CN116299508A - Fast adaptive laser ranging system and method based on silicon photomultiplier tube - Google Patents

Abstract

The invention discloses a rapid self-adaptive laser ranging system and a rapid self-adaptive laser ranging method based on a silicon photomultiplier.A data processing module starts a time sequence control circuit to drive an arterial laser emitter to generate laser, the laser is shaped by a transmitting lens component and irradiates on a measured object, and a time-digital conversion module synchronously starts timing; the back wave optical signal is received by the receiving lens component and uniformly distributed on the receiving surface of the silicon photomultiplier through the diaphragm to carry out photoelectric conversion, and then the signal is amplified by the amplifying circuit; the signal processing module measures the background light intensity in real time as threshold voltage and outputs the threshold voltage to the comparator, and the comparator shapes and discriminates the background light intensity to obtain an effective signal, and the effective signal is transmitted to the time digital conversion module and the timing is finished at the same time; and obtaining the target distance position by comparing the time delay between the starting timing signal and the ending timing signal. The invention can fully reduce the influence of background light, rapidly collect distance information and keep the overvoltage of the silicon photomultiplier constant by automatically adjusting the voltage.

Description

Fast adaptive laser ranging system and method based on silicon photomultiplier tube

technical field

The invention belongs to the technical field of laser radar detection, in particular to a fast self-adaptive laser ranging system and method based on a silicon photomultiplier tube.

Background technique

Laser ranging technology is a technology developed based on the good directionality and monochromaticity of lasers. It has the advantages of high precision, long transmission distance, and fast transmission speed. It has been widely used in civilian and military fields. . In the laser ranging system, due to the weak strength of the echo signal that needs to be received, the traditional optical detector cannot detect the weak light signal, and it is necessary to use a detector that is accurate to the single photon level to receive the signal.

Silicon photomultiplier tube SiPM is a new type of high-performance semiconductor photodetector. It is composed of a parallel array of multiple pixels working in Geiger mode. Each pixel is composed of an avalanche photodiode and a quenching resistor in series. . SiPM has the characteristics of single-photon level sensitivity, excellent photon counting capability, and picosecond-level high-speed response capability. Since SiPM is composed of thousands of avalanche photodiodes, its detection area is relatively large, and it can respond to a large number of photons at a time. Therefore, it is necessary to expand the incident surface of the signal to fully utilize the detection performance of SiPM, and because of its high sensitivity, it is necessary to Control the influence of the background light, and at the same time, SiPM is susceptible to errors due to the influence of temperature. It is necessary to control its overvoltage in real time to ensure accuracy during actual operation. The SiPM-based laser ranging system can perform real-time measurement while improving the sensitivity of the system and simplifying the system, which is of great significance for the application of laser radar.

At present, silicon photomultiplier tubes have been used as detectors in laser ranging systems at home and abroad. Due to the large detection area and many pixels of silicon photomultiplier tubes, the existing technology has not fully utilized the detection capabilities of silicon photomultiplier tubes. , At the same time, due to the high sensitivity of silicon photomultiplier tubes, they are easily affected by background light. At present, no laser ranging system based on silicon photomultiplier tubes has been designed to adaptively adjust the threshold.

Contents of the invention

The purpose of the present invention is to solve the problem that the existing ranging system cannot fully utilize the large detection surface of the silicon photomultiplier tube, is easily affected by the background light, and cannot adjust the threshold voltage in real time with the change of the background light.

