Method and system for expanding non-fuzzy distance based on polarization multiplexing double optical combs

Abstract

The invention discloses a method and system for expanding a non-fuzzy distance based on polarization multiplexing double optical combs, and the method comprises the following steps: the polarization multiplexing double optical combs generate two groups of pulse sequences with different repetition frequencies, one part of the pulse sequences serves as local oscillator light, and the other part of the pulse sequences serves as probe light to enter a distance measurement module; the detection light is divided into two parts, the two parts enter a reference light path and a target light path respectively and then are reflected by two reflectors respectively, then the two parts and the local oscillation light are subjected to frequency beating respectively, two groups of interferograms carrying reference position information and target position information respectively are obtained, and the time interval in the two groups of interferograms is measured and combined with the repetition frequency of a double-optical-comb pulse sequence, so that the target position information is obtained. And the distance to be measured, namely the length difference between the reference light path and the target light path, can be calculated. The problem that the non-fuzzy distance of a traditional double-optical-comb system is small is solved in a simple and reliable mode, and the measurable absolute distance is increased by multiple orders of magnitude.

Description

Technical Field

[0001] This invention belongs to the field of dual-comb ranging technology, specifically relating to a method and system for extending unambiguous distance based on polarization multiplexing dual-comb. Background Technology

[0002] Dual-comb ranging is a high-precision laser ranging method that combines time-of-flight and optical frequency comb technology. This method utilizes two femtosecond lasers with slightly different repetition frequencies to generate two sets of highly coherent optical frequency comb signals. One set of optical combs (signal combs), after being reflected from the target, interferes with the other set of optical combs (local combs) used as a reference, generating a series of time-expanded interference signals. By analyzing these interference signals, the round-trip time of the light pulse between the target and the receiver can be accurately extracted, thus achieving absolute distance measurement. Because the tiny difference in repetition frequency between the two optical combs introduces a time-scale expansion, ultrafast processes that were originally in the picosecond or femtosecond range are mapped to the microsecond range, greatly simplifying data acquisition and processing requirements. Compared to traditional laser ranging methods, dual-comb ranging offers advantages such as high speed, high precision, and high resolution, making it particularly suitable for long-distance, dynamic target ranging in complex environments.

[0003] A key aspect of laser ranging is the unambiguous distance, which refers to the maximum range of distances that can be accurately identified in a single measurement. Beyond this range, the actual position of the target cannot be correctly determined. In a dual-comb ranging system, the unambiguous distance is determined by the repetition frequency of the comb pulses. When the measured distance exceeds this range, the correspondence between the transmitted and returned pulses cannot be determined, leading to confusion in the measurement results and loss of accuracy. To address this distance ambiguity issue, a common method is to make minor adjustments to the repetition frequency of the probe comb or to swap the positions of the signal comb and the local comb for remeasurement (Rapid and precise absolute distance measurements at long range). Since the unambiguous distances corresponding to the two measurements differ slightly, the true distance can be deduced by analyzing the relationship between the two results. Although this method theoretically extends the unambiguous measurement range, it requires adjusting system parameters and performing two measurements, making the process complex and significantly impacting the real-time performance and update speed of dual-comb ranging. Furthermore, the time interval between the two measurements can also introduce errors, such as fluctuations in the repetition frequency or changes in environmental conditions. These factors can all lead to distance calculation failures, making it particularly unsuitable for real-time ranging of dynamic targets. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a method and system for extending unambiguous distance based on polarization multiplexed dual optical combs. By using polarization multiplexed dual optical combs to generate two polarization pulses with different repetition frequencies in the same laser cavity, these pulses can simultaneously participate in dual optical comb ranging based on the time-of-flight method. This allows for the extension of the measurement range of unambiguous distance without changing the pulse repetition frequency or exchanging the signal comb and local comb, and enables real-time dynamic measurement of the true value of the distance to be measured.

[0005] The present invention is achieved by at least one of the following technical solutions.

[0006] A method for extending unambiguous distance based on polarization multiplexing dual optical combs includes the following steps:

[0007] A. The mode-locked laser generates two sets of asynchronous pulse sequences with different repetition frequencies. The asynchronous pulses are divided into two parts by the first coupler. One part is used as probe light and enters the ranging module, while the other part is used as local oscillator light and enters the polarization controller.

