A dual optical frequency comb ranging system and method

Abstract

The present application is applicable to the technical field of dual optical frequency comb ranging, and provides a dual optical frequency comb ranging system and method, wherein the dual optical frequency comb ranging system includes a first optical frequency comb, a second optical frequency comb, a first circulator, a second circulator, a third circulator, a dispersion module, a first coupler and a second coupler. The present application performs time domain stretching on the first optical frequency comb and the second optical frequency comb through the dispersion module, thereby eliminating the mutual restriction between the unambiguous measurement range and the measurement rate in the traditional dual optical frequency comb ranging system, and improving the measurement rate while ensuring that the system has a large measurement range; at the same time, with the help of time domain stretching, the direct measurement dimension of the system is converted from the time domain to the frequency domain, so that the measurement accuracy of the system does not deteriorate due to the broadening of the optical pulse during the time domain stretching process, and realizes large-range, high-speed and high-precision dual optical frequency comb distance measurement.

Description

Technical Field

[0001] The present application belongs to the field of dual optical frequency comb (OFC) ranging technology, and in particular, relates to a dual optical frequency comb ranging system and method. Background Art

[0002] Optical frequency combs are widely used in the fields of optical atomic clocks, distance measurement, spectral measurement, coherent optical communication, radio frequency signal generation, and bioimaging. Although dual optical frequency combs have achieved MHz-level measurement rates and kilometers-level measurement distances in ranging systems, it is difficult to optimize both the measurement rate and (unambiguous) measurement distance at the same time. This is mainly due to the mutual constraints between the measurement distance, sampling accuracy, and measurement rate of the dual optical frequency comb ranging system. In a dual optical frequency comb ranging system, the measurement rate of the system is equal to the repetition frequency detuning of the two optical frequency combs, while the measurement distance is inversely proportional to the repetition frequency of the optical frequency combs. Therefore, in theory, to achieve fast and long-distance measurement, a dual optical frequency comb with a large repetition frequency detuning and a low repetition frequency should be used. However, in order to achieve accurate distance information measurement during ranging, the asynchronous sampling accuracy of the dual optical frequency combs should be as high as possible. Therefore, in order to ensure sufficient sampling accuracy, a dual optical frequency comb with a small repetition frequency detuning or a high repetition frequency is usually required, which runs counter to the conditions for achieving fast and long distance. Summary of the invention

[0003] The embodiments of the present application provide a dual-optical frequency comb ranging system and method to solve the problem in the existing dual-optical frequency comb ranging system that the measurement rate and the measurement distance are difficult to be optimized simultaneously due to the mutual constraints among the measurement distance, sampling accuracy and measurement rate.

[0004] A first aspect of an embodiment of the present application provides a dual optical frequency comb ranging system, including a first optical frequency comb, a second optical frequency comb, a first circulator, a second circulator, a third circulator, a dispersion module, a first coupler, and a second coupler;

[0005] The first optical frequency comb is used to generate a reference optical signal at a first preset repetition frequency, and the reference optical signal is transmitted to the dispersion module via the first circulator for time domain stretching and then transmitted to the second coupler via the second circulator;

[0006] The second optical frequency comb is used to generate a measurement optical signal at a second preset repetition frequency, the measurement optical signal is transmitted to the dispersion module via the second circulator for time domain stretching, and then sequentially transmitted to the first coupler via the first circulator and the third circulator, and then respectively transmitted to the reflector and the object to be measured after being split by the first coupler, and there is a preset detuning amount between the first preset repetition frequency and the second preset repetition frequency;

[0007] The first reflected light signal reflected by the reflector and the second reflected light signal reflected by the object to be measured are combined via the first coupler and then transmitted to the second coupler via the third circulator;

[0008] The reference light signal, the first reflected light signal and the second reflected light signal interfere with each other in the second coupler to generate an interference light signal, which is then transmitted to a measuring device;

[0009] The measuring device is used to measure the time domain information of the interference light signal.

[0010] In one embodiment, the dispersion module includes at least one of a single mode optical fiber, a grating, and an on-chip waveguide.

