阅读说明：本技术 一种基于粗精测尺差频调制与解调的协作式相位激光测距装置及其测距方法 (Cooperative phase laser ranging device based on coarse and fine measuring scale difference frequency modulation and demodulation and ranging method thereof ) 是由 杨宏兴 李婧 胡鹏程 邢旭 谭久彬 于 2021-08-12 设计创作，主要内容包括：本发明是一种基于粗精测尺差频调制与解调的协作式相位激光测距装置及其测距方法。本发明在相位激光测距系统的待测目标处设置协作端,能够将测量光光强放大后照射回测量端,改善远距离测距光强衰减造成测距精度不高的问题。协作端探测粗测尺信号并以差频调制的方式调制激光器；协作端通过差频解调方法探测精测尺信号,后通过混频复原精测尺信号并调制协作端激光器,实现了对测量光强的放大。该发明方法与装置打破了探测器带宽、调制带宽对测尺频率的限制,使协作式相位激光测距技术能够兼顾大范围和高精度的测距要求,可实现数十万千米的测量范围并达到亚毫米甚至微米级的测量精度。(The invention relates to a cooperative phase laser ranging device based on coarse and fine measuring scale difference frequency modulation and demodulation and a ranging method thereof. According to the invention, the cooperation end is arranged at the position of the target to be measured of the phase laser ranging system, so that the measuring light intensity can be amplified and then irradiated back to the measuring end, and the problem of low ranging precision caused by attenuation of the light intensity of long-distance ranging is solved. The cooperative end detects the rough measuring scale signal and modulates the laser in a difference frequency modulation mode; the cooperative end detects the precision measuring scale signal through a difference frequency demodulation method, then recovers the precision measuring scale signal through frequency mixing and modulates the laser of the cooperative end, and amplification of the measured light intensity is achieved. The method and the device break through the limitation of the detector bandwidth and the modulation bandwidth on the measuring scale frequency, so that the cooperative phase laser ranging technology can meet the ranging requirements of large range and high precision, can realize the measuring range of hundreds of thousands of meters and can reach the measuring precision of sub-millimeter or even micron level.)

1. A cooperative phase laser ranging device based on coarse and fine measuring scale difference frequency modulation and demodulation is characterized in that: the device comprises: the measuring end comprises a multi-frequency generation module, a laser modulation module, a measuring end optical path and an optical signal receiving and processing module, the multi-frequency generation module generates three paths of output, two paths of the output are input into the laser modulation module to modulate laser, the other path of the output is input into the optical signal processing and receiving module, the output of the laser modulation module is input into the measuring end optical path, and the two paths of the output of the measuring end optical path are respectively measuring light and reference light signals which are input into the measuring end optical signal receiving and processing module to measure phase.

2. The cooperative phase laser ranging device based on rough and fine measurement scale difference frequency modulation and demodulation as claimed in claim 1, wherein: the multi-frequency generation module comprises a first crystal oscillator, a second crystal oscillator, a third crystal oscillator, a first phase-locked frequency doubling circuit, a second phase-locked frequency doubling circuit, a third phase-locked frequency doubling circuit, a fourth phase-locked frequency doubling circuit, a first to fifth amplifying circuits, a first power synthesizer and a second power synthesizer;

the output end of the first crystal oscillator is connected to the input end of the first phase-locked frequency doubling circuit and passes through the first amplifying circuit; the output signal of the first crystal oscillator is connected to the input end of the second phase-locked frequency doubling circuit and passes through the second amplifying circuit, the output end of the second crystal oscillator is connected to the input end of the third amplifying circuit, and the output signal of the third crystal oscillator is connected to the input end of the third phase-locked frequency doubling circuit and passes through the fourth amplifying circuit; the output signal of the third crystal oscillator is connected to the input end of the fourth phase-locked frequency multiplier circuit and passes through the fifth amplifying circuit; the output end of the first amplifying circuit and the output end of the fifth amplifying circuit are respectively input to two input ends of a first power synthesizer, the output end of the first power synthesizer is connected to the input end of the first electro-optical modulator to be used as a driving signal, the output end of the second power synthesizer is connected to the input end of the second electro-optical modulator to be used as a driving signal, and the output end of the second amplifying circuit (14) is connected to the input ends of the third electro-optical modulator and the fourth electro-optical modulator to be used as a driving signal.

3. The cooperative phase laser ranging device based on rough and fine measurement scale difference frequency modulation and demodulation as claimed in claim 2, wherein: the laser modulation module comprises a laser, a first electro-optic modulator, a second electro-optic modulator, a first double-path light splitting optical fiber and a second double-path light splitting optical fiber; the output of the laser is connected to the first double-path branching optical fiber and divided into two paths, one path of output end of the first double-path branching optical fiber is connected to the input end of the first electro-optical modulator, the other path of output end of the first double-path branching optical fiber is connected to the input end of the second electro-optical modulator, the output ends of the first electro-optical modulator and the second electro-optical modulator are respectively connected to the two input ends of the second double-path branching optical fiber, and the output end of the second double-path branching optical fiber is connected to the input end of the measuring optical path.

4. The cooperative phase laser ranging device based on rough and fine measurement scale difference frequency modulation and demodulation as claimed in claim 3, wherein: the measuring light path comprises a first collimator, a second collimator, a third collimator, a spectroscope and a beam expander set; the output end of the second double-path branching optical fiber is connected to the input end of the first collimator, the output end of the first collimator is connected to the spectroscope, one path of output of the spectroscope is connected to the input end of the second collimator as reference light, the output end of the second collimator is connected to one input end of the optical signal receiving and processing module, the other path of output of the spectroscope is connected to the input end of the beam expanding lens group, the output end of the beam expanding lens group is connected to the input end of the cooperation end optical path, the output end of the cooperation end optical path is connected to the input end of the spectroscope through the beam expanding lens group, the output end of the spectroscope is connected to the input end of the third collimating lens as measuring light, and the output end of the third collimating lens reaches the other input end of the optical signal receiving and processing module.

5. The cooperative phase laser ranging device based on rough and fine measurement scale difference frequency modulation and demodulation as claimed in claim 4, wherein: the optical signal receiving and processing module comprises a third double-path light splitting optical fiber, a fourth double-path light splitting optical fiber, a third electro-optic modulator, a fourth electro-optic modulator, a first to fourth photoelectric detectors, a sixth to ninth amplifying circuit, a first to fourth filter circuit and a high-precision phase measurement board card; one output end of the measuring light path is used as reference light and is connected with the input end of a third double-path light splitting optical fiber and then is divided into two paths, one output end of the third double-path light splitting optical fiber is connected to the input end of a third electro-optical modulator, the input end of the third electro-optical modulator is connected to the input end of a first photoelectric detector, the output end of the first photoelectric detector, a sixth amplifying circuit and a first filtering circuit are sequentially connected, the output end of the first filtering circuit is connected to the high-precision phase measurement board card, and the other output end of the third double-path light splitting optical fiber is connected to the input end of a second photoelectric detector, and then is sequentially connected to the high-precision phase measurement board card through a seventh amplifying circuit and a second filtering circuit;

the other output end of the measuring light path is used as measuring light and is connected with the input end of a fourth double-path branching optical fiber and is divided into two paths, one output end of the fourth double-path branching optical fiber is connected to the input end of a fourth electro-optical modulator, the output end of the fourth electro-optical modulator, a third photoelectric detector, an eighth amplifying circuit and a third filtering circuit are sequentially connected, and the output end of the third filtering circuit is connected to the high-precision phase measurement board card; and the other output end of the fourth double-path branching optical fiber is connected to the input end of the fourth photoelectric detector and is connected to the high-precision phase measurement board card sequentially through a ninth amplifying circuit and a fourth filter circuit.