[0008] B. In the ranging module, the probe light is converted into spatial light by the first collimator and then enters the reference optical path and the target optical path through the spatial light beam splitter. In the reference optical path and the target optical path, the first and second reflectors respectively return the light to the spatial light beam splitter for beam combining. Then, the second collimator converts it into fiber light. The distance to be measured is the length difference L between the reference optical path and the target optical path.

[0009] C. The probe fiber light and the local oscillator light, whose polarization state has been adjusted by the polarization controller, converge at the second coupler, so that the two local oscillator lights with different repetition frequencies beat the probe light respectively.

[0010] D. The converging light enters the fiber-optic polarization beam splitter, which separates the p-polarization state and s-polarization state of the local oscillator light. One path passes through the first low-pass filter and the first photodetector, while the other path passes through the second low-pass filter and the second photodetector. Then, the two channels of the oscilloscope simultaneously acquire the interferogram.

[0011] E. The distance to be measured can be obtained by combining the repetition frequency and repetition frequency difference of the asynchronous pulse with the time interval between the two sets of interferograms acquired by the oscilloscope.

[0012] Furthermore, the polarization multiplexed dual optical comb generated by the mode-locked laser is generated in the same mode-locked laser cavity. The polarization multiplexed dual optical comb contains two asynchronous pulse sequences with repetition frequencies. It is assumed that the repetition frequency of the first pulse is f1, corresponding to the p polarization state of light, and the repetition frequency of the second pulse is f2, corresponding to the s polarization state of light, where f2>f1. The difference in repetition frequencies between the first pulse and the second pulse is Δf=f2-f1.

[0013] Furthermore, the probe light and the local oscillator light separated by the first coupler each contain p-polarization and s-polarization states, respectively; the polarization controller adjusts the polarization state of the local oscillator light to correspond to the polarization state of the probe light, and then enters the fiber-optic polarization beam splitter to completely separate the p-polarization and s-polarization states of the local oscillator light.

[0014] Furthermore, in the light separated by the fiber-optic polarization beam splitter, the light entering the first low-pass filter and the first photodetector contains the p-polarization state of the local oscillator light, the p-polarization state of the probe light, and the s-polarization state of the probe light; the light entering the second low-pass filter and the second photodetector contains the s-polarization state of the local oscillator light, the p-polarization state of the probe light, and the s-polarization state of the probe light.

[0015] Furthermore, the time-domain information obtained by beating the p-polarization state of the local oscillator light with the probe light is acquired by an oscilloscope after passing through a first low-pass filter and a first photodetector; the time-domain information obtained by beating the s-polarization state of the local oscillator light with the probe light is acquired by an oscilloscope after passing through a second low-pass filter and a second photodetector.

[0016] Furthermore, the probe light creates a reference interferogram for the first reflecting mirror and a target interferogram for the second reflecting mirror;

[0017] The first channel of the oscilloscope acquires the first reference interferogram and the first target interferogram at a time interval of τ1; the second channel of the oscilloscope acquires the second reference interferogram and the second target interferogram at a time interval of τ2.

[0018] The absolute distance L to be measured is calculated based on the time-of-flight method combined with the vernier effect: the distance is acquired and measured using the first channel of the oscilloscope. Oscilloscope second channel acquisition and measurement distance Where c is the speed of light, n is the refractive index of the propagation medium, and the absolute distance L = mΛ1 + L1 = mΛ2 + L2, where the unambiguous distances corresponding to the two optical combs with different repetition frequencies are respectively and m is a positive integer. By combining the above equations, we can directly obtain the actual value of the distance to be measured, L = f1τ2 - f2τ1.

[0019] Furthermore, the second reflector is attached to the surface of the piezoelectric transducer. When a voltage signal of a fixed frequency is applied to the piezoelectric transducer, the piezoelectric transducer generates periodic mechanical vibration of the corresponding frequency, thereby driving the second reflector to vibrate back and forth, simulating the high-speed dynamic change of the target distance.