In order to realize the object of the present invention, the present invention is based on a silicon photomultiplier tube fast self-adaptive laser ranging system, including a timing control circuit, a pulsed laser transmitter, a transmitting lens assembly, a receiving lens assembly, an aperture, a silicon photomultiplier tube, Amplifying circuit, signal processing module, comparator, data processing module, and time-to-digital conversion module; the timing control circuit is started by the data processing module, and the timing control circuit drives the pulse laser transmitter to generate laser light, which is shaped by the emitting lens assembly and irradiates to the measured At the same time, the timing control circuit gives the start timing signal to make the time-to-digital conversion module start timing synchronously; after the laser reaches the target position, the echo optical signal is received by the receiving lens assembly, and the echo optical signal is evenly distributed on the silicon through the diaphragm. On the receiving surface of the photomultiplier tube, the photoelectric conversion is performed by the silicon photomultiplier tube, and then the signal is amplified by the amplifier circuit; the signal processing module is used to measure the background light intensity in real time and output it to the comparator as a threshold voltage, and then the signal is shaped by the comparator and screening, obtain effective signals and transmit them to the time-to-digital conversion module and end timing at the same time; when the set detection cycle is completed, according to the photon signal sequence collected in the cycle, the distribution of photon events in all detection cycles is counted, and by comparing the time The time delay between the start timing signal and the end timing signal of the digital conversion module transmits the data to the data processing module to obtain the target distance position.

Further, the temperature sensor is used to monitor the working temperature of the silicon photomultiplier tube in real time and transmit the information to the power module with temperature compensation function; the power module automatically adjusts the output voltage according to the temperature sensor, so that the silicon photomultiplier tube is in a stable working state.

Further, the signal processing module first calculates the output voltage of the silicon photomultiplier tube without a laser signal, and superimposes it with the set rated voltage; then sets the delayer through the FPGA to retain the current voltage as a comparison voltage, when the silicon photomultiplier tube receives After the pulse signal is received, it will be compared with the voltage at the previous moment, and the light intensity will be measured in real time as the threshold voltage; if the pulse signal received by the silicon photomultiplier tube is greater than the voltage at the previous moment, the end timing signal will be transmitted to the time-to-digital conversion module.

Furthermore, each pixel of the silicon photomultiplier tube is composed of a silicon avalanche photodiode APD working in the Geiger mode in series with a quenching resistor; several such pixels are connected in parallel to form a two-dimensional array structure and share a power terminal and an output terminal.

Further, the time-to-digital conversion module transmits to the data processing module through the SPI communication protocol to obtain the actual transmission distance.

In order to realize the purpose of the present invention, the present invention also discloses a method for fast self-adaptive laser ranging based on silicon photomultiplier tubes, comprising the following steps:

Step 1. Start the timing control circuit through the data processing module, and the timing control circuit drives the pulsed laser transmitter to generate laser light, which is shaped by the emitting lens assembly and irradiated onto the measured object; at the same time, the timing control circuit gives a start timing signal to make the time digital The conversion module starts timing synchronously;

Step 2. After the laser reaches the target position, the echo optical signal is received by the receiving lens assembly, and the echo optical signal is evenly distributed on the receiving surface of the silicon photomultiplier tube through the diaphragm, and the photoelectric conversion is performed by the silicon photomultiplier tube. The amplifying circuit amplifies the signal, uses the signal processing module to measure the background light intensity in real time and outputs it to the comparator as a threshold voltage, and then the signal is shaped and screened by the comparator to obtain an effective signal and transmit it to the time-to-digital conversion module to end the timing;

Step 3. After the set detection period is completed, according to the photon signal sequence collected in the period, the distribution of photon events in all detection periods is counted, and the time between the start timing signal and the end timing signal of the time-to-digital conversion module is compared Delay, transmit the data to the data processing module to obtain the target distance position.