6. The cooperative phase laser ranging device based on rough and fine measurement scale difference frequency modulation and demodulation as claimed in claim 5, wherein:

the cooperative end is positioned at a measured target and comprises a cooperative end light path, a cooperative end laser modulation module, a multi-frequency modulation signal processing module and a cooperative end optical signal receiving and processing module; the optical signal receiving and processing module of the cooperation end generates three outputs and is connected to the multi-frequency modulation signal processing module as an input, the multi-frequency modulation signal processing module generates three outputs, wherein the two outputs are input to the laser modulation module of the cooperation end, and the other one is input to the optical signal receiving and processing module of the cooperation end.

7. A cooperative phase laser ranging method based on coarse and fine measurement scale frequency difference modulation and demodulation, the method is based on the cooperative phase laser ranging apparatus based on coarse and fine measurement scale frequency difference modulation and demodulation as described in claim 6, and is characterized in that: the method comprises the following steps:

step 1: a multi-frequency generation module at the measuring end generates a frequency v₁、v₁-f₁、v₂、v₃And v₃A + f sine signal, which is used for modulating the intensity of a laser beam output by the laser by an electro-optical intensity modulation method to generate a frequency v₁、v₂、v₃And v₃The light beam of the optical signal of + f is divided into two beams, one beam is taken as measuring light and emitted to a target to be measured, and the other beam is taken as a reference signal of a measuring end; wherein the frequency of the precision measuring ruler is v₁The frequency of the secondary precision measuring ruler is v₂The frequency of the rough measuring ruler is f;

step 2: the distance measurement cooperation end is positioned at the target to be measured and generates a sine electric signal Receiving a measuring signal from a measuring end at a cooperative end, dividing the measuring signal into two parts, secondarily modulating a part of light beams by an electro-optical intensity modulator, and enabling the frequency of a fine measuring scale signal at the cooperative end to be v₁-f₁Is generated at a frequency f under the modulation of the sine wave of₁Of the difference frequency signal ofWith precision measuring rule v₁Using a photodetector and a filter to convert and separate the frequency f₁Of the difference frequency electric signalDetecting another part of the measuring beam v by a photodetector₃And v₃The difference frequency signal f of + f is used as a coarse measuring scale, and the phase of the difference frequency signal fFor rough measurement, a secondary fine measuring rule v is converted and separated by using a photoelectric detector and a filter₂And the electrical signals of the rough measuring ruler f are respectively

And step 3: the extracted electric signal with the phase information is used as a modulation signal to carry out intensity modulation on the output light of the laser at the cooperative end; will have the electrical signal of the accurate survey chi range finding phase place informationFrequency with the cooperating end is v₁-f₁Of (2) a signalFrequency mixing, restoring precision measuring rule v with precision measuring phase information₁(ii) a Will measure roughlyFrequency v generated by the cooperative terminal₃Electrical signal ofMixing to obtain a frequency v₃An electrical signal of + f; the frequency generated is v₁、v₂、v₃And v₃The electrical signal of + f modulates the laser beam output by the cooperative end in an intensity modulation mode;

and 4, step 4: the laser of the cooperative end is modulated to be used as the measurement return light of a target end and is divided into two beams, wherein one beam is transmitted back to the measurement end, the other beam is used as a reference signal of the cooperative end, and the reference signal is input to an optical signal receiving and processing module of the cooperative end to measure and compensate the additional phase delay amount of the cooperative end; firstly, the frequency of the modulation is v at the cooperative end by an electro-optical modulator₁-f₁Of (2) a signalGenerating frequency f under modulation₁Of the difference frequency signalAnd with a return light middle precision measuring ruler v₁And the frequency f obtained by processing in the measuring light₁Electrical signal ofMeasuring the phase difference, the measured phase differenceThe additional value of the phase of the precision measuring scale generated by the cooperative end changes along with the change of environmental parameters of the cooperative end, which has great influence on the distance measuring precision and can be used for measuring the distance of the objectThe real-time compensation method comprises the steps of sending the data to a measuring end in real time through a laser communication module, and performing real-time compensation at the measuring end; while a rough measuring rule f and a secondary fine measuring rule v₂The drift of the additional phase value at the cooperative end has no influence on the precision of the distance measurement, the additional phase value is calibrated in advance through a phase difference calibration and compensation unit, and the fixed compensation phase value corresponding to the measuring scale is introduced at the measuring end

And 5: receiving the measured return light at the measuring end, demodulating partial light in the reference signal and the measured return light signal of the measuring end respectively by a method of electric light intensity secondary modulation, and obtaining the frequency v at the measuring end₁-f₁Is modulated by an electrical signal of (3) to generate a frequency f₁With precision measuring rule v₁The phase information of (a) is converted into an electric signal by a photodetector; converting the reference signal of the measuring end and the other part of the measured return light signal into electric signals by using a photoelectric detector, and separating by using a filter to obtain the frequency of the electric signalsIs v is₂And f, wherein f is the frequency of the rough measuring scale, is the frequency v in the reference light signal and the measured return light₃And v₃The phase of the difference frequency signal of the optical signal of + f is the measuring result of the rough ruler; respectively measuring frequency f₁、v₂F the phase difference between the reference electrical signal and the electrical signal for measuring the return light isThe distance measurement result of the multiple measuring rulers is obtained

And 6, synthesizing the three phase difference values by a data synthesis unit of the high-precision phase measurement board card to generate a distance value, wherein the frequency of the rough measurement ruler is f, the wavelength is lambda, and the distance measurement value of the rough measurement ruler is represented by the following formula:

frequency v₂The signal of (a) is a secondary rough measuring scale with a wavelength of lambda₂The distance measurement of the secondary rough rule is represented by:

frequency v₁The signal of (A) is a precision measuring ruler with a wavelength of lambda₁The measured distance is represented by the following formula:

wherein the floor () function is a rounding function.

Technical Field

The invention relates to the technical field of absolute distance laser measurement, in particular to a cooperative phase laser ranging device based on coarse and fine measurement scale difference frequency modulation and demodulation and a ranging method thereof.