[0020] Furthermore, the second reflector is replaced with a dart coated with a highly reflective material. When the dart flies at high speed along a direction perpendicular to the incident light, the probe light will be reflected on its surface at different times to form a dynamic signal.

[0021] The system for implementing the method of extending unambiguous distance based on polarization multiplexing dual optical comb includes a mode-locked laser, a first coupler, a ranging module, a polarization controller, a second coupler, an optical fiber polarization beam splitter, a first low-pass filter, a second low-pass filter, a first photodetector, a second photodetector, and an oscilloscope.

[0022] The mode-locked laser generates two sets of asynchronous pulse sequences with different repetition frequencies. After passing through the first coupler, the asynchronous pulse sequences are divided into two parts. One part is used as probe light and enters the ranging module, while the other part is used as local oscillator light and enters the polarization controller. The local oscillator light, after its polarization state is adjusted by the polarization controller, enters the second coupler.

[0023] The output of the second coupler is connected to the input of the fiber optic polarization beam splitter; the inputs of the first low-pass filter and the second low-pass filter are both connected to the output of the fiber optic polarization beam splitter; the outputs of the first low-pass filter and the second low-pass filter are respectively connected to the inputs of the first photodetector and the second photodetector; and the outputs of the first photodetector and the second photodetector are both connected to the input of the oscilloscope.

[0024] Furthermore, the ranging module includes a first collimator, a spatial beam splitter, a first reflector, a second reflector, and a second collimator. The probe light enters the first collimator, is converted into spatial light by the first collimator, and then enters the reference optical path and the target optical path through the spatial beam splitter. In the reference optical path and the target optical path, the first reflector and the second reflector respectively return the light to the spatial beam splitter for beam combining. The light is then converted into fiber light by the second collimator and enters the second coupler. Finally, the fiber light and the local oscillator light, whose polarization state has been adjusted by the polarization controller, converge at the second coupler. The two polarization states of the local oscillator light with different repetition frequencies beat with the probe light respectively.

[0025] Compared with existing technologies, the beneficial effects of the present invention are as follows:

[0026] This invention provides a method and system for extending unambiguous distance based on polarization-multiplexed dual optical combs. By generating two orthogonal polarization states with slightly different repetition frequencies within the same laser cavity, a polarization-multiplexed dual optical comb structure is achieved. This allows for the acquisition of two sets of interference signals in a single measurement, effectively extending the unambiguous distance range using the vernier effect. It eliminates the need to adjust the pulse repetition frequency or exchange the positions of the signal comb and the local comb, simplifying the operation process and avoiding the complexity and uncertainty caused by parameter adjustments and multiple measurements in traditional methods. This significantly improves the system's real-time performance and ranging efficiency. Furthermore, due to the high coherence and stability of the two optical combs, the influence of repetition frequency fluctuations and environmental disturbances on the measurement results is effectively suppressed, enhancing the accuracy and robustness of the ranging system. It is particularly suitable for high-precision real-time ranging of dynamic targets or in complex environments, possessing significant technical advantages and application value. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a system for extending unambiguous distance based on polarization multiplexing dual optical combs, provided in Embodiment 1 of the present invention.

[0029] Figure 2 In the method and system for extending unambiguous distance based on polarization multiplexing dual optical comb provided in Embodiment 1 of the present invention, the first reference interferogram and the first target interferogram are acquired by the first channel of the oscilloscope using the repetition frequency pulse corresponding to the p polarization state of the local oscillator light.

[0030] Figure 3 In the method and system for extending unambiguous distance based on polarization multiplexing dual optical comb provided in Embodiment 1 of the present invention, the second reference interferogram and the second target interferogram are acquired by the second channel of the oscilloscope by measuring the repetition frequency corresponding to the s-polarization state of the local oscillator light.

[0031] Figure 4 The actual distance measured within 10ms by the method and system for extending unambiguous distance based on polarization multiplexing dual optical combs provided in Embodiment 1 of the present invention;

[0032] Figure 5 This is a schematic diagram of a system for extending unambiguous distance based on polarization multiplexing dual optical combs, provided in Embodiment 2 of the present invention.

[0033] Figure 6This is a schematic diagram of a system for extending unambiguous distance based on polarization multiplexing dual optical combs, as provided in Embodiment 3 of the present invention.