[0011] In one embodiment, the single-mode optical fiber includes at least one of a common single-mode optical fiber, a dispersion-compensating optical fiber, a large effective area optical fiber, and a dispersion-shifted optical fiber;

[0012] The grating includes at least one of a fiber Bragg grating and a spatial grating.

[0013] In one embodiment, the first optical frequency comb and the second optical frequency comb include at least one of a mode-locked laser and a microcavity optical frequency comb.

[0014] In one embodiment, the mode-locked laser is an erbium-doped fiber mode-locked laser, an ytterbium-doped fiber mode-locked laser or a titanium sapphire mode-locked laser, which is used to emit a near-infrared or mid-infrared mode-locked optical signal;

[0015] The microcavity optical frequency comb is realized based on at least one of silicon, silicon dioxide, silicon nitride, lithium niobate, calcium fluoride and magnesium fluoride.

[0016] In one embodiment, the dual optical frequency comb ranging system further includes a scanning galvanometer;

[0017] The scanning galvanometer is used to adjust the incident position of the measuring light signal transmitted to the object to be measured, so as to achieve two-dimensional or three-dimensional scanning of the object to be measured.

[0018] In one embodiment, the dual optical frequency comb ranging system further includes a first collimator and a second collimator;

[0019] The measuring light signal is split by the first coupler and then transmitted to the first collimator and the second collimator for collimation, and then transmitted to the reflector and the object to be measured respectively;

[0020] The first reflected light signal and the second reflected light signal are transmitted to the first coupler via the first collimator and the second collimator respectively for beam combination, and then transmitted to the second coupler via the third circulator.

[0021] In one embodiment, the dual optical frequency comb ranging system further includes at least one of a first polarization controller and a second polarization controller;

[0022] The first polarization controller is used to control the polarization states of the first reflected light signal and the second reflected light signal;

[0023] The second polarization controller is used to control the polarization state of the reference optical signal.

[0024] A second aspect of the embodiments of the present application provides a dual-optical frequency comb ranging method, which is implemented based on the dual-optical frequency comb ranging system of the first aspect. The method includes:

[0025] Controlling the first optical frequency comb to generate a reference optical signal at a first preset repetition frequency;

[0026] Controlling the second optical frequency comb to generate a measurement optical signal at a second preset repetition frequency, wherein there is a preset detuning amount between the first preset repetition frequency and the second preset repetition frequency;

[0027] The distance information of the object to be measured is obtained according to the time domain information of the interference light signal measured by the measuring device.

[0028] In one embodiment, obtaining the distance information of the object to be measured according to the time domain information of the interference light signal measured by a measuring device includes:

[0029] Dividing the time domain information of the interference light signal, determining a first effective interference light signal formed by the interference of the reference light signal and the first reflected light signal and a corresponding reference position, and a second effective interference light signal formed by the interference of the reference light signal and the second reflected light signal and a corresponding measurement position;

[0030] Performing Fourier transform on the first effective interference light signal to obtain first relative depth information;

[0031] Performing Fourier transform on the second effective interference light signal to obtain second relative depth information;

[0032] The absolute distance information of the object to be measured is obtained according to the number of envelopes between the reference position and the measurement position and the first relative depth information and the second relative depth information.

[0033] In one embodiment, the calculation formula of the first relative depth information is:

[0034]

[0035] Among them, δd 1represents the first relative depth information, ΔB 1 represents the radio frequency corresponding to the interference light signal at the reference position, Φ represents the dispersion amount of the dispersion module, and λ 0 represents the central wavelength of the overlapping portion of the spectrum of the first optical frequency comb and the second optical frequency comb;

[0036] The calculation formula of the second relative depth information is:

[0037]

[0038] Among them, δd 2 represents the second relative depth information, ΔB 2 Indicates the radio frequency corresponding to the interference light signal at the measurement position;

[0039] The calculation formula of the absolute distance information is:

[0040] d=mΔd+δd 1 +δd 2

[0041]

[0042] Wherein, d represents the absolute distance information, m represents the number of envelopes, Δd represents the distance between adjacent envelopes, c represents the speed of light in vacuum, Δf represents the preset detuning amount, and f 1 represents the first preset repetition frequency, f 2 Indicates the second preset repetition frequency.