Background

The laser ranging technology has the advantages of high measurement accuracy, strong anti-interference capability, high space-time and vertical resolution and the like, is widely applied to the fields of large-scale equipment manufacturing, spacecraft deep space navigation, rendezvous and docking, distributed formation satellites and the like, and becomes an indispensable key technology in aerospace, major scientific devices and national economic development research. With the development of scientific technology, especially the rapid advance of aerospace technology, higher performance requirements are put forward on the measurement range, measurement precision and stability of the measurement technology. In recent years, aiming at a space physical exploration research task, collaborative exploration of complex physical processes in space by using formation minisatellites becomes a research hotspot, such as GRACE-FO satellites of NASA in the United states, NMP ST-5 plan, Proba-3 satellites of European Bureau, Gemini satellites of Germany and the like, the distance between the minisatellites is from hundreds of meters to dozens of kilometers, and the measurement precision requirement of the distance reaches millimeter, submillimeter or even dozens of micrometers. In the research of space gravitational wave detection, the maximum arm length difference caused by the dissociation of the inter-satellite orbit respectively reaches 30 ten thousand kilometers, and in order to correctly capture gravitational wave signals, the absolute distance measurement precision of the arm length needs to reach 30 cm. The processing and integral assembly of large components also put forward higher requirements for distance measurement technology, and large and ultra-large single radio telescopes are taken as examples, in order to ensure the detection sensitivity and imaging precision of celestial bodies and interplanetary molecules, the caliber of the reflecting surface of hundreds of meters to thousands of meters is measured in real time and integrally controlled, and the measurement precision requirement of each reflecting surface is superior to several millimeters or even hundreds of micrometers. Therefore, with the enlargement of the space exploration range and the improvement of the detection precision requirement of people, the distance measurement technology is urgently required to simultaneously consider the ultra-long acting distance, the precision measurement accuracy and the high real-time property, and the sub-millimeter or even micron-scale precision measurement of the target in the range of hundreds of meters to hundreds of thousands of meters is realized.

However, the ultra-precise measurement methods such as laser interference ranging and the ultra-long distance measurement methods such as differential GPS ranging, pseudo-random code modulation ranging, pulse laser ranging, visible light vision measurement technology, electro-optical modulation optical frequency comb absolute ranging, etc. adopted at present limit further improvement of the performance thereof in principle or technology. For example, patent [ remote laser ranging system based on high-speed pseudo-random code modulation and photon counting, publication No.: the pseudo-random code modulation ranging method proposed by CN102928832A is similar to the pulse laser ranging method, is a measuring method based on pulse time, is limited by the influence of principle errors and device noise, and has centimeter-level measuring accuracy approaching the technical limit. Patent [ femtosecond optical frequency comb-based sine phase modulation interference absolute distance measuring device and method, publication No.: CN108120378A ] proposed optical frequency comb absolute distance measurement method is high in measurement accuracy, but it is limited by coherence length and difficult to be used for measurement distances of hundreds of kilometers to hundreds of thousands of kilometers.

Patent [ multifrequency synchronous modulation wide-range high-precision fast laser ranging method and device, publication No.: CN1825138A ] the proposed method and apparatus for measuring distance by using multi-wavelength modulated phase laser measure the absolute distance between the modulated light wave emitted from the measuring end and the modulated light wave reflected back from the measured target. Because the phase difference can only be between 0 and 2 pi, the measurement length cannot exceed one half of the wavelength, in order to ensure the distance measurement precision and the measurement range, a modulation method is adopted to generate a plurality of measuring rule wavelengths from coarse to fine for step-by-step measurement and step-by-step optimization, the longer measuring rule is used for meeting the measurement range, the shorter measuring rule is used for realizing the measurement precision, and the other measuring rules are used as transition measuring rules for connecting the coarse measuring rule and the fine measuring rule; accurate sub-millimeter and even micron scale measurements of targets in the range of hundreds of meters to hundreds of thousands of kilometers can be theoretically achieved. However, in the long-distance multi-wavelength modulation phase laser ranging, the measuring light is transmitted back and forth between the measuring end and the target end, the return light power is sharply attenuated by a fourth power function of the measured distance due to the divergence effect in the light beam propagation process, and the signal-to-noise ratio of the measuring signal is low, which becomes an important factor for limiting the phase laser ranging to perform long-distance measurement. Due to the limitations of the performance of the detecting device, the load of the detected object, the safety problem of the laser, and the like, it is difficult to increase the return light energy of the system by increasing the laser power and the aperture of the cooperative target.

Patent [ active cooperative phase laser ranging method and device, publication No.: CN101349757A proposes an internal modulation active ranging cooperative terminal based on current modulation, which detects and amplifies a measuring optical signal at the ranging cooperative terminal, modulates the measuring optical signal onto a laser of the cooperative terminal, and irradiates the measuring terminal, so that the cooperative work of an active cooperative target terminal device and a measuring terminal device is realized to jointly complete distance measurement, the attenuation form of the return optical energy of the measuring system is changed from a quadric attenuation function of the measured distance to a quadratic attenuation function, the return optical energy and the signal-to-noise ratio of the system are increased, and the effect in remote measurement is remarkable. However, for the requirement of distance measurement with micron-scale precision in a measurement range of hundreds of kilometers or more, the wavelength of a rough measurement ruler is more than 200km, the frequency of the corresponding rough measurement ruler is lower than 1.5KHz, and under the condition that the phase discrimination precision is 0.08 degrees, the required wavelength of a synthetic precise measurement ruler is 9mm, the frequency of the corresponding measurement ruler is 33.3GHz, so that the modulation bandwidth of laser at least covers 1.5KHz to 33.3 GHz. The current modulation adopted in the distance measuring method is limited by the laser lasing action and circuit parameters, the modulation bandwidth is narrow, the frequency of the produced accurate measuring ruler is insufficient, the required bias current is large, the working temperature is high, the output light power is unstable, and the accuracy and the stability of the accurate measuring result are influenced. Therefore, the method is difficult to meet the requirements of large-range and high-precision absolute distance measurement.

Patent [ a laser phase method range unit, publication No.: CN202351429U adopts an electro-optical modulator to generate a measuring tape signal with the frequency of more than 1GHz, but the high-bandwidth electro-optical modulator (more than 10G) is influenced by radio frequency line impedance, radio frequency joule effect and the like, so that the physical properties of an electrode and a waveguide are changed, the low-frequency modulation effect is poor, and the high-bandwidth electro-optical modulator cannot be simultaneously used for modulating low-frequency signals below 1MHz under the condition of ensuring the precision. Therefore, the modulation mode used at present cannot meet the ultra-wide modulation range from tens of Hz to tens of GHz, which causes the limitation of the cooperative phase laser ranging method in micron-level high-precision measurement in the ultra-long distance range, and further research on a high-bandwidth laser modulation method, namely a measuring tape generation mode, is needed, especially the non-ideal characteristic of low-frequency signal modulation is overcome, and the measurement range is expanded.

Secondly, the cooperative phase laser ranging technology needs a photoelectric detector to convert a coarse measuring rule and a fine measuring rule into electric signals for subsequent signal processing and phase discrimination, but the existing photoelectric detector has poor detection effect or even can not directly detect measuring rule signals up to dozens of GHz or even hundreds of GHz. Patent [ superheterodyne and heterodyne combined anti-optical aliasing laser ranging device and method, publication No.: CN104049248A adopts a photoelectric detection method combining heterodyne and superheterodyne, and obtains a precision phase measurement result by detecting superheterodyne signals, thereby avoiding direct detection of precision measurement ruler signals up to dozens to hundreds of GHz. However, since the optical paths of the measurement light and the reference light are different, when the optical path difference is larger than the coherence length, the interference signal-to-noise ratio is lowered, and it is difficult to perform phase extraction. Therefore, the method is limited by the coherence length, and the measurement range is limited to several kilometers and is difficult to further improve while ensuring high-precision measurement.

