Method and device for measuring interstellar gravitational potential difference of optical frequency signal

Abstract

The application discloses a kind of light frequency signal interplanetary gravity potential difference measurement methods, comprising: respectively establishing light clock light frequency comparison system on two planets needing to measure gravity potential difference, to construct planet-planet three-frequency combination light frequency comparison link;According to the planet-planet three-frequency combination light frequency comparison link constructed, bidirectional light frequency signal transmission, reception and reflection between two planets are carried out, respectively record the emission frequency f1 of planet one to planet two to planet one link, reflection frequency and receiving frequency, the emission frequency f2 and receiving frequency of link;According to the one-way frequency transmission model between stars, in combination with the frequency recorded, extract the gravitational redshift frequency shift between two planets;According to the relationship between gravitational redshift frequency shift and gravity potential difference, the gravity potential difference between two planets is calculated.

Description

Technical Field

[0001] This invention relates to multiple fields such as space precision measurement technology, geophysics, astronomy, and precision time and frequency transmission. Specifically, it relates to a method and device for measuring interstellar gravitational potential difference by using high-precision optical clock optical frequency signals and quantum optical frequency comb fusion technology. It is applicable to scenarios such as interstellar gravitational potential difference measurement, planetary gravitational field modeling, and interstellar navigation. Background Technology

[0002] Gravitational potential is a fundamental physical quantity describing the strength of a gravitational field. Accurately measuring the gravitational potential difference between different celestial bodies within the solar system (such as Earth, Mars, and Jupiter's moons) is crucial for deepening the testing of gravitational theories (such as verifying Einstein's theory of general relativity), understanding the internal structure of celestial bodies, constructing high-precision interplanetary spacetime benchmarks, supporting future autonomous deep-space navigation, and studying the internal structure of celestial bodies. With the advancement of deep-space exploration missions, research in interstellar gravity field modeling, gravitational wave detection, and interstellar navigation has created an urgent need for high-precision gravitational potential difference measurements.

[0003] On Earth, gravitational potential is typically measured using gravitational gradiometers and satellite gravity measurements. However, applying these techniques directly to interplanetary scales presents significant challenges. In interplanetary space, the gravitational potential variations caused by celestial bodies such as the Sun and planets are very gradual, but their absolute differences are enormous. Traditional Earth gravity field measurement techniques (such as microwave ranging used in the GRACE mission) have an accuracy on the order of microgales, but when extended to baselines hundreds of millions of kilometers, the interplanetary signal becomes extremely weak, and both their relative and absolute accuracy are insufficient to resolve the fine gravitational potential structure caused by the mass distribution of celestial bodies. Measurements on Earth can rely on a fixed reference ellipsoid, but currently, there is a lack of a unified measurement benchmark for interplanetary gravitational potential differences. Therefore, there is an urgent need to establish a global gravity field model with the solar system's center of mass as a reference.

[0004] Existing technologies (such as Doppler tracking) indirectly infer the gravitational field by detecting orbital perturbations of spacecraft. This is an indirect, model-dependent method with significant error accumulation. While the most sophisticated interplanetary ranging technologies can achieve meter-level or even sub-meter-level distance measurement accuracy, they measure geometric distances. However, according to general relativity, the gravitational field directly affects spacetime itself, causing changes in signal propagation time (the Shapiro time delay effect). Simple geometric distance measurements cannot directly and accurately isolate this gravitational effect.

[0005] High-precision measurements rely on a highly stable time and frequency reference. While traditional spaceborne atomic clocks (such as rubidium clocks and hydrogen clocks) are highly stable, long-term synchronization with ground-based references is difficult, and their microwave frequencies are susceptible to interference such as plasma delays on interplanetary links. Summary of the Invention

[0006] To overcome the long-standing limitation of time and frequency references and measurement standards, which makes it difficult to accurately determine the gravitational potential difference between different interstellar planets in the solar system, this invention provides a method for measuring interstellar gravitational potential difference using optical frequency signals. This method determines the gravitational potential difference between different planets by means of frequency transmission, based on the correspondence between gravitational potential difference and the speed difference of a precision clock.