[0043] The dual-optical frequency comb ranging system provided in the first aspect of the embodiments of the present application performs time-domain stretching on the first optical frequency comb and the second optical frequency comb through a dispersion module, thereby eliminating the limitations of the unambiguous measurement range and measurement rate in the traditional dual-optical frequency comb ranging system, and improving the measurement rate while ensuring that the system has a large measurement range; at the same time, with the help of time domain stretching, the direct measurement dimension of the system is converted from the time domain to the frequency domain, so that the measurement accuracy of the system does not deteriorate due to the broadening of the optical pulse during the time domain stretching process, thereby realizing large-range, high-speed and high-precision dual-optical frequency comb distance measurement.

[0044] It can be understood that the beneficial effects of the second aspect mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 This is a schematic diagram of the first structure of the dual optical frequency comb ranging system provided in the embodiment of the present application;

[0047] Figure 2 This is a second structural schematic diagram of the dual optical frequency comb ranging system provided in an embodiment of the present application;

[0048] Figure 3 This is a third structural schematic diagram of the dual optical frequency comb ranging system provided in an embodiment of the present application;

[0049] Figure 4 are the measurement results of the dual optical frequency comb ranging system provided by the embodiment of the present application at different measurement rates;

[0050] Figure 5 This is a schematic diagram of the first process of the dual optical frequency comb ranging method provided in the embodiment of the present application;

[0051] Figure 6 This is a second flow chart of the dual optical frequency comb ranging method provided in an embodiment of the present application;

[0052] Figure 7 It is the measurement result of the dual optical frequency comb ranging system provided in the embodiment of the present application at a measurement rate. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application.

[0054] The term "comprising" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method or system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. In addition, the terms "first", "second" and "third" etc. are used to distinguish different objects, rather than to describe a specific order.

[0055] like Figure 1 As shown, the embodiment of the present application provides a dual optical frequency comb ranging system, including a first optical frequency comb 11, a second optical frequency comb 12, a first circulator 21, a second circulator 22, a third circulator 23, a dispersion module 3, a first coupler 41 and a second coupler 42;

[0056] The first optical frequency comb 11 is used to generate a reference optical signal at a first preset repetition frequency. The reference optical signal is transmitted to the dispersion module 3 via the first circulator 21 for time domain stretching and then transmitted to the second coupler 42 via the second circulator 22.

[0057] The second optical frequency comb 12 is used to generate a measurement optical signal at a second preset repetition frequency. The measurement optical signal is transmitted to the dispersion module 3 via the second circulator 22 for time domain stretching, and then transmitted to the first coupler 41 via the first circulator 21 and the third circulator 23 in sequence. Then, after being split by the first coupler 41, it is transmitted to the reflector 511 of the first measuring arm 51 and the object to be measured 521 of the second measuring arm 52, respectively. There is a preset detuning amount between the first preset repetition frequency and the second preset repetition frequency.

[0058] The first reflected light signal reflected by the reflector 511 and the second reflected light signal reflected by the object to be measured 521 are combined by the first coupler 41 and then transmitted to the second coupler 42 via the third circulator 23;

[0059] The reference light signal, the first reflected light signal and the second reflected light signal interfere with each other in the second coupler 42 to generate an interference light signal which is then transmitted to the measuring device 6;

[0060] The measuring device 6 is used to measure the time domain information of the interference light signal.

[0061] In applications, the components of the dual-optical frequency comb ranging system can be connected by optical fiber to form an all-optical fiber-connected ranging system, which makes the entire system easy to move and will not cause interruption of the transmission optical path due to slight position changes between the components.

