Green laser phase range finder and ranging method

Abstract

The present invention relates to the field of laser ranging, and discloses a green laser phase range finder and a ranging method. The range finder comprises a DDS, a frequency mixing filter circuit, an MCU, a first amplification circuit, an analog switch, a first laser beam module, a second laser beam module, a second amplification circuit, an avalanche photodiode, a third amplification circuit and a band-pass filter circuit, an ADC module, a receiving lens, and a high-voltage circuit. The first laser beam module is provided with a green laser diode; and the second laser beam module is provided with a red laser diode. In the present invention, the green laser diode and the red laser diode are combined to implement ranging. The present invention has the characteristics of low power consumption, low cost, and high measurement precision.

Description

Green laser phase rangefinder and ranging method Technical Field

[0001] The present invention relates to the field of laser ranging, and in particular to a green laser phase rangefinder and a ranging method. Background Art

[0002] With advances in materials, green semiconductor laser diode technology is becoming increasingly mature. Some manufacturers, both domestically and internationally, have pioneered mass production of semiconductor laser diodes in the 510-530nm wavelength range, which appears green. Traditional handheld laser rangefinders use laser diodes in the 630-660nm wavelength range, which appears red. Due to the structure of the human eye, it is more sensitive to green light, resulting in a higher degree of visibility.

[0003] Because the human eye is more sensitive to green lasers, green lasers are increasingly common in handheld laser rangefinders. A comparative experiment was conducted: with a laser power of 1mW and an outdoor white wall illuminated at 5000 lux (Lux is a unit of light intensity; higher lux indicates stronger light). A person holding a laser rangefinder shines a laser dot onto the wall and steps back perpendicular to the wall, observing the laser dot with their naked eye to determine if it is visible. When the laser wavelength is 650nm, the visible distance is approximately 10m; when the laser wavelength is 520nm, the visible distance is 30m. Therefore, under the same conditions, the visible distance of green laser light is approximately three times that of red light. Because handheld laser rangefinders require the laser dot to locate a point before measuring, this gives green lasers significant advantages in handheld laser rangefinders.

[0004] One existing green laser handheld rangefinder solution operates as follows: an MCU controls a DDS to generate frequencies f1 and f2. Frequency f1 is amplified by an amplifier circuit and then modulated on green laser diode 1. Frequency f2 is modulated on an APD by amplifier circuit 2. Frequency f1 and f2 are simultaneously input to a mixing filter circuit, whose output is fed into the MCU for synchronization with the measurement signal. During ranging, the MCU powers on green laser diode 1. Frequency f1 is amplified and then modulated on green laser diode 1, causing the emitted laser beam 1 to vary in brightness at a frequency consistent with frequency f1. Laser beam 1 strikes the object being measured and is reflected by the surface. The reflected light passes through a receiving lens and is received by the APD, which converts the optical signal into an electrical signal with a frequency of f1. The frequency f2 coupled to the APD is mixed with the frequency f1 by the APD to generate two new frequency signals: f1+f2 and f1-f2 (where f1 > f2). The APD outputs these two signals to amplifier circuit 3 and a bandpass filter circuit (the center frequency of the bandpass filter circuit is f1-f2), leaving only an electrical signal with a frequency of f1-f2. This signal is the measurement signal. After being synchronized with f3, its phase represents the measured distance D1. This solution uses a single green laser for distance measurement. When the external ambient temperature fluctuates, the temperature changes will cause phase drift in the electronic components and the laser diode, resulting in temperature-dependent accuracy changes. Therefore, a laser rangefinder using a single green laser diode has limited measurement accuracy.