[0007] According to one aspect of the present invention, a method for measuring interstellar gravitational potential difference using optical frequency signals is provided, comprising:

[0008] Optical clock and optical frequency comparison systems were established on two planets where gravitational potential differences needed to be measured, in order to construct a planet-to-planet three-frequency combined optical frequency comparison link;

[0009] Based on the constructed planet-to-planet three-frequency optical frequency comparison link, bidirectional optical frequency signal transmission, reception, and reflection are performed between the two planets. The transmission frequency f1 and reflection frequency of the link from planet one to planet two to planet one are recorded respectively. and receiving frequency And the transmit frequency f2 and receive frequency of the Planet 2 to Planet 1 link. ;

[0010] Based on the interplanetary one-way frequency transfer model and combined with the recorded frequencies, the gravitational redshift frequency shift between the two planets is extracted.

[0011] Based on the relationship between gravitational redshift frequency shift and gravitational potential difference, the gravitational potential difference between the two planets is calculated.

[0012] As a further technical solution, based on the constructed planet-to-planet three-frequency combined optical frequency comparison link, bidirectional optical frequency signal transmission, reception, and reflection are performed between the two planets, including:

[0013] By using optical clocks positioned on two planets, simultaneously generating signals with an accuracy better than 10... -19 Optical frequency signals of magnitude;

[0014] The generated optical frequency signal is downconverted to a frequency suitable for spatial transmission.

[0015] Each planetary station simultaneously receives optical frequency signals from the other and extracts the frequency signals.

[0016] As a further technical solution, the inter-interplane unidirectional frequency transfer model is expressed as follows:

[0017] ,

[0018] Where K represents the downconversion coefficient of the femtosecond optical comb. This represents the frequency difference between two clocks in a relativistic reference frame. This indicates the nominal frequency of an atomic clock within a relativistic reference frame. This indicates the transmission frequency of one of the planetary ends. This indicates the receiving frequency at the other planetary end. This indicates the frequency shift caused by the gravitational redshift effect. This indicates that relativistic effects cause a transverse Doppler frequency shift. This indicates the frequency shift caused by the deep space interplanetary environment between planets. and This indicates the frequency shift caused by the atmospheric environments of the two planets. Indicates the nominal frequency of the optical signal.

[0019] As a further technical solution, the method also includes:

[0020] Based on the interstellar one-way frequency transfer model, frequency shift equations are obtained for the links from Planet 1 to Planet 2 to Planet 1 and from Planet 2 to Planet 1, respectively. Based on the frequency shift equations, the gravitational redshift frequency shift is extracted.

[0021] As a further technical solution, the extracted gravitational redshift frequency shift is represented as:

[0022] ,

[0023] in This represents the residual frequency shift related to the propagation frequency caused by different factors, where i represents the different factors.

[0024] As a further technical solution, the relationship between gravitational redshift frequency shift and gravitational potential difference is expressed as follows:

[0025] ,

[0026] in, The measured gravitational redshift frequency shift is given by c, where c is the speed of light. For higher-order terms, Let be the gravitational potential difference between the two planets.

[0027] As a further technical solution, bidirectional optical frequency signal transmission is conducted between the two planets, and the signals at each frequency are recorded separately. This also includes:

[0028] At each planetary station, the received optical frequency signal from the other side is optically coherently heterodyned or optically phase-locked with the optical frequency reference signal generated by the local optical clock to generate a beat frequency signal, and the frequency of the beat frequency signal is measured.

[0029] Measure the bidirectional distance and relative velocity between two planets;

[0030] The frequency, bidirectional distance, relative speed, and recorded timestamps of the beat frequency signal are packaged into raw measurement data.