[0062] like Figure 1As shown, the connection structure of each component in the dual optical frequency comb ranging system when connected by optical fiber is exemplarily shown, which is as follows:

[0063] The output end of the first optical frequency comb 11 is connected to the input end of the first circulator 21 through an optical fiber;

[0064] The output end of the second optical frequency comb 12 is connected to the input end of the second circulator 22 through an optical fiber;

[0065] The output end of the first circulator 21 is connected to the input end of the third circulator 23 through an optical fiber, and the input and output ends of the first circulator 21 are connected to the first input and output ends of the dispersion module 3 through an optical fiber;

[0066] The output end of the second circulator 22 is connected to the second input end of the second coupler 42 through an optical fiber, and the input and output ends of the second circulator 22 are connected to the second input and output ends of the dispersion module 3 through an optical fiber;

[0067] The input and output ends of the third circulator 23 are connected to the first input end of the second coupler 42 through optical fibers, and the output end of the third circulator 23 is connected to the first input and output ends of the first coupler 41 through optical fibers;

[0068] The second input and output end of the first coupler 41 is connected to the first measuring arm 51 through an optical fiber, and the third input and output end of the first coupler 41 is connected to the second measuring arm 52 through an optical fiber;

[0069] The output end of the second coupler 42 is connected to the input end of the measuring device 6 via an optical fiber.

[0070] In the application, the first optical pulse generated by the first optical frequency comb at the first preset repetition frequency is used as a reference optical signal. The reference optical signal is first transmitted to the dispersion module via the first circulator for time domain stretching, and then transmitted to the second coupler via the second circulator.

[0071] The second optical pulse generated by the second optical frequency comb at the second preset repetition frequency is used as a measuring optical signal. The measuring optical signal is first transmitted to the dispersion module via the second circulator for time domain stretching, and then transmitted to the first coupler via the first circulator and the third circulator in sequence, and then split into two measuring optical signals via the first coupler and transmitted to the first measuring arm and the second measuring arm respectively. The first measuring arm is provided with a reflector for calibrating a reference position, and the second measuring arm is provided with an object to be measured. The two measuring optical signals are respectively reflected by the reflector of the first measuring arm and the object to be measured of the second measuring arm to obtain two reflected optical signals. The two reflected optical signals are combined into one reflected optical signal via the first coupler, and then transmitted to the second coupler via the third circulator.

[0072] The reference light signal and the reflected light signal interfere with each other in the second coupler to generate an interference light signal, and the interference light signal is transmitted to the measuring device;

[0073] The measuring device performs photoelectric conversion and quantitative measurement on the received interference light signal to obtain the time domain information of the interference light signal.

[0074] In the application, the first optical frequency comb and the second optical frequency comb can be formed by the same or different types of mode-locked lasers, for example, erbium-doped fiber mode-locked lasers, ytterbium-doped fiber mode-locked lasers or titanium sapphire mode-locked lasers, etc.; different types of microcavity optical frequency combs can also be used, for example, based on silicon (Si), silicon dioxide (SiO 2 ), silicon nitride (Si 3 N 4 ), lithium niobate (LiNbO 3 ), calcium fluoride (CaF 2 ) and magnesium fluoride (MgF 2 ) can be selected according to actual needs. The repetition frequencies of the first optical frequency comb and the second optical frequency comb are similar, but have a certain detuning amount, and the detuning amount is adjustable. Specifically, the detuning amount can be adjusted by adjusting the repetition frequencies of the first optical frequency comb and the second optical frequency comb. For example, the repetition frequency of the first optical frequency comb is adjusted to a first preset repetition frequency, and the repetition frequency of the second optical frequency comb is adjusted to a second preset repetition frequency, so as to adjust the detuning amount between the two to a preset detuning amount that meets the measurement requirements, and the preset detuning amount is equal to the difference between the first preset repetition frequency and the second preset repetition frequency.

[0075] In an application, the first preset repetition frequency and the second preset repetition frequency may be set to about 100 MHz, and the preset detuning amount between the two may be set to 100 kHz to 250 kHz, specifically 100 kHz, 200 kHz or 250 kHz.

