CN116299508A - Quick self-adaptive laser ranging system and method based on silicon photomultiplier - 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

Quick self-adaptive laser ranging system and method based on silicon photomultiplier

Technical Field

The invention belongs to the technical field of laser radar detection, and particularly relates to a rapid self-adaptive laser ranging system and method based on a silicon photomultiplier.

Background

The laser ranging technology is a technology developed based on good directivity and monochromaticity of laser, has the advantages of high precision, long transmission distance, high transmission speed and the like, and is widely applied to civil and military fields. In a laser ranging system, because the intensity of an echo signal to be received is weak, a traditional optical detector cannot detect a weak optical signal, and a detector accurate to a single photon level is required to receive the signal.

The silicon photomultiplier SiPM is a new high-performance semiconductor photoelectric detector, which is composed of an array of a plurality of pixels which are mutually connected in parallel and work in a Geiger mode, and each pixel is formed by connecting an avalanche photodiode and a quenching resistor in series. Sipms have single photon level sensitivity, excellent photon counting capability, picosecond high-speed response capability, and other characteristics. Because the SiPM is composed of thousands of avalanche photodiodes, the detection surface is larger, and can respond to more photon numbers at a time, so that the detection performance of the SiPM can be fully utilized by enlarging the incidence surface of a signal, and because the sensitivity is higher, the influence of background light needs to be controlled, meanwhile, the SiPM is easy to be influenced by temperature and has errors, and the overvoltage of the SiPM needs to be controlled in real time to ensure the accuracy when the SiPM is actually operated. The SiPM-based laser ranging system can perform real-time measurement, improve the sensitivity of the system, simplify the system and have important significance for application of a laser radar.

At present, a silicon photomultiplier is used as a detector in a laser ranging system at home and abroad, the detection surface of the silicon photomultiplier is large, the pixels are more, the detection capability of the silicon photomultiplier cannot be fully utilized in the prior art, and meanwhile, the sensitivity of the silicon photomultiplier is high and is easy to influence by background light, so that the laser ranging system for adaptively adjusting the threshold value based on the design of the silicon photomultiplier is not yet available.

Disclosure of Invention

The invention aims to solve the problems that the existing ranging system cannot fully utilize the larger detection surface of a silicon photomultiplier, is easily affected by background light, and cannot adjust the threshold voltage in real time along with the change of the background light.

The invention aims to realize the purpose, and discloses a rapid self-adaptive laser ranging system based on a silicon photomultiplier, which comprises a time sequence control circuit, a pulse laser emitter, a transmitting lens component, a receiving lens component, a diaphragm, the silicon photomultiplier, an amplifying circuit, a signal processing module, a comparator, a data processing module and a time-digital conversion module; starting a time sequence control circuit through a data processing module, driving an arterial laser emitter to generate laser by the time sequence control circuit, shaping through an emitting lens component, and irradiating the laser to a measured object; simultaneously, the time sequence control circuit gives out a starting timing signal to enable the time digital conversion module to synchronously start timing; after the laser reaches the target position, the echo optical signal is received by a receiving lens assembly, and is uniformly distributed on a receiving surface of a silicon photomultiplier through a diaphragm, and is subjected to photoelectric conversion by the silicon photomultiplier, and then is amplified by an amplifying circuit; the signal processing module is used for measuring the background light intensity in real time and outputting the background light intensity to the comparator as threshold voltage, and then the signal is shaped and screened by the comparator to obtain an effective signal and transmitted to the time-digital conversion module to finish timing at the same time; 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 data is transmitted to the data processing module to obtain the target distance position by comparing the time delay between the starting timing signal and the ending timing signal of the time digital conversion module.

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

Further, the signal processing module firstly calculates the output voltage of the silicon photomultiplier under no laser signal and superimposes the output voltage with the set rated voltage; the current voltage is reserved as a comparison voltage through an FPGA, and after the silicon photomultiplier receives the pulse signal, the current voltage is compared with the voltage at the previous moment, and the light intensity is measured in real time and used as a threshold voltage; if the pulse signal received by the silicon photomultiplier is larger than the voltage at the previous moment, the timing signal is transmitted to the time-digital conversion module.

