A dual-wavelength ranging system and method for improving measurement dynamic range

Abstract

A dual-wavelength ranging system and method for improving the measurement dynamic range, which adopts a polarized light output subsystem including two different wavelength lasers as a continuous light source, introduces different frequency radio frequency modulation signals through an electro-optical modulator, uses a half-wave plate and a beam combination end to realize the alignment of the fast axis and the slow axis in the polarization maintaining optical fiber, thereby achieving the double channel isolation of different wavelengths in polarization and frequency, improves the energy of the detection light through an optical fiber amplifier and outputs through an optical fiber coupler, uses a Michelson interference system based on an optical fiber beam splitter, changes the length of the interference arm through an electrically adjustable delay line, uses a polarization beam splitter and a photoelectric detector to realize the micron-level adjustment of the ambiguous distance in the high-precision interference background, realizes the transformation of the non-ambiguous distance of the ranging system from the kilometer level to the sub-micron level, and accurately measures the relative position of the measured target, so that it has the ability of long-distance, high-precision and large dynamic range ranging.

Description

Technical Field

[0001] This invention relates to a dual-wavelength ranging system and method for improving the dynamic range of measurements, belonging to the field of optical measurement. Background Technology

[0002] With the continuous advancement of human industrial development, higher requirements are being placed on measurement accuracy in industrial and commercial ranging fields such as large-scale structure distance measurement, micro-displacement measurement, autonomous driving, and drone flight. In recent years, human exploration in the aerospace field has been continuously expanding into deep space, requiring even more precise ranging methods to achieve the desired measurement results. High-precision, real-time distance measurement technology is of great significance for space scientific research projects such as satellite formation flying, space debris detection, space rendezvous and docking, gravitational wave detection, reconstruction of the Earth's gravity field, and planetary exploration.

[0003] Traditional ranging technology primarily focuses on microwave ranging. Microwave ranging is an electromagnetic wave ranging method that uses microwaves with wavelengths of 0.8–10 cm as carrier waves. It involves placing two instruments, a primary and a secondary instrument, at opposite ends of the measurement line. The ranging signal transmitted by the primary instrument is received by the secondary instrument, which then relays it back to the primary instrument. Simultaneously, the secondary instrument also transmits a signal to the primary instrument while the primary instrument is transmitting its own. After mixing, the phase hysteresis difference generated by the signal transmitted by the primary instrument traveling back and forth along the measurement line can be calculated, thus determining the distance to be measured. Microwave rangefinders, on the other hand, use the Doppler signal generated by the reciprocating motion of a dual-frequency radar to achieve accurate ranging of stationary targets. Microwave ranging offers advantages such as high measurement accuracy, fast response speed, good directionality, and non-contact operation. However, the high production cost, large size, and susceptibility to electromagnetic interference of microwave ranging equipment have hindered its application in spatial ranging.

[0004] Currently, laser ranging technology, as a fundamental technology in high-end technologies such as laser tracking, laser 3D imaging, and LiDAR, is widely used in the field of space ranging. Laser ranging technology is a technique that uses laser signals to accurately measure the distance to a target. The laser ranging method uses a laser to emit a laser beam towards the target. After the beam is reflected from the target's surface, it is received by a photoelectric element. By measuring the time from emission to reception of the laser beam, the distance between the laser source and the target can be calculated. The main advantages of laser ranging equipment are its small size, low power consumption, portability, and low operating costs. Its high measurement accuracy and fast measurement speed also make it particularly suitable for high-end measurement scenarios.

[0005] Laser ranging methods can be broadly categorized into Time-of-Flight (TOF), multi-wavelength interferometry, synthetic wavelength interferometry, and frequency-modulated continuous wave (FM-CWHW) methods. Each method has its own advantages and disadvantages. Measurement accuracy, measurement speed, and unambiguous range are all dimensions used to evaluate the performance of a ranging system, but balancing these dimensions is quite difficult. Therefore, finding a method that can improve ranging accuracy while also expanding the unambiguous range is particularly important, enabling higher-precision and longer-distance ranging, and providing technical support for the further development of my country's deep space exploration. Summary of the Invention

[0006] The technical problem solved by this invention is that, in the current technology, there is a lack of a method that can balance ranging accuracy and expand the non-ambiguity range. Therefore, a dual-wavelength ranging system and method for improving the dynamic range of measurement are proposed.