[0005] Another solution works as follows: The MCU controls the DDS to generate frequencies f1, f2, and f3. After being amplified by the amplifier circuit, f1 is modulated on green laser diode 1 and green laser diode 2. After being modulated on the APD by amplifier circuit 2, f2 is modulated on the APD. f3 is input to the MCU for synchronization with the measurement signal. During distance measurement, the MCU first powers on green laser diode 1 and powers off green laser diode 2. This causes the laser beam 1 emitted by green laser diode 1 to vary in brightness, with a frequency matching that of f1. After laser beam 1 strikes the object being measured, it is reflected by the surface. The reflected light passes through a receiving lens and is received by the APD, which converts the optical signal into an electrical signal with a frequency of f1. The electrical signal at frequency f2, coupled to the APD, is mixed with the electrical signal at frequency f1 to generate two new electrical signals at different frequencies: f1+f2 and f1-f2 (where f1>f2). The APD outputs these two signals to amplifier circuit 3 and a bandpass filter circuit (the center frequency of the bandpass filter circuit is f1-f2), leaving only an electrical signal with frequencies f1-f2. This signal is the measurement signal. When synchronized with f3, its phase represents the measured distance D1. Similarly, the MCU controls the power supply of green laser diode 1 to turn off and that of green laser diode 2 to turn on. Laser beam 2 irradiates the rangefinder's internal cavity, where it is reflected and received by the APD. The distance D2 (D2 is a fixed value) traveled within the cavity can be measured. The final distance D = D1 - D2. Subtracting the internal and external distances can minimize the impact of ambient temperature on the rangefinder. This solution uses two green lasers for distance measurement. Because green laser diodes consume approximately four times the power of red laser diodes, they tend to generate heat during operation. Furthermore, green laser diodes are approximately 15 times more expensive than red laser diodes. Using two green laser diodes to construct a laser rangefinder has the following disadvantages: high cost and high power consumption.

[0006] In summary, the existing green laser handheld laser rangefinder has the disadvantages of high power consumption, high cost and low measurement accuracy. Summary of the Invention

[0007] The present invention aims to provide a green laser phase rangefinder and a distance measurement method, which have the characteristics of low power consumption, low cost and high measurement accuracy.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] A green laser phase rangefinder includes: a DDS, a frequency mixing filter circuit, an MCU, a first amplifier circuit, an analog switch, a first laser beam module, a second laser beam module, a second amplifier circuit, an avalanche photodiode, a third amplifier circuit and a bandpass filter circuit, an ADC module, a receiving lens, and a high-voltage circuit; a green laser diode is provided in the first laser beam module; and a red laser diode is provided in the second laser beam module.

[0010] The DDS generates a frequency f1 signal, a frequency f2 signal, and a frequency f3 signal; the frequency f1 signal passes through a first amplifier circuit and enters an analog switch; the analog switch inputs the amplified frequency f1 signal into the first laser beam module and the second laser beam module, respectively; the frequency f2 signal passes through a second amplifier circuit and is modulated on an avalanche photodiode; the frequency f1 signal and the frequency f2 signal pass through a mixing filter circuit and are input into an MCU; the frequency f3 signal is input into the MCU for synchronous measurement of the signal;

[0011] During distance measurement, the MCU controls the power supply of the green laser diode in the first laser beam module to turn on, and the power supply of the red laser diode in the first laser beam module to turn off; the MCU also controls the analog switch to modulate the amplified frequency f1 signal on the green laser diode, and disconnect the amplified frequency f1 signal from the red laser diode; so that the first laser beam emitted by the green laser diode produces light and dark changes, and the frequency of the change is consistent with the frequency f1; after the first laser beam is irradiated on the object to be measured, it is reflected by the surface of the object, and the reflected light is received by the avalanche photodiode through the receiving lens, and the avalanche photodiode converts the optical signal into an electrical signal with a frequency of f1; at the same time, the electrical signal with a frequency of f2 coupled to the avalanche photodiode is mixed with the electrical signal with a frequency of f1 on the avalanche photodiode to generate two new The avalanche photodiode outputs the two new frequency electrical signals to the third amplifying circuit and the bandpass filtering circuit to obtain a measurement signal; after the measurement signal is synchronized with the signal of frequency f3 or the output signal of the mixing filter circuit, the measured distance D1 is determined according to the phase of the synchronized measurement signal; the MCU controls the power supply of the green laser diode to turn off and the power supply of the red laser diode to turn on; the MCU also controls the analog switch to disconnect the amplified frequency f1 signal from the green laser diode and modulate the amplified frequency f1 signal onto the red laser diode; the second laser beam is irradiated into the internal cavity of the rangefinder and is received by the avalanche photodiode after reflection, thereby measuring the distance D2 traveled by the second laser beam in the internal cavity of the rangefinder; the measured distance D is determined according to the difference between the measured distance D1 and the distance D2.

