: The second power supply module, resistor R4, and switch Q1; the second power supply module is connected to the first end of resistor R4 for outputting an enable signal; the second end of resistor R4 is connected to the base of switch Q1; the first connection end of switch Q1 is connected to resistor R0 of the laser emitting circuit, and the second connection end of switch Q1 is connected to ground; wherein the enable signal is a pulse signal with adjustable duty cycle.

[0007] In some embodiments, the laser brightness control circuit further includes: The control module is connected to the second power module and the laser receiving circuit respectively, and is used to control the second power module to adjust the duty cycle of the enable signal according to the output signal of the laser receiving circuit.

[0008] In some embodiments, the control module is also connected to the first power module and is used to control the first power module to output the reference signal; wherein the reference signal is synchronized with the enable signal and has the same duty cycle.

[0009] In some embodiments, the laser ranging sensor further includes a signal processing circuit, and the laser brightness control circuit further includes: An amplifier circuit is connected to the laser receiving circuit, the control module, and the signal processing circuit, respectively, and is used to amplify the output signal and output it to the control module and the signal processing circuit respectively. The control module is also used to adjust the amplification factor of the amplifier circuit according to the amplified output signal.

[0010] In some embodiments, the control module is further configured to: When the amplification factor of the amplifier circuit is the first factor, if the control coefficient is higher than the first coefficient threshold, the amplifier circuit is controlled to adjust the amplification factor to the second factor. When the amplification factor is the second amplification factor, if the control coefficient is lower than the second coefficient threshold, the amplification circuit is controlled to adjust the amplification factor to the first amplification factor. When the amplification factor of the amplifier circuit is the second factor, if the control coefficient is higher than the third coefficient threshold, the amplifier circuit is controlled to adjust the amplification factor to the third factor. When the amplification factor of the amplifier circuit is the third factor, if the control coefficient is lower than the fourth coefficient threshold, the amplifier circuit is controlled to adjust the amplification factor to the second factor. Wherein, the control coefficient is equal to the product between the amplification factor and the duty cycle of the enable signal; the first amplification factor, the second amplification factor, and the third amplification factor are arranged in ascending order, and the second coefficient threshold, the first coefficient threshold, the fourth coefficient threshold, and the third coefficient threshold are arranged in ascending order.

[0011] In some embodiments, the amplification circuit includes two amplification modules, each of which can achieve two amplification gains to form the first gain, the second gain, and the third gain.

[0012] In some embodiments, the primary amplification module includes resistors R5, R6, and R7, operational amplifier U2, and switch S1; the first end of resistor R5 is connected to the laser receiving circuit, and the second end of resistor R5 is connected to the first connection terminal of operational amplifier U2; the first end of resistor R6 is used to receive a bias voltage, and the second end of resistor R6 is connected to the second connection terminal of operational amplifier U2, the first end of resistor R7, and the first end of switch S1; the output terminal of operational amplifier U2 is connected to the second end of resistor R7, the second end of switch S1, and the secondary amplification module.

[0013] In some embodiments, the secondary amplification module includes resistors R8, R9, and R10, operational amplifier U3, and switch S2; the first end of resistor R8 is connected to the output terminal of operational amplifier U2, and the second end of resistor R8 is connected to the first connection terminal of operational amplifier U3; the first end of resistor R9 is used to receive the bias voltage, and the second end of resistor R9 is connected to the second connection terminal of operational amplifier U3, the first end of resistor R10, and the first end of switch S2; the output terminal of operational amplifier U3 is connected to the second end of resistor R10, the second end of switch S2, the control module, and the signal processing circuit.

[0014] A laser ranging system includes a laser ranging sensor and a laser brightness control circuit as described in any of the above embodiments. The aforementioned laser brightness control circuit and laser ranging system monitor and feedback the laser source brightness using a photodiode D1, generating a current proportional to the light intensity. This current is converted into a voltage signal through resistor R1 and then sent to the inverting input of operational amplifier U1. Operational amplifier U1 compares this voltage signal with a reference signal and controls the conduction or disconnection of transistor Q0 in the laser emitting circuit based on their magnitudes. This achieves negative feedback regulation of the light signal emission, ensuring that the laser diode can only operate stably within a certain brightness range, thus improving the ranging accuracy of the laser ranging sensor due to temperature drift. Attached Figure Description