[0007] The present invention solves the above-mentioned technical problem through the following technical solution:

[0008] A dual-wavelength ranging system for improving measurement dynamic range includes a polarization output subsystem, an optical fiber beam splitter, an optical fiber amplifier, a polarization beam splitter, an electrically tunable delay fiber, an optical fiber coupler, and a telescope. The output end of the polarization output subsystem is connected to the input end of the optical fiber beam splitter. The output end of the optical fiber beam splitter is connected to the electrically tunable delay fiber and the optical fiber amplifier, respectively. The optical fiber amplifier is then connected to the optical fiber coupler and the telescope in sequence. The polarization beam splitter is positioned between the output end of the polarization output subsystem and the optical fiber beam splitter.

[0009] The polarization output subsystem outputs a combined beam to the fiber optic beam splitter. After being split by the fiber optic beam splitter, each beam is output to the fiber optic amplifier for amplification. After amplification, one beam passes through the fiber optic coupler and the telescope to illuminate the surface of the object under test.

[0010] Electrically tunable delay fiber is positioned between the output of the fiber beam splitter and the fiber amplifier. After one beam is split, the beam returns to the fiber beam splitter after the length of the interference arm is changed by the electrically tunable delay fiber. The reflected beam from the surface of the object under test is transmitted to the fiber beam splitter, interferes with the beam returned by the electrically tunable delay fiber, and then passes through a polarization beam splitter to separate the polarization state optical signals. After separation, the two optical signals are converted into electrical signals by a photodetector connected to the polarization beam splitter.

[0011] The polarization output subsystem includes a first laser, a second laser, a first electro-optic modulator, a second electro-optic modulator, a first half-wave plate, a second half-wave plate, and a beam combiner, wherein:

[0012] A first laser and a second laser emit continuous light sources of different wavelengths to a first electro-optic modulator and a second electro-optic modulator, respectively. The first electro-optic modulator performs radio frequency modulation on the beam emitted by the first laser and outputs it. The second electro-optic modulator performs radio frequency modulation on the beam emitted by the second laser and outputs it. A first half-wave plate polarizes the beam output by the first electro-optic modulator, aligning the beam polarization direction with the slow axis of the polarization-maintaining fiber before outputting it to the beam combiner. A second half-wave plate polarizes the beam output by the second electro-optic modulator, aligning the beam polarization direction with the fast axis of the polarization-maintaining fiber before outputting it to the beam combiner. The beam combiner combines the two beams and outputs them to the fiber optic beam splitter.

[0013] The distance between the object under test and the binoculars is calculated based on the output of two electrical signals. This is achieved through a dual-wavelength radio frequency band synthesis wavelength algorithm, a micrometer-level vernier effect algorithm, and a target relative position determination algorithm based on orthogonal measurement and Lissajous diagram.

[0014] The wavelengths of the two continuous optical signals output by the first laser and the second laser are determined according to the measurement requirements of the object under test; or two continuous optical signals of different frequencies are output by a single laser and a frequency shifting device; the frequency difference between the first laser and the second laser or the frequency difference between the two continuous optical signals output by a single laser is determined according to the measurement accuracy requirements of the measurement task of the object under test.

[0015] The first electro-optic modulator adjusts the frequency of the continuous light signal output by the first laser by adjusting the radio frequency input signal to improve the scanning of the object under test at an unknown distance. The second electro-optic modulator adjusts the frequency of the continuous light signal output by the second laser to improve the scanning of the object under test at an unknown distance.

[0016] The photodetector employs a photomultiplier tube or a single-photon detector array to increase the detection distance at the same output power.

[0017] The electrically tunable delay fiber changes the delay optical path by altering the length of the interferometer arm of the received beam, thereby performing nanometer-level unambiguous distance scanning on the object under test to improve ranging accuracy.