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

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

In order to achieve the purpose of the invention, the invention also discloses a rapid self-adaptive laser ranging method based on the silicon photomultiplier, which comprises the following steps:

step 1, starting a time sequence control circuit through a data processing module, driving an arterial laser emitter to generate laser by the time sequence control circuit, shaping through an emitting lens component, and irradiating the laser to a measured object; simultaneously, the time sequence control circuit gives out a starting timing signal to enable the time digital conversion module to synchronously start timing;

step 2, after laser reaches a target position, an echo optical signal is received by a receiving lens assembly, the echo optical signal is uniformly distributed on a receiving surface of a silicon photomultiplier through a diaphragm, the silicon photomultiplier performs photoelectric conversion, the signal is amplified through an amplifying circuit, a signal processing module is used for measuring background light intensity in real time and outputting the background light intensity as threshold voltage to a comparator, and then the signal is shaped and screened through the comparator to obtain an effective signal and is transmitted to a time-digital conversion module to finish timing at the same time;

and 3, after the set detection period is completed, counting the distribution of photon events in all detection periods according to the photon signal sequences acquired in the period, and transmitting data to a data processing module to obtain the target distance position by comparing the time delay between the starting timing signal and the ending timing signal of the time digital conversion module.

Compared with the prior art, the invention has the remarkable progress that: 1) The diaphragm is designed, the diaphragm hole is positioned on the focal plane and is equal to the focal plane in area, the influence of background light can be fully reduced through the design, and echo signals are all received; 2) The distance between the photosensitive surface and the aperture of the diaphragm is calculated and determined, so that the echo light signal passes through the diaphragm and then covers the photosensitive surface of the silicon photomultiplier, and as the silicon photomultiplier is formed by connecting thousands of photodiodes in parallel, the receiving surface of the silicon photomultiplier is larger, the diaphragm can stop the background light and simultaneously enable the echo signal to completely cover the receiving surface of the silicon photomultiplier through diffusion, thereby fully utilizing the characteristics of the silicon photomultiplier; 3) The output voltage of the silicon photomultiplier is measured in real time through a designed signal processing module, the current output voltage is overlapped with the set rated voltage through an adder to be used as a comparison voltage, when the silicon photomultiplier receives a pulse signal, the output voltage of the current silicon photomultiplier is compared with the overlapped output voltage at the previous moment due to the existence of a delay device, the system can be adjusted in real time along with the change of background light in a self-adaptive manner through the design, and the distance information can be rapidly acquired due to the adoption of a comparison discrimination method; 4) The power module with the temperature compensation function is adopted, meanwhile, the temperature sensor is adopted to measure the working temperature of the silicon photomultiplier in real time, and the overvoltage of the silicon photomultiplier is kept constant by automatically adjusting the voltage.

In order to more clearly describe the functional characteristics and structural parameters of the present invention, the following description is made with reference to the accompanying drawings and detailed description.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:

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

FIG. 2 is a schematic diagram of a silicon photomultiplier receiving a wave signal;

FIG. 3 is a schematic diagram of a signal processing module;

FIG. 4 is a flow chart of a fast adaptive laser ranging method based on a silicon photomultiplier;

the reference numerals in the drawings are: the pulse laser device comprises a time sequence control circuit 1, a pulse laser emitter 2, a transmitting lens assembly 3, a receiving lens assembly 4, a diaphragm 5, a silicon photomultiplier 6, an amplifying circuit 7, a signal processing module 8, a comparator 9, a power supply module 10, a temperature sensor 11, a data processing module 12 and a time-digital conversion module 13.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention; all other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