[0076] In applications, the dispersion module can be composed of at least one of a single-mode fiber with dispersion function, a grating, and an on-chip waveguide (SIW). The single-mode fiber can be composed of at least one of a common single-mode fiber, a dispersion-compensating fiber, a large effective area fiber, and a dispersion-shifted fiber. The grating can be specifically composed of at least one of a fiber Bragg grating and a spatial grating. The dispersion module can also be composed of two or more materials in combination to achieve different dispersion characteristics.

[0077] In the application, in order to ensure that the chirp characteristics of the reference optical signal and the measurement optical signal after time domain stretching are consistent, the same dispersion module is used to realize bidirectional transmission of the two optical pulse signals.

[0078] In applications, the first coupler and the second coupler may be implemented by a power beam splitter (Beam Splitter, BS) to achieve beam splitting and beam combining of incident optical signals.

[0079] In applications, the reflector can be realized by a plane reflector or a retroreflector.

[0080] In applications, the measuring device can be implemented by any device that can perform photoelectric conversion on an optical signal and measure its time domain information, for example, a photodetector in conjunction with an oscilloscope or a spectrum analyzer.

[0081] like Figure 2 As shown, in one embodiment, the dual optical frequency comb ranging system provided in the embodiment of the present application further includes a first collimator 71 and a second collimator 72;

[0082] The first collimator 71 is connected to the second input and output ends of the first coupler 41 through an optical fiber;

[0083] The second collimator 72 is connected to the third input and output end of the first coupler 41 through an optical fiber;

[0084] The measuring light signal is split into two measuring light signals via the first coupler 41 . The two measuring light signals are collimated via the first collimator 71 and the second collimator 71 , and then transmitted to the first measuring arm 51 and the second measuring arm 52 , respectively.

[0085] The two measurement light signals are respectively reflected by the reflector 511 to obtain a first reflected light signal and reflected by the object to be measured 521 to obtain a second reflected light signal. The first reflected light signal and the second reflected light signal are respectively transmitted to the first coupler 41 via the first collimator 71 and the second collimator 72 to be combined into one reflected light signal, and then transmitted to the second coupler 42 via the third circulator 23.

[0086] In applications, the first collimator and the second collimator can be implemented by collimating lenses, and are respectively used to collimate the two measurement light signals, so that the two measurement light signals can be accurately incident on the two measurement arms.

[0087] like Figure 3 As shown, in one embodiment, the dual optical frequency comb ranging system provided in the embodiment of the present application further includes a first polarization controller 81 and a second polarization controller 82;

[0088] The first polarization controller 81 is connected between the output end of the third circulator 23 and the first input end of the second coupler 42 through an optical fiber, and is used to control the polarization state of the first reflected light signal and the second reflected light signal;

[0089] The second polarization controller 82 is connected between the output end of the second circulator 22 and the second input end of the second coupler 42 through an optical fiber, and is used to control the polarization state of the reference optical signal.

[0090] In applications, the dual-optical frequency comb ranging system may include only one of the first polarization controller and the second polarization controller.

[0091] In one embodiment, the second measuring arm comprises a scanning galvanometer;

[0092] When the dual optical frequency comb ranging system does not include a second collimator, the scanning galvanometer is arranged between the second input and output end of the first coupler and the object to be measured;

[0093] When the dual optical frequency comb distance measurement system includes a second collimator, the scanning galvanometer is arranged between the second collimator and the object to be measured;

[0094] The scanning galvanometer is used to adjust the incident position of the measuring light signal transmitted to the object to be measured, so as to achieve two-dimensional or three-dimensional scanning of the object to be measured.

[0095] In applications, the scanning galvanometer can be composed of a motor and a reflector moving in a two-dimensional space to achieve a two-dimensional scanning of the surface contour of the object to be measured; the scanning galvanometer can also be composed of a motor and a reflector moving in a three-dimensional space to achieve a three-dimensional scanning of the surface contour of the object to be measured. By setting up the scanning galvanometer, the dual optical frequency comb ranging system can not only be used to measure the absolute distance of the object to be measured, but also to measure the surface contour of the object to be measured, so that it can be used to perform two-dimensional imaging or three-dimensional imaging of the surface contour of the object to be measured.