[0031] As a further technical solution, after acquiring the raw measurement data, it also includes:

[0032] Using the measured relative velocity, the first-order Doppler frequency shift caused by the relative motion of the satellite is calculated and eliminated;

[0033] Based on the principles of general relativity, an accuracy to c is established. -4 A high-order gravity frequency shift model of magnitude 1.5 is used, and based on the high-order gravity frequency shift model, combined with bidirectional distance and orbital data, the second-order Doppler effect and dispersive frequency shift are calculated and eliminated;

[0034] Based on the mechanism by which planetary atmospheres affect the frequency of optical signals, a system accurate to c is established. -18 An environmental noise frequency shift correction model of magnitude is developed, and the frequency shift caused by environmental noise between time-frequency satellites and planets is corrected based on the environmental noise frequency shift correction model.

[0035] According to one aspect of the present invention, an optical frequency signal interstellar gravity difference measurement device is provided, comprising:

[0036] An optical clock-frequency comparison system is established on two planets where gravitational potential differences need to be measured, to construct a planet-to-planet three-frequency combined optical frequency comparison link. Based on the constructed planet-to-planet three-frequency combined optical frequency comparison link, bidirectional optical frequency signal transmission, reception, and reflection are performed between the two planets, and the transmission frequency f1 and reflection frequency of the link from planet one to planet two to planet one are recorded respectively. and receiving frequency And the transmit frequency f2 and receive frequency of the Planet 2 to Planet 1 link. ;

[0037] The data processing system is used to extract the gravitational redshift frequency shift between two planets based on the interstellar one-way frequency transfer model and the recorded frequencies; and to calculate the gravitational potential difference between the two planets based on the relationship between the gravitational redshift frequency shift and the gravitational potential difference.

[0038] As a further technical solution, the optical clock-frequency comparison system integrates an atomically stabilized laser, and simultaneously monitors the operating environment of the optical clock, optical comb and laser in real time, and establishes an environmental noise frequency drift correction model for the optical clock-frequency comparison system to perform real-time dynamic compensation and correction for frequency shift caused by environmental noise.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] 1. The gravitational redshift effect can be directly measured using optical clock frequency signals, thereby directly obtaining the gravitational potential difference and avoiding the indirect errors caused by orbital dynamics inversion.

[0041] 2. The optical frequency employs a three-frequency optical frequency combination and joint differential measurement technology, achieving optical frequency signal extraction through interplanetary three-frequency optical frequency combination time-frequency signal transmission between planets. The three-frequency link can also effectively eliminate the influence of planetary atmospheres, local oscillator phase noise, and some interplanetary medium disturbances during signal propagation, significantly improving the signal-to-noise ratio and robustness of the measurement.

[0042] 3. The bidirectional link can also effectively eliminate the effects of spacecraft platform vibration, local oscillator phase noise, and some interplanetary medium disturbances, significantly improving the signal-to-noise ratio and robustness of the measurement.

[0043] 4. By comparing the frequencies of optical clocks carried by planets, the gravitational frequency shift between interstellar spaces can be measured, thereby obtaining the interstellar gravitational potential difference. This method can provide unprecedented experimental data for verifying the correctness of general relativity on a solar system scale and for the distribution of mass inside planets. It also lays the core measurement foundation for building the next generation of quantum technology-based "solar system internet" and autonomous deep space navigation system.

[0044] 5. By utilizing the extremely high frequency stability of optical signals (especially laser frequency combs), the measurement accuracy of gravitational potential difference can be improved by several orders of magnitude, potentially reaching 10... -18 The magnitude is even higher, far exceeding existing radio technology. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a flowchart illustrating the method for measuring interstellar gravity difference using optical signals, as provided in an embodiment of the present invention.

[0047] Figure 2 This is a schematic diagram illustrating the measurement of interplanetary gravitational potential difference between Mars and Earth, provided as an embodiment of the present invention.