[0015] Figure 1 This is a circuit diagram of a traditional laser emitting circuit; Figure 2 This is a circuit diagram of a laser brightness control circuit according to an embodiment of this application; Figure 3 This is a circuit diagram of a laser brightness control circuit according to another embodiment of this application; Figure 4 This is a structural diagram of a laser brightness control circuit at the laser receiver end according to an embodiment of this application; Figure 5 A circuit diagram of the signal processing section of a laser brightness control circuit according to an embodiment of this application; Figure 6 This is a schematic diagram illustrating the magnification state transition in this application. Detailed Implementation

[0016] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0018] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly. The connection can be a direct connection or an indirect connection.

[0019] Figure 2This is a circuit diagram of a laser brightness control circuit according to an embodiment of the present invention. This laser brightness control circuit is applied to a laser ranging sensor, which includes a laser emitting circuit 101 and a laser receiving circuit 102, as shown below. Figure 2 As shown, the laser brightness control circuit includes: a photodiode D1, resistors R1, R2, and R3, a capacitor C1, an operational amplifier U1, and a first power supply module V1. The cathode of photodiode D1 is connected to the power supply, and the anode of photodiode D1 is connected to the first terminal of resistor R1, the inverting terminal of operational amplifier U1, and the first terminal of capacitor C1. The second terminal of resistor R1 is connected to ground. The first power supply module V1 is connected to the non-inverting terminal of operational amplifier U1 via resistor R2 to provide a reference signal. The output terminal of operational amplifier U1 is connected to the second terminal of capacitor C1 and the first terminal of resistor R3. The second terminal of resistor R3 is connected to the base of transistor Q0 in laser emitting circuit 101. Photodiode D1 is used to receive the light signal emitted by the laser emitting circuit and generate a detection signal corresponding to the light intensity of the light signal at the inverting terminal of operational amplifier U1, so that operational amplifier U1 controls the emission of laser emitting circuit 101 according to the voltage difference between the reference signal and the detection signal.

[0020] The laser emitting circuit 101 includes a laser diode LD1, a transistor Q0, and a resistor R0. (Ref) Figure 1 and Figure 2 As shown, the laser emitting circuit 101 in this embodiment can control the luminous intensity of the laser diode LD1 by controlling the conduction of the transistor Q0. When the laser diode LD1 emits a light signal, and the photodiode D1 receives the light signal, it generates a current proportional to the light intensity of the light signal. This current flows through resistor R1 and forms a potential signal at the first end of resistor R1. The inverting input of operational amplifier U1 is connected to the first end of resistor R1 to receive the potential signal, and is simultaneously connected to the output through capacitor C1 for filtering and voltage regulation. The non-inverting input receives a reference signal through resistor R2. Operational amplifier U1 is responsible for comparing the reference signal and the potential signal, and outputs a voltage to the transistor Q0 of the laser emitting circuit 101 according to the comparison result, thereby controlling whether the transistor Q0 is turned on or off, and thus controlling whether the laser diode emits light.

[0021] The reference signal is used to characterize the laser brightness level under non-temperature drift conditions. For example, operational amplifier U1 compares the reference signal with the detection signal. When temperature drift occurs, assuming the laser diode's light signal brightness increases, the light intensity received by photodiode D1 increases, the reverse current increases, and the voltage at the inverting input increases. When the inverting input voltage is greater than the voltage at the non-inverting input, operational amplifier U1 outputs a low level, Q1 is turned off, and the laser diode stops working. Similarly, assuming the laser diode's light signal brightness decreases, the light intensity received by photodiode D1 decreases, the reverse current decreases, and the voltage at the inverting input decreases. When the inverting input voltage is less than the voltage at the non-inverting input, operational amplifier U1 outputs a high level, Q1 is turned on, and the laser diode starts working. By setting photodiode D1 to monitor and perform negative feedback adjustment, the laser diode can only operate stably when its brightness is maintained in a non-temperature drift state, improving the measurement accuracy of the laser rangefinder caused by temperature drift.

