Laser interference measurement precision traceability system and method

Abstract

The invention provides a laser interference measurement precision traceability system and method. The system comprises an atomic clock, a femtosecond optical frequency comb, a spectrum spreading and frequency doubling module, a beat frequency module and a traceability processing module. The repetition frequency of a spectrum output by a femtosecond optical frequency comb and the frequency reference of an atomic clock are locked, frequency beating is carried out on a femtosecond laser spectrum and an interference measurement light source through spectrum broadening, optical frequency doubling and frequency beating detection, and traceability comparison is carried out on an obtained frequency beating signal and laser interference measurement data. The measurement precision of the to-be-measured laser interferometer is traced to the atomic clock frequency reference, and the traceability of laser interference measurement data is realized. Compared with the prior art, the laser interference measurement precision traceability system measures the wavelength by using the atomic clock frequency reference, has higher precision and resolution, and can realize on-site traceability of laser interference measurement data precision. And through precision traceability, the precision and stability of laser interference measurement are also improved.

Description

Technical Field

[0001] The present application relates to the field of laser measurement technology, and in particular to a laser interferometry measurement accuracy tracing system and method. Background Art

[0002] Laser interferometry is a displacement measurement technology based on the principle of light wave interference. It has the advantages of non-contact measurement, high precision and high sensitivity. It is widely used in the measurement of displacement, length, angle, surface shape, medium refractive index change, vibration, etc. According to different measurement optical path structures, commonly used interferometers include Michelson interferometer, Mach-Zehnder interferometer, Fizeau interferometer, Zeeman-Green interferometer, etc.

[0003] Laser interferometer is an indispensable measuring system in modern precision measurement and precision machining due to its high measurement accuracy, long measurement distance and convenient use. It is the most important length measurement and online monitoring instrument for large-scale mechanical structure parameters in large-scale precision manufacturing fields such as aircraft, submarines, and manned spaceflight. It is widely used in length-related measurements such as linear position, diameter, angle, flatness, straightness, speed, pitch and yaw. In addition, laser interferometer is also widely used in the fields of precise positioning, on-site monitoring and machining compensation of CNC machine tools and machining centers. Therefore, the accuracy traceability of laser interferometer is crucial.

[0004] Traceability is the ability to relate the measurement results of a given instrument to a national or international standard, thereby providing an unbroken calibration chain from the standard to the instrument. This is essential to ensure the accuracy and consistency of measurement results across locations and over time.

[0005] Existing laser interferometry accuracy traceability methods usually use a comparison method to compare the measurement results of the laser interferometer with the measurement results of a reference instrument calibrated to national or international standards, and transmit the accuracy of the standard to the laser interferometer to provide a direct connection with the standard. For example, a common method for laser interferometry accuracy traceability is to use a frequency-stabilized laser to produce a highly stable and reproducible laser light source, and then use a standard laser interferometer based on a frequency-stabilized laser to provide a highly accurate and stable reference measurement, and then compare the reference measurement with the measurement data of the calibrated laser interferometer. The measurement data comparison results are used to determine the accuracy of the calibrated laser interferometer.

[0006] The existing laser interferometer measurement accuracy traceability generally involves moving the calibrated laser interferometer to a laboratory where a standard laser interferometer is placed for measurement and comparison. However, the standard laser interferometer cannot be moved to the measurement site where the calibrated laser interferometer is located. Therefore, in high-precision interferometer measurement applications, accuracy traceability of on-site measurements cannot be achieved. Summary of the invention

[0007] The purpose of this application is to provide a laser interferometry accuracy traceability system and method.

[0008] The first aspect of the present application provides a laser interferometry accuracy traceability system, comprising:

[0009] Atomic clock, femtosecond optical frequency comb, spectrum spreading and frequency doubling module, beat frequency module and source tracing processing module; among them,

[0010] The output end of the atomic clock is connected to the input end of the femtosecond optical frequency comb;

[0011] The output end of the femtosecond optical frequency comb is connected to the input end of the spectrum spreading and frequency doubling module;

[0012] The output end of the spectrum spreading and frequency doubling module is connected to the first input end of the beat frequency module, and the second input end of the beat frequency module is connected to the output end of the single-frequency stabilized laser of the laser interferometer to be tested;

[0013] The output end of the beat frequency module is connected to the first input end of the traceability processing module, and the output end of the laser interferometer to be measured is connected to the second input end of the traceability processing module.