In order to break through the limitation of sharp attenuation of the return light energy of the measuring laser which returns back and forth in a long distance on the phase laser ranging technology and enable the phase laser ranging technology to meet the requirements of large-range and high-precision measurement, the cooperative phase laser ranging device and the measuring method are improved to enable the cooperative phase laser ranging device and the measuring method to meet the requirement of measuring range of hundreds of thousands of meters and simultaneously achieve sub-millimeter or even micron-scale measuring precision.

Disclosure of Invention

The invention aims to solve the problem of rapid attenuation of return light energy of ultra-long distance round-trip detection and avoid low ranging precision and even difficulty in ranging caused by weak signal-to-noise ratio of a measuring signal. The method has the advantages that the requirements for large-range and high-precision measurement are met, the phase laser ranging technology can achieve sub-millimeter or even micron-scale accurate measurement in the measurement range of hundreds of thousands of meters, and the requirements in the fields of future large-scale equipment manufacturing, spacecraft deep space navigation, rendezvous and docking, distributed formation satellites and the like can be met. The invention provides a cooperative phase laser ranging device based on coarse and fine measuring scale difference frequency modulation and demodulation and a ranging method thereof, and the invention provides the following technical scheme:

a cooperative phase laser ranging device based on coarse and fine caliper difference frequency modulation and demodulation, the device comprising: the measuring end comprises a multi-frequency generation module, a laser modulation module, a measuring end optical path and an optical signal receiving and processing module, the multi-frequency generation module generates three paths of output, two paths of the output are input into the laser modulation module to modulate laser, the other path of the output is input into the optical signal processing and receiving module, the output of the laser modulation module is input into the measuring end optical path, and the two paths of the output of the measuring end optical path are respectively measuring light and reference light signals which are input into the measuring end optical signal receiving and processing module to measure phase.

Preferably, the multi-frequency generation module comprises a first crystal oscillator, a second crystal oscillator, a third crystal oscillator, a first phase-locked frequency doubling circuit, a second phase-locked frequency doubling circuit, a third phase-locked frequency doubling circuit, a fourth phase-locked frequency doubling circuit, a first to fifth amplification circuits, a first power synthesizer and a second power synthesizer;

the output end of the first crystal oscillator is connected to the input end of the first phase-locked frequency doubling circuit and passes through the first amplifying circuit; the output signal of the first crystal oscillator is connected to the input end of the second phase-locked frequency doubling circuit and passes through the second amplifying circuit, the output end of the second crystal oscillator is connected to the input end of the third amplifying circuit, and the output signal of the third crystal oscillator is connected to the input end of the third phase-locked frequency doubling circuit and passes through the fourth amplifying circuit; the output signal of the third crystal oscillator is connected to the input end of the fourth phase-locked frequency multiplier circuit and passes through the fifth amplifying circuit; the output end of the first amplifying circuit and the output end of the fifth amplifying circuit are respectively input to two input ends of a first power synthesizer, the output end of the first power synthesizer is connected to the input end of the first electro-optical modulator to be used as a driving signal, the output end of the second power synthesizer is connected to the input end of the second electro-optical modulator to be used as a driving signal, and the output end of the second amplifying circuit (14) is connected to the input ends of the third electro-optical modulator and the fourth electro-optical modulator to be used as a driving signal.

Preferably, the laser modulation module comprises a laser, a first electro-optic modulator, a second electro-optic modulator, a first double-path light splitting optical fiber and a second double-path light splitting optical fiber; the output of the laser is connected to the first double-path branching optical fiber and divided into two paths, one path of output end of the first double-path branching optical fiber is connected to the input end of the first electro-optical modulator, the other path of output end of the first double-path branching optical fiber is connected to the input end of the second electro-optical modulator, the output ends of the first electro-optical modulator and the second electro-optical modulator are respectively connected to the two input ends of the second double-path branching optical fiber, and the output end of the second double-path branching optical fiber is connected to the input end of the measuring optical path.

Preferably, the measurement light path comprises a first collimator, a second collimator, a third collimator, a spectroscope and a beam expander lens group; the output end of the second double-path branching optical fiber is connected to the input end of the first collimator, the output end of the first collimator is connected to the spectroscope, one path of output of the spectroscope is connected to the input end of the second collimator as reference light, the output end of the second collimator is connected to one input end of the optical signal receiving and processing module, the other path of output of the spectroscope is connected to the input end of the beam expanding lens group, the output end of the beam expanding lens group is connected to the input end of the cooperation end optical path, the output end of the cooperation end optical path is connected to the input end of the spectroscope through the beam expanding lens group, the output end of the spectroscope is connected to the input end of the third collimating lens as measuring light, and the output end of the third collimating lens reaches the other input end of the optical signal receiving and processing module.

Preferably, the optical signal receiving and processing module comprises a third double-path light splitting optical fiber, a fourth double-path light splitting optical fiber, a third electro-optical modulator, a fourth electro-optical modulator, a first to fourth photoelectric detectors, a sixth to ninth amplifying circuit, a first to fourth filter circuit and a high-precision phase measurement board card; one output end of the measuring light path is used as reference light and is connected with the input end of a third double-path light splitting optical fiber and then is divided into two paths, one output end of the third double-path light splitting optical fiber is connected to the input end of a third electro-optical modulator, the input end of the third electro-optical modulator is connected to the input end of a first photoelectric detector, the output end of the first photoelectric detector, a sixth amplifying circuit and a first filtering circuit are sequentially connected, the output end of the first filtering circuit is connected to the high-precision phase measurement board card, and the other output end of the third double-path light splitting optical fiber is connected to the input end of a second photoelectric detector, and then is sequentially connected to the high-precision phase measurement board card through a seventh amplifying circuit and a second filtering circuit;

the other output end of the measuring light path is used as measuring light and is connected with the input end of a fourth double-path branching optical fiber and is divided into two paths, one output end of the fourth double-path branching optical fiber is connected to the input end of a fourth electro-optical modulator, the output end of the fourth electro-optical modulator, a third photoelectric detector, an eighth amplifying circuit and a third filtering circuit are sequentially connected, and the output end of the third filtering circuit is connected to the high-precision phase measurement board card; and the other output end of the fourth double-path branching optical fiber is connected to the input end of the fourth photoelectric detector and is connected to the high-precision phase measurement board card sequentially through a ninth amplifying circuit and a fourth filter circuit.

Preferably, the cooperation end is located at the target to be measured, and comprises a cooperation end optical path, a cooperation end laser modulation module, a multi-frequency modulation signal processing module and a cooperation end optical signal receiving and processing module; the optical signal receiving and processing module of the cooperation end generates three outputs and is connected to the multi-frequency modulation signal processing module as an input, the multi-frequency modulation signal processing module generates three outputs, wherein the two outputs are input to the laser modulation module of the cooperation end, and the other one is input to the optical signal receiving and processing module of the cooperation end.

