A self-referenced long-distance high-resolution dispersion interference ranging method

Abstract

The present invention provides a self-referenced long-distance high-resolution dispersion interferometry ranging method, which includes transmitting two sets of optical frequency combs with repetition frequency difference to a dispersion interferometry ranging system to generate distance interference spectra; performing Fourier transform on the two sets of distance interference spectra respectively, and performing rough distance measurement based on the peak value of the interference spectrum after Fourier transform to obtain the measured distance L respectively. DPI1 and L DPI2 ; For measuring distance L DPI1 and L DPI2 Performing a difference or summation to obtain the current result ΔL1 or ΔL2, the half-cycle number of the current actual distance on the corresponding relationship curve is determined based on the corresponding relationship between the half-cycle number and ΔL1 and the current result ΔL1, or based on the corresponding relationship between the half-cycle number and ΔL2 and the current result ΔL2; and calculating the current actual distance based on the equation relationship between the current actual distance and its half-cycle number on the corresponding relationship curve, the half-cycle size of the corresponding relationship curve, the wavelength of the extreme point selected in the corresponding distance interference spectrum, and the multiplication coefficient. This invention can improve the accuracy of distance measurement.

Description

Technical Field

[0001] The present invention belongs to the field of distance measurement, and in particular relates to a self-referenced long-distance high-resolution dispersion interferometry distance measurement method. Background Art

[0002] Optical frequency comb ranging technology typically uses dispersive interferometry, which can theoretically measure distances up to thousands of kilometers with sub-micron accuracy. This technology is primarily supported by the following key technologies: First, the optical frequency comb, which appears in the time domain as a series of pulses with equal time intervals and a repetition rate of hundreds to tens of GHz. In the frequency domain, it appears as a series of comb teeth with equal frequency intervals. A single pulse contains a rich spectral component spanning tens or even hundreds of nanometers, making it an ideal light source for this technology. Second, the Michelson interferometer structure is used for distance sensing. When the reference pulse and the sensor pulse meet, interference occurs. Finally, due to the linear relationship between the measured distance and the free spectral range (FSR) of the interferometer spectrum, the FSR of the interferometer spectrum decreases with increasing distance difference between the two interferometer arms and increases with decreasing distance difference between the two arms. Therefore, the measured distance can be determined based on the FSR of the interferometer spectrum.

[0003] When using an optical frequency comb to achieve high-resolution long-distance ranging, the relationship curve between the measured distance and the actual distance changes periodically, and within each period, the measured distance and the actual distance show a triangular wave relationship. After obtaining the measured distance based on the interference signal, it is only necessary to use this triangular wave relationship to determine the corresponding actual distance. However, the measured distance cannot determine the period of the triangular wave (that is, the period of the actual distance), resulting in a periodic ambiguity problem.

[0004] To address periodic ambiguity, coarse measurement techniques are often required to determine the period within which the current actual distance falls. This undoubtedly increases system complexity. Furthermore, because the coarse measurement technique differs from the optical path traversed by the original dispersion interferometry (DI) ranging method, it can introduce ranging errors within the system itself. Furthermore, due to the limited spectral range of the light source, DI, as a coarse ranging method, typically only achieves micron-level resolution using Fourier transform peak location. For high-precision ranging, it is often necessary to combine DI with homodyne interferometry. After using DI to determine the period within which the current actual distance falls, homodyne interferometry is then used to further improve the distance measurement resolution to the nanometer level by determining the phase change at a specific wavelength. However, during homodyne interferometry, the selected wavelength may be offset due to factors such as thermal noise in the laser, thus affecting the accuracy of the measurement results. Furthermore, because the phase is acquired by inferring the intensity signal, the measurement accuracy determined by this process is easily affected by intensity noise, resulting in measurement errors. Consequently, existing ranging methods suffer from low accuracy. Summary of the Invention

[0005] The present invention provides a self-referenced long-distance high-resolution dispersion interferometry ranging method to solve the problem of low ranging accuracy at present.

[0006] According to a first aspect of an embodiment of the present invention, a self-referenced long-distance high-resolution dispersive interferometry ranging method is provided, comprising:

[0007] Step S110: transmitting two sets of optical frequency combs with repetition frequency differences to a dispersion interferometry ranging system, wherein each set of optical frequency combs generates a corresponding range interference spectrum during transmission in the dispersion interferometry ranging system;

[0008] Step S120: Perform Fourier transform on the two sets of distance interference spectra respectively, and perform rough distance measurement based on the peak value of the interference spectrum after Fourier transform to obtain the measured distance L respectively. DPI1 and L DPI2 ;

[0009] Step S130: measuring the distance L DPI1 and L DPI2 Do the difference or sum to get the current result ΔL 1 or ΔL 2 In the relationship curves corresponding to each set of optical frequency combs, the relationship between the measured distance and the actual distance changes periodically. Each cycle is divided into two half cycles. The half cycle number of the actual distance is the same as ΔL 1 or ΔL 2 There is a corresponding relationship, according to the half-cycle sequence number andΔL 1 The corresponding relationship and the current result ΔL 1 , or according to the half-cycle number and ΔL 2 The corresponding relationship and the current result ΔL 2 , determine the half-cycle sequence number of the current actual distance on the corresponding relationship curve of the optical frequency comb;

[0010] Step S140: There is an equation relationship between the current actual distance and its half-cycle number on the corresponding relationship curve, the half-cycle size of the corresponding relationship curve, the wavelength of the extreme point selected in the corresponding distance interference spectrum, and the multiplication coefficient of the wavelength. According to the half-cycle numbers k1 and k2 of the current actual distance on the two sets of optical frequency comb corresponding relationship curves, the corresponding half-cycle size L of the two relationship curves, pp1 / 2 and L pp2 / 2, the wavelengths of k extreme points selected from the first optical frequency comb corresponding to the first distance interference spectrum and the multiplication coefficient of each wavelength, the wavelengths of k extreme points selected from the second optical frequency comb corresponding to the first distance interference spectrum and the multiplication coefficient of each wavelength, based on the equation relationship, establish 2k equations and solve them to obtain the corresponding multiplication coefficients, where k is an integer greater than 1;

[0011] Step S150: Substitute the multiplication coefficient obtained by solving the equation to calculate the current actual distance.

[0012] In one optional implementation, for each set of optical frequency combs, the relationship curve between the measured distance and the actual distance is an isosceles triangular wave relationship within each cycle of the relationship curve. Each actual distance corresponds to a half-cycle, and as the actual distance increases, the sequence number of the half-cycle increases.

[0013] For each triangular wave in the first relationship curve, a triangular wave is selected from the second relationship curve and associated with the triangular wave in the first relationship curve. For each pair of associated triangular waves, the actual distance corresponding to the maximum measured distance of the first triangular wave and the actual distance corresponding to the maximum measured distance of the second triangular wave in the pair of associated triangular waves are respectively used as the first actual distance and the second actual distance, and the difference between the first actual distance and the second actual distance is less than the half-cycle actual distance. The area between the first actual distance and the second actual distance is used as the first area, and the area between the actual distances corresponding to the minimum measured distances on one side of the first triangular wave and the second triangular wave is used as the second area, and the second area is located before the first area. The area between the actual distances corresponding to the minimum measured distances on the other side of the first triangular wave and the second triangular wave is used as the third area, and the third area is located after the first area. The area between the first area and the second area and between the first area and the third area is used as the fourth area. ΔL 1 Indicates that the actual distance is within the fourth area, the measured distance L DPI1 Subtract L DPI2 The result obtained is, ΔL 2 When the actual distance is located in the first area, the second area and the third area respectively, the measured distance L DPI1 and L DPI2 The result of the summation; the two fourth regions correspond to ΔL 1 The first area, the second area and the third area correspond to ΔL 2 The sizes of are different. For each area, the corresponding ΔL 1 or ΔL 2 same.