[0014] In a possible implementation, the beat frequency module includes a first 1 / 2 wave plate, a second 1 / 2 wave plate, a 1 / 4 wave plate, a polarization beam splitter cube, a polarizer, a grating, a reflector, an aperture stop, a photodetector and a radio frequency spectrometer; wherein,

[0015] The first input end of the beat frequency module is connected to the first input end of the polarization beam splitting cube through a quarter wave plate and a first half wave plate in sequence;

[0016] The second input end of the beat frequency module is connected to the second input end of the polarization beam splitter cube through a second 1 / 2 wave plate;

[0017] The output end of the polarization beam splitter cube is connected to a radio frequency spectrum analyzer through a polarizer, a grating, a reflector, an aperture stop, and a photoelectric detector in sequence.

[0018] In a possible implementation, the beat frequency module further includes a first isolator and a second isolator;

[0019] in,

[0020] The first input end of the beat frequency module is connected to the 1 / 4 wave plate through a first isolator;

[0021] The second input end of the beat frequency module is connected to the second 1 / 2 wave plate through a second isolator.

[0022] In a possible implementation, the beat frequency module further includes a first optical fiber collimator and a second optical fiber collimator; wherein,

[0023] The first input end of the beat frequency module is connected to a quarter wave plate through a first isolator and a first fiber collimator;

[0024] The second input end of the beat frequency module is connected to the second 1 / 2 wave plate through a second isolator and a second optical fiber collimator.

[0025] In a possible implementation, the frequency reference of the atomic clock is 10 MHz.

[0026] The second aspect of the present application provides a laser interferometry accuracy tracing method, using the laser interferometry accuracy tracing system described in the first aspect, the method comprising:

[0027] Locking the repetition frequency of the femtosecond pulse signal emitted by the femtosecond optical frequency comb to the frequency reference of the atomic clock;

[0028] The spectrum spreading and frequency doubling module performs spectrum broadening and optical frequency doubling on the femtosecond pulse signal to obtain an optical frequency component of a target wavelength, and outputs the component after filtering.

[0029] The beat frequency module beats the laser signal of the target wavelength output by the single-frequency stabilized laser of the laser interferometer to be tested with the optical frequency component of the target wavelength output by the spectrum spreading and frequency doubling module to generate a beat frequency signal, samples the beat frequency signal and calculates the beat frequency to obtain the beat frequency data of the beat frequency signal;

[0030] The traceability processing module compares the beat frequency data with the interference measurement data output by the laser interferometer to be measured to obtain the frequency change;

[0031] The traceability processing module performs precision traceability on the interference measurement data output by the laser interferometer to be measured according to the frequency variation, so as to trace the measurement precision of the laser interferometer to be measured to the frequency reference of the atomic clock.

[0032] In a possible implementation, the beat frequency module beats the laser signal of the target wavelength output by the single-frequency stabilized laser of the laser interferometer to be measured with the optical frequency component of the target wavelength output by the spectrum spreading and frequency doubling module to generate a beat frequency signal, samples the beat frequency signal and calculates the beat frequency to obtain the beat frequency data of the beat frequency signal, including:

[0033] The optical frequency component of the target wavelength output by the spectrum spreading and frequency doubling module is input to the first input end of the beat frequency module, and the laser signal of the target wavelength output by the single-frequency stabilized laser of the laser interferometer to be measured is input to the second input end of the beat frequency module;

[0034] The optical frequency component of the target wavelength is polarized by the quarter wave plate and the first half wave plate and then enters the polarization splitter cube. The laser signal of the target wavelength is polarized by the second half wave plate and then enters the polarization splitter cube, so as to spatially combine the two light beams in the polarization splitter cube and output them to the polarizer.

