High dynamic-accuracy laser phase range finder

Abstract

A high dynamic accuracy laser phase range finder comprising an optical module and a signal processing module, the optical module comprising a light emitting device and a light receiving device arrange

Description

[0001] The present disclosure relates to the technical field of laser ranging, and in particular, to a high-dynamic-accuracy laser phase range finder. BACKGROUND

[0002] Laser ranging is a common measurement technology that is widely used in many fields, such as architecture, engineering, manufacturing, geographical surveying and robotics. Common laser ranging types include a time-of-flight method, a phase method, and a trigonometry method. The time-of-flight method calculates the round-trip time of laser and calculates the distance on the basis of the constant speed of light. This solution is suitable for longer distance measurements, such as satellite topographic survey and earth-moon distance measurement The phase method calculates the phase difference of round-trip modulated laser, and indirectly calculates the displacement. By changing the frequency of the modulated laser, the range and accuracy may be transformed. The phase method is suitable for medium and short-range measurements. The phase method can not only be used for accurate measurements in scientific experiments, but also for long-distance exploration such as a lidar and a remote sensing device. Trigonometric ranging is based on the similar triangle principle of a paraxial optical path. The position of returned light is detected through a high-resolution CCD, and then the displacement is calculated on the basis of the similar triangle principle. This solution is suitable for measurement of extremely small ranges. When the detection distance becomes longer, the accuracy drops seriously, so this solution is often used in surface measurement, sweeping robots, etc.

[0003] The hardware design of the existing phase laser range finder includes circuit structure design and optical path structure design. For example, Cheng Naipeng discloses the research and design of a high-accuracy laser range finder based on a phase method, and the published patent CN102419166A discloses a high-accuracy multi-frequency synchronous phase laser range finder device and method. Specifically, in an optical path module of a phase laser range finder, the laser device is a light source, which shapes laser spots through a collimating lens, then the laser is reflected after being in contact with a measured surface, the light returns to a receiving lens, the returned laser is collected as far as possible and gathered to a photoelectric sensor, and finally, a photoelectric sensor converts an optical signal into an electrical signal. In a circuit module, the laser device is modulated first, followed by a clock generation part. For a modulation frequency signal of the laser device, during the measurement of a larger range, a low-frequency modulation frequency signal may be generated by a single-chip microcontroller. If short-distance measurement is required, a high-frequency modulation frequency signal is required, and a special clock generation chip is required. For a photoelectric conversion module, the employed photoelectric sensor is an avalanche photodiode (APD). A high-voltage reverse bias circuit and a signal processing circuit need to operate together to drive the APD and convert the optical signal into an electrical signal that may be collected. It is very difficult to directly sample higher frequency signals, so existing solutions have chosen to use mixing methods for processing, and are implemented through integrated mixing chips. The signal sampling and phase calculation are completed using the single-chip microcontroller. The mixed initial signal and return signal are collected using the ADC (Analog to Digital Signal Conversion) function of the single-chip microcontroller, the phase values of two signals are measured through a phase calculation program inside a chip, and then the difference is converted into a distance value for output. The above solutions have the following problems: the result output rate is low during short-distance measurement; the distance value may be calculated only one to three times per second; the measurement of a still object is not affected; if the object is in a state of high-speed motion, the lower measurement and solution frequency will lead to very large errors, and timely detection cannot be implemented; and to improve the progress of phase solution, it is necessary to increase the number of sampling bits and the number of signal operation bits, and when signals that are too large and long are calculated, the CPU operation will slow down, resulting in a slower final output. In addition, in terms of processing accuracy, the accuracy of the existing phase laser range finders is ±1 mm. If it is desired to continue to improve the accuracy, the hardware pressure of high-frequency signal processing and the accuracy of phase resolution inevitably occur. SUMMARY

[0004] An objective of the present invention is to provide a high-dynamic-accuracy laser phase range finder, which not only solves the problem of slow output of the existing range finders under high-accuracy conditions, but also further improves the accuracy without reducing the output speed.

[0005] For this purpose, the technical solutions of the present disclosure are as follows:

[0006] A high-dynamic-accuracy laser phase range finder, including an optical module and a signal processing module provided in a range finder housing, where

[0007] a light source module includes a light source emitting device and a light source receiving device arranged in parallel; the light source emitting device includes a laser diode and a collimating lens group respectively fixed at a front end and a rear end of a first closed lens barrel; the collimating lens group includes two parallel collimating lenses arranged at an interval; the laser diode is provided with a laser emitting end facing a center of the collimating lens group; the light source receiving device includes a converging lens and an avalanche photodiode (APD) respectively fixed at a front end and a rear end of a second closed lens barrel; the APD is provided with a light source receiving end facing a center of the converging lens;

[0008] the signal processing module includes a single-chip microcomputer, a signal generation module, a laser emitting module, a high-voltage bias module, a transimpedance amplifier and low-pass filter module, and a switch triode mixing-LR low-pass filtering module, where

[0009] the single-chip microcomputer includes a CPU kernel, a DAC output module, a serial port output module, an IIC communication module, a GPIO instruction module, a DMA signal storage module, a first ADC signal sampling module, and a second ADC signal sampling module; a first output terminal of the CPU kernel is connected to an input terminal of the IIC communication module, a second output terminal of the CPU kernel is connected to an input terminal of the GPIO instruction module, a third output terminal of the CPU kernel is connected to an input terminal of the DAC output module, and a fourth output terminal of the CPU kernel is connected to an input terminal of the serial port output module; an output terminal of the DMA signal storage module is connected to an input terminal of the CPU kernel; an output terminal of the first ADC signal sampling module and an output terminal of the second ADC signal sampling module are respectively connected to two input terminals of the DMA signal storage module to respectively input sampling signals of the two ADC signal sampling modules into two independent blocks of the DMA signal storage module for storage and to respectively transmit the sampling signals into the CPU kernel according to a time sequence;

[0010] an input terminal of the signal generation module is connected to an output terminal of the IIC communication module to activate the signal generation module through the DC communication module and to specify the signal generation module to generate an eigen frequency signal and a modulation frequency signal having different frequencies;

[0011] the laser emitting module is separately connected to the laser diode, the GPIO instruction module, and the signal generation module to activate the laser emitting module through the GPIO instruction module, and the laser emitting module with the eigen frequency signal inputs send by the signal generation module and a pulse width modulation (PWM) frequency signal controlled by the GPIO instruction module, and outputs to the laser diode is an electrical signal allowing light intensity to change periodically;

[0012] the high-voltage bias module is separately connected to the APD and the GPIO instruction module to activate the high-voltage bias module through the GPIO instruction module and to provide a reverse bias voltage to the APD;

[0013] the APD is further connected to a modulation frequency signal output terminal of the signal generation module to receive the modulation frequency signal and detect a returned optical signal and to output a high and low frequency mixed signal subjected to difference frequency processing; the switch triode mixing-LR low-pass filtering module is separately connected to the signal generation module and the second ADC signal sampling module to receive the eigen frequency signal and the modulation frequency signal for frequency mixing processing, to remove a high-frequency component in a mixed signal, and to output a low-frequency component to the second ADC signal sampling module; and

[0014] the transimpedance amplifier and low-pass filter module is separately connected to the APD and the first ADC signal sampling module to convert a current mixing component outputted by the APD into a voltage mixing signal, to remove a high-frequency component in the voltage mixing signal, and to output a low-frequency component to the first ADC signal sampling module.