[0022] Thus, by setting up photodiode D1 to monitor and provide feedback on the brightness of the laser source, a current proportional to the light intensity is generated. This current is converted into a voltage signal through resistor R1 and then sent to the inverting input of operational amplifier U1. Operational amplifier U1 compares this voltage signal with a reference signal and controls the conduction or disconnection of transistor Q0 in laser emitting circuit 101 based on the magnitude of the two signals. This achieves negative feedback regulation of the light signal emission, ensuring that the laser diode can only operate stably when its brightness remains within a certain range, thereby improving the ranging accuracy of the laser rangefinder caused by temperature drift.

[0023] In one embodiment, such as Figure 3 As shown, the laser brightness control circuit also includes a second power supply module Ven, a resistor R4, and a switch Q1; the second power supply module Ven is connected to the first end of the resistor R4 and is used to output an enable signal; the second end of the resistor R4 is connected to the base of the switch Q1; the first connection end of the switch Q1 is connected to the resistor R0 of the laser emitting circuit 101, and the second connection end of the switch Q1 is connected to ground; wherein the enable signal is a pulse signal with an adjustable duty cycle.

[0024] The laser rangefinder can be a CMOS type, and the second power supply module Ven can be a signal generator. It outputs a pulse signal with an adjustable duty cycle, thereby adjusting the ratio of the on and off states of the switch Q1. When the enable signal is high, switch Q1 is on, and the laser diode LD1 starts working; when the enable signal is low, switch Q1 is off, and the laser diode LD1 stops working. Therefore, by adjusting the duty cycle of the enable signal, the operating time of the laser diode LD1 can be controlled, thus adjusting the brightness of the laser diode. Compared to traditional constant current source control, this is more flexible and precise, and can better adapt to the needs of different application scenarios. Switch Q1 can be a transistor.

[0025] In one embodiment, the laser brightness control circuit further includes a control module 120. Figure 5 As shown in the figure, the control module 120 is connected to the second power module Ven and the laser receiving circuit 102 respectively, and is used to control the second power module Ven to adjust the duty cycle of the enable signal according to the output signal (represented by Vcoms) of the laser receiving circuit 102.

[0026] It is understandable that the signal amplitude of the output signal Vcoms of the laser receiving circuit 102 can characterize the intensity of the received light. When the signal amplitude is too small, it indicates that there may be problems such as weak laser diode light intensity, long measurement distance, or weak reflection from the measured object. In this case, the duty cycle of the enable signal can be increased, thereby increasing the emission time of the laser diode (provided that the transistor Q0 is also in the conducting state), and improving the brightness of the laser diode. In this way, by adjusting the duty cycle of the enable signal, the brightness of the laser diode can be adjusted, ultimately improving the ranging accuracy. The method is simple and the light intensity control is more flexible.

[0027] In one embodiment, the control module 120 is also connected to the first power module V1 for controlling the first power output reference signal; wherein the reference signal is synchronized with the enable signal and has the same duty cycle.

[0028] It is understood that the reference signal can be generated by the control module 120. By setting the operating parameters of the first power module V1, a reference signal with the desired duty cycle can be obtained. The reference signal and the enable signal can coordinately control the emission of the laser diode. Setting it to be synchronized with the enable signal and having the same duty cycle avoids energy waste. Furthermore, the two power modules can share the same clock and PWM modulation, simplifying the circuit structure. The reference signal and the enable signal can be synchronized with the exposure time of the laser receiving circuit 102, thereby avoiding signal drift and improving ranging accuracy.

[0029] In one embodiment, such as Figure 4As shown, the laser ranging sensor also includes a signal processing circuit 103, and the laser brightness control circuit also includes an amplifier circuit 110. (Refer to...) Figure 4 As shown, the amplifier circuit 110 is connected to the laser receiving circuit 102, the control module 120 and the signal processing circuit 103 respectively, and is used to amplify the output signal Vcoms and output it to the control module 120 and the signal processing circuit 103 respectively; the control module 120 is also used to adjust the amplification factor of the amplifier circuit 110 according to the amplified output signal Vcoms.

[0030] Initially, the amplification factor of the amplifier circuit 110 can be set to the default value to amplify the output signal Vcoms. Then, the control module 120 adjusts the amplification factor according to whether the signal amplitude of the output signal reaches the expected range.

[0031] It is understandable that the light intensity of the laser diode can be adjusted by the above-mentioned negative feedback adjustment and enable signal duty cycle adjustment, so that it is maintained within a certain safe range. However, due to the possibility of long measurement distance or weak reflection of the measured object, the signal amplitude of the output signal Vcoms of the laser receiving circuit 102 is still very small when the enable signal duty cycle is adjusted to the maximum. To address this, the desired signal amplitude can be obtained by setting up the amplifier circuit 110 and controlling the amplification factor of the amplifier circuit 110 by the control module 120.