Compared with the prior art, the remarkable progress of the present invention lies in: 1) design the diaphragm, its diaphragm hole is located on the focal plane and equal to the area of the focal plane, the influence of the background light can be fully reduced through this design, and the echo signal Then all are received; 2) Determine the distance between the photosensitive surface and the aperture hole by calculation, so that the echo light signal passes through the aperture and covers the photosensitive surface of the silicon photomultiplier tube. Since the silicon photomultiplier tube is formed by parallel connection of thousands of photodiodes , and its receiving surface is relatively large. Through this design, the aperture can block the background light and at the same time allow the echo signal to completely cover the receiving surface of the silicon photomultiplier tube through diffusion, making full use of the characteristics of the silicon photomultiplier tube; 3) through Design a signal processing module to measure the output voltage of the silicon photomultiplier tube in real time, and use the adder to superimpose the current output voltage and the set rated voltage as a comparison voltage. When the silicon photomultiplier tube receives a pulse signal, due to the existence of the delayer The output voltage of the current silicon photomultiplier tube will be compared with the superimposed output voltage at the previous moment. Through this design, the system can be adjusted in real time with the change of background light, and because of the comparison and discrimination method, it can Quickly collect distance information; 4) Use a power module with temperature compensation function, and use a temperature sensor to measure the working temperature of the silicon photomultiplier tube in real time, and keep the overvoltage of the silicon photomultiplier tube constant by automatically adjusting the voltage.

In order to more clearly illustrate the functional characteristics and structural parameters of the present invention, further description will be given below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention and constitute a part of the application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 is a schematic structural diagram of a fast adaptive laser ranging system based on a silicon photomultiplier tube;

Fig. 2 is the schematic diagram that silicon photomultiplier tube receives the echo signal;

Fig. 3 is a schematic structural diagram of a signal processing module;

Fig. 4 is the schematic flow chart of the fast self-adaptive laser ranging method based on silicon photomultiplier tube;

The reference numerals in the figure are: including timing control circuit 1, pulse laser transmitter 2, transmitting lens assembly 3, receiving lens assembly 4, aperture 5, silicon photomultiplier tube 6, amplification circuit 7, signal processing module 8, comparator 9. A power supply module 10 , a temperature sensor 11 , a data processing module 12 , and a time-to-digital conversion module 13 .

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them; based on The embodiments of the present invention and all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

As shown in Figure 1, a fast adaptive laser ranging system based on silicon photomultiplier tubes includes a timing control circuit 1, a pulsed laser transmitter 2, a transmitting lens assembly 3, a receiving lens assembly 4, an aperture 5, a silicon photoelectric Multiplier tube 6 , amplifier circuit 7 , signal processing module 8 , comparator 9 , power supply module 10 , temperature sensor 11 , data processing module 12 , and time-to-digital conversion module 13 . The data processing module 12 is connected with the timing control circuit 1 for storing data and emitting pulse signals to control the operation of the entire system; the timing control circuit 1 controls the pulse laser transmitter 2 to emit pulse laser signals, and sends the start timing signal to time digital conversion module; the transmitting lens assembly 3 greatly compresses the divergence angle, and collimates the laser signal so that it is emitted to the target object; the receiving lens assembly 4 is used to refocus the diffusely reflected echo signal after reaching the target position on the silicon The receiving surface of the photomultiplier tube 6; the diaphragm 5 is used to block part of the background light, and at the same time diffuse the optical signal to the surface of the silicon photomultiplier tube 6; the silicon photomultiplier tube 6 is used to receive the laser echo signal and convert it into a current signal For subsequent processing; the amplifier circuit 7 is used to convert the weak current signal transmitted by the silicon photomultiplier tube 6 into a larger voltage signal; the comparator 9 is used to convert the amplified analog signal into a digital signal by setting different equivalent threshold voltages signal and send the stop timing signal to the time digital conversion module 13; the signal processing module 8 is used to change the threshold voltage in real time according to the background light intensity; the temperature sensor 11 obtains the real-time temperature of the silicon photomultiplier tube 6 and transmits it to the power module 10, so that the power module 10 adjust the voltage according to the temperature to make the silicon photomultiplier tube 6 be in a stable working state; the time-to-digital conversion module 13 obtains the delay time by calculating the start timing signal and the stop time signal; the data processing module 12 communicates with the time-to-digital conversion module 13 for post-processing by SPI The actual transmission distance is obtained from the data, and the distance is displayed through the relevant interface.