[0014] In another optional implementation, the first optical frequency comb is transmitted to the dispersion interferometry ranging system before the second optical frequency comb, and the measured distance L obtained based on the first optical frequency comb is DPI1 On the first relationship curve, the measured distance L obtained based on the second optical frequency comb is DPI2 On the second relationship curve; for each pair of associated triangular waves, in the pair of associated triangular waves, a first actual distance of the first triangular wave on the first relationship curve is greater than a second actual distance of the second triangular wave on the second relationship curve, or the first actual distance of the first triangular wave is less than the second actual distance of the second triangular wave;

[0015] When the first actual distance is greater than the second actual distance, for each pair of associated triangle waves, the fourth area preceding the first area corresponds to ΔL 1 is negative, the fourth area after the first area corresponds to ΔL 1 is positive, and the absolute value of the former is smaller than the latter; the first area, the third area and the second area correspond to ΔL 2 The value of gradually decreases;

[0016] When the first actual distance is less than the second actual distance, for each pair of associated triangle waves, the fourth area preceding the first area corresponds to ΔL 1 is positive, the fourth area after the first area corresponds to ΔL 1 is negative, and the former is greater than the absolute value of the latter; the first area, the second area and the third area correspond to ΔL 2 The value gradually decreases.

[0017] In another optional implementation, for each region in each pair of associated triangular waves, the first cycle of the first relationship curve in the region and the second cycle of the second relationship curve in the region are determined, and the first half cycle number of the first relationship curve in the region and the second half cycle number of the second relationship curve in the region are determined according to the first cycle and the second cycle corresponding to the region, and the first half cycle number of the first relationship curve in the region and the second half cycle number of the second relationship curve in the region are established. ΔL 1 or ΔL 2 The first correspondence with the first half cycle number, and the region ΔL 1 or ΔL 2 A second corresponding relationship with the second half cycle sequence number.

[0018] In another optional implementation, for each region in each pair of associated triangular waves, determining the first period of the first relationship curve in the region and the second period of the second relationship curve in the region includes: for the first region and the fourth region, the first period of the first relationship curve in the region is the period of the first triangular wave on the first relationship curve, and the second period of the second curve in the region is the period of the second triangular wave on the second relationship curve;

[0019] When the first actual distance is greater than the second actual distance, for the second area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve minus 1, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve; for the third area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve plus 1;

[0020] When the first actual distance is less than the second actual distance, for the second area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve minus 1; for the third area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve plus 1, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve.

[0021] In another optional implementation, determining, based on the first period and the second period corresponding to the region, the first half-period sequence number of the first relationship curve in the region and the second half-period sequence number of the second relationship curve in the region includes:

[0022] When the first actual distance is greater than the second actual distance, if ΔL 1 If it is negative, then ΔL 1 Corresponding to the fourth region located before the first region, the first half cycle sequence number of the first relationship curve in the fourth region is the sequence number of the first half cycle in the first cycle corresponding to the fourth region, and the second half cycle sequence number of the second relationship curve in the fourth region is the sequence number of the first half cycle in the second cycle corresponding to the fourth region; if ΔL 1 is positive, then the ΔL 1 For a fourth region following the first region, the first half-cycle sequence number of the first relationship curve in the fourth region is the sequence number of the next half-cycle in the first cycle corresponding to the fourth region, and the second half-cycle sequence number of the second relationship curve in the fourth region is the sequence number of the next half-cycle in the second cycle corresponding to the fourth region;

[0023] like ΔL 2 The first area, the second area and the third area correspond to ΔL 2The maximum value in ΔL 2 Corresponding to the first region, the first half-cycle sequence number of the first relationship curve in the first region is the sequence number of the first half-cycle in the first cycle corresponding to the first region, and the second half-cycle sequence number of the second relationship curve in the first region is the sequence number of the second half-cycle in the second cycle corresponding to the first region;

[0024] like ΔL 2 The first area, the second area and the third area correspond to ΔL 2 The second largest value in ΔL 2 Corresponding to the third region, the first half-cycle sequence number of the first relationship curve in the third region is the sequence number of the next half-cycle in the first cycle corresponding to the third region, and the second half-cycle sequence number of the second relationship curve in the third region is the sequence number of the previous half-cycle in the second cycle corresponding to the third region;

[0025] like ΔL 2 The first area, the second area and the third area correspond to ΔL 2 The minimum value in ΔL 2 Corresponding to the second region, the first half-cycle sequence number of the first relationship curve in the second region is the sequence number of the second half-cycle in the first cycle corresponding to the second region, and the second half-cycle sequence number of the second relationship curve in the second region is the sequence number of the first half-cycle in the second cycle corresponding to the second region;

[0026] When the first actual distance is less than the second actual distance, if ΔL 1 is positive, then the ΔL 1 Corresponding to the fourth region located before the first region, the first half-cycle sequence number of the first relationship curve in the fourth region is the sequence number of the first half-cycle in the first cycle corresponding to the fourth region, and the second half-cycle sequence number of the second relationship curve in the fourth region is the sequence number of the first half-cycle in the second cycle corresponding to the fourth region; if ΔL 1 If it is negative, then ΔL 1 Corresponding to a fourth region located after the first region, the first half-cycle sequence number of the first relationship curve in the fourth region is the sequence number of the next half-cycle in the first cycle corresponding to the fourth region, and the second half-cycle sequence number of the second relationship curve in the fourth region is the sequence number of the next half-cycle in the second cycle corresponding to the fourth region;

[0027] like ΔL 2 The first area, the second area and the third area correspond to ΔL 2 The maximum value in ΔL 2 Corresponding to the first region, the first half-cycle sequence number of the first relationship curve in the first region is the sequence number of the second half-cycle in the first cycle corresponding to the first region, and the second half-cycle sequence number of the second relationship curve in the first region is the sequence number of the first half-cycle in the second cycle corresponding to the first region;

[0028] like ΔL 2 The first area, the second area and the third area correspond to ΔL 2 The second largest value in ΔL 2 Corresponding to the second region, the first half-cycle sequence number of the first relationship curve in the second region is the sequence number of the first half-cycle in the first cycle corresponding to the second region, and the second half-cycle sequence number of the second relationship curve in the second region is the sequence number of the second half-cycle in the second cycle corresponding to the second region;

[0029] like ΔL 2 The first area, the second area and the third area correspond to ΔL 2 The minimum value in ΔL 2 Corresponding to the third region, the first half-cycle sequence number of the first relationship curve in the third region is the sequence number of the first half-cycle in the first cycle corresponding to the third region, and the second half-cycle sequence number of the second relationship curve in the third region is the sequence number of the second half-cycle in the second cycle corresponding to the third region.