[0035] By rotating the polarizer, two spatial light beams with perpendicular polarization directions are polarized so that the polarization directions of the two light beams are consistent, thereby generating a beat frequency signal;

[0036] The beat frequency signal is spectrally separated and filtered using a grating, a reflector and an aperture stop. The beat frequency signal with corresponding spectral components is detected by a photoelectric detector and then enters a radio frequency spectrum analyzer for storage and processing. The photoelectric detector obtains the beat frequency data of the beat frequency signal after detection.

[0037] Compared with the prior art, the laser interferometer measurement accuracy traceability system and method provided by the present application, by locking the repetition frequency of the output spectrum of the femtosecond optical frequency comb with the atomic clock frequency reference, and then beating the femtosecond laser spectrum with the interferometric measurement light source through spectrum broadening, optical frequency doubling, and beat frequency detection, and tracing and comparing the obtained beat frequency signal with the laser interferometer measurement data, and tracing the measurement accuracy of the laser interferometer to be measured to the atomic clock frequency reference, to achieve the traceability of the laser interferometer measurement data. Compared with the prior art, the laser interferometer measurement accuracy traceability system of the present application, which uses the atomic clock frequency reference to measure the wavelength, has higher accuracy and resolution, and can achieve on-site traceability of the accuracy of laser interferometer measurement data. Through precision tracing, the accuracy and stability of laser interferometer measurement are also improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0039] Figure 1 A schematic diagram of the structure of a laser interferometry precision traceability system provided by the present application is shown;

[0040] Figure 2 A schematic diagram of the laser interferometry accuracy tracing process provided by the present application is shown;

[0041] Figure 3 It shows a schematic diagram of the structure of the beat frequency module provided by the present application;

[0042] Figure 4 A flow chart of a laser interferometry accuracy tracing method provided in the present application is shown. DETAILED DESCRIPTION

[0043] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0044] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by technicians in the field to which this application belongs.

[0045] In addition, the terms "first" and "second" etc. are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products or devices.

[0046] The embodiments of the present application provide a laser interferometer measurement accuracy tracing system and a laser interferometer measurement accuracy tracing method, and a computer-readable storage medium, which are described below in conjunction with the accompanying drawings.

[0047] Please refer to Figure 1 , which shows a schematic diagram of the structure of a laser interferometry accuracy traceability system provided by some embodiments of the present application, such as Figure 1 As shown, the laser interferometry precision traceability system includes: an atomic clock 10, a femtosecond optical frequency comb 20, a spectrum spreading and frequency doubling module 30, a beat frequency module 40 and a traceability processing module 50.

[0048] Specifically, the output end of the atomic clock 10 is connected to the input end of the femtosecond optical frequency comb 20. Optionally, the frequency reference of the atomic clock 10 may be 10 MHz, and other atomic clocks may be selected according to actual conditions.

[0049] Specifically, the output end of the femtosecond optical frequency comb 20 is connected to the input end of the spectrum spreading and frequency doubling module 30 .

[0050] Femtosecond optical frequency comb is a frequency-stabilized femtosecond laser. It uses femtosecond mode-locked laser to generate an equidistant optical pulse sequence in the optical time domain, which is manifested as frequency comb teeth with equidistant frequency intervals in the optical frequency domain. Each mode provides excellent absolute frequency accuracy and has a very narrow linewidth, which can provide guarantee for accurate measurement. Femtosecond optical frequency comb has three characteristics: ultra-short time domain width, high peak power and wide spectral range. Femtosecond optical frequency comb can trace the optical frequency to the microwave frequency standard through frequency locking. As a bridge between microwave frequency and optical frequency, it can realize direct frequency transfer from megahertz to terahertz, laying the foundation for the establishment of time frequency standard and research on frequency transfer. Femtosecond optical frequency comb can convert the measurement of laser frequency into the measurement of microwave frequency, making it possible to directly and absolutely measure the laser frequency. The unique time domain and frequency domain characteristics of femtosecond optical frequency comb have great advantages and application prospects in frequency standard transfer, absolute distance measurement, laser noise description, astronomical measurement and spectral measurement.