[0015] Furthermore, the laser diode is a laser diode capable of being externally modulated; the collimating lens is a spherical lens made of K9 glass, with a diameter of 5 mm and a thickness of 1-2 mm; a distance between the two collimating lenses is 5 mm; and a distance between the laser emitting end of the laser diode and the adjacent collimating lens is 7 mm.

[0016] Furthermore, the converging lens is a circular lens made of K9 glass, with a convex spherical outer side surface, a flat inner side surface, a maximum thickness of 8 mm, a minimum thickness of 5 mm, and a diameter of 10 times the diameter of the APD; and the APD is located at one focal length of the converging lens.

[0017] Furthermore, the single-chip microcomputer is an STM32-series single-chip microcomputer.

[0018] Furthermore, the signal generation module includes an active crystal oscillator and a signal generation chip, where the signal generation chip is connected to die active crystal oscillator to provide a stable clock oscillation through the active crystal oscillator; and the signal generation chip is connected to the IIC communication module to generate and output the eigen frequency signal and the modulation frequency signal having the same phase and different frequencies by receiving a clock signal and a data signal sent by the IIC communication module.

[0019] Furthermore, the laser emitting module includes an operational amplifier, a Zener diode, and a crystal triode, where the operational amplifier is connected to an emitting transistor of the laser diode and an eigen frequency signal output terminal of the signal generation module respectively through the Zener diode and the crystal triode; the operational amplifier is further connected to the GPIO instruction module to activate the laser diode through the GPIO instruction module and to input the PWM frequency signal, such that the laser diode outputs, under the action of the PWM frequency signal and the eigen frequency signal, a laser signal corresponding to the frequency of the eigen frequency signal; and the operational amplifier is further connected to a receiving transistor of the laser diode to form negative feedback, such that operating power of the laser diode LD1 is regulated with temperature.

[0020] Furthermore, the high-voltage bias module includes a field-effect transistor, a Zener diode, and a booster chip; the booster chip is connected to the GPIO instruction module to activate the high-voltage bias module and to input the PWM frequency signal; and the booster chip is connected to the APD through the field-effect transistor and the Zener diode to form a high bias voltage and to provide the high bias voltage to the APD.

[0021] Furthermore, the transimpedance amplifier and low-pass filter module includes a transimpedance amplifier and an active low-pass filter; the transimpedance amplifier is connected to the APD to convert a current signal outputted by the APD into a voltage signal in the transimpedance amplifier; a low-pass filtering module is separately connected to the transimpedance amplifier and the first ADC signal sampling module; and the low-pass filtering module removes the high-frequency component in the voltage signal inputted by the transimpedance amplifier, and transmits the low-frequency component into the first ADC signal sampling module for sampling.

[0022] Furthermore, the switch triode mixing-LR low-pass filtering module includes a first-order passive RC high-pass filter, a first-order passive high-pass filter, a crystal triode, and an LR n type filtering bridge; one end of the first-order passive RC high-pass filter is connected to the eigen frequency signal output terminal of the signal generation module, and the other end of the first-order passive RC high-pass filter is connected to a base of the crystal triode, one end of the first-order passive high-pass filter is connected to the modulation frequency signal output terminal of the signal generation module, and the other end of the first-order passive high-pass filter is connected to an emitter of the crystal triode, such that the eigen frequency signal and the modulation frequency signal are mixed into a mixed signal; and one end of the LR 7i type filtering bridge is connected to a collector of the crystal triode, and the other end of the LR k type filtering bridge is connected to the second ADC signal sampling module, such that after the high-frequency component in the mixed signal is filtered away, the low-frequency component is outputted to the second ADC signal sampling module.

[0023] Compared with the prior art, the high-dynamic-accuracy laser phase range finder has the following beneficial effects:

[0024] In the structural design of the optical module, the light source emitting device includes the laser diode and the collimating lens group. The collimating lens group includes two collimating lenses having a specific structure and distance. A laser beam is shaped by the collimating lens group, such that no matter how far a measured surface is from a light source, the size of light spots remains unchanged, thereby ensuring the transmission effect of the laser signal. The light source receiving device includes the converging lens and the APD. The converging lens further improves the corresponding intensity of the APD, thereby ensuring that the outputted current signal is more accurate, and reducing subsequent errors in the circuit. The basis is provided for simplifying the signal processing module through the mixing function of the APD, the computing power of the single-chip microcomputer is released to improve the data processing effect, and the overall signal processing speed is accelerated.

[0025] In the structural design of the signal processing module, the signal processing module includes a single-chip microcomputer, a signal generation module, a laser emitting module, a high-voltage bias module, a transimpedance amplifier and low-pass filter module, and a switch triode mixing-LR low-pass filtering module. As a source of modulation signals and intrinsic signals, the signal generation module can accurately and real-time generate modulation signals without phase errors, enabling the accuracy of the phase range finder to be achieved from the source. The laser emitting module can quickly respond to the signal of a signal transmitting module, thereby emitting laser with periodic changes in high-frequency light intensity that meets the requirements, such that the measurement signal can be emitted efficiently and without error, further improving the stability of high-frequency modulation and ensuring the stability of the measurement speed. The high-voltage bias module provides an accurate high-frequency voltage to the APD, such that the APD is always in an online linear operating state, thereby achieving rapid response and improving accuracy. The transimpedance amplifier and low-pass filter module converts the optical signal into an electrical signal, which strengthens the effective signal and eliminates noise, thereby laying the foundation for accurate sampling of echo signals. The switch transistor mixing-LR low-pass filtering module replaces the conventional mixing chip and employs an analog structure to greatly increase the signal mixing speed, reduce the signal processing time, and speed up signal transmission.

[0026] In conclusion, the high-dynamic-accuracy laser phase range finder solves the problems in the prior art that the output is slow under high-accuracy conditions and the accuracy cannot be improved when the output speed is not reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 is a schematic structural diagram of a high-dynamic-accuracy laser phase range finder according to the present disclosure;

[0028] FIG. 2 is a schematic diagram of an operating principle of a high-dynamic-accuracy laser phase range finder according to the present disclosure;

[0029] FIG. 3 is a schematic diagram of a circuit structure of a signal generation module of a high-dynamic-accuracy laser phase range finder according to the present disclosure;

[0030] FIG. 4 is a schematic diagram of a circuit structure of a laser emitting module of a high-dynamic-accuracy laser phase range finder according to the present disclosure;

[0031] FIG. 5 is a schematic diagram of a circuit structure of a high-voltage bias module of a high-dynamic-accuracy laser phase range finder according to the present disclosure;

[0032] FIG. 6 is a schematic diagram of a circuit structure of a transimpedance amplifier and low-pass filter module of a high-dynamic-accuracy laser phase range finder according to the present disclosure; and

[0033] FIG. 7 is a schematic diagram of a circuit structure of a switch triode mixing-LR low-pass filtering module of a high-dynamic-accuracy laser phase range finder according to the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The present disclosure will be described in more detail below in conjunction with the accompanying drawings and specific embodiments, but the following embodiments are not intended to limit the present disclosure.

[0035] Referring to FIG. 1, the high-dynamic-accuracy laser phase range finder includes an optical module and a signal processing module provided in a range finder housing.