[0030] In another optional implementation, in step S130, according to the half cycle number and ΔL 1 The corresponding relationship and the current result ΔL 1 , or according to the half-cycle number and ΔL 2 The corresponding relationship and the current result ΔL 2 , the half-cycle sequence number of the current actual distance on the corresponding relationship curve of the optical frequency comb is determined to include:

[0031] Find the first corresponding relationship that matches the current result ΔL 1 orΔL 2 The first half-cycle number k1 of the corresponding current actual distance on the first relationship curve corresponding to the first optical frequency comb;

[0032] Find the second corresponding relationship that matches the current result ΔL 1 or ΔL 2 The corresponding current actual distance is the second half-cycle number k2 on the second relationship curve corresponding to the second optical frequency comb.

[0033] In another optional implementation, step S140 specifically includes:

[0034] Step S141: The equation relationship between the current actual distance, its half-cycle number on the corresponding relationship curve, the half-cycle size of the corresponding relationship curve, the wavelength of the extreme point selected in the corresponding distance interference spectrum, and the multiplication coefficient of the wavelength is: current actual distance La = half-cycle number on the corresponding relationship curve * half-cycle size of the corresponding relationship curve + wavelength of the extreme point selected in the corresponding distance interference spectrum * multiplication coefficient of the wavelength;

[0035] Select two maximum or minimum points from the first optical frequency comb corresponding to the first distance interference spectrum, and determine the wavelengths λ of the two maximum or minimum points 11 and λ 12 , wavelength λ 11 and λ 12 The multiplication coefficients are m 11 and m 12 , select two maximum or minimum points from the second distance interference spectrum corresponding to the second optical frequency comb, and determine the wavelength λ of the two maximum or minimum points 21 and λ 22 , wavelength λ 21 and λ 22 The multiplication coefficients are m 21 and m 22 ,

[0036] Step S142: Establish the following four equations based on the equation relationship:

[0037] k1*L pp1 / 2+m 11 *λ 11 =k2*L pp2 / 2+m 21 *λ 21

[0038] k1*L pp1 / 2+m 11 *λ 11 =k2*Lpp2 / 2+m 22 *λ 22

[0039] k1*L pp1 / 2+m 12 *λ 12 =k2*L pp2 / 2+m 21 *λ 21

[0040] k1*L pp1 / 2+m 12 *λ 12 =k2*L pp2 / 2+m 22 *λ 22 ;

[0041] Solve the four equations simultaneously to obtain the multiplication coefficient m 11 , m 12 , m 21 , m 22 .

[0042] In another optional implementation, step S150 specifically includes:

[0043] According to the formula La=k1*L pp1 / 2+m 11 *λ 11 , calculate the current actual distance La.

[0044] In another optional implementation, in step S140, for each set of optical frequency comb corresponding range interferometry spectrum, the extreme points in the range interferometry spectrum are selected according to the following steps:

[0045] Determine k maximum values or minimum values collected in the distance interference spectrum;

[0046] For each determined extreme point, the extreme point and its corresponding points nearby are fitted to obtain the fitted extreme point, which is used as the selected extreme point.

[0047] The beneficial effects of the present invention are:

[0048] 1. When determining the half-cycle number of the current actual distance and the current actual distance, the present invention transmits two sets of optical frequency combs with a repetition frequency difference to the same dispersion interferometry ranging system. The half-cycle number of the current actual distance and the current actual distance are determined based on the measured distances obtained by the two sets of optical frequency combs. Since only one set of dispersion interferometry ranging system is used to determine the half-cycle number and the current actual distance, no other measurement components are required, making the entire system simpler. In addition, the optical path traversed by the two sets of optical frequency combs is the same, thus eliminating the systematic errors caused by other methods of half-cycle positioning during long-distance measurement. In other words, even for long-distance measurement, the accuracy of determining the current actual distance is still high. It can be improved; when the present invention improves the distance measurement resolution to the nanometer level, it is based on two sets of optical frequency combs with a repetition frequency difference, and determines the current actual distance according to the equation relationship between the current actual distance and its half-cycle sequence number on the relationship curve of the corresponding optical frequency comb, the half-cycle size of the corresponding relationship curve, the extreme point wavelength selected in the corresponding distance interference spectrum, and the multiplication coefficient of the wavelength. When determining the current actual distance, the present invention only involves the positioning of the extreme point wavelength, and does not need to determine the current actual distance based on the phase change amount, nor does it need to infer the phase based on the intensity signal. Therefore, the present invention can avoid the intensity noise introduced in the phase inversion process, thereby improving the accuracy of determining the current actual distance;

[0049] 2. The present invention selects to associate two triangle waves whose actual distance difference corresponding to the maximum value of the measured distance in the two relationship curves is less than the actual distance of half a period, which can ensure that the corresponding distance of each position in each divided area is ΔL 1 or ΔL 2 The present invention selects a triangle wave from each of the two relationship curves for correlation, and divides the two associated triangle waves into the first area, the second area, the third area and the fourth area according to the waveform relationship. Therefore, no matter which area the current actual distance is in, the current result can be used to calculate the distance. ΔL 1 Corresponding to each fourth area ΔL 1 Compare and convert the current results Δ L 2 Corresponding to the first, second and third areas ΔL 2 Comparison is performed to determine the area where the current actual distance is located. It can be seen that the present invention can determine the area where the current actual distance is located of any length, thereby realizing long-distance measurement;

[0050] 3. When solving the multiplication coefficient, the present invention selects the same number of extreme points from the two distance interference spectra to establish an equation system. This can eliminate common mode errors, thereby reducing system errors and improving the accuracy of determining the multiplication coefficient. When the multiplication coefficient is substituted into the equation relationship to calculate the current actual distance, the accuracy of determining the current actual distance can be improved.

[0051] 4. When selecting the extreme point, the present invention fits the extreme point and its nearby corresponding points, and uses the fitted extreme point as the selected extreme point, thereby improving the accuracy of determining the extreme point. Compared with using only one comb tooth to determine the extreme point, the present invention uses the fitted extreme point, which reduces the impact of the laser thermal noise on the determination of the current actual distance, and improves the accuracy of determining the current actual distance; when calculating the current actual distance and performing wavelength positioning, the present invention performs wavelength positioning on the fitted extreme point, and the error of wavelength positioning is at the nanometer level. The wavelength positioning error is greatly reduced, thereby further improving the accuracy of determining the current actual distance; since the wavelength positioning resolution is at the nanometer level, when the present invention calculates the current actual distance based on the extreme point wavelength, the accuracy of determining the current actual distance can also reach the nanometer level. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a flow chart of an embodiment of the self-referenced long-distance high-resolution dispersive interferometry ranging method of the present invention;

[0053] Figure 2 1 is a schematic diagram showing the relationship between the first relationship curve and the second relationship curve according to an embodiment of the present invention;

[0054] Figure 3 is a schematic diagram of the relationship between the first relationship curve and the second relationship curve according to another embodiment of the present invention;

[0055] Figure 4 It is a block diagram of an embodiment of the self-referenced long-distance high-resolution dispersive interferometry ranging system of the present invention. DETAILED DESCRIPTION

[0056] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention and to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0057] In the description of the present invention, unless otherwise specified and limited, it should be noted that the term "connection" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection between two elements. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meaning of the above terms can be understood according to the specific circumstances.