[0051] In the present application, the repetition frequency of the femtosecond pulse signal emitted by the femtosecond optical frequency comb 20 is locked to the frequency reference of the atomic clock 10. The spectrum spreading and frequency doubling module 30 can perform spectrum broadening and optical frequency doubling on the femtosecond pulse signal emitted by the femtosecond optical frequency comb 20 to obtain the optical frequency component of the target wavelength, and output it after filtering. For example, the laser repetition frequency of 200MHz and 1550nm emitted by the femtosecond optical frequency comb 20 is locked to the frequency reference of the atomic clock 10, and then passes through the spectrum spreading and frequency doubling module 30 to output the optical frequency component with a wavelength of 633nm.

[0052] The output end of the spectrum spreading and frequency doubling module 30 is connected to the first input end of the beat frequency module 40 , and the second input end of the beat frequency module 40 is connected to the output end of the single-frequency stabilized laser of the laser interferometer to be tested.

[0053] The single-frequency stabilized laser is the light source of the laser interferometer to be tested, and can output a laser signal of a target wavelength, such as a laser signal of a wavelength of 633 nm. The beat module 40 beats the laser signal of the target wavelength output by the single-frequency stabilized laser of the laser interferometer to be tested with the optical frequency component of the target wavelength output by the spectrum spreading and frequency doubling module 30 to generate a beat signal.

[0054] The output end of the beat frequency module 40 is connected to the first input end of the traceability processing module 50, and the output end of the laser interferometer to be measured is connected to the second input end of the traceability processing module. The traceability processing module 50 can compare the beat frequency data of the beat frequency signal with the interference measurement data output by the laser interferometer to be measured to obtain the frequency change, and then perform precision traceability on the interference measurement data output by the laser interferometer to be measured based on the frequency change, so as to trace the measurement accuracy of the laser interferometer to be measured to the frequency reference of the atomic clock 10. It can be understood that the present application pre-establishes a traceability transfer model between the frequency change and the interference measurement data, and the traceability processing module 50 can quickly perform precision traceability on the interference measurement data output by the laser interferometer to be measured based on the traceability transfer model.

[0055] For ease of understanding, this application provides Figure 2 The schematic diagram of the laser interferometry accuracy traceability process is shown in Figure 1. Figure 2 As shown, the laser repetition frequency of 200MHz and 1550nm emitted by the femtosecond optical frequency comb is locked to the frequency reference of the atomic clock, and then passes through the spectrum spreading and frequency doubling module to output an optical frequency component with a wavelength of 633nm. The optical frequency component with a wavelength of 633nm is combined and beat with the laser signal with a wavelength of 633nm output by the single-frequency stabilized laser of the laser interferometer to be measured to obtain a beat frequency signal, which is then filtered and measured to obtain the optical frequency change of the laser under test and the locked femtosecond laser spectrum. The traceability processing module performs a traceability comparison between the interference measurement data output by the laser interferometer to be measured and the beat frequency signal, and the interference measurement data can be traced along the Figure 2 The direction of the dotted arrow in the figure can be traced back to the atomic clock frequency standard.

[0056] According to some embodiments of the present application, Figure 3 As shown, the beat frequency module 40 includes a first 1 / 2 wave plate 401 , a second 1 / 2 wave plate 402 , a 1 / 4 wave plate 403 , a polarization splitter cube 404 , a polarizer 405 , a grating 406 , a reflector 407 , an aperture stop 408 , a photodetector 409 and a radio frequency spectrometer 410 .

[0057] The first input end of the beat frequency module 40 is connected to the first input end of the polarization splitter cube 404 through a 1 / 4 wave plate 403 and a first 1 / 2 wave plate 401 in sequence; the second input end of the beat frequency module 40 is connected to the second input end of the polarization splitter cube 404 through a second 1 / 2 wave plate 402; the output end of the polarization splitter cube 404 is connected to the radio frequency spectrometer 410 through a polarizer 405, a grating 406, a reflector 407, an aperture stop 408, and a photodetector 409 in sequence.