[0036] The range finder housing includes an optical module mounting box 1, a signal processing module mounting plate 3, and a bottom plate 2 which are sequentially arranged from top to bottom. The optical module mounting box 1 is a box body having a cavity inside and an opening at the bottom; and in the length direction, one side of the box body is higher than the other side, such that the box body is stepped. The optical module is mounted in a high box body, and correspondingly, the vertical plate mounted at a junction between the high box body and a low box body is an optical module mounting vertical plate. A first light source module mounting hole and a second light source module mounting hole are formed at an interval in the center of the optical module mounting vertical plate, and an aviation jack is formed in the plate surface of one side thereof. The bottom plate 2 is a rectangular plate having a size adapted to the size of an opening at the bottom end of the optical module mounting box 1, a groove for arranging the signal processing module mounting plate 3 is formed in the top surface of the bottom plate 2, and the bottom plate 2 is sealed at the opening at the bottom end of the optical module mounting box 1 through a plurality of screws arranged in the circumferential direction. Two long edge sides of the bottom end of the optical module mounting box 1 respectively extend outward in the horizontal direction to form fixed plates, such that the bottom plate 2 is detachably fixed at the bottom of the optical module mounting box 1 through a plurality of bolts provided on the fixed plates on the two sides of the optical module mounting box 1.

[0037] The light source module includes a light source emitting device and a light source receiving device. The light source emitting device includes a first closed lens barrel, a laser diode 9, and a collimating lens group. The first closed lens barrel is horizontally fixed in the optical module mounting box 1, and the front end thereof is fixed at the first light source module mounting hole. The collimating lens group is fixed at an opening at the front end of the first closed lens barrel, and includes a first collimating lens 7 and a second collimating lens 8 which are arranged in parallel at an interval. The laser diode 9 is fixed at an opening at the rear end of the first closed lens barrel such that the laser emitting end thereof faces the center of the collimating lens group. The light source receiving device includes a converging lens 4, a second closed lens barrel 5, and an APD 6. The second closed lens barrel 5 is horizontally fixed in the optical module mounting box 1, and the front end thereof is fixed at a second light source module mounting hole. The converging lens 4 is fixed at an opening at the front end of the second closed lens barrel 5. The APD is fixed at an opening at the rear end of the second closed lens barrel 5 such that the light source receiving end thereof faces the center of the converging lens 4.

[0038] In the light source emitting device, as a laser source, the laser diode 1 is specifically an externally modulated laser diode to achieve periodic changes in light intensity and modulate the light intensity by changing the output of the laser (for example, setting the light intensity change frequency of the laser to 200 MHz). However, the beam emitted by the laser diode is a Gaussian beam and contains a certain scattering angle. Therefore, the collimating lens group 2 is arranged on a laser emitting path of the laser diode 1 to shape the laser beam, such that no matter how far the measured surface is from the light source, the size of light spots remains unchanged. Specifically, the collimating lens is a spherical lens made of K9 glass, with a diameter of 5 mm and a thickness of 1-2 mm; a distance between the two collimating lenses is 5 mm; and a distance between the laser emitting end of the laser diode 1 and the adjacent collimating lens is 7 mm. Compared with a single collimating lens or a collimating lens group composed of three collimating lenses, the collimating lens group composed of two collimating lenses has the best imaging effect.

[0039] In the light source receiving device, as a photoelectric sensor, the APD 3 can still detect a returned signal after diffuse reflection and form a higher output current. Moreover, to allow the APD 3 to receive the returned signal as much as possible, the imaging fills the entire lens, i.e., enhancing the response intensity of the APD 3, such that the outputted current signal is more accurate, and subsequent errors in the circuit are reduced. The converging lens 4 is arranged on an optical signal receiving path of the APD 3. The converging lens 4 is a circular lens made of K9 glass, with a convex spherical outer side surface, a flat inner side surface, a maximum thickness of 8 mm, a minimum thickness of 5 mm, and a diameter of 10 times the diameter of the APD 3. In this embodiment, on the basis that the diameter of the APD 3 is 2 mm and the diameter of the converging lens 4 is 20 mm, the distance between the converging lens 4 and the APD 3 satisfies: the APD 3 is located at one focal length of the converging lens 4. The function of the closed lens barrel 5 is to cover a receiving light path of the APD 3 to prevent the noise from increasing due to the entry of other stray light.

[0040] The essence of phase ranging is to detect the phases of emitted light and received light. However, the single-chip microcomputer cannot sample high-frequency optical signals. Therefore, to achieve sampling, two original optical signals need to be mixed, so as to achieve the purpose of sampling of the single-chip microcomputer. On this basis, referring to FIG. 2, the signal processing module includes a single-chip microcomputer, a signal generation module, a laser emitting module, a high-voltage bias module, a transimpedance amplifier and low-pass filter module, and a switch triode mixing-LR low-pass filtering module.

[0041] the single-chip microcomputer includes a CPU kernel, a DAC output module, a serial port output module, an IIC communication module, a GPIO instruction module, a DMA signal storage module, a first ADC signal sampling module, and a second ADC signal sampling module. A first output terminal of the CPU kernel is connected to an input terminal of the IIC communication module, and a second output terminal of the CPU kernel is connected to an input terminal of the GPIO instruction module. An output terminal of the first ADC signal sampling module and an output terminal of the second ADC signal sampling module are respectively connected to two input terminals of the DMA signal storage module to respectively input sampling signals of the two ADC signal sampling modules into two independent blocks of the DMA signal storage module for storage. An output terminal of the DMA signal storage module is connected to an input terminal of the CPU kernel, such that the sampling signals are transmitted into the CPU kernel according to a time sequence, and the CPU kernel processes the sampling signals to obtain displacement data. A third output terminal of the CPU kernel is connected to an input terminal of the DAC output module to convert the displacement signal obtained by the processing of the CPU kernel into a voltage value, to transmit the voltage value to a user equipment in the form of a voltage signal, and to facilitate real-time monitoring. A fourth output terminal of the CPU kernel is connected to the serial port output module to output the displacement signal obtained by the processing of the CPU kernel into a computer.

[0042] Specifically, the single-chip microcomputer is an STM32-series single-chip microcomputer. In this embodiment, the single-chip microcomputer is an STM32H750 single-chip microcomputer.

[0043] According to the principle of phase ranging, under a certain phase identification accuracy, the length of a measuring ruler is determined by the frequency of modulated laser. The higher the frequency of the laser, the higher the ranging accuracy. The modulation frequency needs to be at least 150 MHz. In addition, according to the principle of difference frequency phase measurement, two frequency signals need to be generated, one for modulation, and the other one serves as the intrinsic signal. The frequency difference between the two is strictly required. The phase consistency between the two generated frequency signals must be ensured. For the generation of a high-frequency signal, a general crystal oscillator cannot meet the needs, so a new signal generation module needs to be designed as needed.

[0044] In the present disclosure, the signal generation module is designed based on a signal generation chip. The signal generation chip is connected to an active crystal oscillator to provide a stable clock oscillation for the module through the active crystal oscillator. The signal generation chip is also connected to an SCL end and an SDA end of the IIC communication module to activate the signal generation module through an activation signal sent by the SCL end of the IIC communication module and to enable, through a frequency signal sent by the SDA end of the IIC communication module, the signal generation module to generate two signals having the same phase and different frequencies, i.e., an eigen frequency signal IF1 and a modulation frequency signal IF2. The two frequency signals are mixed with an optical signal, so only when the phases of only the two frequency signals are the same, the phase changes of two sampling signals are completely caused by the ranging distance changes.