[0096] like Figure 4 As shown, the measurement results of the dual optical frequency comb ranging system at different measurement rates are exemplarily shown; wherein the repetition frequency of the first optical frequency comb and the second optical frequency comb is about 100 MHz, the horizontal axis represents the measurement time, and the vertical axis represents the intensity of the optical signal, Figure 4 (a) is the measurement result of the system when the measurement rate Δf = 100kHz, Figure 4 (b) is the measurement result of the system when the measurement rate Δf = 200kHz, Figure 4 (c) is the measurement result of the system when the measurement rate Δf = 250kHz, Figure 4 The measuring distances of the objects to be measured corresponding to (a) to (c) are 400 mm, 802 mm, and 1000 mm, respectively.

[0097] Depend on Figure 4It can be seen that the dual-optical frequency comb ranging system provided in the embodiment of the present application uses a dual-optical frequency comb with a repetition frequency of the order of 100 MHz, and can achieve a measurement rate of 100 kHz or even MHz. Compared with the existing dual-optical frequency comb ranging system, the measurement rate can be increased by 2 to 3 orders of magnitude.

[0098] like Figure 5 As shown, the embodiment of the present application also provides a dual optical frequency comb ranging method implemented based on the dual optical frequency comb ranging system, which can be specifically executed by a processor of a control device when running a corresponding computer program. The method includes the following steps S1 to S3:

[0099] S1, controlling the first optical frequency comb to generate a reference optical signal at a first preset repetition frequency;

[0100] S2, controlling the second optical frequency comb to generate a measurement optical signal at a second preset repetition frequency, wherein there is a preset detuning amount between the first preset repetition frequency and the second preset repetition frequency;

[0101] S3. Obtaining distance information of the object to be measured according to the time domain information of the interference light signal measured by the measuring device.

[0102] In application, the control device can be electrically connected to at least one of the laser of the first optical frequency comb, the laser of the second optical frequency comb, the measuring device and the scanning galvanometer to control the working states of these components and realize the measurement of the distance information of the object to be measured. The laser of the first optical frequency comb, the laser of the second optical frequency comb and the measuring device can also work independently without being controlled by the control device.

[0103] In applications, the control device may be a computing device capable of performing data processing functions, such as a desktop computer, a notebook computer, a netbook, a personal digital assistant (PDA), etc.

[0104] In applications, the processor may be implemented by a central processing unit (CPU), other general-purpose processors, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0105] In application, the dual optical frequency comb ranging system and control device may include but are not limited to the above components. Those skilled in the art will understand that Figure 1 to Figure 3 What is shown is merely an example of a dual-optical frequency comb ranging system and does not constitute a limitation of the dual-optical frequency comb ranging system. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the control device may also include storage, input and output devices, network access equipment, etc.

[0106] In application, the control device may also include a memory electrically connected to the processor, for storing a computer program executable by the processor, and when the processor executes the computer program, it realizes the control of the working state of each component electrically connected to the control device. In some embodiments, the memory may be an internal storage unit of the control device, for example, a hard disk or memory of the control device. In other embodiments, the memory may also be an external storage device of the control device, for example, a plug-in hard disk equipped on the control device, a smart memory card (Smart Media Card, SMC), a secure digital (SecureDigital, SD) card, a flash card (Flash Card), etc. Further, the memory may also include both an internal storage unit of the control device and an external storage device. The memory is used to store an operating system, an application program, a boot loader (BootLoader), data, and other programs, such as the program code of a computer program, etc. The memory may also be used to temporarily store data that has been output or is to be output.

[0107] like Figure 6 As shown, in one embodiment, step S3 includes the following steps S31 to S34:

[0108] Step S31, dividing the time domain information of the interference light signal, determining a first effective interference light signal formed by the interference of the reference light signal and the first reflected light signal and a corresponding reference position, and a second effective interference light signal formed by the interference of the reference light signal and the second reflected light signal and a corresponding measurement position;

[0109] Step S32, performing Fourier transform on the first effective interference light signal to obtain first relative depth information;

[0110] Step S33, performing Fourier transform on the second effective interference light signal to obtain second relative depth information;

[0111] Step S34: Obtain absolute distance information of the object to be measured according to the number of envelopes between the reference position and the measurement position and the first relative depth information and the second relative depth information.