[0048] Figure 3 This is a schematic diagram illustrating the measurement of gravitational potential difference between Earth, Moon, and Mars, provided in an embodiment of the present invention. Detailed Implementation

[0049] The advent of high-precision optical clocks and optical frequency combs has made it possible to measure interstellar gravitational potential differences. Optical clocks can directly generate optical frequencies of several hundred THz, which, when combined with an optical comb, produce a series of extremely stable, equally spaced laser pulse signals. This results in extremely high time resolution (on the femtosecond scale) and frequency stability. However, a feasible and systematic technical solution for effectively applying optical frequency comb technology to the direct measurement of gravitational potential at the interstellar scale is currently lacking. Therefore, there is an urgent need in this field for a method capable of measuring the gravitational potential difference between two points in interstellar space with high precision.

[0050] In recent years, with the maturation of clock manufacturing technology, clocks with an accuracy of 10 have been successfully developed internationally. -19 Clocks of this magnitude, including spaceborne clocks, also achieve an accuracy of 10. -18 This scale provides hardware support for implementing gravitational potential measurement using time-frequency signals. Addressing the long-standing challenge of accurately measuring interstellar gravitational potential differences due to limitations in time-frequency and measurement standards, this invention, supported by advancements in high-precision optical clocks and optical combs, provides a method for accurately measuring interstellar gravitational potential differences. This method offers high measurement accuracy and provides crucial data for constructing a high-precision gravitational field model of the solar system and verifying fundamental physical laws.

[0051] To determine interstellar gravitational potential differences, this invention utilizes the principles of general relativity and, based on the correspondence between gravitational potential differences and combinations of three optical frequencies, determines the gravitational potential differences between different planets through frequency transmission. Unlike direct satellite-to-ground signal comparisons on Earth, interstellar measurements require the establishment of a time-frequency comparison link between planets in synchronous orbits and these time-frequency satellites, enabling remote interstellar gravitational potential difference determination.

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0053] This invention provides a method for measuring interstellar gravitational potential difference using optical frequency signals, such as... Figure 1 As shown, this method first establishes optical clock frequency comparison systems on the two planets whose gravitational potential difference needs to be measured, to construct a planet-to-planet three-frequency combined optical frequency comparison link; then, based on the constructed planet-to-planet three-frequency combined optical frequency comparison link, bidirectional optical frequency signal transmission, reception, and reflection are performed between the two planets, and the transmission frequency f1 and reflection frequency of the link from planet one to planet two to planet one are recorded respectively. and receiving frequency And the transmit frequency f2 and receive frequency of the Planet 2 to Planet 1 link. Subsequently, based on the interstellar one-way frequency transfer model and the recorded frequencies, the gravitational redshift frequency shift between the two planets was extracted. Finally, based on the relationship between the gravitational redshift frequency shift and the gravitational potential difference, the gravitational potential difference between the two planets was calculated.

[0054] This invention relates to a method for determining interstellar gravitational potential differences using interstellar optical clock frequency comparison. The method includes the following steps:

[0055] (1) Construction of interplanetary three-frequency optical frequency matching link

[0056] Observation stations were set up at the probe ends of the two planets where gravitational potential differences needed to be measured, and optical clock-frequency comparison systems were established on each to generate highly stable frequency sources. These frequency sources have a stability better than 10... -19 A high-precision optical clock is provided, which is down-converted to a frequency f suitable for space transmission via an optical frequency comb. Simultaneously, high-precision optical transceiver antennas, precision positioning units, and a real-time system environment monitoring system are configured at each detection end to construct a planet-to-planet three-frequency combined optical frequency comparison link.

[0057] (2) Interstellar optical frequency signal transmission

[0058] (a) Establishing optical frequency comparison links between planets (e.g.) Figure 2 The link between Earth and Mars, via optical clocks on the planets, generates an accuracy better than 10. -19 The magnitude of the optical clock signal v;

[0059] (b) The optical frequency signal generated by the optical clock is downconverted to an optical frequency f that is suitable for the interstellar space environment by using a femtosecond optical comb and an ultra-stable laser.