[0045] The signal generation chip is specifically an SI5351 chip. The signal generation chip is an integrated phase-locked loop chip, may directly perform data transmission with the STM32 singlechip microcomputer, and can simultaneously output multiple frequency signals having the same phase and different frequencies, which respectively serve as the eigen frequency signal and the modulation frequency signal. Moreover, this integrated frequency signal has the advantage of small frequency error, which can make the measurement range accurate, and has the advantage of no phase error, such that the errors caused by hardware will be further reduced, thereby further improving the accuracy.

[0046] specifically, the signal generation module is specifically implemented based on a signal generation circuit. Referring to FIG. 3, the signal generation circuit includes an active crystal oscillator Yl, a signal generation chip, a first resistor RI, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor Cl, a second capacitor C2, and a third capacitor C3. Two negative electrode ends of the active crystal oscillator Y1 are commonly grounded, and two positive electrode ends of the active crystal oscillator Y1 are respectively connected to an XA end and an XB end of the signal generation chip. A CLKO end of the signal generation chip is connected to a first end of the third resistor R3, a second end of the third resistor R3 is connected to a first end of the third capacitor C3, and a second end of the third capacitor C3 serves as an output terminal of the eigen frequency signal IF1. A CLK2 end of the signal generation chip is connected to a first end of the fourth resistor R4, and a second end of the fourth resistor R4 serves as an output terminal of the modulation frequency signal IF2. A VDD end of the signal generation chip serves as a first external end 0UT1, and is connected to a 3.3 V external power supply. An SCL end of the signal generation chip, a first end of the first resistor RI, and a first end of the first capacitor Cl are commonly connected; an SDA end of the signal generation chip, a first end of the second resistor R2, and a first end of the second capacitor C2 are commonly connected; and a second end of the first capacitor Cl and a second end of the second capacitor C2 are separately grounded. A second end of the first resistor RI and a second end of the second resistor R2 serve as second external ends, and are connected to a 3.3 V external power supply. The SCL end and the SDA end of the signal generation chip are respectively connected to the SCL end and the SDA end of the IIC communication module. A VDDO end of the signal generation chip serves as a third external end, and is connected to a 3.3 V external power supply. A GND end of the signal generation chip is grounded. A CLK1 end of the signal generation chip is suspended and is not used.

[0047] In the signal generation circuit, the active crystal oscillator Y1 is connected to the chip SI5351 through two output ports to provide an external stable clock oscillation therefor, and the oscillation frequency is 25 MHz. The signal generation chip completes the definition of high and low levels through the GND terminal and VDDO terminal to generate a signal of a specified frequency inside the chip. The SCL end and SDA end of the signal generation chip are also respectively connected to the SCL end and SDA end of the IIC communication module to respectively receive the activation signal and the data signal sent by the IIC communication module. The CLKO terminal of the signal generation chip is configured to transmit a first clock signal, which is formed into a high-pass filter through the third resistor and the third capacitor, i.e., the eigen frequency signal, and is emitted outward through the output terminal of the eigen frequency signal IF1. The CLK2 end of the signal generation chip is configured to transmit a second clock signal, which is formed into the modulation frequency signal through the fourth resistor, and is transmitted outward through the output terminal of the modulation frequency signal IF2. Specifically, the eigen frequency signal IF1 is outputted to the laser emitting module and the switch triode mixing-LR low-pass filtering module, and the modulation frequency signal IF2 is outputted to the high-voltage bias module and the switch triode mixing-LR low-pass filtering module. In summary, the signal generation module, as a source of modulated signals and intrinsic signals, can accurately and realtime generate modulated signals without phase errors, enabling the accuracy of the phase range finder to be achieved from the source.

[0048] The laser emitting module is built based on the GPIO function of the single-chip microcomputer. The GPIO instruction module of the single-chip microcomputer includes an activation signal output terminal and a PWM output terminal. The laser emitting module is connected to the GPIO instruction module to input the activation signal or the PWM frequency signal into the laser emitting module through the GPIO instruction module. The laser emitting module is separately connected to the signal generation module and the laser diode to receive the eigen frequency signal IF1 sent by the signal generation module, and to emit the laser signal to the laser diode by combining the PWM frequency signal to periodically perform external modulation on the light intensity of the laser diode, such that the laser diode emits modulated light of a specific frequency.

[0049] Specifically, the laser emitting module is specifically implemented based on a laser emitting circuit. Referring to FIG. 4, the laser emitting circuit includes a first inductor LI, a fifth resistor R5, a fourth capacitor C4, an operational amplifier UI, a first Zener diode DI and a crystal triode QI. A positive electrode of the first inductor LI serves as a fourth external end, and is connected to a 3.3 V external power supply. A negative electrode of the first inductor LI, a first end of the fifth resistor R5, a positive electrode of an emitting transistor of the laser diode LD1, and a negative electrode of a receiving transistor of the laser diode LD1 are commonly connected. A negative electrode of the emitting transistor of the laser diode LD1 is connected to a collector of the crystal triode QI, serves as a fifth external end OUT5, and is connected to a second end of the third capacitor C3 in the signal generation circuit to input the eigen frequency signal IF1. A second end of the fifth resistor R5, a first end of the first capacitor C4, a pin 5 of the operational amplifier UI, a base of the crystal triode QI, and a negative electrode of the first Zener diode DI are commonly grounded. An emitter of the crystal triode QI is grounded. A positive electrode of the first Zener diode DI, a pin 1 of the operational amplifier UI, a positive electrode of the receiving transistor of the laser diode LD1, and a pin 4 of the operational amplifier UI are commonly connected. A pin 2 of the operational amplifier UI is grounded. A pin 3 of the operational amplifier UI serves as a sixth external end OUT6, and is separately connected to an activation instruction output terminal of the GPIO instruction module and a PWM output terminal of the GPIO instruction module to input an activation instruction and a PWM frequency signal. The laser diode is specifically a 650 nm red light semiconductor laser device. The operational amplifier is specifically a high-speed and high- bandwidth chip TP1561 produced by the 3peak company, which has a high slew rate, is suitable for extremely fast response scenarios, and has a gain bandwidth of 6 MHz. The crystal triode is specifically an NPN-type transistor MMBT3646.