[0032] Thus, by adjusting the negative feedback and the duty cycle of the enable signal, and adjusting the gain of the co-amplifier circuit 110, the output signal amplitude can be adaptively adjusted while ensuring the stability of the laser diode light intensity, thereby improving the ranging accuracy of the laser rangefinder.

[0033] In one embodiment, the control module 120 is further configured to: when the amplification factor of the amplifier circuit 110 is a first factor, if the control coefficient is higher than a first coefficient threshold, then control the amplifier circuit 110 to adjust the amplification factor to a second factor; when the amplification factor is a second factor, if the control coefficient is lower than a second coefficient threshold, then control the amplifier circuit 110 to adjust the amplification factor to the first factor; when the amplification factor of the amplifier circuit 110 is a second factor, if the control coefficient is higher than a third coefficient threshold, then control the amplifier circuit 110 to adjust the amplification factor to a third factor; when the amplification factor of the amplifier circuit 110 is a third factor, if the control coefficient is lower than a fourth coefficient threshold, then control the amplifier circuit 110 to adjust the amplification factor to the second factor; wherein, the control coefficient is equal to the product between the amplification factor and the duty cycle of the enable signal; the first factor, the second factor, and the third factor are arranged in ascending order, and the second coefficient threshold, the first coefficient threshold, the fourth coefficient threshold, and the third coefficient threshold are arranged in ascending order.

[0034] It is understandable that a control coefficient can be defined to reflect the signal amplitude of the output signal, thereby quantifying the degree of light source adjustment. Based on the current amplification factor, by comparing the control coefficient with the coefficient threshold, it can be determined whether the settings of the enable signal duty cycle and amplification factor are appropriate. Both duty cycle and amplification factor can be used to adjust the signal amplitude. The duty cycle determines the light intensity of the laser diode, and the amplification factor determines the gain of the signal amplitude. If the duty cycle is too large and the amplification factor is too small, it will lead to increased power consumption and increased temperature; while if the duty cycle is too small and the amplification factor is too large, it will cause a decrease in ranging accuracy; if the amplification factor is too large...

[0035] Specifically, the amplification factor can be set to three levels, with the first, second, and third amplification factors arranged in ascending order. When the amplification factor of amplifier circuit 110 is the first level, if the control coefficient is higher than the first coefficient threshold, it indicates that the duty cycle is too large and the amplification factor is too small. In this case, control module 120 can adjust the amplification factor from the first level to the second level, thereby increasing the signal amplitude. Based on the increased signal amplitude, control module 120 can reduce the duty cycle of the enable signal, thereby reducing power consumption. Similarly, when the amplification factor of amplifier circuit 110 is the second level, if the control coefficient is higher than the third coefficient threshold, control module 120 can adjust the amplification factor from the second level to the third level.

[0036] When the amplification factor of amplifier circuit 110 is the second factor, if the control coefficient is lower than the second factor threshold, it indicates that the duty cycle is too small and the amplification factor is too large. In this case, control module 120 can adjust the second factor to the first factor, thereby reducing the signal amplitude. Based on the reduced signal amplitude, control module 120 can increase the duty cycle of the enable signal, thereby improving the ranging accuracy. Similarly, when the amplification factor of amplifier circuit 110 is the third factor, if the control coefficient is lower than the fourth factor threshold, control module 120 can adjust the amplification factor from the third factor to the second factor.

[0037] Furthermore, this embodiment employs a dual threshold method to adjust the amplification factor. Specifically, the threshold coefficient for switching from the first amplification factor to the second amplification factor is different from that for switching from the second amplification factor to the first amplification factor, and the threshold coefficient for switching from the second amplification factor to the third amplification factor is different from that for switching from the third amplification factor to the second amplification factor. This avoids the abnormal phenomenon of repeated adjustment at the threshold edge during light source adjustment and improves the overall stability of the circuit.

[0038] In some embodiments, the first magnification, the second magnification, and the third magnification can be equal to 3, 6, and 18, respectively; the first coefficient threshold, the second coefficient threshold, the third coefficient threshold, and the fourth coefficient threshold can be equal to 60, 12, 480, and 360, respectively. A diagram illustrating the state transitions of the magnification can be found here. Figure 6 As shown.