[0060] (c) Analyze the mechanisms by which planetary atmospheres, such as Earth's troposphere and ionosphere, affect the frequency of optical signals, and establish corresponding environmental noise frequency shift correction models. The model accuracy needs to reach 10. -19 Magnitude;

[0061] (d) Analyze the impact of the interplanetary deep space environment on optical frequency signals and establish a frequency shift correction model for interplanetary environmental noise;

[0062] (e) Based on the descriptions in (a~d), establish a one-way frequency transfer model between interstellar spaces (e.g., Figure 2 As shown):

[0063] (1),

[0064] Where K represents the downconversion coefficient of the femtosecond optical comb. This represents the frequency difference between two clocks in a relativistic reference frame. This indicates the nominal frequency of an atomic clock within a relativistic reference frame. This indicates the transmission frequency of one of the planetary ends. This indicates the receiving frequency at the other planetary end. This indicates that relativistic effects cause a transverse Doppler frequency shift. This indicates the frequency shift caused by the gravitational redshift effect. This indicates the frequency shift caused by the deep space interplanetary environment between planets. and This indicates the frequency shift caused by the atmospheric environment of planets 1 and 2 (including the troposphere, ionosphere, etc. on Earth).

[0065] (3) Frequency shift extraction caused by interstellar environmental noise

[0066] by Figure 2 Transmit frequency f1 and receive frequency in Earth For example, we use the model in formula (1). Since the fundamental frequencies of both the uplink and downlink are... Therefore, it is assumed that the frequency shifts caused by planetary atmospheres and interstellar environments in the uplink and downlink are symmetrical, hence the difference:

[0067] (2),

[0068] Among them, the transmission frequency f1 and the receiving frequency At the same location, the gravitational potential remains essentially unchanged during the time interval between signal transmission and reception; therefore, the frequency shift caused by the gravitational redshift effect is negligible. This link combination can effectively eliminate the gravitational redshift effect and extract the frequency shift caused by planetary atmosphere and interstellar environment.

[0069] Then, combined with the frequency f2 extracted from the link between planet two and planet one, Frequency shift equation:

[0070] (3),

[0071] In formulas (2) and (3), the superscript and This represents the frequency shift caused by different link environments. Subtracting the two formulas above extracts the gravitational redshift effect. However, since f1 and f2 operate in different frequency bands and their propagation paths are not entirely identical during propagation, the difference can result in a frequency shift residual caused by path and frequency differences. This residual cannot be eliminated by link combination alone and requires modeling and elimination using planetary environmental parameters, interstellar magnetic fields, and other parameters. Therefore, the gravitational redshift effect considering the residuals from various environmental factors can be expressed as:

[0072] (4),

[0073] in Let represent the residual frequency shift related to the propagation frequency caused by different factors, where i represents the different factors. The error correction model established in (a~d) is used to eliminate the residual frequency shift caused by different factors.

[0074] Using the model described above (4), an experiment was conducted between any two planets to compare three-frequency optical signals and determine the gravitational potential difference. The gravitational redshift effect between the two planets was accurately extracted, and the c-axis of gravitational redshift and gravitational potential transformation was established. -4 A high-precision conversion model was used to determine the interplanetary gravitational potential difference between two planets.

[0075] (5) Joint Differential Measurement and Raw Data Acquisition Steps: At each measurement end, the received optical frequency signal is optically coherently heterodyned or optically phase-locked with the optical frequency reference signal generated by the local optical clock to generate a beat frequency signal. The frequency of this beat frequency signal is accurately measured. Simultaneously, using the interplanetary time synchronization and precision positioning unit, the two-way distance and relative velocity between the two planets are accurately measured. The beat frequency, two-way distance, relative velocity, and precise timestamp are packaged into raw measurements for data processing.