[0050] In the laser emitting circuit, the negative electrode of the first inductor LI serves as a fourth external end OUT4 and is connected to an external power supply to supply power to the circuit. The first inductor LI is configured to preliminarily filter out a high-frequency noise voltage, and then the voltage passes through to power the laser diode LD1 and the operational amplifier UI. The fifth external end OUT5 is connected to the signal generation circuit to receive the eigen frequency signal and implement periodic external modulation of the light intensity of the laser diode LD1. The sixth external end OUT6 is connected to the PWM output terminal of the GPIO instruction module. When there is no PWM frequency signal, the crystal triode QI is in a cut-off state, and the current value in the laser diode LD1 is very small and lower than its threshold current, and no laser is generated. When there is a PWM frequency signal inputted, the signal is first converted into a current signal through the operational amplifier UI, and then passes through the Zener diode DI to increase the voltage value of the base of the crystal triode QI, to enable operation in an amplification area. The current of the crystal triode QI is greater than the threshold current of the laser diode LD1 at this time. The laser diode LD1 operates in a linear area and combines the internal modulation of the eigen frequency signal IF1 to output a laser signal value corresponding to the frequency of the eigen frequency signal IF1. The laser diode LD1 also receives a feedback current signal from the positive electrode (PD+ electrode). That is, when the laser diode LD1 operates for a long time, the temperature thereof will rise. At this time, PD+ will increase the output cun-ent signal, which will reduce the current value at the pin 1 of the operational amplifier UI, thereby reducing the voltage at the base of transistor QI. As a result, die output current is reduced, the overall power of the laser diode LD1 is reduced, and the temperature is reduced accordingly, thereby achieving a negative feedback effect, making the laser generation module always stable, and reducing errors caused by power instability. In summary, the laser emitting module can quickly respond to the signal of the signal emitting module, thereby emitting laser with periodic changes in high-frequency light intensity that meets the requirements, such that the measurement signal can be emitted efficiently and without error, thereby further improving the stability of high-frequency modulation, and allowing the stability of the measurement speed to be guaranteed.

[0051] As a laser ranging system, the photoelectric detection element thereof has a crucial impact on the ranging result. The present disclosure takes the APD as the photoelectric detection element to complete the response to the laser, and higher internal gain thereof may obtain a higher signal-to-noise ratio signal. In use scenarios of the laser range finders, there are often no cooperative targets, and the surfaces of the ranging objects are mostly rough surfaces, which are prone to diffuse reflection, resulting in low energy of the echo signal, so gain amplification is also required. In addition, the internal mixing function of the APD may directly output an electrical signal with low frequency but retaining phase information. When the APD is in use, a high-voltage reverse bias module is required to provide a reverse bias voltage to the APD.

[0052] The high-voltage bias module is connected to the APD and the GPIO instruction module. The high-voltage bias module is connected to the GPIO instruction module to generate an operation activation signal to enable the high-voltage bias module to operate. The high-voltage bias module is connected to the APD to provide a reverse bias voltage to the APD.

[0053] The high-voltage bias module includes a field-effect transistor, a Zener diode, and a booster chip; the booster chip is connected to the GPIO instruction module to activate the high-voltage bias module and to input the PWM frequency signal; and the booster chip is connected to the APD through the field-effect transistor and the Zener diode to form a high bias voltage and to provide the high bias voltage to the APD.

[0054] Specifically, the high-voltage bias module is specifically implemented based on a high-voltage bias circuit. Referring to FIG. 5, the high-voltage bias circuit includes a field-effect transistor XI, a second Zener diode D2, a sixth resistor R6, a fifth resistor R5, a second inductor L2, and a booster chip U2. An EXT end of the booster chip U2 is connected to a first end of the fieldeffect transistor XI, a second end of the field-effect transistor XI is connected to a positive electrode of the second Zener diode D2, and a third end of the field-effect transistor XI is grounded. A negative electrode of the second Zener diode D2 serves as a seventh external end OUT7, i.e., a high-voltage output terminal, and is connected to the APD. A FB end of the booster chip U2 is connected to a first end of the sixth resistor R6; and a second end of the sixth resistor R6 serves as an eighth external end OUT8, is connected to the PWM input terminal of the GPIO instruction module, and is grounded. A VDD end of the booster chip U2, a first end of the fifth capacitor R6, and a negative electrode end of the second inductor L2 are commonly connected; a second end of the fifth capacitor R6 is grounded; and a positive electrode end of the second inductor L2 serves as a tenth external end OUT10, and is connected to a 3.3 external power supply. A CE end of the booster chip U2 serves as a ninth external end OUT9, and is connected to the activation signal output terminal of the GPIO instruction module. A GND end of the booster chip U2 is grounded. The booster chip is specifically a large current booster chip ME209.

[0055] The high-voltage bias circuit takes the booster chip U2 as the core. Specifically, a second end of the fifth external end OUT5 is connected to a 3.3 external power supply to supply power to the high-voltage bias circuit. The ninth external end OUT9 is connected to the activation signal output terminal of the GPIO instruction module to activate the booster chip to operate through the activation signal sent by the GPIO instruction module. The eight external end 0UT8 is connected to the PWM output terminal of the GPIO instruction module to input the PWM frequency signal. When the duty ratio of the PWM signal is high, the outputted voltage is high. The EXT end of the booster chip U2 serves as a chip output terminal to output a voltage signal, and the voltage signal sequentially passes through the field-effect transistor XI and the forwards conducted second Zener diode D2 to form a higher bias voltage at the negative electrode of the second Zener diode D2. The bias voltage is outputted to the APD through the seventh external end OUT7, such that the APD operates at the reverse bias voltage, detects the returned optical signal, and converts the optical signal into an electrical signal. In summary, the high-voltage bias module provides an accurate high-frequency voltage to the APD, allowing the APD to accurately and stably operate in a linear operation module. Only the APD in the linear operation state may achieve rapid response to improve accuracy.

[0056] The APD is also connected to a second section of the fourth resistor R4 of the signal generation circuit to input the modulation frequency signal IF2 into the APD, the mixing function of the APD is employed to perform difference frequency operation on the returned optical signal detected thereby and the modulation frequency signal IF2, and finally, a low-frequency current signal with phase difference information is outputted.

[0057] In the laser range finder, it is necessary to performing sampling and phase identification on the emitted signal and the returned optical signal. The returned optical signal employs the mixing function of the APD to meet the difference frequency requirement. For the emitted signals, a switch triode mixing-LR low-pass filtering module needs to be designed to implement the mixing difference frequency of the emitted signal.

[0058] The switch triode mixing-LR low-pass filtering module includes a first-order passive RC high-pass filter, a first-order passive high-pass filter, a crystal triode, and an LR k type filtering bridge; one end of the first-order passive RC high-pass filter is connected to the eigen frequency signal output terminal of the signal generation module, and the other end of the first-order passive RC high-pass filter is connected to a base of the crystal triode, one end of the first-order passive high-pass filter is connected to the modulation frequency signal output terminal of the signal generation module, and the other end of the first-order passive high-pass filter is connected to an emitter of the crystal triode, such that the eigen frequency signal and the modulation frequency signal are mixed into a mixed signal; and one end of the LR k type filtering bridge is connected to a collector of the crystal triode, and the other end of the LR it type filtering bridge is connected to the second ADC signal sampling module, such that after the high-frequency component in the mixed signal is filtered away, the low-frequency component is outputted to the second ADC signal sampling module. Specifically, the switch triode mixing-LR low-pass filtering module is implemented based on a switch triode mixing-LR low-pass filtering circuit. Referring to FIG. 6, the switch triode mixing-LR low-pass filtering circuit includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor RIO, an eleventh resistor Rll, a twelfth resistor RI2, a thirteenth resistor RI 3, a third inductor L3, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, and a second crystal triode Q2. A first end of the seventh resistor R7 serves as an eleventh external end OUT11, and is connected to a 3.3 V external power supply. A second end of the seventh resistor R7 is connected to a positive electrode of the third inductor L3. A negative electrode of the third inductor L3, a first end of the ninth resistor R9, a collector of the second crystal triode Q2, a first end of the sixth capacitor C6, and a first end of the eighth resistor R8 are commonly connected, and a second end of the sixth capacitor C6 is grounded. A second end of the eighth resistor R8 is connected to the seventh capacitor C7, and the two serve as a thirteen external end 0UT13, i.e., a mixed signal output terminal, which is connected to an input terminal of the second ADC signal sampling module. A second end of the seventh capacitor C7 is grounded. An emitter of the second crystal triode Q2, a first end of the ninth capacitor C9, and a first end of the thirteenth resistor RI3 are commonly connected. A second end of the ninth capacitor C9 serves as a fourteenth external end OUT 14, and is connected to a second end of the fourth resistor R4 to input the modulation frequency signal IF2. A second end of the thirteenth resistor RI3 is grounded. A second end of the ninth capacitor C9, a base of the second crystal triode Q2, a first end of the twelfth resistor RI2, and a first end of the eighth capacitor C8 are commonly connected. A second end of the eighth capacitor C8, a first end of the eleventh resistor Rll, and a first end of the tenth resistor RIO are commonly connected. A second end of the eleventh resistor Rll is grounded, and a second end of the twelfth resistor R12 is grounded. A second end of the tenth resistor RIO serves as a twelfth external end OUT 12, and is connected to the second end of the fourth capacitor to input the eigen frequency signal IF1.