[0112] In one embodiment, the calculation formulas of the parameters in steps S31 to S34 are as follows:

[0113] The calculation formula of the first relative depth information is:

[0114]

[0115] Among them, δd 1 Represents the first relative depth information, ΔB 1 represents the RF frequency corresponding to the interference light signal at the reference position, Φ represents the dispersion amount of the dispersion module, and λ 0 represents the central wavelength of the overlapping portion of the spectrum of the first optical frequency comb and the second optical frequency comb;

[0116] The calculation formula of the second relative depth information is:

[0117]

[0118] Among them, δd 2 Represents the second relative depth information, ΔB 2 The radio frequency corresponding to the interference light signal representing the measurement position;

[0119] The calculation formula for absolute distance information is:

[0120] d=mΔd+δd 1 +δd 2

[0121]

[0122] Where d represents the absolute distance information, m represents the number of envelopes, Δd represents the distance between adjacent envelopes, c represents the speed of light in a vacuum, Δf represents the preset detuning amount, and f 1 represents the first preset repetition frequency, f 2 Indicates the second preset repetition frequency.

[0123] In applications, since the frequency domain information of the interference light signal is converted to the time domain with the help of time domain stretching, it is necessary to perform Fourier transform (FT) on the time domain information of the interference light signal to obtain relative distance information, and to process the time positions (i.e., reference position and measurement position) of the first effective interference signal and the second effective interference signal in the interference light signal in combination to obtain accurate distance information.

[0124] like Figure 7 As shown, an exemplary Figure 4 (b) The measurement results of the dual optical frequency comb ranging system at a measurement rate of Δf = 200kHz; the interference light signal is locally amplified (such as Figure 7As shown in (b) to (d), it can be seen that effective interference signals appear only at the measurement position and the reference position, while at other positions, only envelope information exists due to the bandwidth limitation of the measuring equipment. The distance information of the surface of the object to be measured can be obtained by performing Fourier transform on the effective interference signals at the measurement position and the reference position respectively and combining the number of envelope signals between the measurement position and the reference position.

[0125] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0126] Those of ordinary skill in the art will appreciate that the devices of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0127] In the embodiments provided in this application, it should be understood that the disclosed device can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple devices can be combined or integrated.

[0128] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A dual optical frequency comb ranging system, It is characterized in that It includes a first optical frequency comb, a second optical frequency comb, a first circulator, a second circulator, a third circulator, a dispersion module, a first coupler and a second coupler; The first optical frequency comb is used to generate a reference optical signal at a first preset repetition frequency, and the reference optical signal is transmitted to the dispersion module via the first circulator for time domain stretching and then transmitted to the second coupler via the second circulator; The second optical frequency comb is used to generate a measurement optical signal at a second preset repetition frequency, the measurement optical signal is transmitted to the dispersion module via the second circulator for time domain stretching, and then sequentially transmitted to the first coupler via the first circulator and the third circulator, and then respectively transmitted to the reflector and the object to be measured after being split by the first coupler, and there is a preset detuning amount between the first preset repetition frequency and the second preset repetition frequency; The first reflected light signal reflected by the reflector and the second reflected light signal reflected by the object to be measured are combined via the first coupler and then transmitted to the second coupler via the third circulator; The reference light signal, the first reflected light signal and the second reflected light signal interfere with each other in the second coupler to generate an interference light signal, which is then transmitted to a measuring device; The measuring device is used to measure the time domain information of the interference light signal.

2. The dual optical frequency comb ranging system as claimed in claim 1, It is characterized in that The dispersion module includes at least one of a single-mode optical fiber, a grating, and an on-chip waveguide.

3. The dual optical frequency comb ranging system as claimed in claim 2, It is characterized in that The single-mode optical fiber includes at least one of ordinary single-mode optical fiber, dispersion-compensating optical fiber, large effective area optical fiber and dispersion-shifted optical fiber; The grating includes at least one of a fiber Bragg grating and a space grating.