[0012] Optionally, the first laser beam module includes: a first power supply circuit, a first switch and a green laser diode.

[0013] Optionally, the second laser beam module includes: a second power supply circuit, a second switch and a red laser diode.

[0014] Optionally, the frequencies of the electrical signals of the two new frequencies are: f1+f2 and f1-f2; f1>f2.

[0015] Optionally, the center frequency of the band-pass filter circuit in the third amplifying circuit and the band-pass filter circuit is f1-f2.

[0016] A measurement method for a green laser phase rangefinder is applied to the green laser phase rangefinder; the measurement method comprises:

[0017] The green laser phase rangefinder is placed at a position L0 away from the target surface;

[0018] According to the green laser phase rangefinder, the distance is measured using ruler 1, and distances D1, D2, and D3 are obtained respectively; the distance D1 corresponds to ruler 1; the distance D2 corresponds to ruler 2; and the distance D3 corresponds to ruler 3; the frequency of ruler 1 is higher than that of rulers 2 and 3;

[0019] Using distance D1 as the reference distance, determine the deviation of ruler 2 relative to ruler 1. D2-D1 And the deviation of ruler 3 relative to ruler 1▽ D3-D1 ;

[0020] Take advantage of ▽ D2-D1 Correct the distance D2 to obtain the distance D2';

[0021] Exploiting bias D3-D1 Correct the distance D3 to obtain the distance D3';

[0022] Connect the distance measurement D1, the distance measurement D2' and the distance measurement D3' to obtain the distance measurement D;

[0023] The distance C0 is obtained based on the difference between the standard distance L0 and the distance D;

[0024] According to the green laser phase rangefinder, different measuring scales are used to measure the distance of the measured target, and the distance D4 after connection is determined;

[0025] The target distance is determined based on the difference between the distance D4 and the distance C0 after the connection.

[0026] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0027] The present invention provides a green laser phase rangefinder and ranging method. When measuring distance, the MCU controls the power supply of the green laser diode in the first laser beam module to turn on, and the power supply of the red laser diode in the first laser beam module to turn off; the MCU simultaneously controls the analog switch to modulate the amplified signal of frequency f1 on the green laser diode, and disconnects the amplified signal of frequency f1 from the red laser diode; the first laser beam emitted by the green laser diode produces light and dark changes, and the frequency of the change is consistent with the frequency f1; after the first laser beam is irradiated on the object to be measured, it is reflected by the surface of the object, and the reflected light is received by the avalanche photodiode through the receiving lens, and the avalanche photodiode converts the optical signal into an electrical signal, and the frequency of the electrical signal is f1; at the same time, the electrical signal with a frequency of f2 coupled to the avalanche photodiode and the electrical signal with a frequency of f1 are coupled in the avalanche photodiode. The diode is mixed to generate two electrical signals of new frequencies; the avalanche photodiode outputs the two electrical signals of new frequencies to the third amplifier circuit and the bandpass filter circuit to obtain a measurement signal; after the measurement signal is synchronized with the signal of frequency f3 or the output signal of the frequency mixing filter circuit, the measured distance D1 is determined based on the phase of the synchronized measurement signal; the MCU controls the power supply of the green laser diode to turn off and the power supply of the red laser diode to turn on; the MCU simultaneously controls the analog switch to disconnect the amplified signal of frequency f1 from the green laser diode and modulate the amplified signal of frequency f1 onto the red laser diode; the second laser beam is irradiated into the internal cavity of the rangefinder and, after reflection, is received by the avalanche photodiode, thereby measuring the distance D2 traveled by the second laser beam in the internal cavity of the rangefinder; the measured distance D is determined based on the difference between the measured distance D1 and the distance D2. That is, the present invention achieves distance measurement by controlling the first laser beam module and the second laser beam module, and combines the green laser diode with the red laser diode, thereby ensuring measurement accuracy and reducing power consumption and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] FIG1 is a schematic structural diagram of a green laser phase rangefinder provided by the present invention;