[0034] Among them, 1-mode-locked laser; 2-first coupler; 3-first collimator; 4-spatial beam splitter; 5-first reflector; 6-second reflector; 7-second collimator; 8-polarization controller; 9-second coupler; 10-fiber polarization beam splitter; 11-first low-pass filter; 12-second low-pass filter; 13-first photodetector; 14-second photodetector; 15-oscilloscope; 16-piezoelectric transducer; 17-dart. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0037] Example 1

[0038] like Figure 1 As shown, this embodiment provides a system for extending unambiguous distance based on polarization multiplexing dual optical combs, including a mode-locked laser 1, a first coupler 2, a ranging module, a polarization controller 8, a second coupler 9, an optical fiber polarization beam splitter 10, a first low-pass filter 11, a second low-pass filter 12, a first photodetector 13, a second photodetector 14, and an oscilloscope 15.

[0039] The mode-locked laser 1 generates two sets of asynchronous pulse sequences with different repetition frequencies. The asynchronous pulse sequences are divided into two parts after passing through the first coupler 2. One part is used as probe light and enters the ranging module, while the other part is used as local oscillator light and enters the polarization controller 8. The local oscillator light, after its polarization state is adjusted by the polarization controller 8, enters the second coupler 9.

[0040] The ranging module includes a first collimator 3, a spatial beam splitter 4, a first reflector 5, a second reflector 6, and a second collimator 7. The probe light enters the first collimator 3, is converted into spatial light, and then passes through the spatial beam splitter 4 into the reference optical path and the target optical path. In the reference optical path and the target optical path, the first reflector 5 and the second reflector 6 respectively return the light to the spatial beam splitter 4 for beam combining. The second collimator 7 then converts the light into fiber light, which enters the second coupler 9. Finally, the fiber light merges with the local oscillator light, whose polarization state has been adjusted by the polarization controller 8, at the second coupler 9. The two local oscillator lights with different repetition frequencies beat with the probe light.

[0041] The output of the second coupler 9 is connected to the input of the fiber optic polarization beam splitter 10. The inputs of the first low-pass filter 11 and the second low-pass filter 12 are both connected to the output of the fiber optic polarization beam splitter 10. The outputs of the first low-pass filter 11 and the second low-pass filter 12 are respectively connected to the inputs of the first photodetector 13 and the second photodetector 14. The outputs of the first photodetector 13 and the second photodetector 14 are both connected to the input of the oscilloscope 15.

[0042] Based on the above system, this embodiment also provides a method for extending unambiguous distance based on polarization multiplexing dual optical combs, including the following steps:

[0043] A. The mode-locked laser 1 generates two sets of pulse sequences with different repetition frequencies. The asynchronous pulses are divided into two parts by the first coupler 2. One part is used as probe light and enters the ranging module, while the other part is used as local oscillator light and enters the polarization controller 8.

[0044] B. In the ranging module, the probe light is converted into spatial light by the first collimator 3, then passes through the spatial light beam splitter 4 and enters the reference optical path and the target optical path. In the reference optical path and the target optical path, the first reflector 5 and the second reflector 6 respectively return the light to the spatial light beam splitter 4 for beam combining, and then the second collimator 7 converts it into fiber light, which enters the second coupler 9. The distance to be measured is the length difference L between the reference optical path and the target optical path.

[0045] C. The probe light carrying distance information and the local oscillator light whose polarization state has been adjusted by the polarization controller 8 are combined at the second coupler 9, so that the local oscillator light with two polarization states having different repetition frequencies beats with the probe light respectively.

[0046] D. The converging light enters the fiber-optic polarization beam splitter 10, which separates the p-polarization state and s-polarization state of the local oscillator light. One path passes through the first low-pass filter 11 and the first photodetector 13, while the other path passes through the second low-pass filter 12 and the second photodetector 14. Then, the two channels of the oscilloscope 15 simultaneously acquire the interferogram.

[0047] E. The distance L to be measured can be obtained by combining the repetition frequency of the asynchronous pulse, the repetition frequency difference, and the time interval between the two sets of interferograms acquired by the oscilloscope 15.