A cooperative phase laser ranging method based on coarse and fine measurement scale difference frequency modulation and demodulation comprises the following steps:

step 1: a multi-frequency generation module at the measuring end generates a frequency v₁、v₁-f₁、v₂、v₃And v₃The + f sine signal is produced by modulating the intensity of a laser beam output by the laser by an electro-optical intensity modulation methodThe frequency of generation is v₁、v₂、v₃And v₃The light beam of the optical signal of + f is divided into two beams, one beam is taken as measuring light and emitted to a target to be measured, and the other beam is taken as a reference signal of a measuring end; wherein the frequency of the precision measuring ruler is v₁The frequency of the secondary precision measuring ruler is v₂The frequency of the rough measuring ruler is f;

step 2: the distance measurement cooperation end is positioned at the target to be measured and generates a sine electric signal Receiving a measuring signal from a measuring end at a cooperative end, dividing the measuring signal into two parts, secondarily modulating a part of light beams by an electro-optical intensity modulator, and enabling the frequency of a fine measuring scale signal at the cooperative end to be v₁-f₁Is generated at a frequency f under the modulation of the sine wave of₁Of the difference frequency signal ofWith precision measuring rule v₁Using a photodetector and a filter to convert and separate the frequency f₁Of the difference frequency electric signalDetecting another part of the measuring beam v by a photodetector₃And v₃The difference frequency signal f of + f is used as a coarse measuring scale, and the phase of the difference frequency signal fFor rough measurement, a secondary fine measuring rule v is converted and separated by using a photoelectric detector and a filter₂And the electrical signals of the rough measuring ruler f are respectively

And step 3: the extracted electric signal with phase information is used as a modulation signal to be output to a laser at a cooperative endIntensity modulation is carried out on the emergent light; will have the electrical signal of the accurate survey chi range finding phase place informationFrequency with the cooperating end is v₁-f₁Of (2) a signalFrequency mixing, restoring precision measuring rule v with precision measuring phase information₁(ii) a Will measure roughlyFrequency v generated by the cooperative terminal₃Electrical signal ofMixing to obtain a frequency v₃An electrical signal of + f; the frequency generated is v₁、v₂、v₃And v₃The electrical signal of + f modulates the laser beam output by the cooperative end in an intensity modulation mode;

and 4, step 4: the laser of the cooperative end is modulated to be used as the measurement return light of a target end and is divided into two beams, wherein one beam is transmitted back to the measurement end, the other beam is used as a reference signal of the cooperative end, and the reference signal is input to an optical signal receiving and processing module of the cooperative end to measure and compensate the additional phase delay amount of the cooperative end; firstly, the frequency of the modulation is v at the cooperative end by an electro-optical modulator₁-f₁Of (2) a signalGenerating frequency f under modulation₁Of the difference frequency signalAnd with a return light middle precision measuring ruler v₁And the frequency f obtained by processing in the measuring light₁Electrical signal ofMeasuring the phase difference, the measured phase differenceThe additional value of the phase of the precision measuring scale generated by the cooperative end changes along with the change of environmental parameters of the cooperative end, which has great influence on the distance measuring precision and can be used for measuring the distance of the objectThe real-time compensation method comprises the steps of sending the data to a measuring end in real time through a laser communication module, and performing real-time compensation at the measuring end; while a rough measuring rule f and a secondary fine measuring rule v₂The drift of the additional phase value at the cooperative end has no influence on the precision of the distance measurement, the additional phase value is calibrated in advance through a phase difference calibration and compensation unit, and the fixed compensation phase value corresponding to the measuring scale is introduced at the measuring end

And 5: receiving the measured return light at the measuring end, demodulating partial light in the reference signal and the measured return light signal of the measuring end respectively by a method of electric light intensity secondary modulation, and obtaining the frequency v at the measuring end₁-f₁Is modulated by an electrical signal of (3) to generate a frequency f₁With precision measuring rule v₁The phase information of (a) is converted into an electric signal by a photodetector; converting the other part of the reference signal and the measured return light signal of the measuring end into electric signals by using a photoelectric detector, and separating by using a filter to obtain the electric signals with the frequency v₂And f, wherein f is the frequency of the rough measuring scale, is the frequency v in the reference light signal and the measured return light₃And v₃The phase of the difference frequency signal of the optical signal of + f is the measuring result of the rough ruler; respectively measuring frequency f₁、v₂F the phase difference between the reference electrical signal and the electrical signal for measuring the return light isThe distance measurement result of the multiple measuring rulers is obtained

And 6, synthesizing the three phase difference values by a data synthesis unit of the high-precision phase measurement board card to generate a distance value, wherein the frequency of the rough measurement ruler is f, the wavelength is lambda, and the distance measurement value of the rough measurement ruler is represented by the following formula:

frequency v₂The signal of (a) is a secondary rough measuring scale with a wavelength of lambda₂The distance measurement of the secondary rough rule is represented by:

frequency v₁The signal of (A) is a precision measuring ruler with a wavelength of lambda₁The measured distance is represented by the following formula:

wherein the floor () function is a rounding function.

The invention has the following beneficial effects:

the distance measurement cooperation end can solve the problems of low distance measurement precision and even incapability of completing distance measurement caused by rapid attenuation of optical energy and weak signal to noise ratio in remote measurement application, detects measurement signals and respectively filters and amplifies the measurement signals, and then synchronously modulates the measurement signals onto a laser of the cooperation end through an optical intensity modulation method to serve as measurement return light, so that the amplification of the measurement optical signals is realized under the condition of ensuring that the phase is not changed, the measurement return light energy and the signal to noise ratio are increased, and the measurement return light energy is changed from the quadric attenuation of the measured distance to the quadratic attenuation.

Different from the existing active cooperative phase laser ranging method, the measuring end and the cooperative end externally modulate the exciter through an electro-optical intensity modulation method, the modulation mode has large bandwidth, a coarse measuring rule and a fine measuring rule which range from dozens of MHz to dozens of GHz can be synchronously modulated, the frequency of the generated fine measuring rule is higher, and the theoretical precision which can be achieved is higher; and simultaneously, the cooperative terminal reproduces the rough measuring scale signal f by adopting a difference frequency modulation method. The cooperative end detects the rough measuring scale signal and generates two paths of frequency difference f through frequency mixing, and the high-frequency signal with the phase difference being the rough measuring result carries out difference frequency modulation on the cooperative end laser, so that the frequency of the rough measuring scale can be as low as dozens of kHz or even dozens of Hz. The method and the device avoid the limitation of modulation bandwidth on the frequency of the rough and fine measuring rule, and enable the cooperative phase laser ranging technology to meet the measurement requirements of long distance and high precision under the condition of not increasing the laser emergent power, which is one of the innovation points of the invention for distinguishing the existing device.