[0058] See also Figure 1 , is a flow chart of an embodiment of the self-referenced long-distance high-resolution dispersion interferometry ranging method of the present invention. The self-referenced long-distance high-resolution dispersion interferometry ranging method may include the following steps:

[0059] Step S110: Transmit two sets of optical frequency combs with repetition frequency difference to the dispersion interferometry ranging system, and each set of optical frequency combs generates a corresponding distance interference spectrum during the transmission process of the dispersion interferometry ranging system.

[0060] Step S120: Perform Fourier transform on the two sets of distance interference spectra respectively, and perform rough distance measurement based on the peak value of the interference spectrum after Fourier transform to obtain the measured distance L respectively. DPI1 and L DPI2 .

[0061] In this step, the two sets of range interference spectra can be separated by wavelength interval first, and then the two sets of range interference spectra are Fourier transformed. When the range is roughly measured based on the peak value of the Fourier transformed interference spectrum, the more spectral components in the range interference spectrum, the higher the accuracy of the interference spectrum peak positioning.

[0062] Step S130: measuring the distance L DPI1 and L DPI2 Do the difference or sum to get the current result ΔL 1 or ΔL 2 In the relationship curves corresponding to each set of optical frequency combs, the relationship between the measured distance and the actual distance changes periodically. Each cycle is divided into two half cycles. The half cycle number of the actual distance is the same as ΔL 1 or ΔL 2 There is a corresponding relationship, according to the half-cycle sequence number and ΔL 1 The corresponding relationship and the current result ΔL 1 , or according to the half-cycle number and ΔL 2 The corresponding relationship and the current result ΔL 2 , determine the half-cycle number corresponding to the current actual distance obtained based on the set of optical frequency combs.

[0063] In this step, the first relationship curve and the second relationship curve corresponding to the two sets of optical frequency combs can be as follows: Figure 2As shown in the figure, it can be seen that the horizontal coordinate in the relationship curve represents the actual distance, the vertical coordinate represents the measured distance, the solid line represents the first relationship curve corresponding to the first optical frequency comb, and the dotted line represents the second relationship curve corresponding to the second optical frequency comb. The first optical frequency comb is transmitted to the dispersion interferometry ranging system before the second optical frequency comb. For the relationship curve between the measured distance and the actual distance corresponding to each set of optical frequency combs, the relationship curve between the measured distance and the actual distance in the relationship curve changes periodically (for example, the first relationship curve shown by the solid line and the second relationship curve shown by the dotted line in the figure change periodically). In each period of the relationship curve, the measured distance and the actual distance are in an isosceles triangular wave relationship, and each period can be divided into two half-periods symmetrical with respect to the vertical direction. From Figure 2 It can also be seen that as the period increases synchronously, at the same measured distance, the difference between the actual distances corresponding to the measured distances in the two relationship curves increases. For example, in the nth period of the two relationship curves, at a measured distance, the corresponding actual distance in the two relationship curves is D1. In the n+1th period of the two relationship curves, at the same measured distance, the actual distance in the two relationship curves is D2, which is greater than D1, where n is an integer greater than 0. Each actual distance corresponds to a half-period, and as the actual distance increases, the sequence number of the half-period in which it occurs increases.

[0064] For each triangular wave in the first relationship curve, a triangular wave is selected from the second relationship curve to be associated with the triangular wave in the first relationship curve. For each pair of associated triangular waves, the actual distance corresponding to the maximum value of the measured distance of the first triangular wave in the pair of associated triangular waves and the actual distance corresponding to the maximum value of the measured distance of the second triangular wave are respectively used as the first actual distance and the second actual distance, and the difference between the first actual distance and the second actual distance is less than the half-cycle actual distance. ​ and ​ As shown, the area between the first actual distance and the second actual distance is taken as the first area, and the area between the actual distance corresponding to the minimum distance measured on one side of the first triangular wave and the second triangular wave is taken as the second area, and the second area is located before the first area; the area between the actual distance corresponding to the minimum distance measured on the other side of the first triangular wave and the second triangular wave is taken as the third area, and the third area is located after the first area; the area between the first area and the second area and between the first area and the third area is taken as the fourth area. ​ 1 Indicates that the actual distance is within the fourth area, the measured distance L DPI1 Subtract L DPI2 The result obtained is, ​ 2When the actual distance is located in the first area, the second area and the third area respectively, the measured distance L DPI1 and L DPI2 The result of the summation; the two fourth regions correspond to ​ 1 The first area, the second area and the third area correspond to ​ 2 The sizes of are different. For each area, the corresponding ​ L 1 or ​ 2 same.

[0065] Since the first optical frequency comb is transmitted to the dispersion interferometry ranging system before the second optical frequency comb, the triangle wave on the first relationship curve corresponding to the first optical frequency comb is usually located after the triangle wave of the same period on the second relationship curve corresponding to the second optical frequency comb, such as ​ As shown, however, as the distance to be measured increases, for the triangle waves at the same period in the two relationship curves, the difference between the actual distances corresponding to the maximum values of the two triangle wave measured distances may be greater than the actual distance of half a period, that is, the triangle wave on the first relationship curve is located before the triangle wave with the same period on the second relationship curve, as shown in ​ As shown, if we still associate the two triangle waves in the same period in the two relationship curves, we cannot guarantee that the corresponding positions in each divided area ​ 1 or ​ 2 Therefore, the present invention chooses to associate the two triangle waves whose actual distance difference corresponding to the maximum value of the measured distance in the two relationship curves is less than the actual distance of half a period, which can ensure that the corresponding distance of each position in each divided area is the same. ​ 1 or ​ 2 The present invention selects a triangle wave from each of the two relationship curves for correlation, and divides the two associated triangle waves into the first area, the second area, the third area and the fourth area according to the waveform relationship. Therefore, no matter which area the current actual distance is in, the current result can be used to calculate the distance. ​ 1 Corresponding to each fourth area ​ 1 Compare and convert the current results ​ 2 Corresponding to the first, second and third areas ​ 2By performing a comparison to determine the area where the current actual distance is located, it can be seen that the present invention can determine the area where the current actual distance is located of any length, thereby realizing long-distance measurement.

[0066] The first optical frequency comb is transmitted to the dispersion interferometry ranging system before the second optical frequency comb, and the measured distance L obtained based on the first optical frequency comb is DPI1 On the first relationship curve, the measured distance L obtained based on the second optical frequency comb is DPI2 For each pair of associated triangle waves, in the pair of associated triangle waves, the first actual distance of the first triangle wave on the first relationship curve is greater than the second actual distance of the second triangle wave on the second relationship curve (such as ​ ), or the first actual distance of the first triangular wave is less than the second actual distance of the second triangular wave (as shown ​ shown).

[0067] When the first actual distance is greater than the second actual distance, as ​ As shown, for each pair of associated triangle waves, the fourth area preceding the first area corresponds to ​ 1 is negative, the fourth area after the first area corresponds to ​ 1 is positive, and the absolute value of the former is smaller than the latter; the first area, the third area and the second area correspond to ​ 2 The value of gradually decreases; when the first actual distance is less than the second actual distance, ​ As shown, for each pair of associated triangle waves, the fourth area preceding the first area corresponds to ​ 1 is positive, the fourth area after the first area corresponds to ​ 1 is negative, and the former is greater than the absolute value of the latter; the first area, the second area and the third area correspond to ​ 2 The value gradually decreases.