[0030] Figure 2 is a schematic diagram of the analog switch structure;

[0031] FIG3 is a schematic diagram of the first switch structure;

[0032] FIG4 is a schematic diagram of the second switch structure. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] The present invention aims to provide a green laser phase rangefinder and a distance measurement method, which have the characteristics of low power consumption, low cost and high measurement accuracy.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] As shown in Figure 1, a green laser phase rangefinder provided by the present invention includes: a DDS, a mixing filter circuit, an MCU, a first amplifier circuit, an analog switch, a first laser beam module, a second laser beam module, a second amplifier circuit, an avalanche photodiode APD, a third amplifier circuit and a bandpass filter circuit, an ADC module, a receiving lens, and a high-voltage circuit; a green laser diode is provided in the first laser beam module; and a red laser diode is provided in the second laser beam module.

[0037] The DDS generates signals with frequencies f1, f2, and f3. The signal with frequency f1 passes through the first amplifier circuit and enters the analog switch. The analog switch inputs the amplified signal with frequency f1 into the first laser beam module and the second laser beam module, respectively, as shown in Figure 2. The signal enters the analog switch (U3) input channel (pin 4). The analog switch outputs two channels (pins 1 and 3) that are connected to the green laser diode (J1) (the green laser diode has a wavelength between 490nm and 560nm) and the red laser diode (J2) (the red laser diode has a wavelength between 580nm and 905nm). The signal with frequency f2 passes through the second amplifier circuit and is modulated on the avalanche photodiode. The signals with frequencies f1 and f2 are input into the MCU through the mixing and filtering circuit. The signal with frequency f3 is input into the MCU for synchronous measurement of the signal.

[0038] During distance measurement, the MCU controls the power supply of the green laser diode in the first laser beam module to turn on, and the power supply of the red laser diode in the first laser beam module to turn off; the MCU also controls the analog switch to modulate the amplified frequency f1 signal on the green laser diode, and disconnect the amplified frequency f1 signal from the red laser diode; so that the first laser beam emitted by the green laser diode produces light and dark changes, and the frequency of the change is consistent with the frequency f1; after the first laser beam is irradiated on the object to be measured, it is reflected by the surface of the object, and the reflected light is received by the avalanche photodiode through the receiving lens, and the avalanche photodiode converts the optical signal into an electrical signal with a frequency of f1; at the same time, the electrical signal with a frequency of f2 coupled to the avalanche photodiode is mixed with the electrical signal with a frequency of f1 on the avalanche photodiode to generate two new The avalanche photodiode outputs the two new frequency electrical signals to the third amplifier circuit and bandpass filter circuit to obtain a measurement signal. After the measurement signal is synchronized with the signal at frequency f3 or the output signal of the mixing filter circuit, the measured distance D1 is determined based on the phase of the synchronized measurement signal. The MCU controls the power supply of the green laser diode to turn off and the power supply of the red laser diode to turn on. The MCU also controls the analog switch to disconnect the amplified frequency f1 signal from the green laser diode and modulate the amplified frequency f1 signal to the red laser diode. The second laser beam is irradiated into the rangefinder's internal cavity and, after reflection, is received by the avalanche photodiode, which measures the distance D2 traveled by the second laser beam within the rangefinder's internal cavity. The measured distance D is determined based on the difference between the measured distance D1 and the distance D2. The frequencies of the two new frequency electrical signals are: f1+f2 and f1-f2; f1>f2. The center frequency of the bandpass filter circuit in the third amplifier circuit and bandpass filter circuit is f1-f2.

[0039] The first laser beam module includes: a first power supply circuit, a first switch, and a green laser diode. A schematic diagram of the structure of the first switch is shown in FIG4 .

[0040] The second laser beam module includes: a second power supply circuit, a second switch, and a red laser diode. A schematic diagram of the structure of the second switch is shown in FIG3 .