[0076] (6) Data Joint Processing and Gravitational Potential Difference Extraction Steps: Raw measurement data from all measurement ends are collected at the processing center. Through joint processing, the following core operations are performed: (a) Doppler Shift Elimination: Using precisely measured bidirectional relative velocities, the Doppler shift caused by planetary relative motion is calculated and eliminated, taking into account the first-order Doppler shift; (b) Higher-Order Relativistic Effects and Medium Dispersion Correction: Based on general relativity, a higher-order gravity shift model is established, with the model accuracy needing to be accurate to c. -4 The algorithm calculates and eliminates the dispersive frequency shift caused by the second-order Doppler effect (time dilation) and media such as interstellar plasma. It then uses a frequency shift correction model based on environmental noise between the satellite and planet to perform relevant frequency shift corrections. After eliminating the frequency shift caused by non-gravitational potential differences, the remaining stable frequency offset is the pure gravitational frequency shift caused by the gravitational potential difference between the two locations.

[0077] According to the formula of general relativity: .in, The measured gravitational redshift is given by c, where c is the speed of light. It is a higher-order term. This is the gravitational potential difference between the two planets.

[0078] As a preferred embodiment, the embodiments of the present invention use Figure 3 Taking the measurement of the gravitational potential difference between Earth, Moon, and Mars as an example, this invention illustrates the implementation process of determining the interstellar gravitational potential difference through interstellar optical clock frequency comparison:

[0079] a. Ground station construction and optical clock deployment: Deploy ultra-high precision optical atomic clocks on Earth, Mars, and the Moon, respectively, with a frequency stability of 10⁻⁶. -19 The scale is measured in minute frequency variations caused by sensitive gravitational potential differences. An optical signal transmission / reception system is constructed for optical link comparison with distant planets. An ultra-stable environment (such as vacuum, cryogenics, and magnetic shielding) is provided for the operation of the atomic clock. A local time and frequency reference is established and synchronized with International Atomic Time (TAI).

[0080] b. Establishment of a remote time-frequency comparison link: Compare three-frequency optical signals between Earth, Mars, and the Moon; record the timestamps of signal transmission and reception (accurate to the picosecond level). Perform combined three-frequency optical measurements between the three planets, and accurately extract the gravitational redshift effect according to the above principles.

[0081] c. Path delay and error correction: Calculate the effects of special relativistic time dilation (velocity effect) and general relativistic gravitational redshift (difference between the gravitational potential of the satellite and the ground) caused by satellite orbital motion, use three-frequency combination technology to eliminate the effects of atmospheric turbulence, ionosphere and Sagnac effect, and establish corresponding frequency shift correction models, etc.

[0082] d. Gravity potential difference calculation and verification: Separate the gravity frequency shift caused by gravity potential difference, improve the signal-to-noise ratio through the star-to-ground optical clock optical frequency comparison link and multiple measurements; compare the optical clock comparison results with traditional gravity measurements (such as absolute gravimeters, satellite gravity field models) to verify consistency; analyze the sources of uncertainty (such as optical clock stability), and finally output the gravity potential difference and its confidence interval.

[0083] e. Ultra-long-distance optical clock frequency comparison between Mars, Earth, and the Moon's time-frequency satellites: Compare the three-frequency optical signals between Earth, Mars, and the Moon and their time-frequency satellites; record the timestamps of signal transmission and reception (accurate to the picosecond level). Then, measure the frequency difference of the optical frequencies of distant planets, and combine the environmental noise correction model from b to d with real-time measurement data to accurately extract the gravitational redshift. Based on general relativity, establish the conversion relationship between gravitational redshift and gravitational potential difference: Ultimately, this will enable the determination of the gravitational potential difference between the three planets: Mars, Earth, and the Moon.

[0084] By using remote optical clock frequency comparison to determine gravitational potential difference, the gravitational potential difference between any two planets can be obtained, enabling high-precision gravitational redshift verification.