[0068] In accordance with ​ 1 or ​ 1After determining the area where the current actual distance is located, in order to determine the half-cycle number where the current actual distance is located, it is necessary to establish a corresponding relationship between each area and the half-cycle number. To this end, the present invention determines the first cycle of the first relationship curve in the area and the second cycle of the second relationship curve in the area for each area in each pair of associated triangular waves. According to the first cycle and second cycle corresponding to the area, the first half-cycle number of the first relationship curve in the area and the second half-cycle number of the second relationship curve in the area are determined, and the corresponding half-cycle number of the area is established. ​ 1 or ​ 2 The first correspondence with the first half cycle number, and the region ​ 1 or ​ 2 A second corresponding relationship with the second half cycle sequence number.

[0069] Among them, for each area in each pair of associated triangular waves, determining the first period of the first relationship curve in the area and the second period of the second relationship curve in the area may include: for the first area and the fourth area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve, and the second period of the second curve in the area is the period of the second triangular wave on the second relationship curve.

[0070] When the first actual distance is greater than the second actual distance, as ​ As shown, for the second area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve minus 1, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve; for the third area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve plus 1. When the first actual distance is less than the second actual distance, as ​ As shown, for the second area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve minus 1; for the third area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve plus 1, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve.

[0071] In addition, according to the first period and the second period corresponding to the area, determining the first half period sequence number of the first relationship curve in the area and the second half period sequence number of the second relationship curve in the area may include: when the first actual distance is greater than the second actual distance, such as ​ As shown, if ​ 1 If it is negative, then ​ 1 Corresponding to the fourth region located before the first region, the first half cycle sequence number of the first relationship curve in the fourth region is the sequence number of the first half cycle in the first cycle corresponding to the fourth region, and the second half cycle sequence number of the second relationship curve in the fourth region is the sequence number of the first half cycle in the second cycle corresponding to the fourth region; if ​ 1 is positive, then the ​ 1 Corresponding to the fourth region located after the first region, the first half-cycle sequence number of the first relationship curve in the fourth region is the sequence number of the next half-cycle in the first cycle corresponding to the fourth region, and the second half-cycle sequence number of the second relationship curve in the fourth region is the sequence number of the next half-cycle in the second cycle corresponding to the fourth region.

[0072] like ​ 2 The first area, the second area and the third area correspond to ​ 2 The maximum value in ​ 2 Corresponding to the first region, the first half cycle sequence number of the first relationship curve in the first region is the sequence number of the first half cycle in the first cycle corresponding to the first region, and the second half cycle sequence number of the second relationship curve in the first region is the sequence number of the second half cycle in the second cycle corresponding to the first region; if ​ 2 The first area, the second area and the third area correspond to ​ 2 The second largest value in ​ 2 Corresponding to the third region, the first half-cycle sequence number of the first relationship curve in the third region is the sequence number of the next half-cycle in the first cycle corresponding to the third region, and the second half-cycle sequence number of the second relationship curve in the third region is the sequence number of the first half-cycle in the second cycle corresponding to the third region; if ​ 2 The first area, the second area and the third area correspond to ​ 2 The minimum value in ​ 2Corresponding to the second region, the first half-cycle sequence number of the first relationship curve in the second region is the sequence number of the latter half-cycle in the first cycle corresponding to the second region, and the second half-cycle sequence number of the second relationship curve in the second region is the sequence number of the former half-cycle in the second cycle corresponding to the second region.

[0073] When the first actual distance is smaller than the second actual distance, ​ As shown, if ​ 1 is positive, then the ​ 1 Corresponding to the fourth region located before the first region, the first half-cycle sequence number of the first relationship curve in the fourth region is the sequence number of the first half-cycle in the first cycle corresponding to the fourth region, and the second half-cycle sequence number of the second relationship curve in the fourth region is the sequence number of the first half-cycle in the second cycle corresponding to the fourth region; if ​ 1 If it is negative, then ​ 1 Corresponding to the fourth region located after the first region, the first half-cycle sequence number of the first relationship curve in the fourth region is the sequence number of the next half-cycle in the first cycle corresponding to the fourth region, and the second half-cycle sequence number of the second relationship curve in the fourth region is the sequence number of the next half-cycle in the second cycle corresponding to the fourth region.

[0074] like ​ 2 The first area, the second area and the third area correspond to ​ 2 The maximum value in ​ 2 Corresponding to the first region, the first half-cycle sequence number of the first relationship curve in the first region is the sequence number of the next half-cycle in the first cycle corresponding to the first region, and the second half-cycle sequence number of the second relationship curve in the first region is the sequence number of the previous half-cycle in the second cycle corresponding to the first region; if ​ 2 The first area, the second area and the third area correspond to ​ 2 The second largest value in ​ 2 Corresponding to the second region, the first half-cycle sequence number of the first relationship curve in the second region is the sequence number of the first half-cycle in the first cycle corresponding to the second region, and the second half-cycle sequence number of the second relationship curve in the second region is the sequence number of the second half-cycle in the second cycle corresponding to the second region; if ​ 2 The first area, the second area and the third area correspond to​ 2 The minimum value in ​ 2 Corresponding to the third region, the first half-cycle sequence number of the first relationship curve in the third region is the sequence number of the first half-cycle in the first cycle corresponding to the third region, and the second half-cycle sequence number of the second relationship curve in the third region is the sequence number of the second half-cycle in the second cycle corresponding to the third region.

[0075] In establishing various regions ​ 1 or ​ 2 The first correspondence with the first half cycle number, and the ​ 1 or ​ 2 After the second correspondence between the half cycle number and the second half cycle number, in step S130, ​ 1 The corresponding relationship and the current result ​ 1 , or according to the half-cycle number and ​ 2 The corresponding relationship and the current result ​ 2 , determining the half-cycle sequence number of the current actual distance on the corresponding relationship curve of the set of optical frequency combs may include:

[0076] Find the first corresponding relationship that matches the current result ​ 1 or ​ 2 The first half-cycle number k1 of the corresponding current actual distance on the first relationship curve corresponding to the first optical frequency comb;

[0077] Find the second corresponding relationship that matches the current result ​ 1 or ​ 2 The corresponding current actual distance is the second half-cycle number k2 on the second relationship curve corresponding to the second optical frequency comb.

[0078] To determine the half-cycle number of the current actual distance and the current actual distance, the present invention transmits two optical frequency combs with a repetition frequency difference to the same dispersive interferometry ranging system. The half-cycle number of the current actual distance and the current actual distance are then determined based on the measured distances obtained by the two optical frequency combs. Because the half-cycle number and the current actual distance are determined using only one dispersive interferometry ranging system, no other measuring components are required, simplifying the entire system. Furthermore, the optical path traversed by the two optical frequency combs is identical, eliminating systematic errors introduced by other methods of half-cycle positioning during long-distance measurements. This improves the accuracy of determining the current actual distance even for long-distance measurements.