[0041] Connect the MCU's EX_LDEN pin to one end of R37, the other end of R37 to Q10's pin 1, Q10's pin 3 to ground, and Q10's pin 2 to Q11's pin 1. Connect the 7V power supply to one end of L14, the other end of L14 to R48, and then to Q11's pin 2. Connect the green laser diode J1's pin 1 to U3's pin 3. Connect J1's pin 2 to one end of C8, the other end of C8 to ground. Connect J1's pin 3 to one end of R4, the other end of R4 to ground.

[0042] Connect the MCU INT_LDEN pin to Q9 pin 1, the 3.3V power output to one end of L3, the other end of L3 to Q9 pin 2, Q9 pin 3 to red laser diode J2 pin 2, and J2 pin 1 to U3 pin 1. Connect J2 pin 2 to one end of C10, the other end of C10 is grounded, and J1 pin 3 to J2 pin 3.

[0043] Connect the MCU's SW pin to U3's pin 5. The 3.3V power supply output is connected to one end of C28, which is then connected to U3's pin 2. The other end of C28 is grounded. Connect Q1's pin 1 to one end of R8, which is grounded. Q1's pin 3 is grounded. The 3.3V supply is connected to one end of R5, which is then connected to one end of C5, which is then connected to Q1's pin 2 and Q3's pin 1. The other end of C5 is grounded. Q3's pin 3 is grounded. Q3's pin 2 is connected to one end of L7, which is connected to U3's pin 1.

[0044] As a specific example, after the first laser beam strikes the object being measured, it is reflected by the surface. The reflected light passes through a receiving lens and is received by an APD (D1). The APD (D1) converts the optical signal into an electrical signal with a frequency of f1. Simultaneously, the electrical signal with a frequency of f2 coupled to the APD (D1) is mixed with the electrical signal with a frequency of f1 within the APD to produce two new electrical signals with different frequencies: f1+f2 and f1-f2 (where f1>f2). The APD outputs these two signals to a third amplifier circuit and a bandpass filter circuit (the center frequency of the bandpass filter circuit is f1-f2), leaving only the electrical signal with a frequency of f1-f2, which serves as the measurement signal. The MCU divides the frequency of f3 by N, such that f3 / N = f1-f2. The MCU controls the ADC to sample the measurement signal at the rising edge of the synchronization signal (f3 / N). Fourier transform analysis is performed on the sampled signal to obtain the phase value P1 of the measurement signal (the sum of the phase difference p1 caused by the transmission of laser beam 1 and the phase delay p1' caused by the circuit and laser). According to the theory of indirect difference frequency measurement, the distance represented by p1 is the distance traveled by the signal laser beam 1. Similarly, the MCU controls the power supply of the green laser diode (J1) to be turned off and the power supply of the red laser diode (J2) to be turned on. The MCU also controls the analog switch to disconnect the modulation signal f1 from the green laser diode (J1) and modulate the modulation signal f1 to the red laser diode (J2). Laser beam 2 irradiates the internal cavity of the rangefinder, is reflected, and is received by the APD (D1). Similarly, the phase value P1' of the measurement signal can be obtained (the sum of the phase difference p1'' caused by the transmission of laser beam 2 and the phase delay p1''' caused by the circuit and laser).

[0045] Assume f1=150MHz, f2=150M-5Khz, f3=5KHz, and the speed of light C=3*10 8m / s; the propagation distance of laser beam 1 is d1 (d1 ≥ 20 cm), and the propagation distance of laser beam 2 is d (d ≤ 10 cm); the phase delay of the circuit and laser diode 1 to f1 is p1'', and the phase delay of the circuit and laser diode 2 to f1 is p1'''.

[0046] Let λ1=C / f1 / 2, where λ1 is the measuring ruler corresponding to the frequency of 150MHz.

[0047] According to the above method:

[0048] d1=(p1 / 360)*λ1+(p1' / 360)*2*λ1.

[0049] d=(p1'' / 360)*2*λ1+(p1''' / 360)*2*λ1.

[0050] In the dual laser diode ranging system, we use d1 minus d to eliminate the influence of temperature on the ranging system. The ranging result D=(d1-d)=(p1-2*p1'') / 360*λ1+(p1'-p1''') / 360*2*λ1.