[0018] A dual-wavelength ranging method for improving the dynamic range of measurement based on a dual-wavelength ranging system includes:

[0019] The first laser and the second laser of the polarization output subsystem output optical signals of different wavelengths respectively. The first laser outputs a beam after being radio frequency modulated by the first electro-optic modulator and then polarized by the first half-wave plate, and outputs a first polarized beam to the beam combiner. The second laser outputs a beam after being radio frequency modulated by the second electro-optic modulator and then polarized by the second half-wave plate, and outputs a second polarized beam to the beam combiner.

[0020] The two polarized beams are combined at the beam combiner and then output to the fiber optic beam splitter.

[0021] The two beams output by the fiber optic beam splitter are amplified by a fiber optic amplifier and then pass through a fiber optic coupler and a telescope to illuminate the surface of the object under test. The other beam is returned to the fiber optic beam splitter after passing through an electrically tunable delay fiber to change the length of the interference arm.

[0022] The reflected beam from the surface of the object under test is received by an optical fiber beam splitter, and after interfering with the beam returned by the electrically tunable delay fiber, it is input into the polarization beam splitter.

[0023] The polarization beam splitter separates the polarization state optical signals of the interfering beams. After separation, the two optical signals are converted into electrical signals by a photodetector connected to the polarization beam splitter.

[0024] The first and second lasers of the polarized light output subsystem output light signals of different wavelengths, and the frequency difference between the two output light signals is determined according to the measurement accuracy requirements of the measurement task of the object under test.

[0025] The distance between the object under test and the binoculars is calculated based on the output of two electrical signals. This is achieved through a dual-wavelength radio frequency band synthesis wavelength algorithm, a micrometer-level vernier effect algorithm, and a target relative position determination algorithm based on orthogonal measurement and Lissajous diagram.

[0026] The advantages of this invention compared to the prior art are:

[0027] (1) The present invention provides a dual-wavelength ranging system and method for improving the dynamic range of measurement. It uses two lasers of different wavelengths as continuous light emission sources. Through the vernier effect algorithm at different scales, the non-ambiguous distance of the ranging system can be transformed from the kilometer level to the submicron level, enabling it to perform long-distance high-precision ranging. It utilizes the optical carrier frequency modulation synthesis wavelength method, which can effectively extend the non-ambiguous range to the kilometer level, greatly improving the deep space long-distance detection capability.

[0028] (2) This invention uses the vernier effect between the longitudinal modes of the laser to improve the unambiguous range of the ranging while ensuring the ranging accuracy, which is at the submicron level. It utilizes a method for determining the relative position of the object to be measured by combining orthogonal measurement and Lissajous diagram, which can efficiently, quickly and accurately determine the precise position of the target relative to the previous measurement, thereby improving the measurement efficiency of the measurement system for moving targets. Attached Figure Description

[0029] Figure 1 The dual-wavelength laser ranging optical path principle provided for the invention;

[0030] Figure 2 A schematic diagram of the principle for determining the relative position of an object under test based on a Lissajous diagram, provided for the invention; Detailed Implementation

[0031] A dual-wavelength ranging system and method for improving the dynamic range of measurements employs a polarized light output subsystem comprising two lasers of different wavelengths as a continuous light emission source. Radio frequency modulation signals of different frequencies are introduced through an electro-optic modulator. Dual channel isolation in polarization and frequency is achieved by aligning the fast and slow axes of the polarization-maintaining fiber using a half-wave plate and a beam combiner. The energy of the probe light is increased by an fiber amplifier and output through a fiber coupler. A Michelson interferometer system based on a fiber beam splitter is used, and the length of the interferometer arms is changed by an electrically tunable delay line. Micrometer-level adjustment of fuzzy distance under high-precision interferometric background is achieved using a polarization beam splitter and a photodetector. Through vernier effect algorithms at different scales, and by utilizing orthogonal measurement and Lissajous diagrams, the unfuzzy distance of the ranging system can be transformed from the kilometer level to the sub-micrometer level, and the relative position of the target can be accurately measured, enabling it to achieve long-distance, high-precision, and large dynamic range ranging capabilities.