[0079] Step S140: There is an equation relationship between the current actual distance and its half-cycle number on the corresponding relationship curve, the half-cycle size of the corresponding relationship curve, the wavelength of the extreme point selected in the corresponding distance interference spectrum, and the multiplication coefficient of the wavelength. According to the half-cycle numbers k1 and k2 of the current actual distance on the two sets of optical frequency comb corresponding relationship curves, the corresponding half-cycle size L of the two relationship curves, pp1 / 2 and L pp2 / 2, the wavelengths of k extreme points selected from the first optical frequency comb corresponding to the first distance interference spectrum and the multiplication coefficient of each wavelength, the wavelengths of k extreme points selected from the second optical frequency comb corresponding to the first distance interference spectrum and the multiplication coefficient of each wavelength, based on the equation relationship, establish 2k equations and solve them to obtain the corresponding multiplication coefficients, where k is an integer greater than 1.

[0080] In this step, since the optical frequency comb is discrete in frequency, to avoid measurement dead zones, an optical frequency comb with a large interdigital spacing is typically used as the measurement light source. Thus, the range interferometry spectrum corresponding to the optical frequency comb is also discrete. In step S140, for each set of range interferometry spectra corresponding to the optical frequency comb, the following steps are performed to select the extreme points in the range interferometry spectrum: k maxima or minima collected in the range interferometry spectrum are determined; for each determined extreme point, the extreme point and its corresponding nearby points are fitted to obtain a fitted extreme point, which is then used as the selected extreme point. In the present invention, when selecting the extreme point, fitting the extreme point and its corresponding nearby points is performed, and the fitted extreme point is used as the selected extreme point. This improves the accuracy of extreme point determination. Compared to using only a single comb tooth to determine the extreme point, the present invention uses the fitted extreme point to reduce the impact of laser thermal noise on the current actual distance determination, thereby improving the accuracy of the current actual distance determination.

[0081] The step S140 may specifically include:

[0082] Step S141: The equation relationship between the current actual distance, its half-cycle number on the corresponding relationship curve, the half-cycle size of the corresponding relationship curve, the wavelength of the extreme point selected in the corresponding distance interference spectrum, and the multiplication coefficient of the wavelength is: current actual distance La = half-cycle number on the corresponding relationship curve * half-cycle size of the corresponding relationship curve + wavelength of the extreme point selected in the corresponding distance interference spectrum * multiplication coefficient of the wavelength;

[0083] Select two maximum or minimum points from the first optical frequency comb corresponding to the first distance interference spectrum, and determine the wavelengths λ of the two maximum or minimum points 11 and λ 12 , wavelength λ 11 and λ 12 The multiplication coefficients are m 11 and m 12 , select two maximum or minimum points from the second distance interference spectrum corresponding to the second optical frequency comb, and determine the wavelength λ of the two maximum or minimum points 21 and λ 22 , wavelength λ 21 and λ 22 The multiplication coefficients are m 21 and m 22 ,

[0084] Step S142: Establish the following four equations based on the equation relationship:

[0085] k1*L pp1 / 2+m 11 *λ 11 =k2*L pp2 / 2+m 21 *λ 21

[0086] k1*L pp1 / 2+m 11 *λ 11 =k2*L pp2 / 2+m 22 *λ 22

[0087] k1*L pp1 / 2+m 12 *λ 12 =k2*L pp2 / 2+m 21 *λ 21

[0088] k1*L pp1 / 2+m 12 *λ 12 =k2*L pp2 / 2+m 22 *λ22 ;

[0089] Solve the four equations simultaneously to obtain the multiplication coefficient m 11 , m 12 , m 21 , m 22 .

[0090] When solving the multiplication coefficient, the present invention may introduce systematic errors caused by frequency jitter if only extreme points are selected from one distance interference spectrum to establish the equation system, so the present invention selects the same number of extreme points from two distance interference spectra to establish the equation system. This can eliminate common-mode errors, thereby reducing systematic errors and improving the accuracy of determining the multiplication coefficient. When the multiplication coefficient is substituted into the equation relationship to calculate the current actual distance, the accuracy of determining the current actual distance can be improved.

[0091] Step S150: Substitute the multiplication coefficient obtained by the solution into the equation to calculate the current actual distance. Step S150 may specifically include: according to the formula La=k1*L pp1 / 2+m 11 *λ 11 , calculate the current actual distance La.

[0092] Homodyne interferometry requires determining the phase change at a certain wavelength to improve the distance measurement resolution to the nanometer level. The present invention, when improving the distance measurement resolution to the nanometer level, uses two sets of optical frequency combs with a repetition frequency difference to determine the current actual distance based on the equation between the current actual distance and its half-cycle number on the relationship curve of the corresponding optical frequency comb, the half-cycle size of the corresponding relationship curve, the wavelength of the extreme point selected in the corresponding distance interference spectrum, and the multiplication coefficient of the wavelength. The present invention only involves the location of the extreme point wavelength when determining the current actual distance, and does not need to determine the current actual distance based on the phase change, nor does it need to infer the phase based on the intensity signal. Therefore, the present invention can avoid the intensity noise introduced during the phase inversion process, thereby improving the accuracy of determining the current actual distance. In addition, when calculating the current actual distance and performing wavelength location, the present invention performs wavelength location on the fitted extreme point. The wavelength location error is at the nanometer level, which greatly reduces the wavelength location error, thereby further improving the accuracy of determining the current actual distance. Since the wavelength location resolution is at the nanometer level, the present invention can also achieve nanometer-level accuracy when calculating the current actual distance based on the extreme point wavelength. In this embodiment, the linewidth of each set of optical frequency combs can be more than ten Hz, its spectral range can be hundreds of nanometers, the pulse repetition frequency can be about 50 GHz, and the repetition frequency difference between the two sets of optical frequency combs is adjustable. The measurement distance of the present invention can reach hundreds of kilometers. The measurement rate is mainly limited by the refresh frame rate of the spectrometer. In actual applications, if there are higher requirements for the measurement rate, it is only necessary to replace the spectrometer with a higher refresh rate.

[0093] See also ​ , is a block diagram of an embodiment of a self-referenced, long-distance, high-resolution, dispersive interferometry ranging system according to the present invention. The system may include a laser and a dispersive interferometry ranging system connected in sequence. The laser transmits two optical frequency combs with repetition frequency differences to the dispersive interferometry ranging system. The dispersive interferometry ranging system may include a first collimator, a beam splitter, a reference mirror, a measuring mirror, a second collimator, and a spectrometer. For each optical frequency comb, the first collimator collimates the comb and transmits it to the beam splitter. The beam splitter splits the comb into two paths, which are transmitted as reference light and measurement light to the reference mirror and the measuring mirror, respectively. The reference mirror and the measuring mirror return reflected light to the beam splitter, where the reflected light from the reference mirror and the measuring mirror interferes at the beam splitter, generating an interference light signal. The beam splitter transmits the interference light signal to the second collimator, which then collimates the signal and transmits it to the spectrometer, allowing the spectrometer to obtain a corresponding distance interference spectrum. The second collimator and the spectrometer can be replaced by a grating and a high-speed linear array CCD. The grating is used to receive interference signals, and its output end is connected to the input end of the high-speed linear array CCD. The output end of the high-speed linear array CCD is connected to the spectrometer.