[0059] In the switch triode mixing-LR low-pass filtering circuit, starting from the eigen frequency signal IF1 inputted through a ninth input terminal IN9, the eigen frequency signal IF1 first passes through a first-order passive RC high-pass filter consisting of the tenth resistor RIO, the eleventh resistor Rll, the twelfth resistor R12, and the eighth capacitor C8, and then is inputted into the base of the second crystal triode Q2 as a switch triode. Meanwhile, the modulation frequency signal IF2 inputted through an eighth input terminal IN8 first passes through a first-order passive high-pass filter consisting of a ninth capacitor C9 and a thirteenth resistor RI3, and then is inputted into the emitter of the second crystal triode Q2. Then, the eigen frequency signal IF1 and the modulation frequency signal IF2 are formed into a signal including a high-frequency component and a low-frequency component under the mixing function of the second crystal triode Q2. The signal is outputted from the collector of the second crystal triode Q2 to an LRII filtering bridge consisting of the sixth capacitor C6, the eighth resistor R8 and the seventh capacitor C7 to filter away the high-frequency component in the new signal. Finally, the signal only including the low-frequency component is transmitted to the second ADC signal sampling module of the single-chip microcomputer through the thirteenth external end OUT 13 for sampling. In conclusion, the switch triode mixing-LR low-pass filtering module replaces a mixing chip, and employs a simulated structure to greatly increase the signal mixing speed, reduce the signal processing time and accelerate the signal transmission.

[0060] The transimpedance amplifier and low-pass filter module includes a transimpedance amplifier and an active low-pass filter. The transimpedance amplifier is connected to the APD to convert a current signal outputted by the APD into a voltage signal in the transimpedance amplifier, thereby bringing more convenience for subsequent circuit processing and ADC sampling. A low-pass filtering module is separately connected to the transimpedance amplifier and the first ADC signal sampling module to filter away the high-frequency component in the voltage signal and output the low-frequency component, and then the signal is sent into the first ADC signal sampling module of the STM32 single-chip microcomputer for sampling.

[0061] Specifically, the transimpedance amplifier and low-pass filter module is implemented based on a transimpedance amplifier and low-pass filter circuit. Referring to FIG. 7, the transimpedance amplifier and low-pass filter circuit includes a dual operational amplifier chip, a fourteenth resistor R14, a fifteenth resistor RI5, a sixteenth resistor RI 6, a seventeenth resistor RI7, an eighteenth resistor R19, a tenth capacitor CIO, an eleventh capacitor Cll, and a twelfth capacitor C12. The dual operational amplifier chip consists of a first operational amplifier U3 and a second operational amplifier U4.

[0062] A pin 1 of the first operational amplifier U3, a first end of the eleventh capacitor Cl 1, a first end of the twelfth capacitor Cl2, and a first end of the eighteenth resistor are commonly connected. A pin 2 of the first operational amplifier U3, a second end of the eleventh capacitor Cll, and a second end of the eighteenth resistor are commonly connected. A second end of the twelfth capacitor C12 is connected to a first end of the seventeenth resistor R17. A pin 3 of the first operational amplifier U3 serves as a fifteenth external end OUT15, and is connected to a signal output terminal of the APD. A pin 4 of the first operational amplifier U3 is grounded. A pin 8 of the first operational amplifier U3 serves as a sixteenth external end OUT16, and is connected to a 3.3 external power supply. A pin 5 of the second operational amplifier U4, a first end of the fifteenth resistor RI 5, a first end of the sixteenth resistor RI 6, and a first end of the tenth capacitor are commonly connected. A second end of the fifteenth resistor is connected to a seventeenth external end 0UT17, and the two serve as the seventeenth external end 0UT17, which is connected to a 3.3 external power supply. A second end of the sixteenth resistor RI 6 is grounded. A second end of the tenth capacitor is grounded. A pin 6 of the second operational amplifier U4, a second end of the seventeenth R17, and a first end of the fourteenth resistor R14 are commonly connected. A pin 7 of the second operational amplifier U4 is connected to a second end of the fourteenth resistor R14, and the two serve as the eighteenth external end OUT 18, which is connected to an input terminal of the first ADC signal sampling module. The dual operational amplifier chip is specifically a TP 1542 chip, which is a high-gain and low-noise chip, and the gain bandwidth product may reach up to 1.3 MHz.

[0063] In the transimpedance amplifier and low-pass filter circuit, the first operational amplifier U3 of the dual operational amplifier chip, the eighteenth resistor RI 8, and the eleventh capacitor Cll form a transimpedance amplifier. Specifically, taking the fifteenth external end OUT 15 as a starting end, the high and low-frequency mixed signal with phase information outputted by the APD is inputted through the pin 3 (positive input terminal) of the dual operational amplifier chip. The pin 1 and the pin 2 of the dual operational amplifier chip form a negative feedback loop through the eighteenth resistor RI8 and the eleventh capacitor Cll in parallel, such that after the high and low-frequency mixed signal with phase information passes through the eighteenth resistor RI8, the current value and the resistance are multiplied to form a voltage signal, which is outputted from the pin 1 of the dual operational amplifier chip. The twelfth capacitor Cl2, the seventeenth resistor RI7, the fourteenth resistor RI 4, and the second operational amplifier U4 of the dual operational amplifier chip form an active low-pass filter. Specifically, the voltage signal outputted by the transimpedance amplifier enters the active low-pass filter for filtering. A filtering result is outputted from a pin 7 of the second operational amplifier U4, and is transmitted to the first ADC signal sampling module through the eighteenth external end OUT 18. In conclusion, the transimpedance amplifier and low-pass filter module converts the optical signal into an electrical signal, and performs reinforcement and noise elimination on a valid signal, to lay the foundation for accurate sampling of the echo signal.