As shown in fig. 1, the rapid self-adaptive laser ranging system based on the silicon photomultiplier comprises a time sequence control circuit 1, a pulse laser emitter 2, a transmitting lens component 3, a receiving lens component 4, a diaphragm 5, a silicon photomultiplier 6, an amplifying circuit 7, a signal processing module 8, a comparator 9, a power supply module 10, a temperature sensor 11, a data processing module 12 and a time-digital conversion module 13. The data processing module 12 is connected with the time sequence control circuit 1 and is used for storing data and transmitting pulse signals to control the operation of the whole system; the time sequence control circuit 1 controls the pulse laser emitter 2 to emit a pulse laser signal and sends a start timing signal to the time digital conversion module; the emission lens component 3 greatly compresses the divergence angle and collimates the laser signal to be emitted to a target object; the receiving lens assembly 4 is used for focusing the echo signals which are diffusely reflected after reaching the target position on the receiving surface of the silicon photomultiplier 6 again; the diaphragm 5 is used for blocking part of background light and diffusing optical signals to the surface of the silicon photomultiplier 6; the silicon photomultiplier 6 is used for receiving the laser echo signals and converting the laser echo signals into current signals for subsequent processing; the amplifying circuit 7 is used for converting the weak current signal transmitted by the silicon photomultiplier 6 into a larger voltage signal; the comparator 9 is used for converting the amplified analog signal into a digital signal by setting different equivalent threshold voltages and sending a stop timing signal to the time-digital conversion module 13; the signal processing module 8 is used for changing 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 6 and transmits the real-time temperature to the power module 10, so that the power module 10 adjusts the voltage according to the temperature to enable the silicon photomultiplier 6 to be in a stable working state; the time digital conversion module 13 obtains delay time by calculating a start timing signal and a stop time signal; the data processing module 12 communicates with the time-digital conversion module 13 through the SPI to process the data to obtain the actual transmission distance, and displays the distance through the relevant interface.

Specifically, in the present embodiment, the power module 10 is a power module with a temperature compensation function, and specifically operates by detecting the ambient temperature of the silicon photomultiplier 6 by the temperature sensor 11, and comparing the ambient temperature with the reference source of the silicon photomultiplier 6, which is a reference voltage of 25V when the ambient temperature is 25 ℃. When the ambient temperature increases, the required breakdown voltage increases, and when the operating voltage is constant, the overvoltage decreases, which results in a decrease in detection efficiency, and the silicon photomultiplier 6 maintains a constant overvoltage using the power module 10 having a temperature compensation function.

Specifically, in the present embodiment, the specific model of the pulse laser emitter 3 is RLD650005, the specific model of the silicon photomultiplier 6 is JSP-TP3050-SMT, the specific model of the amplifying circuit 7 is OPA657, 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 the present embodiment, each pixel of the silicon photomultiplier 6 is constituted by a plurality of pixels operating in a geiger mode connected in parallel with each other, each pixel being constituted by an avalanche diode and a quenching resistor connected in series with each other.

As shown in fig. 2, the echo signal is received by the receiving lens assembly 4, the optical signal is gradually converged to a focal plane, the aperture of the optical signal is matched with the focal plane through the diaphragm 5 designed by the system, and the background light noise is filtered as far as possible, and the diaphragm 5 designed by the system extends the distance between the focal plane and the silicon photomultiplier 6 due to the larger receiving surface of the silicon photomultiplier 6, so that the echo optical signal is diffused and fully incident on the photosensitive surface of the silicon photomultiplier 6SiPM, and the detection performance of the SiPM is fully exerted, wherein the diameter of the focal plane is as follows:

wherein u is the detection distance, R _T For the aperture, f is the focal length of the system, the diameter R of the focal plane can be calculated by the formula, and the thickness of the diaphragm can be calculated by the size of the detection surface of the silicon photomultiplier.

As shown in fig. 3, the output voltage of the silicon photomultiplier under no laser signal is calculated, and is superimposed with the set rated voltage, the current voltage is reserved as a comparison voltage by the FPGA set delay device, and when the silicon photomultiplier receives the pulse signal, the comparison voltage is compared with the voltage at the previous moment, and the module can measure the light intensity in real time and serve as a threshold voltage, so as to realize the function of self-adapting the light intensity of the system.

As shown in fig. 4, a rapid self-adaptive laser ranging method based on a silicon photomultiplier comprises the following steps:

step 1, starting a time sequence control circuit through a data processing module, wherein the time sequence control circuit drives an arterial laser emitter to generate laser for emitting to a target surface; simultaneously, the digital conversion module synchronously starts timing;

and 2, after the laser reaches the target position, the receiving lens component receives the echo light signal and transmits the echo light signal to the silicon photomultiplier through the diaphragm, the silicon photomultiplier receives and processes the echo light signal into a voltage signal, the voltage signal is compared with the output voltage of the background light noise obtained by the signal processing module, and the voltage signal is transmitted to the time-value conversion module after an effective signal is obtained.