[0094] In one example, a dual optical frequency comb with a central wavelength of 1560nm, a spectral bandwidth of 100nm, and repetition rates of 50GHz and 50.05GHz passes through a first collimator and is then split into two paths by a 90:10 beam splitter. The low-power path is used as the reference light, and the high-power path is used as the measurement light, which is directly irradiated onto the measuring mirror. The reflected light from the measuring mirror and the reflected light from the reference mirror return along their original paths and meet at the beam splitter, generating an interference light signal. The interference light is coupled to the optical fiber through a second collimator, and the signal is collected and stored by a spectrometer. Due to the optical path difference between the two optical signals in the reference arm and the signal arm, the different densities of the FSR of the interference spectrum are reflected in the spectrum. This measurement method enables long-distance distance measurement with nanometer resolution.

[0095] Other embodiments of the present invention will readily occur to those skilled in the art after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

[0096] It will be appreciated that the present invention is not limited to the precise construction that has been described above and shown in the accompanying drawings, and that various modifications and variations can be made without departing from its scope, which is governed solely by the appended claims.

Claims

1. A self-referenced long-distance high-resolution dispersive interferometry ranging method, characterized in that: include: Step S110: transmitting two sets of optical frequency combs with repetition frequency differences to a dispersion interferometry ranging system, wherein each set of optical frequency combs generates a corresponding range interference spectrum during transmission in the dispersion interferometry ranging system; Step S120: Perform Fourier transform on the two sets of distance interference spectra respectively, and perform rough distance measurement based on the peak value of the interference spectrum after Fourier transform to obtain the measured distance L respectively. DPI1 and L DPI2 ; Step S130: measuring the distance L DPI1 and L DPI2 Performing a difference or summation to obtain a current result ΔL1 or ΔL2. In the relationship curves corresponding to each set of optical frequency combs, the relationship between the measured distance and the actual distance varies periodically, and each cycle is divided into two half-cycles. The half-cycle number of the actual distance corresponds to ΔL1 or ΔL2. Based on the correspondence between the half-cycle number and ΔL1 and the current result ΔL1, or based on the correspondence between the half-cycle number and ΔL2 and the current result ΔL2, the half-cycle number of the current actual distance on the corresponding relationship curve of the set of optical frequency combs is determined. Step S140: There is an equation relationship between the current actual distance and its half-cycle number on the corresponding relationship curve, the half-cycle size of the corresponding relationship curve, the wavelength of the extreme point selected in the corresponding distance interference spectrum, and the multiplication coefficient of the wavelength. According to the half-cycle numbers k1 and k2 of the current actual distance on the two sets of optical frequency comb corresponding relationship curves, the corresponding half-cycle size L of the two relationship curves, pp1 / 2 and L pp2 / 2, the wavelengths of k extreme points selected from the first optical frequency comb corresponding to the first distance interference spectrum and the multiplication coefficient of each wavelength, the wavelengths of k extreme points selected from the second optical frequency comb corresponding to the first distance interference spectrum and the multiplication coefficient of each wavelength, based on the equation relationship, establish 2k equations and solve them to obtain the corresponding multiplication coefficients, where k is an integer greater than 1; Step S150: Substitute the multiplication coefficient obtained by solving the equation to calculate the current actual distance.

2. The self-referenced long-distance high-resolution dispersive interferometry ranging method according to claim 1, characterized in that: For each set of optical frequency combs, the relationship curve between the measured distance and the actual distance is an isosceles triangular wave relationship within each cycle of the relationship curve. Each actual distance corresponds to a half-cycle, and as the actual distance increases, the sequence number of the half-cycle increases. For each triangular wave in the first relationship curve, a triangular wave is selected from the second relationship curve to be associated with the triangular wave in the first relationship curve. For each pair of associated triangular waves, the actual distance corresponding to the maximum value of the measured distance of the first triangular wave in the pair of associated triangular waves and the actual distance corresponding to the maximum value of the measured distance of the second triangular wave are respectively used as the first actual distance and the second actual distance, and the difference between the first actual distance and the second actual distance is less than the half-cycle actual distance; the area between the first actual distance and the second actual distance is used as the first area, and the area between the actual distances corresponding to the minimum values of the measured distances on one side of the first triangular wave and the second triangular wave is used as the second area, and the second area is located before the first area; the area between the actual distances corresponding to the minimum values of the measured distances on the other side of the first triangular wave and the second triangular wave is used as the third area, and the third area is located after the first area; the area between the first area and the second area and between the first area and the third area is used as the fourth area; ΔL1 indicates that when the actual distance is within the fourth area, the measured distance L DPI1 Subtract L DPI2 The result obtained, ΔL2, represents the actual distance when the actual distance is located in the first area, the second area and the third area respectively. DPI1 and L DPI2 The summation result is that the sizes of ΔL1 corresponding to the two fourth regions are different; the sizes of ΔL2 corresponding to the first region, the second region and the third region are different, and for each region, the ΔL1 or ΔL2 corresponding to each position in the region is the same.

3. The self-referenced long-distance high-resolution dispersive interferometry ranging method according to claim 2, characterized in that: The first optical frequency comb is transmitted to the dispersion interferometry ranging system before the second optical frequency comb, and the measured distance L obtained based on the first optical frequency comb is DPI1 On the first relationship curve, the measured distance L obtained based on the second optical frequency comb is DPI2 On the second relationship curve; for each pair of associated triangular waves, in the pair of associated triangular waves, a first actual distance of the first triangular wave on the first relationship curve is greater than a second actual distance of the second triangular wave on the second relationship curve, or the first actual distance of the first triangular wave is less than the second actual distance of the second triangular wave; When the first actual distance is greater than the second actual distance, for each pair of associated triangular waves, the ΔL1 corresponding to the fourth area before the first area is negative, and the ΔL1 corresponding to the fourth area after the first area is positive, and the absolute value of the former is smaller than the latter; the values of ΔL2 corresponding to the first area, the third area, and the second area gradually decrease; When the first actual distance is less than the second actual distance, for each pair of associated triangular waves, the ΔL1 corresponding to the fourth area located before the first area is positive, and the ΔL1 corresponding to the fourth area located after the first area is negative, and the former is greater than the absolute value of the latter; the values of ΔL2 corresponding to the first area, the second area, and the third area gradually decrease.

4. The self-referenced long-distance high-resolution dispersive interferometry ranging method according to claim 3, characterized in that: For each region in each pair of associated triangular waves, determine the first period of the first relationship curve in the region and the second period of the second relationship curve in the region; determine the first half-period sequence number of the first relationship curve in the region and the second half-period sequence number of the second relationship curve in the region based on the first period and the second period corresponding to the region; establish a first correspondence between ΔL1 or ΔL2 in the region and the first half-period sequence number, and a second correspondence between ΔL1 or ΔL2 in the region and the second half-period sequence number.

5. The self-referenced long-distance high-resolution dispersive interferometry ranging method according to claim 4, characterized in that: For each region in each pair of associated triangular waves, determining a first period of the first relationship curve in the region and a second period of the second relationship curve in the region includes: for the first region and the fourth region, the first period of the first relationship curve in the region is a period of the first triangular wave on the first relationship curve, and the second period of the second relationship curve in the region is a period of the second triangular wave on the second relationship curve; When the first actual distance is greater than the second actual distance, for the second area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve minus 1, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve; for the third area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve plus 1; When the first actual distance is less than the second actual distance, for the second area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve minus 1; for the third area, the first period of the first relationship curve in the area is the period of the first triangular wave on the first relationship curve plus 1, and the second period of the second relationship curve in the area is the period of the second triangular wave on the second relationship curve.