[0032] The dual-wavelength ranging system includes a polarization output subsystem, an optical fiber beam splitter, an optical fiber amplifier, a polarization beam splitter, an electrically tunable delay fiber, an optical fiber coupler, and a telescope. The output of the polarization output subsystem is connected to the input of the optical fiber beam splitter. The output of the optical fiber beam splitter is connected to the electrically tunable delay fiber and the optical fiber amplifier, respectively. The optical fiber amplifier is then connected to the optical fiber coupler and the telescope. The polarization beam splitter is positioned between the output of the polarization output subsystem and the optical fiber beam splitter. Wherein:

[0033] The polarization output subsystem outputs two continuous optical signals of different wavelengths after polarization processing to the fiber optic beam splitter. After being combined, the beams are split by the fiber optic beam splitter and then output to the fiber optic amplifier for amplification. One beam is then amplified and passed through the fiber optic coupler and telescope to illuminate the surface of the object under test.

[0034] Electrically tunable delay fiber is positioned between the output of the fiber beam splitter and the fiber amplifier. After amplification, the beam passes through the electrically tunable delay fiber to change the length of the interference arm before returning to the fiber beam splitter. The reflected beam from the surface of the object under test is transmitted to the fiber beam splitter, where it interferes with the beam returned by the electrically tunable delay fiber. The beam then passes through a polarization beam splitter to separate the polarization state of the optical signal. After separation, the two optical signals are converted into electrical signals by a photodetector connected to the polarization beam splitter.

[0035] Specifically, the polarization output subsystem includes a first laser, a second laser, a first electro-optic modulator, a second electro-optic modulator, a first half-wave plate, a second half-wave plate, and a beam combiner, wherein:

[0036] A first laser and a second laser emit continuous light sources of different wavelengths to a first electro-optic modulator and a second electro-optic modulator, respectively. The first electro-optic modulator performs radio frequency modulation on the beam emitted by the first laser and outputs it. The second electro-optic modulator performs radio frequency modulation on the beam emitted by the second laser and outputs it. A first half-wave plate polarizes the beam output by the first electro-optic modulator, aligning the beam polarization direction with the slow axis of the polarization-maintaining fiber before outputting it to the beam combiner. A second half-wave plate polarizes the beam output by the second electro-optic modulator, aligning the beam polarization direction with the fast axis of the polarization-maintaining fiber before outputting it to the beam combiner. The beam combiner combines the two beams and outputs them to the fiber optic beam splitter.

[0037] The distance between the object under test and the binoculars is calculated based on the output of two electrical signals. This is achieved through a dual-wavelength radio frequency band synthesis wavelength algorithm, a micrometer-level vernier effect algorithm, and a target relative position determination algorithm based on orthogonal measurement and Lissajous diagram.

[0038] The wavelengths of the two continuous optical signals output by the first and second lasers are determined according to the measurement requirements of the object under test; or two continuous optical signals of different frequencies are output by a single laser and a frequency shifting device; the frequency difference between the first and second lasers or the frequency difference between the two continuous optical signals output by a single laser is determined according to the measurement accuracy requirements of the measurement task of the object under test.

[0039] The electro-optic modulator can adjust the frequency of the continuous optical signal output by the first laser and the second laser by adjusting the radio frequency input signal, thereby improving the scanning of the object under test at an unknown distance.

[0040] Photodetectors employ photomultiplier tubes or single-photon detector arrays to increase the detection distance while maintaining the same output power.

[0041] Electrically tunable delay fiber improves ranging accuracy by changing the length of the interference arm of the received beam to alter the optical path delay, enabling nanometer-level unambiguous distance scanning of the object under test.

[0042] The dual-wavelength ranging system enables a dual-wavelength ranging method that improves the dynamic range of measurements. The specific steps are as follows:

[0043] The first and second lasers of the polarization output subsystem output optical signals of different wavelengths. After being modulated at different frequencies by an electro-optic modulator, they are polarized by the first and second half-wave plates and then output to the beam combiner.

[0044] The two beams are combined at the beam combiner and then output to the fiber optic beam splitter.

[0045] The fiber beam splitter outputs two beams to the fiber amplifier for amplification. One beam, after amplification, passes through the fiber coupler and telescope to illuminate the surface of the object under test. The other beam, after splitting without amplification, passes through an electrically tunable delay fiber to change the length of the interference arm before returning to the fiber beam splitter.