[0039] In one embodiment, the amplifier circuit 110 includes two-stage amplification modules, each capable of amplifying two gains to form a first gain, a second gain, and a third gain.

[0040] It is understandable that the two-stage amplification module can achieve two different gains, and four different gains can be achieved through different combinations of the two-stage amplification module. Therefore, two-stage amplification modules can be set up, and the first, second, and third magnifications can be obtained through the control module 120.

[0041] In some embodiments, such as Figure 5 As shown, the primary amplification module includes resistors R5, R6, and R7, operational amplifier U2, and switch S1. The first end of resistor R5 is connected to the laser receiving circuit 102, and the second end of resistor R5 is connected to the first connection terminal of operational amplifier U2. The first end of resistor R6 is used to receive the bias voltage Vref, and the second end of resistor R6 is connected to the second connection terminal of operational amplifier U2, the first end of resistor R7, and the first end of switch S1. The output terminal of operational amplifier U2 is connected to the second end of resistor R7, the second end of switch S1, and the secondary amplification module.

[0042] It is understood that the control module 120 can control whether the resistor R7 is connected by controlling the opening and closing of the switch S1, thereby controlling the size of the feedback resistor of the first-stage amplification module, so that the first-stage amplification module can obtain amplification with two gains.

[0043] In some embodiments, such as Figure 5 As shown, the secondary amplification module includes resistors R8, R9, and R10, operational amplifier U3, and switch S2. The first end of resistor R8 is connected to the output terminal of operational amplifier U2, and the second end of resistor R8 is connected to the first connection terminal of operational amplifier U3. The first end of resistor R9 is used to receive the bias voltage Vref, and the second end of resistor R9 is connected to the second connection terminal of operational amplifier U3, the first end of resistor R10, and the first end of switch S2. The output terminal of operational amplifier U3 is connected to the second end of resistor R10, the second end of switch S2, control module 120, and signal processing circuit 103.

[0044] Similarly, the control module 120 can control whether the resistor R10 is connected by controlling the opening and closing of the switch S2, thereby controlling the size of the feedback resistor of the secondary amplifier module, so that the secondary amplifier module can obtain amplification with two gains.

[0045] This invention also provides a laser brightness control circuit, including a photodiode D1, resistors R1, R2, and R3, a capacitor C1, an operational amplifier U1, a first power supply module V1, a second power supply module Ven, a resistor R4, a switch Q1, a control module 120, and an amplifier circuit 110. The amplifier circuit 110 includes two stages of amplification modules. The first stage amplification module includes resistors R5, R6, and R7, an operational amplifier U2, and a switch S1. The second stage amplification module includes resistors R8, R9, and R10, an operational amplifier U3, and a switch S2. The connection relationships and working principles between the components can be referred to in the above embodiments, and will not be repeated here.

[0046] This invention also provides a laser ranging system, including a laser ranging sensor and a laser brightness control circuit according to any of the above embodiments.

[0047] In one embodiment, the laser rangefinder can be a laser triangulation rangefinder, which enables the sensor head to automatically adjust the light intensity as the measurement distance changes, thereby achieving a stable CMOS signal amplitude and maximizing the accuracy of the ranging effect.

[0048] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0049] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural changes made based on the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A laser brightness control circuit, characterized in that, This technology is applied to laser rangefinders, which include a laser emitting circuit and a laser receiving circuit. The laser brightness control circuit includes: The system comprises a photodiode D1, resistors R1, R2, and R3, a capacitor C1, an operational amplifier U1, and a first power supply module. The cathode of photodiode D1 is connected to the power supply, and the anode of photodiode D1 is connected to the first terminal of resistor R1, the inverting input of operational amplifier U1, and the first terminal of capacitor C1. The second terminal of resistor R1 is connected to ground. The first power supply module is connected to the non-inverting input of operational amplifier U1 via resistor R2 to provide a reference signal. The output terminal of operational amplifier U1 is connected to the second terminal of capacitor C1 and the first terminal of resistor R3, and the second terminal of resistor R3 is connected to the base of transistor Q0 in the laser emitting circuit. Photodiode D1 receives the light signal emitted by the laser emitting circuit and generates a detection signal corresponding to the light intensity of the light signal at the inverting input of operational amplifier U1, so that operational amplifier U1 controls the light emission of the laser emitting circuit based on the voltage difference between the reference signal and the detection signal.