[0051] Let L = (p1-2*p1'') / 360*λ1, S = (p1'-p1''') / 360*2*λ1, L represents the difference in propagation between laser beam 1 and laser beam 2, S represents the difference in phase delay generated by the circuit related to the green laser diode and the circuit related to the red laser diode, then D = L+S.

[0052] When the laser diode models are the same, p1''' is equal to p1', and S=0. When the laser diode models are different, p1''' is not equal to p1', and S is not equal to 0.

[0053] When using a single ruler, the distance measurement result will be limited by the ruler. When the ruler frequency is higher, the accuracy is higher, the ruler is shorter, and the distance measurement will be limited. When the ruler frequency is lower, the accuracy is lower, the ruler is longer, and the distance measurement accuracy will be limited. The common practice is to select three or more rulers and connect the distance measurement results to achieve the distance measurement accuracy and range requirements of the rangefinder. Now, taking a rangefinder with a range of 100 meters as an example, the following three rulers are selected:

[0054] Measuring ruler 1: f1=150MHz, f2=150M-5Khz, f3=5KHz, then λ1=1m.

[0055] Measuring ruler 2: f1'=15MHz, f2'=15M-5Khz, f3'=5KHz, then λ2=10m.

[0056] Measuring ruler 3: f1''=1.5MHz, f2''=1.5M-5Khz, f3''=5KHz, then λ3=100m.

[0057] The distance measurement results obtained by three rulers measuring the same distance are D1, D2, and D respectively; D1=L1+S1; D2=L2+S2; D3=L3+S3.

[0058] When the laser diode models are the same, S1=S2=S3=0; D1, D2, D3 are connected without any problems. When the laser diode models are different, S1, S2, S3 are not equal to 0 and are not equal, which will cause connection errors and lead to errors in the distance measurement result D, and the following embodiments:

[0059] The present invention also provides a measurement method of a green laser phase rangefinder, which is applied to the green laser phase rangefinder; the measurement method comprises:

[0060] The green laser phase rangefinder is placed at a position at a standard range L0 from the target surface.

[0061] According to the green laser phase rangefinder, ruler 1 is used to measure distances, obtaining distances D1, D2, and D3. Distance D1 corresponds to ruler 1; distance D2 corresponds to ruler 2; and distance D3 corresponds to ruler 3. Ruler 1 has a higher frequency than rulers 2 and 3. D1 = L1 + S1; D2 = L2 + S2; and D3 = L3 + S3.

[0062] Using distance D1 as the reference distance, determine the deviation of ruler 2 relative to ruler 1. D2-D1 =D2-D1 and the deviation of ruler 3 relative to ruler 1▽ D3-D1 =D3-D1.

[0063] Take advantage of ▽ D2-D1 Correct the distance D2 to obtain the distance D2'.

[0064] Exploiting bias D3-D1 Correct the distance D3 to obtain the distance D3'.

[0065] Distance measurement D1, distance measurement D2' and distance measurement D3' are connected to obtain distance measurement D.

[0066] The distance C0 is obtained based on the difference between the standard distance L0 and the distance D.

[0067] According to the green laser phase rangefinder, different measuring scales are used to measure the distance of the measured target to determine the distance D4 after connection.

[0068] The target distance is determined based on the difference between the distance D4 and the distance C0 after the connection.