Specifically, in this embodiment, the power supply module 10 is a power supply module with a temperature compensation function, and its specific working process is that the temperature sensor 11 detects the ambient temperature of the silicon photomultiplier tube 6 and communicates with the silicon photomultiplier tube 6 reference source for comparison. The specific reference source is when the ambient temperature is 25°C and the reference voltage is 25V. When the ambient temperature rises, the required breakdown voltage also increases, and when the operating voltage is constant, the overvoltage decreases, which will lead to a decrease in detection efficiency. Using the power module 10 with temperature compensation function makes the silicon photoelectric The multiplier tube 6 maintains a constant overvoltage.

Specifically, in this embodiment, the specific model of the pulse laser transmitter 3 is RLD650005, the specific model of the silicon photomultiplier tube 6 is JSP-TP3050-SMT, the specific model of the amplifier circuit 7 is OPA657, and the specific model of the power supply module 10 is LM2733, the specific model of the comparator 9 is MAX999, the specific model of the data processing module 12 is STM32F103CBT6, and the specific model of the time-to-digital conversion module 13 is TDC-GP22.

Specifically, in this embodiment, each pixel of the silicon photomultiplier tube 6 is composed of a plurality of pixels working in Geiger mode connected in parallel, and each pixel is composed of an avalanche diode and a quenching resistor connected in series.

As shown in Figure 2, the echo signal is received by the receiving lens assembly 4, and the optical signal gradually converges to a focal plane. The aperture 5 is designed to match the aperture of the focal plane through this system, and the background light noise is filtered out as much as possible. , because the receiving surface of the silicon photomultiplier tube 6 is relatively large, the aperture 5 designed in this system prolongs the distance between the focal plane and the silicon photomultiplier tube 6, so that the diffused echo light signal is all incident on the photosensitive surface of the silicon photomultiplier tube 6SiPM, fully Take advantage of the detection performance of SiPM, where the diameter of the focal plane is:

In the formula, u is the detection distance, R _T is the aperture of the light, and f is the focal length of the system. Through this formula, the diameter R of the focal plane can be calculated, and then the thickness of the aperture can be calculated by the size of the detection surface of the silicon photomultiplier tube. .

As shown in Figure 3, it is a signal processing module. First, calculate the output voltage of the silicon photomultiplier tube without a laser signal, and superimpose it with the set rated voltage. The delayer is set by the FPGA to retain the current voltage as a comparison voltage. When the silicon photomultiplier tube After the photomultiplier tube receives the pulse signal, it will compare it with the voltage at the previous moment. Through this module, the light intensity can be measured in real time and used as the threshold voltage to realize the self-adaptive light intensity function of the system.

As shown in Figure 4, a fast adaptive laser ranging method based on silicon photomultiplier tubes includes the following steps:

Step 1. Start the timing control circuit through the data processing module, and the timing control circuit drives the pulsed laser transmitter to generate laser light and emit it to the target surface; at the same time, the digital conversion module starts timing synchronously;

Step 2. After the laser light arrives at the target position, the receiving lens assembly receives the echo light signal and transmits it to the silicon photomultiplier tube through the diaphragm, and the silicon photomultiplier tube receives and processes it into a voltage signal and performs the process with the output voltage of the background light noise obtained by the signal processing module. After comparison, when a valid signal is obtained, it is transmitted to the time value conversion module.

Step 3. After the set detection period is completed, the distribution of photon events in all detection periods is counted, and the data is obtained through the time-to-digital conversion module and transmitted to the data processing module to obtain the target distance position.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. There is no such actual relationship or order between them. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (6)