2. The laser brightness control circuit according to claim 1, characterized in that, The laser brightness control circuit also includes: The second power supply module, resistor R4, and switch Q1; the second power supply module is connected to the first end of resistor R4 for outputting an enable signal; the second end of resistor R4 is connected to the base of switch Q1; the first connection end of switch Q1 is connected to resistor R0 of the laser emitting circuit, and the second connection end of switch Q1 is connected to ground; wherein the enable signal is a pulse signal with adjustable duty cycle.

3. The laser brightness control circuit according to claim 2, characterized in that, The laser brightness control circuit also includes: The control module is connected to the second power module and the laser receiving circuit respectively, and is used to control the second power module to adjust the duty cycle of the enable signal according to the output signal of the laser receiving circuit.

4. The laser brightness control circuit according to claim 3, characterized in that, The control module is also connected to the first power module and is used to control the first power module to output the reference signal; wherein the reference signal is synchronized with the enable signal and has the same duty cycle.

5. The laser brightness control circuit according to claim 4, characterized in that, The laser ranging sensor further includes a signal processing circuit, and the laser brightness control circuit further includes: An amplifier circuit is connected to the laser receiving circuit, the control module, and the signal processing circuit, respectively, and is used to amplify the output signal and output it to the control module and the signal processing circuit respectively. The control module is also used to adjust the amplification factor of the amplifier circuit according to the amplified output signal.

6. The laser brightness control circuit according to claim 5, characterized in that, The control module is also used for: When the amplification factor of the amplifier circuit is the first factor, if the control coefficient is higher than the first coefficient threshold, the amplifier circuit is controlled to adjust the amplification factor to the second factor. When the amplification factor is the second amplification factor, if the control coefficient is lower than the second coefficient threshold, the amplification circuit is controlled to adjust the amplification factor to the first amplification factor. When the amplification factor of the amplifier circuit is the second factor, if the control coefficient is higher than the third coefficient threshold, the amplifier circuit is controlled to adjust the amplification factor to the third factor. When the amplification factor of the amplifier circuit is the third factor, if the control coefficient is lower than the fourth coefficient threshold, the amplifier circuit is controlled to adjust the amplification factor to the second factor. Wherein, the control coefficient is equal to the product between the amplification factor and the duty cycle of the enable signal; the first amplification factor, the second amplification factor, and the third amplification factor are arranged in ascending order, and the second coefficient threshold, the first coefficient threshold, the fourth coefficient threshold, and the third coefficient threshold are arranged in ascending order.

7. The laser brightness control circuit according to claim 6, characterized in that, The amplifier circuit includes two stages of amplification modules, each of which can achieve two amplification gains to form the first gain, the second gain, and the third gain.

8. The laser brightness control circuit according to claim 7, characterized in that, The primary amplification module includes resistors R5, R6, and R7, operational amplifier U2, and switch S1. The first end of resistor R5 is connected to the laser receiving circuit, and the second end of resistor R5 is connected to the first connection terminal of operational amplifier U2. The first end of resistor R6 is used to receive the bias voltage, and the second end of resistor R6 is connected to the second connection terminal of operational amplifier U2, the first end of resistor R7, and the first end of switch S1. The output terminal of operational amplifier U2 is connected to the second end of resistor R7, the second end of switch S1, and the secondary amplification module.

9. The laser brightness control circuit according to claim 8, characterized in that, The secondary amplification module includes resistors R8, R9, and R10, operational amplifier U3, and switch S2. The first end of resistor R8 is connected to the output terminal of operational amplifier U2, and the second end of resistor R8 is connected to the first connection terminal of operational amplifier U3. The first end of resistor R9 is used to receive the bias voltage, and the second end of resistor R9 is connected to the second connection terminal of operational amplifier U3, the first end of resistor R10, and the first end of switch S2. The output terminal of operational amplifier U3 is connected to the second end of resistor R10, the second end of switch S2, the control module, and the signal processing circuit.

10. A laser ranging system, characterized in that, It includes a laser rangefinder sensor and a laser brightness control circuit as described in any one of claims 1-9.

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