[0058] Specifically, the optical frequency component of the target wavelength output by the femtosecond optical frequency comb 20 through the spectrum spreading and frequency doubling module 30 is input to the first input end of the beat frequency module 40, and the laser signal of the target wavelength output by the single-frequency stabilized laser of the laser interferometer to be tested is input to the second input end of the beat frequency module. The optical frequency component of the target wavelength is polarized by the quarter wave plate 403 and the first half wave plate 401 and then enters the polarization beam splitter cube 404. The laser signal of the target wavelength is polarized by the second half wave plate 402 and then enters the polarization beam splitter cube 404, so that two light beams are spatially combined in the polarization beam splitter cube 404, and the combined light beams are output to the polarizer 405. The two spatial light beams with perpendicular polarization directions are polarized by rotating the polarizer 405 so that the polarization directions of the two light beams are consistent, thereby generating a beat signal. The beat signal is spectrally separated and filtered by using the grating 406, the reflector 407 and the aperture diaphragm 408. The beat signal with the corresponding spectral component is detected by the photodetector 409 and then enters the radio frequency spectrometer 410 for storage and processing. The photodetector 409 samples the beat signal and calculates the beat frequency to obtain the beat frequency data of the beat signal.

[0059] According to some embodiments of the present application, Figure 3 As shown, the beat frequency module further includes a first isolator 411 and a second isolator 412; wherein the first input end of the beat frequency module 40 is connected to the 1 / 4 wave plate 403 through the first isolator 411; and the second input end of the beat frequency module 40 is connected to the second 1 / 2 wave plate 402 through the second isolator 412. The laser signal is output isolated through the isolator to reduce the influence of the noise signal on the beat frequency signal.

[0060] According to some embodiments of the present application, Figure 3 As shown, the beat frequency module 40 also includes a first fiber collimator 413 and a second fiber collimator 414; wherein, the first input end of the beat frequency module 40 is connected to the 1 / 4 wave plate 403 through the first isolator 411 and the first fiber collimator 413; the second input end of the beat frequency module 40 is connected to the second 1 / 2 wave plate 402 through the second isolator 412 and the second fiber collimator 414. The laser signal is output isolated and beam collimated through the isolator and the fiber collimator respectively, which reduces the influence of the noise signal on the beat frequency signal and enables the laser signal to be coupled more efficiently. It can be seen that the embodiment of the present application can obtain a low-noise and high-resolution beat frequency signal, and can solve the technical problems that the single comb tooth power of the existing femtosecond optical frequency comb is very low and the comb teeth are densely distributed, and the signal-to-noise ratio of the beat frequency signal is low and the spectrum components are complex when beating with the laser to be measured.

[0061] In this embodiment, Figure 3As shown, the laser signals output by the single-frequency stabilized laser and the femtosecond optical frequency comb are isolated and collimated by an isolator and a fiber collimator respectively, and then the polarization state is adjusted by a 1 / 2 wave plate before entering the polarization beam splitter cube (PBS) to spatially combine the two beams. The two spatial beams with perpendicular polarization directions are polarized by rotating the polarizer (P) so that the polarization directions of the two laser beams are consistent, thereby generating a beat frequency interference signal. The beat frequency interference signals of the two laser beams are spectrally separated and filtered using a grating, a reflector, and an aperture diaphragm. The beat frequency signals with corresponding spectral components are detected by a photodetector and then enter the radio frequency spectrometer for storage and processing. The beat frequency signals obtained by the photodetector are sampled with high precision, converted into frequency data, and compared and analyzed with the interference measurement data to perform interference data tracing and nonlinear compensation.

[0062] Compared with the prior art, the laser interferometry precision traceability system of the present application uses the atomic clock frequency standard to measure the wavelength, has higher precision and resolution, and can realize on-site traceability of the laser interferometry data precision. Through precision traceability, the accuracy and stability of laser interferometry are also improved.