And step 3, counting the distribution of photon events in all detection periods after the set detection period is completed, obtaining data through a time-to-digital conversion module and transmitting the data to a data processing module to obtain the target distance position.

It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (6)

1. The rapid self-adaptive laser ranging system based on the silicon photomultiplier is characterized by comprising a time sequence control circuit, a pulse laser emitter, a transmitting lens component, a receiving lens component, a diaphragm, the silicon photomultiplier, an amplifying circuit, a signal processing module, a comparator, a data processing module and a time-digital conversion module; starting a time sequence control circuit through a data processing module, driving an arterial laser emitter to generate laser by the time sequence control circuit, shaping through an emitting lens component, and irradiating the laser to a measured object; simultaneously, the time sequence control circuit gives out a starting timing signal to enable the time digital conversion module to synchronously start timing; after the laser reaches the target position, the echo optical signal is received by a receiving lens assembly, and is uniformly distributed on a receiving surface of a silicon photomultiplier through a diaphragm, and is subjected to photoelectric conversion by the silicon photomultiplier, and then is amplified by an amplifying circuit; the signal processing module is used for measuring the background light intensity in real time and outputting the background light intensity to the comparator as threshold voltage, and then the signal is shaped and screened by the comparator to obtain an effective signal and transmitted to the time-digital conversion module to finish timing at the same time; 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 data is transmitted to the data processing module to obtain the target distance position by comparing the time delay between the starting timing signal and the ending timing signal of the time digital conversion module.

2. The rapid adaptive laser ranging system based on a silicon photomultiplier according to claim 1, wherein the operating temperature of the silicon photomultiplier is monitored in real time by a temperature sensor and information is transmitted to a power module with a temperature compensation function; the power supply module automatically adjusts output voltage according to the temperature sensor, so that the silicon photomultiplier is in a stable working state.

3. The rapid self-adaptive laser ranging system based on a silicon photomultiplier according to claim 1, wherein the signal processing module firstly calculates the output voltage of the silicon photomultiplier under no laser signal and superimposes the output voltage with a set rated voltage; the current voltage is reserved as a comparison voltage through an FPGA, and after the silicon photomultiplier receives the pulse signal, the current voltage is compared with the voltage at the previous moment, and the light intensity is measured in real time and used as a threshold voltage; if the pulse signal received by the silicon photomultiplier is larger than the voltage at the previous moment, the timing signal is transmitted to the time-digital conversion module.

4. A rapid adaptive laser ranging system based on silicon photomultiplier according to claim 1, wherein each pixel of the silicon photomultiplier is comprised of a silicon avalanche photodiode APD series quenching resistor operating in geiger mode; a plurality of such pixels are connected in parallel to form a two-dimensional array structure, and share one power supply terminal and one output terminal.

5. The rapid self-adaptive laser ranging system based on a silicon photomultiplier according to claim 1, wherein the time-to-digital conversion module transmits the data to the data processing module through an SPI communication protocol to obtain an actual transmission distance.

6. A rapid adaptive laser ranging method based on a silicon photomultiplier, the method being based on the rapid adaptive laser ranging system based on a silicon photomultiplier according to any one of claims 1-5, comprising the steps of:

step 1, starting a time sequence control circuit through a data processing module, driving an arterial laser emitter to generate laser by the time sequence control circuit, shaping through an emitting lens component, and irradiating the laser to a measured object; simultaneously, the time sequence control circuit gives out a starting timing signal to enable the time digital conversion module to synchronously start timing;

step 2, after laser reaches a target position, an echo optical signal is received by a receiving lens assembly, the echo optical signal is uniformly distributed on a receiving surface of a silicon photomultiplier through a diaphragm, the silicon photomultiplier performs photoelectric conversion, the signal is amplified through an amplifying circuit, a signal processing module is used for measuring background light intensity in real time and outputting the background light intensity as threshold voltage to a comparator, and then the signal is shaped and screened through the comparator to obtain an effective signal and is transmitted to a time-digital conversion module to finish timing at the same time;

and 3, after the set detection period is completed, counting the distribution of photon events in all detection periods according to the photon signal sequences acquired in the period, and transmitting data to a data processing module to obtain the target distance position by comparing the time delay between the starting timing signal and the ending timing signal of the time digital conversion module.

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