[0064] In the structural design of the signal processing module of the present disclosure, the ultimate goal of phase ranging requires measurement of two phases, i.e., one phase when the laser starts to emit (this phase is also called the zero-point phase), and the other phase corresponding to the distance; and the difference between the two is the distance. Therefore, in the switch triode mixing-LR low-pass filtering module, the eigen frequency signal and the modulation frequency signal are first mixed once to obtain a zero-point phase at the beginning of transmission, i.e., a signal with a low-frequency component and a zero-point phase. The method for obtaining the phase corresponding to the distance includes: first employing the eigen frequency signal to emit the laser, and then employing the modulation frequency signal to mix to obtain a signal with a low-frequency component and distance phase after the APD receives the reflection. Finally, the two signals sampled by the first ADC sampling module and the second ADC sampling module are two signals with different phases and the same frequency, which are convenient for processing by the singlechip microcomputer. Meanwhile, in the signal processing module of the present disclosure, different functional modules are designed, thereby solving the problems in the prior art that the output is slow under high-accuracy conditions and the accuracy cannot be improved when the output speed is not reduced. WHAT IS CLAIMED IS: 1. A high-dynamic-accuracy laser phase range finder, comprising an optical module and a signal processing module provided in a range finder housing, wherein a light source module comprises a light source emitting device and a light source receiving device arranged in parallel; the light source emitting device comprises a laser diode and a collimating lens group respectively fixed at a front end and a rear end of a first closed lens barrel; the collimating lens group comprises two parallel collimating lenses arranged at an interval; the laser diode is provided with a laser emitting end facing a center of the collimating lens group; the light source receiving device comprises a converging lens and an avalanche photo diode (APD) respectively fixed at a front end and a rear end of a second closed lens barrel; and the APD is provided with a light source receiving end facing a center of the converging lens; and the signal processing module comprises a single-chip microcomputer, a signal generation module, a laser emitting module, a high-voltage bias module, a transimpedance amplifier and low-pass filter module, and a switch triode mixing-LR low-pass filtering module; the single-chip microcomputer comprises a central processing unit (CPU) kernel, a digital to analog converter (DAC) output module, a serial port output module, an Inter-Integrated Circuit (IIC) communication module, a General-purpose input / output (GPIO) instruction module, a direct memory access (DMA) signal storage module, a first analog to digital converter (ADC) signal sampling module, and a second ADC signal sampling module; a first output terminal of the CPU kernel is connected to an input terminal of the IIC communication module, a second output terminal of the CPU kernel is connected to an input terminal of the GPIO instruction module, a third output terminal of the CPU kernel is connected to an input terminal of the DAC output module, and a fourth output terminal of the CPU kernel is connected to an input terminal of the serial port output module; an output terminal of the DMA signal storage module is connected to an input terminal of the CPU kernel; an output terminal of the first ADC signal sampling module and an output terminal of the second ADC signal sampling module are respectively connected to two input terminals of the DMA signal storage module to respectively input sampling signals of the two ADC signal sampling modules into two independent blocks of the DMA signal storage module for storage and to respectively transmit the sampling signals into the CPU kernel according to a time sequence; an input terminal of the signal generation module is connected to an output terminal of the IIC communication module to activate the signal generation module through the IIC communication module and to specify the signal generation module to generate an eigen frequency signal and a modulation frequency signal having different frequencies; the laser emitting module is separately connected to the laser diode, the GPIO instruction module, and the signal generation module to activate the laser emitting module through the GPIO instruction module, and the laser emitting module with the eigen frequency signal inputs send by the signal generation module and a pulse width modulation (PWM) frequency signal controlled by the GPIO instruction module, and outputs to the laser diode is an electrical signal allowing light intensity to change periodically; the high-voltage bias module is separately connected to the APD and the GPIO instruction module to activate the high-voltage bias module through the GPIO instruction module and to provide a reverse bias voltage to the APD; the APD is further connected to a modulation frequency signal output terminal of the signal generation module to receive the modulation frequency signal and detect a returned optical signal and to output a high and low frequency mixed signal subjected to difference frequency processing; the switch triode mixing-LR low-pass filtering module is separately connected to the signal generation module and the second ADC signal sampling module to receive the eigen frequency signal and the modulation frequency signal for frequency mixing processing, to remove a high-frequency component in a mixed signal, and to output a low-frequency component to the second ADC signal sampling module; and the transimpedance amplifier and low-pass filter module is separately connected to the APD and the first ADC signal sampling module to convert a current mixing component outputted by the APD into a voltage mixing signal, to remove a high-frequency component in the voltage mixing signal, and to output a low-frequency component to the first ADC signal sampling module. 2. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the laser diode is a laser diode capable of being externally modulated; the collimating lens is a spherical lens made of K9 glass, with a diameter of 5 mm and a thickness of 1-2 mm; a distance between the two collimating lenses is 5 mm; and a distance between the laser emitting end of the laser diode and the adjacent collimating lens is 7 mm. 3. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the converging lens is a circular lens made of K9 glass, with a convex spherical outer side surface, a flat inner side surface, a maximum thickness of 8 mm, a minimum thickness of 5 mm, and a diameter of 10 times the diameter of the APD; and the APD is located at one focal length of the converging lens. 4. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the single-chip microcomputer is an STM32-series single-chip microcomputer. 5. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the signal generation module comprises an active crystal oscillator and a signal generation chip, wherein the signal generation chip is connected to the active crystal oscillator to provide a stable clock oscillation through the active crystal oscillator; and the signal generation chip is connected to the IIC communication module to generate and output the eigen frequency signal and the modulation frequency signal having the same phase and different frequencies by receiving a clock signal and a data signal sent by the IIC communication module. 6. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the laser emitting module comprises an operational amplifier, a Zener diode, and a crystal triode, wherein the operational amplifier is connected to an emitting transistor of the laser diode and an eigen frequency signal output terminal of the signal generation module respectively through the Zener diode and the crystal triode; the operational amplifier is further connected to the GPIO instruction module to activate the laser diode through the GPIO instruction module and to input the PWM frequency signal, such that the laser diode outputs, under the action of the PWM frequency signal and the eigen frequency signal, a laser signal corresponding to the frequency of the eigen frequency signal; and the operational amplifier is further connected to a receiving transistor of the laser diode to form negative feedback, such that operating power of the laser diode LD1 is regulated with temperature. 7. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the high-voltage bias module comprises a field-effect transistor, a Zener diode, and a booster chip; the booster chip is connected to the GPIO instruction module to activate the high-voltage bias module and to input the PWM frequency signal; and the booster chip is connected to the APD through the field-effect transistor and the Zener diode to form a high bias voltage and to provide the high bias voltage to the APD. 8. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the transimpedance amplifier and low-pass filter module comprises a transimpedance amplifier and an active low-pass filter; the transimpedance amplifier is connected to the APD to convert a current signal outputted by the APD into a voltage signal in the transimpedance amplifier; a low-pass filtering module is separately connected to the transimpedance amplifier and the first ADC signal sampling module; and the low-pass filtering module removes the high-frequency component in the voltage signal inputted by the transimpedance amplifier, and transmits the low-frequency component into the first ADC signal sampling module for sampling. 9. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the switch triode mixing-LR low-pass filtering module comprises a first-order passive RC high-pass filter, a first-order passive high-pass filter, a crystal triode, and an LR n type filtering bridge; one end of the first-order passive RC high-pass filter is connected to the eigen frequency signal output terminal of the signal generation module, and the other end of the first-order passive RC high-pass filter is connected to a base of the crystal triode, one end of the first-order passive high-pass filter is connected to the modulation frequency signal output terminal of the signal generation module, and the other end of the first-order passive high-pass filter is connected to an emitter of the crystal triode, such that the eigen frequency signal and the modulation frequency signal are mixed into a mixed signal; and one end of the LR it type filtering bridge is connected to a collector of the crystal triode, and the other end of the LR n: type filtering bridge is connected to the second ADC signal sampling module, such that after the high-frequency component in the mixed signal is filtered away, the low-frequency component is outputted to the second ADC signal sampling module. Amendments to the claims have been filed as follows:

Claims

1. A high-dynamic-accuracy laser phase range finder, comprising an optical module and a signal processing module provided in a range finder housing, whereinthe optical module comprises a light source emitting device and a light source receiving device arranged side by side; the light source emitting device comprises a laser diode and a collimating lens group respectively fixed at a front end and a rear end of a first closed lens barrel; the collimating lens group comprises two parallel collimating lenses arranged at an interval; the laser diode is provided with a laser emitting end facing a center of the collimating lens group; the light source receiving device comprises a converging lens and an avalanche photo diode (APD) respectively fixed at a front end and a rear end of a second closed lens barrel; and the APD is provided with a light source receiving end facing a center of the converging lens; andthe signal processing module comprises a single-chip microcomputer, a signal generation module, a laser emitting module, a high-voltage bias module, a transimpedance amplifier and low-pass filtering module, and a switch triode mixing-LR low-pass filtering module; the single-chip microcomputer comprises a central processing unit (CPU) kernel, a digital to analog converter (DAC) output module, a serial port output module, an Inter-Integrated Circuit (IIC) communication module, a General-purpose input / output (GPIO) instruction module, a direct memory access (DMA) signal storage module, a first analog to digital converter (ADC) signal sampling module, and a second ADC signal sampling module; a first output terminal of the CPU kernel is connected to an input terminal of the IIC communication module, a second output terminal of the CPU kernel is connected to an input terminal of the GPIO instruction module, a third output terminal of the CPU kernel is connected to an input terminal of the DAC output module, and a fourth output terminal of the CPU kernel is connected to an input terminal of the serial port output module; an output terminal of the DMA signal storage module is connected to an input terminal of the CPU kernel; an output terminal of the first ADC signal sampling module and an output terminal of the second ADC signal sampling module are respectively connected to two input terminals of the DMA signal storage module to respectively input sampling signals of the two ADC signal sampling modules into two independent blocks of the DMA signal storage module for storage and to respectively transmit the sampling signals into the CPU kernel according to a time sequence; an input terminal of the signal generation module is connected to an output terminal of the IIC communication module to activate the signal generation module through the IIC communication module and to specify the signal generation module to generate an eigen frequency signal and a modulation frequency signal having different frequencies; the laser emitting module is separately connected to the laser diode, the GPIO instruction module, and the05 11 24signal generation module to activate the laser emitting module through the GPIO instruction module, and the laser emitting module with the eigen frequency signal inputs send by the signal generation module and a pulse width modulation (PWM) frequency signal controlled by the GPIO instruction module, and outputs to the laser diode is an electrical signal allowing light intensity to change periodically; the high-voltage bias module is separately connected to the APD and the GPIO instruction module to activate the high-voltage bias module through the GPIO instruction module and to provide a reverse bias voltage to the APD; the APD is further connected to a modulation frequency signal output terminal of the signal generation module to receive the modulation frequency signal and detect a returned optical signal and to output a high and low frequency mixed signal subjected to difference frequency processing; the switch triode mixing-LR low-pass filtering module is separately connected to the signal generation module and the second ADC signal sampling module to receive the eigen frequency signal and the modulation frequency signal for frequency mixing processing, to remove a high-frequency component in a mixed signal, and to output a low-frequency component to the second ADC signal sampling module; and the transimpedance amplifier and low-pass filtering module is separately connected to the APD and the first ADC signal sampling module to convert a current mixing component outputted by the APD into a voltage mixing signal, to remove a high-frequency component in the voltage mixing signal, and to output a low-frequency component to the first ADC signal sampling module.

2. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the laser diode is a laser diode capable of being externally modulated; each collimating lens is a spherical lens made of K9 glass, with a diameter of 5 mm and a thickness of 1-2 mm; a distance between the two collimating lenses is 5 mm; and a distance between the laser emitting end of the laser diode and the adjacent collimating lens is 7 mm.

3. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the converging lens is a circular lens made of K9 glass, with a convex spherical outer side surface, a flat inner side surface, a maximum thickness of 8 mm, a minimum thickness of 5 mm, and a diameter of 10 times the diameter of the APD; and the APD is located at one focal length of the converging lens.

4. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the singlechip microcomputer is an STM32-series single-chip microcomputer.

5. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the signal05 11 24generation module comprises an active crystal oscillator and a signal generation chip, wherein the signal generation chip is connected to the active crystal oscillator to provide a stable clock oscillation through the active crystal oscillator; and the signal generation chip is connected to the IIC communication module to generate and output the eigen frequency signal and the modulation frequency signal having the same phase and different frequencies by receiving a clock signal and a data signal sent by the IIC communication module.

6. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the laser emitting module comprises an operational amplifier, a Zener diode, and a crystal triode, wherein the operational amplifier is connected to an emitting transistor of the laser diode and an eigen frequency signal output terminal of the signal generation module respectively through the Zener diode and the crystal triode; the operational amplifier is further connected to the GPIO instruction module to activate the laser diode through the GPIO instruction module and to input the PWM frequency signal, such that the laser diode outputs, under the action of the PWM frequency signal and the eigen frequency signal, a laser signal corresponding to the frequency of the eigen frequency signal; and the operational amplifier is further connected to a receiving transistor of the laser diode to form negative feedback, such that operating power of the laser diode LD1 is regulated with temperature.

7. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the high-voltage bias module comprises a field-effect transistor, a Zener diode, and a booster chip; the booster chip is connected to the GPIO instruction module to activate the high-voltage bias module and to input the PWM frequency signal; and the booster chip is connected to the APD through the fieldeffect transistor and the Zener diode to form a high bias voltage and to provide the high bias voltage to the APD.

8. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the transimpedance amplifier and low-pass filtering module comprises a transimpedance amplifier and an active low-pass filter; the transimpedance amplifier is connected to the APD to convert a current signal outputted by the APD into a voltage signal in the transimpedance amplifier; a low-pass filtering module is separately connected to the transimpedance amplifier and the first ADC signal sampling module; and the low-pass filtering module removes the high-frequency component in the voltage signal inputted by the transimpedance amplifier, and transmits the low-frequency component into the first ADC signal sampling module for sampling.

9. The high-dynamic-accuracy laser phase range finder according to claim 1, wherein the switch triode mixing-LR low-pass filtering module comprises a first-order passive RC high-pass filter, a first-order passive high-pass filter, a crystal triode, and an LR 7t type filtering bridge; one end of the first-order passive RC high-pass filter is connected to the eigen frequency signal output terminal of the signal generation module, and the other end of the first-order passive RC high-pass filter is connected to a base of the crystal triode, one end of the first-order passive high-pass filter is connected to the modulation frequency signal output terminal of the signal generation module, and the other end of the first-order passive high-pass filter is connected to an emitter of the crystal triode, such that the eigen frequency signal and the modulation frequency signal are mixed into a mixed signal; and one end of the LR 7t type filtering bridge is connected to a collector of the crystal triode, and the other end of the LR 7i type filtering bridge is connected to the second ADC signal sampling module, such that after the high-frequency component in the mixed signal is filtered away, the low-frequency component is outputted to the second ADC signal sampling module.CM

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