6. The self-referenced long-distance high-resolution dispersive interferometry ranging method according to claim 4 or 5, characterized in that: Determining, according to the first period and the second period corresponding to the region, a first half-period sequence number of the first relationship curve in the region and a second half-period sequence number of the second relationship curve in the region includes: When the first actual distance is greater than the second actual distance, if ΔL1 is negative, then ΔL1 corresponds to a fourth region located before the first region, and the first half-cycle sequence number of the first relationship curve in the fourth region is the sequence number of the first half-cycle in the first cycle corresponding to the fourth region, and the second half-cycle sequence number of the second relationship curve in the fourth region is the sequence number of the first half-cycle in the second cycle corresponding to the fourth region; if ΔL1 is positive, then ΔL1 corresponds to a fourth region located after the first region, and the first half-cycle sequence number of the first relationship curve in the fourth region is the sequence number of the next half-cycle in the first cycle corresponding to the fourth region, and the second half-cycle sequence number of the second relationship curve in the fourth region is the sequence number of the next half-cycle in the second cycle corresponding to the fourth region; If ΔL2 is the maximum value among the ΔL2 corresponding to the first region, the second region, and the third region, then ΔL2 corresponds to the first region, the first half-cycle sequence number of the first relationship curve in the first region is the sequence number of the first half-cycle in the first cycle corresponding to the first region, and the second half-cycle sequence number of the second relationship curve in the first region is the sequence number of the second half-cycle in the second cycle corresponding to the first region; If ΔL2 is the second largest value among the ΔL2 values corresponding to the first, second, and third regions, then ΔL2 corresponds to the third region, and the first half-cycle sequence number of the first relationship curve in the third region is the sequence number of the next half-cycle in the first cycle corresponding to the third region, and the second half-cycle sequence number of the second relationship curve in the third region is the sequence number of the previous half-cycle in the second cycle corresponding to the third region; If ΔL2 is the minimum value of ΔL2 corresponding to the first, second, and third regions, then ΔL2 corresponds to the second region, the first half-cycle sequence number of the first relationship curve in the second region is the sequence number of the next half-cycle in the first cycle corresponding to the second region, and the second half-cycle sequence number of the second relationship curve in the second region is the sequence number of the first half-cycle in the second cycle corresponding to the second region; When the first actual distance is less than the second actual distance, if ΔL1 is positive, then ΔL1 corresponds to a fourth region located before the first region, and the first half-cycle sequence number of the first relationship curve in the fourth region is the sequence number of the first half-cycle in the first cycle corresponding to the fourth region, and the second half-cycle sequence number of the second relationship curve in the fourth region is the sequence number of the first half-cycle in the second cycle corresponding to the fourth region; if ΔL1 is negative, then ΔL1 corresponds to a fourth region located after the first region, and the first half-cycle sequence number of the first relationship curve in the fourth region is the sequence number of the next half-cycle in the first cycle corresponding to the fourth region, and the second half-cycle sequence number of the second relationship curve in the fourth region is the sequence number of the next half-cycle in the second cycle corresponding to the fourth region; If ΔL2 is the maximum value among the ΔL2 corresponding to the first region, the second region, and the third region, then ΔL2 corresponds to the first region, the first half-cycle sequence number of the first relationship curve in the first region is the sequence number of the next half-cycle in the first cycle corresponding to the first region, and the second half-cycle sequence number of the second relationship curve in the first region is the sequence number of the previous half-cycle in the second cycle corresponding to the first region; If ΔL2 is the second largest value among the ΔL2 values corresponding to the first, second, and third regions, then ΔL2 corresponds to the second region, and the first half-cycle sequence number of the first relationship curve in the second region is the sequence number of the first half-cycle in the first cycle corresponding to the second region, and the second half-cycle sequence number of the second relationship curve in the second region is the sequence number of the second half-cycle in the second cycle corresponding to the second region; If ΔL2 is the minimum value of ΔL2 corresponding to the first, second, and third regions, then ΔL2 corresponds to the third region, and the first half-cycle sequence number of the first relationship curve in the third region is the sequence number of the first half-cycle in the first cycle corresponding to the third region, and the second half-cycle sequence number of the second relationship curve in the third region is the sequence number of the second half-cycle in the second cycle corresponding to the third region.

7. The self-referenced long-distance high-resolution dispersive interferometry ranging method according to claim 4, characterized in that: In step S130, determining the half-cycle number of the current actual distance on the set of optical frequency comb correspondence curves based on the correspondence between the half-cycle number and ΔL1 and the current result ΔL1, or based on the correspondence between the half-cycle number and ΔL2 and the current result ΔL2, includes: Finding the first half-cycle number k1 of the current actual distance corresponding to the current result ΔL1 or ΔL2 on the first relationship curve corresponding to the first optical frequency comb from the first corresponding relationship; The second half-cycle number k2 of the current actual distance corresponding to the current result ΔL1 or ΔL2 on the second relationship curve corresponding to the second optical frequency comb is found from the second corresponding relationship.

8. The self-referenced long-distance high-resolution dispersive interferometry ranging method according to claim 1, characterized in that: The step S140 specifically includes: Step S141: The equation relationship between the current actual distance, its half-cycle number on the corresponding relationship curve, the half-cycle size of the corresponding relationship curve, the wavelength of the extreme point selected in the corresponding distance interference spectrum, and the multiplication coefficient of the wavelength is: current actual distance La = half-cycle number on the corresponding relationship curve * half-cycle size of the corresponding relationship curve + wavelength of the extreme point selected in the corresponding distance interference spectrum * multiplication coefficient of the wavelength; Select two maximum or minimum points from the first optical frequency comb corresponding to the first distance interference spectrum, and determine the wavelengths λ of the two maximum or minimum points 11 and λ 12 , wavelength λ 11 and λ 12 The multiplication coefficients are m 11 and m 12 , select two maximum or minimum points from the second distance interference spectrum corresponding to the second optical frequency comb, and determine the wavelength λ of the two maximum or minimum points 21 and λ 22 , wavelength λ 21 and λ 22 The multiplication coefficients are m 21 and m 22 , Step S142: Establish the following four equations based on the equation relationship: k1*L pp1 / 2+m 11 *l 11 =k2*L pp2 / 2+m 21 *l 21 k1*L pp1 / 2+m 11 *l 11 =k2*L pp2 / 2+m 22 *l 22 k1*L pp1 / 2+m 12 *l 12 =k2*L pp2 / 2+m 21 *l 21 k1*L pp1 / 2+m 12 *l 12 =k2*L pp2 / 2+m 22 *l 22 ; Solve the four equations simultaneously to obtain the multiplication coefficient m 11 , m 12 , m 21 , m 22 .

9. The self-referenced long-distance high-resolution dispersive interferometry ranging method according to claim 8, characterized in that: The step S150 specifically includes: According to the formula La=k1*L pp1 / 2+m 11 *λ 11 , calculate the current actual distance La.

10. The self-referenced long-distance high-resolution dispersive interferometry ranging method according to claim 1, characterized in that: In step S140, for each set of optical frequency comb corresponding range interferometry spectrum, the extreme points in the range interferometry spectrum are selected according to the following steps: Determine k maximum values or minimum values collected in the distance interference spectrum; For each determined extreme point, the extreme point and its corresponding points nearby are fitted to obtain the fitted extreme point, which is used as the selected extreme point.

Images