4. The dual optical frequency comb ranging system as claimed in claim 1, It is characterized in that The first optical frequency comb and the second optical frequency comb include at least one of a mode-locked laser and a microcavity optical frequency comb.

5. The dual optical frequency comb ranging system as claimed in claim 4, It is characterized in that The mode-locked laser is an erbium-doped fiber mode-locked laser, an ytterbium-doped fiber mode-locked laser or a titanium sapphire mode-locked laser, and is used to emit a near-infrared or mid-infrared mode-locked optical signal; The microcavity optical frequency comb is realized based on at least one of silicon, silicon dioxide, silicon nitride, lithium niobate, calcium fluoride and magnesium fluoride.

6. The dual optical frequency comb ranging system according to any one of claims 1 to 5, It is characterized in that Also includes a scanning galvanometer; The scanning galvanometer is used to adjust the incident position of the measuring light signal transmitted to the object to be measured, so as to achieve two-dimensional or three-dimensional scanning of the object to be measured.

7. The dual optical frequency comb ranging system according to any one of claims 1 to 5, It is characterized in that Also included is a first collimator and a second collimator; The measuring light signal is split by the first coupler and then transmitted to the first collimator and the second collimator for collimation, and then transmitted to the reflector and the object to be measured respectively; The first reflected light signal and the second reflected light signal are transmitted to the first coupler via the first collimator and the second collimator respectively for beam combination, and then transmitted to the second coupler via the third circulator.

8. The dual optical frequency comb ranging system according to any one of claims 1 to 5, It is characterized in that Also comprising at least one of a first polarization controller and a second polarization controller; The first polarization controller is used to control the polarization states of the first reflected light signal and the second reflected light signal; The second polarization controller is used to control the polarization state of the reference optical signal.

9. A dual-optical frequency comb ranging method, It is characterized in that Based on the dual optical frequency comb ranging system according to any one of claims 1 to 8, the method comprises: Controlling the first optical frequency comb to generate a reference optical signal at a first preset repetition frequency; Controlling the second optical frequency comb to generate a measurement optical signal at a second preset repetition frequency, wherein there is a preset detuning amount between the first preset repetition frequency and the second preset repetition frequency; The distance information of the object to be measured is obtained according to the time domain information of the interference light signal measured by the measuring device.

10. The dual optical frequency comb ranging method as claimed in claim 9, It is characterized in that The obtaining the distance information of the object to be measured according to the time domain information of the interference light signal measured by the measuring device includes: Dividing the time domain information of the interference light signal, determining a first effective interference light signal formed by the interference of the reference light signal and the first reflected light signal and a corresponding reference position, and a second effective interference light signal formed by the interference of the reference light signal and the second reflected light signal and a corresponding measurement position; Performing Fourier transform on the first effective interference light signal to obtain first relative depth information; Performing Fourier transform on the second effective interference light signal to obtain second relative depth information; The absolute distance information of the object to be measured is obtained according to the number of envelopes between the reference position and the measurement position and the first relative depth information and the second relative depth information.

11. The dual optical frequency comb ranging method as claimed in claim 10, It is characterized in that The calculation formula of the first relative depth information is: Among them, δd 1 represents the first relative depth information, ΔB 1 represents the radio frequency corresponding to the interference light signal at the reference position, Φ represents the dispersion amount of the dispersion module, and λ 0 represents the central wavelength of the overlapping portion of the spectrum of the first optical frequency comb and the second optical frequency comb; The calculation formula of the second relative depth information is: Among them, δd 2 represents the second relative depth information, ΔB 2 Indicates the radio frequency corresponding to the interference light signal at the measurement position; The calculation formula of the absolute distance information is: d=mΔd+δd 1 +δd 2 Wherein, d represents the absolute distance information, m represents the number of envelopes, Δd represents the distance between adjacent envelopes, c represents the speed of light in vacuum, Δf represents the preset detuning amount, and f 1 represents the first preset repetition frequency, f 2 Indicates the second preset repetition frequency.

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