[0063] In the above-mentioned embodiment, a laser interferometer measurement accuracy tracing system is provided. Correspondingly, the present application also provides a laser interferometer measurement accuracy tracing method. Figure 4 , which shows a flow chart of a laser interferometry accuracy tracing method provided by some embodiments of the present application. Since the method embodiment is basically similar to the system embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the system embodiment. The method embodiment described below is only illustrative.

[0064] like Figure 4 As shown, the laser interferometry accuracy tracing method may include the following steps:

[0065] S101, locking the repetition frequency of the femtosecond pulse signal emitted by the femtosecond optical frequency comb to the frequency reference of the atomic clock;

[0066] S102, the spectrum spreading and frequency doubling module performs spectrum broadening and optical frequency doubling on the femtosecond pulse signal to obtain an optical frequency component of a target wavelength, and outputs the component after filtering;

[0067] S103, the beat frequency module beats the laser signal of the target wavelength output by the single-frequency stabilized laser of the laser interferometer to be tested with the optical frequency component of the target wavelength output by the spectrum spreading and frequency doubling module to generate a beat frequency signal, samples the beat frequency signal and calculates the beat frequency to obtain beat frequency data of the beat frequency signal;

[0068] S104, the traceability processing module compares the beat frequency data with the interference measurement data output by the laser interferometer to be measured to obtain a frequency change;

[0069] S105. The traceability processing module performs precision traceability on the interference measurement data output by the laser interferometer to be measured according to the frequency variation, so as to trace the measurement precision of the laser interferometer to be measured to the frequency reference of the atomic clock.

[0070] According to some implementations of the present application, step S103 specifically includes:

[0071] The optical frequency component of the target wavelength output by the spectrum spreading and frequency doubling module is input to the first input end of the beat frequency module, and the laser signal of the target wavelength output by the single-frequency stabilized laser of the laser interferometer to be measured is input to the second input end of the beat frequency module;

[0072] The optical frequency component of the target wavelength is polarized by the quarter wave plate and the first half wave plate and then enters the polarization splitter cube. The laser signal of the target wavelength is polarized by the second half wave plate and then enters the polarization splitter cube, so as to spatially combine the two light beams in the polarization splitter cube and output them to the polarizer.

[0073] By rotating the polarizer, two spatial light beams with perpendicular polarization directions are polarized so that the polarization directions of the two light beams are consistent, thereby generating a beat frequency signal;

[0074] The beat frequency signal is spectrally separated and filtered using a grating, a reflector and an aperture stop. The beat frequency signal with corresponding spectral components is detected by a photoelectric detector and then enters a radio frequency spectrum analyzer for storage and processing. The photoelectric detector obtains the beat frequency data of the beat frequency signal after detection.

[0075] The laser interferometry accuracy tracing method provided in the above-mentioned embodiment of the present application and the laser interferometry accuracy tracing system provided in the embodiment of the present application are based on the same inventive concept and have the same beneficial effects.

[0076] It should be noted that the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of the boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. 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 replace some or all of the technical features therein by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application.

Claims

1. A laser interferometry precision traceability system, characterized in that: include: Atomic clock, femtosecond optical frequency comb, spectrum spreading and frequency doubling module, beat frequency module and source tracing processing module; among them, The output end of the atomic clock is connected to the input end of the femtosecond optical frequency comb; The output end of the femtosecond optical frequency comb is connected to the input end of the spectrum spreading and frequency doubling module; The output end of the spectrum spreading and frequency doubling module is connected to the first input end of the beat frequency module, and the second input end of the beat frequency module is connected to the output end of the single-frequency stabilized laser of the laser interferometer to be tested; The output end of the beat frequency module is connected to the first input end of the traceability processing module, and the output end of the laser interferometer to be measured is connected to the second input end of the traceability processing module.