The method is limited by the bandwidth of the existing detecting device, direct detection of dozens of GHz accurate measuring scale signals is difficult or the detection effect is poor, the improvement of the frequency of the accurate measuring scale signals is limited, and the further improvement of the precision of the cooperative phase laser ranging technology is also limited in principle. The cooperative end of the invention demodulates the precision measuring scale by adopting a difference frequency modulation method, thereby not only obtaining the precision measuring phase information, but also avoiding the detection of high-frequency signals, and ensuring that the improvement of the frequency of the precision measuring scale is not limited by the bandwidth of the measuring device. Compared with the direct detection measurement signal, the signal-to-noise ratio of the electrical signal detected by the difference frequency modulation method is improved, the signal-to-noise ratio of return light generated by modulating the processed electrical signal to the laser of the cooperative end is also improved, and the phase laser ranging technology with the cooperative end has higher precision. The invention breaks the limit of the detector bandwidth to the precision of the phase type laser ranging technology, so that the cooperative phase laser ranging can meet the measurement requirements of both large range and high precision. This is the second innovation of the present invention to distinguish the existing devices

Drawings

FIG. 1 is a schematic diagram of the general structure of a high-precision multi-frequency synchronous cooperative distance measuring device according to the present invention;

FIG. 2 is a schematic structural diagram of a measuring end of the cooperative distance measuring apparatus;

fig. 3 is a schematic structural diagram of a cooperative end in the cooperative distance measuring apparatus.

1 is a multi-frequency generation module, 2 is a laser modulation module, 3 is a measurement light path, 4 is an optical signal receiving and processing module, 5 is a first crystal oscillator, 6 is a second crystal oscillator, 7 is a third crystal oscillator, 8 is a first phase-locked frequency doubling circuit, 9 is a second phase-locked frequency doubling circuit, 10 is a third phase-locked frequency doubling circuit, 11 is a fourth phase-locked frequency doubling circuit, 12 is a first amplifying circuit, 13 is a second amplifying circuit, 14 is a third amplifying circuit, 15 is a fourth amplifying circuit, 16 is a fifth amplifying circuit, 17 is a first power synthesizer, 18 is a second power synthesizer, 19 is a laser, 20 is a first double-path light splitting optical fiber, 21 is a first electro-optical modulator, 22 is a second electro-optical modulator, 23 is a second double-path optical fiber, 24 is a first light splitter, 25 is a second light collimator, 26 is a third light splitter, 27 is a beam expander set, 28 is a beam expander set, 29 is a cooperative end light path, 30 is a three-way light splitting optical fiber, 31 is a four-way light splitting optical fiber, 32 is a three-way electro-optical modulator, 33 is a four-way electro-optical modulator, 34 is a one-way photodetector, 35 is a two-way photodetector, 36 is a three-way photodetector, 37 is a four-way photodetector, 38 is a six-way amplifying circuit, 39 is a seven-way amplifying circuit, 40 is an eight-way amplifying circuit, 41 is a nine-way amplifying circuit, 42 is a one-way filter circuit, 43 is a two-way filter circuit, 44 is a three-way filter circuit, 45 is a four-way filter circuit, 46 is a high-precision phase measurement board card, 47 is a cooperative end laser modulation module, 48 is a multi-frequency modulation signal processing module, 49 is a cooperative end optical signal receiving and processing module, 50 is a cooperative end beam expanding lens group, 51 is a collimator A, 52 is a collimator B, 53 is a collimator C, 54 is a cooperative end beam splitter, 55 is a two-way optical fiber A, 56 is a two-way optical fiber B, 57 is a two-way branching optical fiber C, 58 is an electro-optical modulator a, 59 is an electro-optical modulator B, 60 is a photodetector a, 61 is a photodetector B, 62 is a photodetector C, 63 is a photodetector D, 64 is an amplifying circuit a, 65 is an amplifying circuit B, 66 is an amplifying circuit C, 67 is an amplifying circuit D, 68 is a filter circuit a, 69 is a filter circuit B, 70 is a filter circuit C, 71 is a filter circuit D, 72 is a phase difference measuring unit, 73 is a laser communication unit, 74 is a phase difference calibrating and compensating unit, 75 is a crystal oscillator a, 76 is a crystal oscillator B, 77 is a phase-locked frequency multiplying circuit a, 78 is a phase-locked frequency multiplying circuit B, 79 is an amplifying circuit E, 80 is an amplifying circuit F, 81 is a filter circuit E, 82 is a filter circuit F, 83 is a mixer a, 84 is a mixer B, 85 is a power combiner a, 86 is a power combiner B, 87 is a cooperative end laser, 88 is a two-way branching optical fiber D, 89 is an electro-optic modulator C, and 90 is an electro-optic modulator D.

Detailed Description

The present invention will be described in detail with reference to specific examples.

The first embodiment is as follows:

as shown in fig. 1 to 3, the cooperative phase laser ranging method based on coarse and fine scale difference frequency modulation and demodulation includes the following steps:

step 1: a multi-frequency generation module at the measuring end generates a frequency v₁、v₁-f₁、v₂、v₃And v₃A + f sine signal, which is used for modulating the intensity of a laser beam output by the laser by an electro-optical intensity modulation method to generate a frequency v₁、v₂、v₃And v₃The optical signal of + f, the light beam is divided into two bundles, one bundle is emergent to the target to be measured as the measuring light, another bundle is the reference signal of the measuring end; wherein the frequency of the precision measuring ruler is v₁The frequency of the secondary precision measuring ruler is v₂The frequency of the rough measuring ruler is f;

step 2: the distance measurement cooperation end is positioned at the target to be measured and generates a sine electric signal Receiving a measuring signal from a measuring end at a cooperative end, dividing the measuring signal into two parts, secondarily modulating a part of light beams by an electro-optical intensity modulator, and enabling the frequency of a fine measuring scale signal at the cooperative end to be v₁-f₁Is generated at a frequency f under the modulation of the sine wave of₁Of the difference frequency signal ofWith precision measuring rule v₁Using photo-detectors and filteringThe wave-filter converting and separating a frequency of f₁Of the difference frequency electric signalDetecting another part of the measuring beam v by a photodetector₃And v₃The difference frequency signal f of + f is used as a coarse measuring scale, and the phase of the difference frequency signal fFor rough measurement, a secondary fine measuring rule v is converted and separated by using a photoelectric detector and a filter₂And the electrical signals of the rough measuring ruler f are respectively

And step 3: taking the extracted electric signal with the phase information as a modulation signal to carry out intensity modulation on the output light of the laser at the cooperative end; firstly, the electric signal with the distance measurement phase information of the precision measuring rulerFrequency with the cooperating end is v₁-f₁Of (2) a signalFrequency mixing, restoring precision measuring rule v with precision measuring phase information₁(ii) a Will measure roughlyFrequency v generated by the cooperative terminal₃Electrical signal ofMixing to obtain a frequency v₃An electrical signal of + f; the frequency generated is v₁、v₂、v₃And v₃The electrical signal of + f modulates the laser beam output by the cooperative end in an intensity modulation mode;

and 4, step 4: the laser of the cooperative end is modulated to be used as the measuring return light of the target end and is divided into two beams, wherein one beam is emitted backThe other beam of the optical signal is used as a reference signal of the cooperative end and is input to an optical signal receiving and processing module of the cooperative end to measure and compensate the additional phase delay amount of the cooperative end; firstly, the frequency of the modulation is v at the cooperative end by an electro-optical modulator₁-f₁Of (2) a signalGenerating frequency f under modulation₁Of the difference frequency signalAnd with a return light middle precision measuring ruler v₁And the frequency f obtained by processing in the measuring light₁Electrical signal ofMeasuring the phase difference, the measured phase differenceThe additional value of the phase of the precision measuring scale generated by the cooperative end changes along with the change of environmental parameters of the cooperative end, which has great influence on the distance measuring precision and can be used for measuring the distance of the objectThe real-time compensation method comprises the steps of sending the data to a measuring end in real time through a laser communication module, and performing real-time compensation at the measuring end; while a rough measuring rule f and a secondary fine measuring rule v₂The drift of the additional phase value at the cooperative end has no influence on the precision of the distance measurement, the additional phase value is calibrated in advance through a phase difference calibration and compensation unit, and the fixed compensation phase value corresponding to the measuring ruler is introduced at the measuring end