[0046] The reflected beam from the surface of the object under test is received by an optical fiber beam splitter, and after interfering with the beam returned by the electrically tunable delay fiber, it is input into the polarization beam splitter.

[0047] The polarization beam splitter separates the polarization state optical signals of the interfering beams. After separation, the two optical signals are converted into electrical signals by a photodetector connected to the polarization beam splitter. The distance between the object under test and the output mirror of the telescope is calculated by the output electrical signal.

[0048] The following description, in conjunction with the accompanying drawings and preferred embodiments, provides further details:

[0049] In the current embodiment, such as Figure 1 As shown, the output optical signals of two lasers (including but not limited to these wavelengths) with operating wavelengths of 1550nm and 1551nm enter the optical path through a polarization-maintaining fiber. The first optical signal output from the first laser 1 is modulated with the required frequency by the first electro-optic modulator 2, and its polarization direction is rotated by 90 degrees using a half-wave plate 3, so that the polarization of the beam is aligned with the slow axis of the polarization-maintaining fiber to reduce system loss. Then, the first beam is coupled into the 50:50 beam splitter 5 through the beam combiner 4 via the polarization-maintaining fiber.

[0050] The second optical signal output from the second laser 1 passes through the second electro-optic modulator 2 and then through the half-wave plate 3 to ensure that its polarization direction is aligned with the fast axis of the polarization-maintaining fiber. After passing through the beam combiner 4 and then through the 50:50 beam splitter 5, it is combined with the first beam at the polarization-maintaining fiber coupler and then enters the fiber amplification system 9. After power amplification, it is input to the telescope system 11 through the fiber coupler 10 and collimated to illuminate the surface of the object under test 12.

[0051] After the probe light from the fiber optic bundle combiner 4 enters the 50:50 beam splitter system 5, a portion passes through the fiber optic bundle splitter system to the electrically tunable delay fiber 8. During measurement, the length of the reference arm in the Michelson interferometer path can be changed via fiber optic bundle splitter 8. After passing through the Bragg reflector, the beam returns to the beam splitter system along the original path. The other path passes through the fiber optic amplification system 9 to increase power, and then uses the fiber optic coupling system 10 and the telescope system 11 to illuminate the object under test 12. After reflection on the surface of the object under test, the beam re-enters the fiber optic bundle splitter 5 and interferes with the light field of the reference arm in the Michelson interferometer system. Then, the beam passes through the polarization beam splitter 6 to separate the mutually perpendicular polarized light signals of different wavelengths, which then enter the first photoelectric detection system 7 and the second photoelectric detection system 7 respectively and are converted into electrical signals. The precise position information of the object under test from the telescope exit end is calculated.

[0052] The methods for calculating the location information of the target include a dual-wavelength radio frequency band synthesized wavelength algorithm and a micrometer-level vernier effect algorithm, as well as a target relative position determination algorithm based on the combination of orthogonal measurement and Lissajous diagram.

[0053] like Figure 2 As shown, the two optical signals originate from the same narrow-linewidth laser source (central wavelength: 1550nm, linewidth ≤ 20Hz), one of which is generated after frequency shifting by f_0 using an acousto-optic modulator. The modulation signal added to the first point light modulation is: Where f_1 is the modulation frequency. As the initial phase, the wavelength of the first optical signal is λ_1; the modulation signal added to the second point light modulation is: Where f_2 is the modulation frequency. Assuming the initial phase is λ_2, and the wavelength of the second optical signal is λ_2; assuming that the intensity, phase, and frequency of the RF signals applied to the two electro-optic modulators can be changed in real time by a computer according to the actual situation, based on the principle of composite wavelength ranging, the composite wavelength of the RF segment of the dual optical signals can be expressed as:

[0054] R_r=c / (2×abs(f_2-f_1))=c / (2×Δf)

[0055] Where abs is the modulo operation and c is the speed of light in a vacuum.