[0048] In practical applications, the polarization-multiplexed dual optical comb generated by the mode-locked laser 1 is produced within the same mode-locked laser cavity. The polarization-multiplexed dual optical comb contains two asynchronous pulse sequences with repetition frequencies. Assuming the repetition frequency of the first pulse is f1, corresponding to the p-polarization state of light, and the repetition frequency of the second pulse is f2, corresponding to the s-polarization state of light, where f2 > f1, the difference in repetition frequencies between the first and second pulses is Δf = f2 - f1.

[0049] As one embodiment, the mode-locked laser cavity has a cavity length of approximately 10 cm. The repetition frequency f1 of the first pulse is 1.04246 GHz, with a center wavelength of 1058 nm, corresponding to the p-polarization state of light. The repetition frequency f2 of the second pulse is 1.042592 GHz, with a center wavelength of 1062 nm, corresponding to the s-polarization state of light. The difference in repetition frequencies between the first and second pulses is Δf = f2 - f1 = 132 kHz.

[0050] The probe light and the local oscillator light separated by the first coupler 2 each contain the p-polarization state and the s-polarization state of the light, respectively.

[0051] The polarization controller 8 adjusts the polarization state of the local oscillator light to correspond to the polarization state of the probe light, and then enters the fiber-optic polarization beam splitter 10 to completely separate the p-polarization state and s-polarization state of the local oscillator light.

[0052] The light split by the fiber polarization beam splitter 10 includes the p-polarization state of the local oscillator light, the p-polarization state of the probe light, and the s-polarization state of the probe light in the first low-pass filter 11 and the first photodetector 13. The light entering the second low-pass filter 12 and the second photodetector 14 includes the s-polarization state of the local oscillator light, the p-polarization state of the probe light, and the s-polarization state of the probe light.

[0053] The probe light creates a reference interferogram for the first reflector 5 and a target interferogram for the second reflector 6.

[0054] The time-domain information obtained by beating the p-polarization state of the local oscillator light with the probe light is acquired by an oscilloscope 15 after passing through a first low-pass filter 11 and a first photodetector 13. The time-domain information obtained by beating the s-polarization state of the local oscillator light with the probe light is acquired by an oscilloscope 15 after passing through a second low-pass filter 12 and a second photodetector 14.

[0055] like Figure 2 As shown, the oscilloscope 15 acquires the first reference interferogram and the first target interferogram through its first channel, with a time interval of τ1; Figure 3As shown, the second channel acquires the second reference interferogram and the second target interferogram, with a time interval of τ2.

[0056] The absolute distance L to be measured is calculated based on the time-of-flight method combined with the vernier effect: the distance is acquired and measured using the first channel of oscilloscope 15. Oscilloscope second channel acquisition and measurement distance Where c is the speed of light, n is the refractive index of the propagation medium, and the absolute distance L = mΛ1 + L1 = mΛ2 + L2, where the unambiguous distances corresponding to the two optical combs with different repetition frequencies are respectively and Where m is a positive integer, the actual value of the distance to be measured, L = f1τ2 - f2τ1, can be directly obtained by combining the above equations. For example... Figure 4 The figure shows the absolute distance of 0.3932 meters measured during a sampling time of 10ms.

[0057] The unambiguous distance from Extended to The measurable absolute distance range has been improved. f is the repetition frequency (f1 or f2) of the mode-locked laser.

[0058] Example 2

[0059] like Figure 5 As shown, the method and system for extending unambiguous distance based on polarization multiplexing dual optical comb provided in this embodiment are basically the same in structure as that in embodiment 1. The main difference is that the object measured in embodiment 1 is static, while the object measured in this embodiment is rapidly changing.

[0060] Specifically, the second reflector 6 is attached to the surface of the piezoelectric transducer 16. When a stable voltage signal with a frequency of 10kHz is applied to the piezoelectric transducer 16, the piezoelectric transducer 16 will generate periodic mechanical vibrations at the corresponding frequency, thereby driving the second reflector 6 attached thereto to vibrate reciprocally at a frequency of 10kHz, simulating the high-speed dynamic change of the target distance. Based on the polarization multiplexing dual optical comb extended unambiguous distance system constructed by this invention, it can simultaneously acquire two sets of interference signals with slightly different repetition frequencies but extremely high coherence, and perform high time resolution and high precision analytical processing on the optical path change caused by the vibration of the reflector, realizing real-time dynamic measurement of the minute distance change caused by the vibration of the reflector, and verifying the system's response capability and measurement accuracy in high-frequency dynamic target ranging scenarios.