And 5: receiving the measured return light at the measuring end, firstly demodulating the reference signal of the measuring end and partial light in the measured return light signal respectively by a method of electric light intensity secondary modulation, wherein the frequency at the measuring end is v₁-f₁Is modulated by an electrical signal of (3) to generate a frequency f₁Difference of (2)Frequency signal with precision measuring rule v₁The phase information of (a) is converted into an electric signal by a photodetector; converting the other part of the reference signal and the measured return light signal of the measuring end into electric signals by using a photoelectric detector, and separating by using a filter to obtain the electric signals with the frequency v₂And f, wherein f is the frequency of the rough measuring scale, is the frequency v in the reference light signal and the measured return light₃And v₃The phase of the difference frequency signal of the optical signal of + f is the measuring result of the rough ruler; respectively measuring frequency f₁、v₂F the phase difference between the reference electrical signal and the electrical signal for measuring the return light isThe distance measurement result of the multiple measuring rulers is obtained

Step 6: the data synthesis unit of the high-precision phase measurement board card synthesizes the three phase difference values to generate a distance value, the frequency of the rough measurement ruler is f, the wavelength is lambda, and the distance measurement value of the rough measurement ruler isFrequency v₂The signal of (a) is a secondary rough measuring scale with a wavelength of lambda₂The distance measured value of the secondary rough measuring rule isFrequency v₁The signal of (A) is a precision measuring ruler with a wavelength of lambda₁The measured distance isWhere the floor () function is a rounding function.

The cooperative phase laser ranging device based on coarse and fine measuring scale difference frequency modulation and demodulation is suitable for the high-precision multi-measuring scale synchronous cooperative phase laser ranging method and comprises a measuring end and a cooperative end; the measuring end consists of a multi-frequency generation module 1, a laser modulation module 2, a measuring end optical path 3 and an optical signal receiving and processing module 4, the multi-frequency generation module 1 generates three paths of output, wherein two paths of output are input into the laser modulation module 2 to modulate laser, the other path of output is input into the optical signal processing and receiving module 4, the output light of the laser modulation module 2 is input into the measuring end optical path 3, and the two paths of output light of the measuring optical path 3 are respectively measuring light and reference light signals which are input into the measuring end optical signal receiving and processing module 4 to measure phase;

the multi-frequency generation module 1 comprises a first crystal oscillator 5, a second crystal oscillator 6, a third crystal oscillator 7, a first phase-locked frequency doubling circuit 8, a second phase-locked frequency doubling circuit 9, a third phase-locked frequency doubling circuit 10, a fourth phase-locked frequency doubling circuit 11, first to fifth amplifying circuits 12 to 16, a first power synthesizer 17 and a second power synthesizer 18, wherein the output end of the first crystal oscillator 5 is connected to the input end of the first phase-locked frequency doubling circuit 8 and passes through the first amplifying circuit 12, the output signal of the first crystal oscillator 5 is connected to the input end of the second phase-locked frequency doubling circuit 9 and passes through the second amplifying circuit 13, the output end of the second crystal oscillator 6 is connected to the input end of the third amplifying circuit 14, the output signal of the third crystal oscillator 7 is connected to the input end of the third phase-locked frequency doubling circuit 10 and passes through the fourth amplifying circuit 15, the output signal of the third crystal oscillator 7 is connected to the input end of the fourth phase-locked frequency doubling circuit 11, and passes through a fifth amplifying circuit 16; the output end of the first amplifying circuit 12 and the output end of the fifth amplifying circuit 16 are respectively input to two input ends of a first power synthesizer 17, the output end of the first power synthesizer 17 is connected to the input end of a first electro-optical modulator 21 to be used as a driving signal, the output end of a second power synthesizer 18 is connected to the input end of a second electro-optical modulator 22 to be used as a driving signal, and the output end of a second amplifying circuit 14 is connected to the input ends of a third electro-optical modulator 32 and a fourth electro-optical modulator 33 to be used as a driving signal;

the laser modulation module 2 is composed of a laser 19, a first electro-optical modulator 21, a second electro-optical modulator 22, a first double-path light splitting optical fiber 20 and a second double-path light splitting optical fiber 23. The output of the laser 19 is connected to the first double-path branching optical fiber 20 and is divided into two paths, one output end of the first double-path branching optical fiber 20 is connected to the input end of the first electro-optical modulator 21, the other output end of the first double-path branching optical fiber is connected to the input end of the second electro-optical modulator 22, the output ends of the first electro-optical modulator 21 and the second electro-optical modulator 22 are respectively connected to the two input ends of the second double-path branching optical fiber 23, and the output end of the second double-path branching optical fiber 23 is connected to the input end of the measuring optical path 3;

the measurement end optical path 3 is composed of a first collimator 24, a second collimator 25, a third collimator 26, a beam splitter 27 and a beam expander set 28. The output end of the second two-way branching optical fiber 23 is connected to the input end of the first collimator 24, the output end of the first collimator 24 is connected to the spectroscope 27, one output of the spectroscope 27 is connected to the input end 25 of the second collimator as reference light, the output end of the second collimator 25 is connected to one input end of the optical signal receiving and processing module 4, the other output of the spectroscope 27 is connected to the input end of the beam expanding lens group 28, the output end of the beam expanding lens group 28 is connected to the input end of the cooperation end optical path 29, the output end of the cooperation end optical path 29 is connected to the input end of the spectroscope 27 through the beam expanding lens group 28, the output end of the spectroscope 27 is connected to the input end of the third collimating lens 26 as measurement light, and the output end of the third collimating lens 26 reaches the other input end of the optical signal receiving and processing module 4;