[0056] By introducing orthogonal detection at the detection end and utilizing the Lissajous diagram principle, unambiguous distances at the kilometer level can be achieved when the frequency difference Δf between the input RF signals to the electro-optic modulator is 150 kHz; meter-level unambiguous distances can be achieved when Δf is 15 MHz; and centimeter-level unambiguous distances can be achieved when Δf is 15 GHz. Combined with the Lissajous diagram, distance resolution at the millimeter or even sub-millimeter level can be achieved. By effectively utilizing unambiguous distance data with different frequency differences and with the aid of a fast digital-to-analog conversion system, rapid switching between different ranging ranges can be achieved, greatly expanding the dynamic range of the extended system's ranging capability.

[0057] On the other hand, when dealing with high-precision ranging applications (measuring accuracy below mm resolution requirements), two optical signals of different wavelengths can be used to perform high-precision distance measurement by utilizing the vernier effect, establishing the following equation:

[0058] m_1*R_1+d_1=d_T; m_2*R_2+d_2=d_T

[0059] Where R_j=c / (2*f_j)(j=1,2) represents the unambiguous distance corresponding to each wavelength, m_j is the integer multiple of the unambiguous distance corresponding to each wavelength in the ranging (which can only be determined by calculation), d_j is the remainder after subtracting the integer multiple of the unambiguous distance from the distance to be measured (the measured value in the distance measurement, which is less than the unambiguous distance), and d_T is the distance to the target to be measured (the value to be measured).

[0060] When d_j << R_j, we have m_1 = m_2 = m, that is:

[0061] m*(R_1-R_2)+(d_1-d_2)=0

[0062] We can obtain: m=((d_2-d_1)) / ((R_1-R_2)), and by combining the measured d_j, we can obtain the measured distance d_T. Since the vernier effect uses a "ruler" of wavelength units, i.e., 1.5μm level for ambiguity distance, and uses wavelength difference Δλ (1nm) as the minimum resolution, its ranging resolution can reach nm accuracy.

[0063] In the current embodiment, the obtained electrical signal is used to achieve micron-level adjustment of fuzzy distance under high-precision interference background. Through vernier effect algorithm at different scales, orthogonal measurement and Lissajous diagram can be used to realize the transformation of the non-fuzzy distance of the ranging system from the kilometer level to the submicron level and the accurate measurement of the relative position of the target (12) to be measured, so that it has long-distance, high-precision large dynamic range ranging capability.

[0064] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0065] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A dual-wavelength ranging system for improving measurement dynamic range, characterized in that: The system includes a polarization output subsystem, an optical fiber beam splitter, an optical fiber amplifier, a polarization beam splitter, an electrically tunable delay fiber, an optical fiber coupler, and a telescope. The output of the polarization output subsystem is connected to the input of the optical fiber beam splitter. The output of the optical fiber beam splitter is connected to the electrically tunable delay fiber and the optical fiber amplifier, which in turn connects to the optical fiber coupler and the telescope. The polarization beam splitter is located at the output of the polarization output subsystem and the optical fiber beam splitter. The polarization output subsystem outputs a combined beam to the fiber optic beam splitter. After being split by the fiber optic beam splitter, one beam is amplified by the fiber optic amplifier and then passes through the fiber optic coupler and telescope to illuminate the surface of the object under test. Electrically tunable delay fiber is placed at the output end of the fiber beam splitter and the fiber amplification device. Another beam after splitting passes through the electrically tunable delay fiber to change the length of the interference arm before returning to the fiber beam splitter. The reflected beam from the surface of the object under test is transmitted to the fiber beam splitter, interferes with the beam returned by the electrically tunable delay fiber, and then passes through a polarization beam splitter to separate the polarization state optical signals. After separation, the two optical signals are converted into electrical signals by a photodetector connected to the polarization beam splitter.

2. The dual-wavelength ranging system for improving the dynamic range of measurement according to claim 1, characterized in that: The polarization output subsystem includes a first laser, a second laser, a first electro-optic modulator, a second electro-optic modulator, a first half-wave plate, a second half-wave plate, and a beam combiner, wherein: A first laser emits a continuous beam to a first electro-optic modulator, and a second laser emits a continuous beam to a second electro-optic modulator. The wavelengths of the continuous beams emitted by the first and second lasers are different. The first electro-optic modulator performs radio frequency modulation on the beam emitted by the first laser and outputs it. The second electro-optic modulator performs radio frequency modulation on the beam emitted by the second laser and outputs it. A first half-wave plate polarizes the beam output from the first electro-optic modulator, aligning the beam polarization direction with the slow axis of the polarization-maintaining fiber before outputting it to the beam combiner. A second half-wave plate polarizes the beam output from the second electro-optic modulator, aligning the beam polarization direction with the fast axis of the polarization-maintaining fiber before outputting it to the beam combiner. The beam combiner combines the two beams and outputs them to the fiber optic beam splitter.