[0069] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0070] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A green laser phase rangefinder, characterized in that: include: DDS, mixing filter circuit, MCU, first amplifier circuit, analog switch, first laser beam module, second laser beam module, second amplifier circuit, avalanche photodiode, third amplifier circuit and bandpass filter circuit, ADC module, receiving lens and high-voltage circuit; a green laser diode is set in the first laser beam module; a red laser diode is set in the second laser beam module; The DDS generates a signal of frequency f1, a signal of frequency f2 and a signal of frequency f3; The signal of frequency f1 enters the analog switch through the first amplifier circuit; the analog switch inputs the amplified signal of frequency f1 into the first laser beam module and the second laser beam module respectively; the signal of frequency f2 passes through the second amplifier circuit and is modulated on the avalanche photodiode; the signal of frequency f1 and the signal of frequency f2 are input into the MCU through the mixing filter circuit; the signal of frequency f3 is input into the MCU for synchronous measurement of the signal; When measuring distance, the MCU controls the power of the green laser diode in the first laser beam module to turn on, and the power of the red laser diode in the first laser beam module to turn off; the MCU also controls the analog switch to modulate the amplified signal of frequency f1 on the green laser diode, and disconnect the amplified signal of frequency f1 from the red laser diode; The first laser beam emitted by the green laser diode is made to produce light and dark changes, and the frequency of the change is consistent with the frequency f1; after the first laser beam is irradiated on the object to be measured, it is reflected by the surface of the object, and the reflected light is received by the avalanche photodiode through the receiving lens, and the avalanche photodiode converts the optical signal into an electrical signal, and the frequency of the electrical signal is f1; at the same time, the electrical signal with a frequency of f2 coupled to the avalanche photodiode is mixed with the electrical signal with a frequency of f1 on the avalanche photodiode to generate two electrical signals with new frequencies; the avalanche photodiode outputs the two electrical signals with new frequencies to the third amplifier circuit and the bandpass filter circuit to obtain a measurement signal; the measurement signal and the frequency After the signal with frequency f3 or the output signal of the mixing filter circuit is synchronized, the measured distance D1 is determined according to the phase of the synchronized measurement signal; the MCU controls the power supply of the green laser diode to turn off and the power supply of the red laser diode to turn on; the MCU also controls the analog switch to disconnect the amplified signal of frequency f1 from the green laser diode and modulate the amplified signal of frequency f1 onto the red laser diode; the second laser beam is irradiated to the internal cavity of the rangefinder, and is received by the avalanche photodiode after reflection, and then the distance D2 transmitted by the second laser beam in the internal cavity of the rangefinder is measured; the distance D is determined according to the difference between the measured distance D1 and the distance D2.

2. A green laser phase rangefinder according to claim 1, characterized in that: The first laser beam module includes: a first power supply circuit, a first switch and a green laser diode.

3. A green laser phase rangefinder according to claim 1, characterized in that: The second laser beam module includes: a second power supply circuit, a second switch and a red laser diode.

4. A green laser phase rangefinder according to claim 1, characterized in that: The frequencies of the electrical signals of the two new frequencies are: f1+f2 and f1-f2; f1>f2.

5. A green laser phase rangefinder according to claim 4, characterized in that: The center frequency of the band-pass filter circuit in the third amplifying circuit and the band-pass filter circuit is f1-f2.

6. A green laser phase rangefinder according to claim 1, characterized in that: The wavelength of the green laser diode is between 490nm and 560nm, and / or the wavelength of the red laser diode is between 580nm and 905nm.

7. A measurement method of a green laser phase rangefinder, applied to a green laser phase rangefinder according to any one of claims 1 to 6; characterized in that: The measuring method comprises: Placing a green laser phase rangefinder according to any one of claims 1 to 6 at a position L0 away from a target surface; According to the green laser phase rangefinder, the distance is measured by using ruler 1, and distances D1, D2 and D3 are obtained respectively; the distance D1 corresponds to ruler 1; the distance D2 corresponds to ruler 2; the distance D3 corresponds to ruler 3; the frequency of ruler 1 is higher than that of ruler 2 and ruler 3; Using distance D1 as reference distance, determine the deviation of ruler 2 relative to ruler 1▽ D2-D1 And the deviation of ruler 3 relative to ruler 1▽ D3-D1 ; Take advantage of ▽ D2-D1 Correct the distance measurement D2 to obtain the distance measurement D2'; Exploiting Bias D3-D1 Correct the distance measurement D3 to obtain the distance measurement D3'; Connect the distance measurement D1, the distance measurement D2' and the distance measurement D3' to obtain the distance measurement D; The distance measurement C0 is obtained according to the difference between the standard distance measurement L0 and the distance measurement D; According to the green laser phase rangefinder, different measuring scales are used to measure the distance of the measured target to determine the distance D4 after connection; The target distance is determined based on the difference between the connected distance measurement D4 and the distance measurement C0.

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