the optical signal receiving and processing module 4 is composed of a third double-path light splitting optical fiber 30, a fourth double-path light splitting optical fiber 31, a third electro-optical modulator 32, a fourth electro-optical modulator 33, first to fourth photoelectric detectors 34 to 37, sixth to ninth amplifying circuits 38 to 41, first to fourth filter circuits 42 to 45 and a high-precision phase measurement board card 46. An output end of the measuring optical path 3 is used as reference light and is connected with an input end of a third double-path light splitting optical fiber 30 and then divided into two paths, an output end of the third double-path light splitting optical fiber 30 is connected with an input end of a third electro-optical modulator 32, an input end of the third electro-optical modulator 32 is connected with an input end of a first photoelectric detector 34, an output end of the first photoelectric detector 34, a sixth amplifying circuit 38 and a first filtering circuit 42 are sequentially connected, an output end of the first filtering circuit 42 is connected with the high-precision phase measurement board card, and the other output end of the third double-path light splitting optical fiber 30 is connected with an input end of a second photoelectric detector 35 and then is connected with the high-precision phase measurement board card after sequentially passing through a seventh amplifying circuit 39 and a second filtering circuit 43; the other output end of the measuring optical path 3 is used as measuring light and connected with the input end of the fourth double-path branching optical fiber 31 and is divided into two paths, one output end of the fourth double-path branching optical fiber 31 is connected with the input end of the fourth electro-optical modulator 33, the output end of the fourth electro-optical modulator 33, the third photoelectric detector 36, the eighth amplifying circuit 40 and the third filter circuit 44 are sequentially connected, and the output end of the third filter circuit 44 is connected with the high-precision phase measurement board card 46; the other output end of the fourth double-path branching optical fiber 31 is connected to the input end of the fourth photoelectric detector 37, and is connected to the high-precision phase measurement board card 46 through the ninth amplifying circuit 41 and the fourth filter circuit 45 in sequence;

the cooperative end is positioned at a measured target and consists of a cooperative end light path 29, a cooperative end laser modulation module 47, a multi-frequency modulation signal processing module 48 and a cooperative end optical signal receiving and processing module 49; the cooperation end optical path 29 receives a measuring signal from a measuring end, the output of the cooperation end laser active modulation module 49 is connected to the input of the cooperation end optical path 29, two outputs of the cooperation end optical path 29 are connected to the cooperation end optical signal receiving and processing module 49, the cooperation end optical signal receiving and processing module 49 generates three outputs and is connected to the multi-frequency modulation signal processing module 48 as an input, the multi-frequency modulation signal processing module 48 generates three outputs, wherein two outputs are input to the cooperation end laser modulation module 47, and the other output is input to the cooperation end optical signal receiving and processing module 49;

the cooperation end optical path 29 consists of a cooperation end beam expander lens group 50, a collimator A51, a collimator B52, a collimator C53, a cooperation end spectroscope 54, a double-path branching optical fiber A55, a double-path branching optical fiber B56 and a double-path branching optical fiber C57; the cooperative end beam expander set 50 receives a measuring optical signal from a measuring end, the output of the cooperative end beam expander set is connected with the cooperative end spectroscope 54, the output of the corresponding spectroscope 54 is connected with the double-path branching optical fiber C57 through a collimator C53, the output of the laser modulation module 47 is connected with the cooperative end spectroscope 54 through a collimator A51 and a double-path branching optical fiber A55, one path of the output is output to the beam expander set 50 corresponding to the double-path output of the spectroscope 54 and is emitted back to the measuring end through the beam expander set 50, and the other path of the output is connected with the double-path branching optical fiber B56 through a collimator B52;

the cooperation end optical signal receiving and processing module 49 consists of an electro-optical modulator A58, an electro-optical modulator B59, photoelectric detectors A-D60-63, amplifying circuits A-D64-67, filter circuits A-D68-71, a phase difference measuring unit 72, a laser communication unit 73 and a phase difference calibrating and compensating unit 74; the output of the multi-frequency modulation signal processing module 49 is connected to the modulation signal input ports of the electro-optical modulator A58 and the electro-optical modulator B59, one output of the dual-path branching optical fiber C57 is sequentially connected with the photoelectric detector A60, the amplifying circuit A64 and the filter circuit A68, the output of the dual-path branching optical fiber C57 is connected with the multi-frequency modulation signal processing module 48, the other output of the dual-path branching optical fiber C57 is sequentially connected with the electro-optical modulator A58, the photoelectric detector B61, the amplifying circuit B65 and the filter circuit B69, the output of the dual-path branching optical fiber C56 is connected with the multi-frequency modulation signal processing module 48 and the phase difference measuring unit 72, one output of the dual-path branching optical fiber B56 is sequentially connected with the electro-optical modulator B59, the photoelectric detector C62, the amplifying circuit C66 and the filter circuit C70, the output of the dual-path branching optical fiber B56 is connected with the photoelectric detector D63, the amplifying circuit D67 and the filter circuit D71, the outputs of which are connected to a phase calibration and compensation unit 74;

the multi-frequency modulation signal processing module 48 comprises a crystal oscillator A75, a crystal oscillator B76, phase-locked frequency doubling circuits A and B77-78, amplifying circuits E and F79-80, filter circuits E and F81-82, mixers A and B83-84 and power synthesizers A and B85-86; the crystal oscillator A75, the phase-locked frequency doubling circuit A77 and the amplifying circuit E79 are connected in sequence, the outputs of the crystal oscillator A75, the phase-locked frequency doubling circuit A77 and the amplifying circuit E79 are connected to the electro-optical modulators A58 and B59 in the optical signal receiving and processing module 49, the optical signal processing module 49 at the cooperative end has three paths of outputs respectively, wherein the output generated by the filter circuit B69 and the outputs generated by the crystal oscillator A75, the phase-locked frequency doubling circuit A77 and the amplifying circuit E79 which are connected in sequence are input to the mixer B84 together, the output generated by the mixer B84 is connected with the filter circuit F82, and the output of the filter circuit F82 is used as a path of modulation signals; a filter A68 of the optical signal receiving and processing module 49 at the cooperative end generates two paths of outputs, wherein one path of output is directly used as a path of modulation signal, the other path of output is connected with outputs generated by sequentially connecting a crystal oscillator B76, a phase-locked frequency doubling circuit B78 and an amplifying circuit F80, and is commonly input to a mixer A83 and connected with a filter circuit E81, the output of the filter circuit E81 is used as a path of modulation signal, the output of the amplifying circuit E79 is also used as a path of modulation signal, the modulation signals output by the filter circuit F82 and the amplifying circuit E79 are commonly input to a power synthesizer A85, the modulation signals output by the filter circuit A68 and the filter circuit E81 are commonly input to a power synthesizer B86, and the outputs of the power synthesizers A and B85-86 are respectively input to the laser modulation module 47 at the cooperative end;

the cooperation end laser modulation module 47 consists of a laser 87, a two-way branching optical fiber D88, an electro-optical modulator C89 and an electro-optical modulator D90; the output of the laser 87 is connected with a double-path branching optical fiber D88 and is divided into two paths, wherein one path of output is connected with an electro-optical modulator C89, the other path of output is connected with an electro-optical modulator D90, the outputs of power combiners A and B85-86 in the multi-frequency modulation signal processing module 48 are respectively connected with modulation signal input ports of the electro-optical modulators C, D89-90, the outputs of the electro-optical modulators C, D89-90 are respectively connected with two input ports of a double-path branching optical fiber A55, and the output of a double-path branching optical fiber A55 is connected with a cooperation end optical path 29.

The above description is only a preferred embodiment of the cooperative phase laser ranging device based on coarse and fine measurement scale frequency difference modulation and demodulation and the ranging method thereof, and the protection range of the cooperative phase laser ranging device based on coarse and fine measurement scale frequency difference modulation and demodulation and the ranging method thereof is not limited to the above embodiments, and all technical schemes belonging to the idea belong to the protection range of the present invention. It should be noted that modifications and variations which do not depart from the gist of the invention will be those skilled in the art to which the invention pertains and which are intended to be within the scope of the invention.