[0061] Example 3

[0062] like Figure 6As shown, the method and system for extending unambiguous distance based on polarization multiplexing dual optical comb provided in this embodiment are basically the same in structure as that in embodiment 1. The main difference is that the object measured in embodiment 1 is static, while the object measured in this embodiment is a dynamic target carrying spatial topography information and in a state of high-speed motion.

[0063] Specifically, the second reflector 6 is replaced with a dart 17 coated with a highly reflective material. When the dart 17 flies at high speed perpendicular to the incident light direction, the probe light is reflected on its surface at different time points, forming dynamic signals. Utilizing the high temporal resolution and high ranging accuracy of the system based on polarization multiplexing dual optical combs to extend the unambiguous distance, the surface contour of the dart can be recorded and reconstructed in real time during its flight. This enables high-precision morphological measurement and information extraction of complex dynamic targets in high-speed motion, further verifying the adaptability and application potential of this invention in dynamic scenes.

[0064] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0065] The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for extending the unambiguous range based on polarization multiplexing dual-comb, characterized in that, The method comprises the following steps: A. The mode-locked laser (1) generates two groups of asynchronous pulse sequences with different repetition frequencies, and the asynchronous pulses are divided into two parts by the first coupler (2), one part of which is used as probe light to enter the distance measuring module, and the other part is used as local light to enter the polarization controller (8); B. In the distance measuring module, the probe light is converted into spatial light by the first collimator (3) and then enters the reference light path and the target light path through the spatial light beam splitter (4) The first mirror (5) and the second mirror (6) are used to return the light to the spatial light beam splitter (4) for beam combination in the reference light path and the target light path, and then the light is converted into fiber light by the second collimator (7); The distance to be measured is the length difference L between the reference light path and the target light path; C. The probe fiber light and the local light with adjusted polarization state through the polarization controller (8) are combined at the second coupler (9), so that the local light with two different polarization states and different repetition frequencies is beat with the probe light; D. The combined light enters the fiber type polarization beam splitter (10), which separates the p polarization state and the s polarization state of the local light, one of which passes through the first low-pass filter (11) and the first photodetector (13), and the other passes through the second low-pass filter (12) and the second photodetector (14), and then the oscilloscope (15) acquires the two channels of the interference pattern at the same time; E. The distance to be measured can be obtained by combining the repetition frequency, the repetition frequency difference, and the time interval of the two groups of interference patterns acquired by the oscilloscope (15).

2. The method of claim 1, wherein the non-ambiguously range is extended by polarization multiplexing dual optical comb. The polarization multiplexed double optical comb generated by the mode-locked laser (1) is generated in the same mode-locked laser cavity, and the polarization multiplexed double optical comb contains two groups of asynchronous pulse sequences with different repetition frequencies. Assuming that the repetition frequency of the first pulse is f1 corresponding to the p polarization state of the light, and the repetition frequency of the second pulse is f2 corresponding to the s polarization state of the light, wherein f2>f1, the repetition frequency difference between the first pulse and the second pulse is Δf=f2-f1.

3. The method of claim 1, wherein the non-ambiguously range is extended by polarization multiplexing dual optical comb. The probe light and the local light separated by the first coupler (2) each contain the p polarization state and the s polarization state of the light; the polarization controller (8) adjusts the polarization state of the local light to correspond to the polarization state of the probe light, and then enters the fiber type polarization beam splitter (10) to completely separate the p polarization state and the s polarization state of the local light.

4. The method of claim 1, wherein the non-ambiguously range is extended by polarization multiplexing dual optical comb. The light entering the first low-pass filter (11) and the first photodetector (13) in the separated light of the fiber type polarization beam splitter (10) contains the p polarization state of the local light, the p polarization state of the probe light, and the s polarization state of the probe light. The light entering the second low-pass filter (12) and the second photodetector (14) contains the s polarization state of the local light, the p polarization state of the probe light, and the s polarization state of the probe light.