3. The dual-wavelength ranging system for improving the dynamic range of measurement according to claim 1, characterized in that: The distance between the object under test and the binoculars is calculated based on the output of two electrical signals. This is achieved through a dual-wavelength radio frequency band synthesis wavelength algorithm, a micrometer-level vernier effect algorithm, and a target relative position determination algorithm based on orthogonal measurement and Lissajous diagram.

4. A dual-wavelength ranging system for improving measurement dynamic range according to claim 2, characterized in that: The wavelengths of the two continuous optical signals output by the first laser and the second laser are determined according to the measurement requirements of the object under test; or two continuous optical signals of different frequencies are output by a single laser and a frequency shifting device; the frequency difference between the first laser and the second laser or the frequency difference between the two continuous optical signals output by a single laser is determined according to the measurement accuracy requirements of the measurement task of the object under test.

5. A dual-wavelength ranging system for improving measurement dynamic range according to claim 4, characterized in that: The first electro-optic modulator adjusts the frequency of the continuous light signal output by the first laser by adjusting the radio frequency input signal to improve the scanning of the object under test at an unknown distance. The second electro-optic modulator adjusts the frequency of the continuous light signal output by the second laser to improve the scanning of the object under test at an unknown distance.

6. A dual-wavelength ranging system for improving measurement dynamic range according to claim 1, characterized in that: The photodetector employs a photomultiplier tube or a single-photon detector array to increase the detection distance at the same output power.

7. A dual-wavelength ranging system for improving measurement dynamic range according to claim 1, characterized in that: The electrically tunable delay fiber changes the delay optical path by altering the length of the interferometer arm of the received beam, thereby performing nanometer-level unambiguous distance scanning on the object under test to improve ranging accuracy.

8. A dual-wavelength ranging method for improving the dynamic range of measurement implemented by the dual-wavelength ranging system according to claim 1, characterized in that... include: The first laser and the second laser of the polarization output subsystem output optical signals of different wavelengths respectively. The first laser outputs a beam after being radio frequency modulated by the first electro-optic modulator and then polarized by the first half-wave plate, and outputs a first polarized beam to the beam combiner. The second laser outputs a beam after being radio frequency modulated by the second electro-optic modulator and then polarized by the second half-wave plate, and outputs a second polarized beam to the beam combiner. The two polarized beams are combined at the beam combiner and then output to the fiber optic beam splitter. The two beams output by the fiber optic beam splitter are amplified by a fiber optic amplifier and then pass through a fiber optic coupler and a telescope to illuminate the surface of the object under test. The other beam is returned to the fiber optic beam splitter after passing through an electrically tunable delay fiber to change the length of the interference arm. The reflected beam from the surface of the object under test is received by an optical fiber beam splitter, and after interfering with the beam returned by the electrically tunable delay fiber, it is input into the polarization beam splitter. The polarization beam splitter separates the polarization state optical signals of the interfering beams. After separation, the two optical signals are converted into electrical signals by a photodetector connected to the polarization beam splitter.

9. A dual-wavelength ranging method for improving the dynamic range of measurement according to claim 8, characterized in that: The first and second lasers of the polarized light output subsystem output light signals of different wavelengths, and the frequency difference between the two output light signals is determined according to the measurement accuracy requirements of the measurement task of the object under test.

10. A dual-wavelength ranging method for improving the dynamic range of measurement according to claim 8, characterized in that: The distance between the object under test and the binoculars is calculated based on the output of two electrical signals. This is achieved through a dual-wavelength radio frequency band synthesis wavelength algorithm, a micrometer-level vernier effect algorithm, and a target relative position determination algorithm based on orthogonal measurement and Lissajous diagram.

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