2. The laser interferometry accuracy traceability system according to claim 1, characterized in that: The beat frequency module includes a first 1 / 2 wave plate, a second 1 / 2 wave plate, a 1 / 4 wave plate, a polarization beam splitter cube, a polarizer, a grating, a reflector, an aperture stop, a photodetector and a radio frequency spectrometer; wherein, The first input end of the beat frequency module is connected to the first input end of the polarization beam splitting cube through a quarter wave plate and a first half wave plate in sequence; The second input end of the beat frequency module is connected to the second input end of the polarization beam splitter cube through a second 1 / 2 wave plate; The output end of the polarization beam splitter cube is connected to a radio frequency spectrum analyzer through a polarizer, a grating, a reflector, an aperture stop, and a photoelectric detector in sequence.

3. The laser interferometry accuracy traceability system according to claim 2, characterized in that: The beat frequency module also includes a first isolator and a second isolator; wherein, The first input end of the beat frequency module is connected to the 1 / 4 wave plate through a first isolator; The second input end of the beat frequency module is connected to the second 1 / 2 wave plate through a second isolator.

4. The laser interferometry accuracy traceability system according to claim 3, characterized in that: The beat frequency module further includes a first optical fiber collimator and a second optical fiber collimator; wherein, The first input end of the beat frequency module is connected to a quarter wave plate through a first isolator and a first fiber collimator; The second input end of the beat frequency module is connected to the second 1 / 2 wave plate through a second isolator and a second optical fiber collimator.

5. The laser interferometry accuracy traceability system according to claim 1, characterized in that: The frequency reference of the atomic clock is 10 MHz.

6. A laser interferometry precision tracing method, using the laser interferometry precision tracing system according to any one of claims 1 to 5, characterized in that: The method comprises: Locking the repetition frequency of the femtosecond pulse signal emitted by the femtosecond optical frequency comb to the frequency reference of the atomic clock; The spectrum spreading and frequency doubling module performs spectrum broadening and optical frequency doubling on the femtosecond pulse signal to obtain an optical frequency component of a target wavelength, and outputs the component after filtering. The beat frequency module beats the laser signal of the target wavelength output by the single-frequency stabilized laser of the laser interferometer to be tested with the optical frequency component of the target wavelength output by the spectrum spreading and frequency doubling module to generate a beat frequency signal, samples the beat frequency signal and calculates the beat frequency to obtain the beat frequency data of the beat frequency signal; The traceability processing module compares the beat frequency data with the interference measurement data output by the laser interferometer to be measured to obtain the frequency change; The traceability processing module performs precision traceability on the interference measurement data output by the laser interferometer to be measured according to the frequency variation, so as to trace the measurement precision of the laser interferometer to be measured to the frequency reference of the atomic clock.

7. The laser interferometry accuracy tracing method according to claim 6, characterized in that: The beat frequency module beats the laser signal of the target wavelength output by the single-frequency stabilized laser of the laser interferometer to be tested with the optical frequency component of the target wavelength output by the spectrum spreading and frequency doubling module to generate a beat frequency signal, samples the beat frequency signal and calculates the beat frequency to obtain the beat frequency data of the beat frequency signal, including: The optical frequency component of the target wavelength output by the spectrum spreading and frequency doubling module is input to the first input end of the beat frequency module, and the laser signal of the target wavelength output by the single-frequency stabilized laser of the laser interferometer to be measured is input to the second input end of the beat frequency module; The optical frequency component of the target wavelength is polarized by the quarter wave plate and the first half wave plate and then enters the polarization splitter cube. The laser signal of the target wavelength is polarized by the second half wave plate and then enters the polarization splitter cube, so as to spatially combine the two light beams in the polarization splitter cube and output them to the polarizer. By rotating the polarizer, two spatial light beams with perpendicular polarization directions are polarized so that the polarization directions of the two light beams are consistent, thereby generating a beat frequency signal; The beat frequency signal is spectrally separated and filtered using a grating, a reflector and an aperture stop. The beat frequency signal with corresponding spectral components is detected by a photoelectric detector and then enters a radio frequency spectrum analyzer for storage and processing. The photoelectric detector obtains the beat frequency data of the beat frequency signal after detection.

Images