1. A fast self-adaptive laser ranging system based on a silicon photomultiplier tube, characterized in that it includes a timing control circuit, a pulsed laser transmitter, a transmitting lens assembly, a receiving lens assembly, an aperture, a silicon photomultiplier tube, and an amplifier circuit , a signal processing module, a comparator, a data processing module, and a time-to-digital conversion module; the timing control circuit is started by the data processing module, and the timing control circuit drives the pulse laser transmitter to generate laser light, which is shaped by the emitting lens assembly and irradiated onto the measured object At the same time, the timing control circuit gives the start timing signal to make the time digital conversion module start timing synchronously; after the laser reaches the target position, the echo optical signal is received by the receiving lens assembly, and the echo optical signal is evenly distributed in the silicon photomultiplier through the aperture On the receiving surface of the tube, a silicon photomultiplier tube is used for photoelectric conversion, and then the signal is amplified by the amplifier circuit; the signal processing module is used to measure the background light intensity in real time and output it to the comparator as a threshold voltage, and then the signal is shaped and screened by the comparator , to obtain an effective signal and transmit it to the time-to-digital conversion module and end the timing at the same time; when the set detection period is completed, according to the photon signal sequence collected in the period, the distribution of photon events in all detection periods is counted, and the time-to-digital conversion is performed by comparing The time delay between the start timing signal and the end timing signal of the module transmits the data to the data processing module to obtain the target distance position. 2. A kind of fast self-adaptive laser ranging system based on silicon photomultiplier tube according to claim 1, is characterized in that, real-time monitoring silicon photomultiplier tube operating temperature and transmission information to the power supply with temperature compensation function by temperature sensor module; the power module automatically adjusts the output voltage according to the temperature sensor, so that the silicon photomultiplier tube is in a stable working state. 3. a kind of fast self-adaptive laser ranging system based on silicon photomultiplier tube according to claim 1, is characterized in that, described signal processing module at first calculates the output voltage of silicon photomultiplier tube under no laser signal, and with The set rated voltage is superimposed; then the delayer is set through the FPGA to retain the current voltage as a comparison voltage. When the silicon photomultiplier tube receives the pulse signal, it will be compared with the voltage at the previous moment, and the light intensity will be measured in real time and used as a threshold Voltage; if the pulse signal received by the silicon photomultiplier tube is greater than the voltage at the previous moment, the transmission end timing signal is sent to the time-to-digital conversion module. 4. A kind of fast self-adaptive laser ranging system based on silicon photomultiplier tube according to claim 1, is characterized in that, each pixel of described silicon photomultiplier tube is made of silicon avalanche photodiode working in Geiger mode The APD is composed of quenching resistors in series; several such pixels are connected in parallel to form a two-dimensional array structure, and share a power supply terminal and an output terminal. 5. A fast adaptive laser ranging system based on silicon photomultiplier tubes according to claim 1, wherein the time-to-digital conversion module is transmitted to the data processing module through the SPI communication protocol to obtain the actual transmission distance. 6. A fast adaptive laser ranging method based on silicon photomultiplier tube, said method is based on a kind of fast adaptive laser ranging system based on silicon photomultiplier tube described in any one of claims 1-5, its It is characterized in that it comprises the following steps: Step 1. Start the timing control circuit through the data processing module, and the timing control circuit drives the pulsed laser transmitter to generate laser light, which is shaped by the emitting lens assembly and irradiated onto the measured object; at the same time, the timing control circuit gives a start timing signal to make the time digital The conversion module starts timing synchronously; Step 2. After the laser reaches the target position, the echo optical signal is received by the receiving lens assembly, and the echo optical signal is evenly distributed on the receiving surface of the silicon photomultiplier tube through the diaphragm, and the photoelectric conversion is performed by the silicon photomultiplier tube. The amplifying circuit amplifies the signal, uses the signal processing module to measure the background light intensity in real time and outputs it to the comparator as a threshold voltage, and then the signal is shaped and screened by the comparator to obtain an effective signal and transmit it to the time-to-digital conversion module to end the timing; Step 3. After the set detection period is completed, according to the photon signal sequence collected in the period, the distribution of photon events in all detection periods is counted, and the time between the start timing signal and the end timing signal of the time-to-digital conversion module is compared Delay, transmit the data to the data processing module to obtain the target distance position.

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