5. The method of claim 1, wherein the nonambiguously resolved range is extended by polarization multiplexing of the two optical combs. The time domain information obtained by beating the p polarization state of the local light with the probe light is acquired by the oscilloscope (15) after passing through the first low-pass filter (11) and the first photodetector (13); the time domain information obtained by beating the s polarization state of the local light with the probe light is acquired by the oscilloscope (15) after passing through the second low-pass filter (12) and the second photodetector (14).

6. The method of claim 1, wherein the non-ambiguously range is extended by polarization multiplexing dual optical comb. The probe light creates a reference interference pattern for the first mirror (5) and a target interference pattern for the second mirror (6); The first channel of the oscilloscope (15) collects the first reference interference pattern and the first target interference pattern, and the time interval is τ1; the second channel of the oscilloscope (15) collects the second reference interference pattern and the second target interference pattern, and the time interval is τ2; The absolute distance L to be measured is calculated according to the time-of-flight method combined with the vernier effect: the oscilloscope (15) collects the measured distance in the first channel The oscilloscope (15) collects the measured distance in the second channel Where c is the speed of light, n is the refractive index of the propagation medium, and the absolute distance L = mΛ1+L1=mΛ2+L2, where the non-ambiguous distances corresponding to the two different repetition frequency optical combs are And m is a positive integer, and the actual value of the distance to be measured L = f1τ2-f2τ1 can be directly obtained by solving the above equations.

7. The method of claim 1, wherein the nonambiguously resolved range is extended by polarization multiplexing of the two optical combs. The second mirror (6) is pasted on the surface of the piezoelectric transducer (16), and when a voltage signal of a fixed frequency is loaded on the piezoelectric transducer (16), the piezoelectric transducer (16) generates periodic mechanical vibration of the corresponding frequency, thereby driving the second mirror (6) to reciprocate, simulating the high-speed dynamic change of the target distance.

8. The method of claim 1, wherein the non-ambiguously range is extended by polarization multiplexing dual optical comb. The second mirror (6) is replaced by a dart (17) coated with high-reflectivity material on the surface, and when the dart (17) flies at a high speed along the direction perpendicular to the incident light, the probe light will reflect on the surface at different time points to form a dynamic signal.

9. A system for implementing the method of claim 1 for extending the unambiguous range based on polarization multiplexing of dual optical combs, characterized in that, The system comprises a mode-locked laser (1), a first coupler (2), a ranging module, a polarization controller (8), a second coupler (9), a fiber-type polarization beam splitter (10), a first low-pass filter (11), a second low-pass filter (12), a first photodetector (13), a second photodetector (14), and an oscilloscope (15). The mode-locked laser (1) generates two groups of asynchronous pulse sequences with different repetition frequencies, and the asynchronous pulse sequences are divided into two parts after passing through the first coupler (2), one part of which enters the ranging module as probe light, and the other part enters the polarization controller (8) as local light. The output end of the second coupler (9) is connected with the input end of the fiber-type polarization beam splitter (10); the input ends of the first low-pass filter (11) and the second low-pass filter (12) are connected with the output end of the fiber-type polarization beam splitter (10), the output ends of the first low-pass filter (11) and the second low-pass filter (12) are connected with the input ends of the first photodetector (13) and the second photodetector (14) respectively, and the output ends of the first photodetector (13) and the second photodetector (14) are connected with the input end of the oscilloscope (15).

10. The system of claim 9, wherein, The ranging module comprises a first collimator (3), a spatial light beam splitter (4), a first mirror (5), a second mirror (6), and a second collimator (7). The probe light enters the first collimator (3), is converted into spatial light by the first collimator (3), and then enters the reference light path and the target light path through the spatial light beam splitter (4). In the reference light path and the target light path, the light is returned to the spatial light beam splitter (4) by the first mirror (5) and the second mirror (6) respectively for beam combination, and then is converted into fiber light by the second collimator (7) and enters the second coupler (9). Finally, the fiber light and the local light with adjusted polarization state by the polarization controller (8) converge at the second coupler (9), and the local light with two different repetition frequencies and two different polarization states generates beat frequency with the probe light.

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