[0085] Based on the same inventive concept as the foregoing embodiments, this embodiment of the invention also provides an optical frequency signal interstellar gravity difference measurement device, comprising:

[0086] An optical clock-frequency comparison system is established on two planets where gravitational potential differences need to be measured, to construct a planet-to-planet three-frequency combined optical frequency comparison link. Based on the constructed planet-to-planet three-frequency combined optical frequency comparison link, bidirectional optical frequency signal transmission, reception, and reflection are performed between the two planets, and the transmission frequency f1 and reflection frequency of the link from planet one to planet two to planet one are recorded respectively. and receiving frequency And the transmit frequency f2 and receive frequency of the Planet 2 to Planet 1 link. ;

[0087] The data processing system is used to extract the gravitational redshift frequency shift between two planets based on the interstellar one-way frequency transfer model and the recorded frequencies; and to calculate the gravitational potential difference between the two planets based on the relationship between the gravitational redshift frequency shift and the gravitational potential difference.

[0088] This embodiment constructs an optical clock frequency comparison system (with an accuracy better than 10) between different planets in different solar systems. -19 The system includes optical clocks, optical combs, frequency-stabilized lasers, optical frequency transmitters and receivers, and other devices of a certain scale. It can transmit and receive interplanetary optical frequency signals through planet-to-planet optical frequency links. It should be noted that the interplanetary optical frequency links adopt a three-frequency combination method to achieve remote optical clock-frequency comparison. Through interplanetary optical clock-frequency comparison, the gravity frequency shift signal can be accurately extracted to achieve interplanetary gravity potential difference measurement.

[0089] The interplanetary optical clock frequency transmission requires the establishment of time-frequency comparison optical frequency links between planets. Utilizing adaptive optics technology and the effects of atmospheric turbulence, the ionosphere, magnetic fields, and the interplanetary deep-space electromagnetic environment on electromagnetic waves, the optimal optical frequency is selected (unlike traditional three-frequency microwave links, optical links have higher frequencies, consume more energy, and are more difficult to propagate in interplanetary space, but their accuracy is higher than microwave frequencies). This ensures long-distance signal transmission. Through three-frequency optical signals, an interplanetary optical clock frequency comparison model and a generalized relativistic model for measuring gravitational potential differences (including c) are constructed. -4 The accuracy of the gravity potential difference measurement model and various error correction models can meet the requirements of 10. -19 Light frequency comparison on a scale of magnitude.

[0090] Considering the extreme temperatures and electromagnetic radiation of deep space, the optical components on planets need to have strong environmental adaptability, remaining undeformed and unaffected in extreme environments. This necessitates the integration of atomically stabilized lasers. Simultaneously, the operating environment (temperature, humidity, pressure, magnetic field, etc.) of the optical clock, optical comb, and laser must be monitored in real time. An environmental noise frequency drift correction model for the optical clock-frequency comparison system must be established to dynamically compensate and correct for frequency shifts caused by environmental noise in real time, ensuring that the frequency sources on the planets and time-frequency satellites maintain high stability.

[0091] The optical frequency link is highly sensitive to planetary environments. Therefore, it is necessary to establish a corresponding environmental impact frequency shift correction model for the optical frequency propagation process, addressing the effects of various environmental factors (atmosphere, pressure, temperature, magnetic field interference, etc.) on the optical signal. (The model needs to meet 10...) -19 (Accuracy requirements); at the same time, a three-frequency optical frequency combination model is used to eliminate the frequency shift caused by environmental factors and accurately extract the interstellar gravity frequency shift signal.

[0092] Furthermore, the planet needs to be equipped with systems with an accuracy better than 10. -19 A high-precision optical clock of magnitude 6.5, a three-frequency combined optical frequency link for interstellar time and frequency transmission, with the near planet transmitting optical frequency signal f1 and receiving reflected signals from the far planet. The signal is combined with the signal f2 transmitted from the remote end to eliminate the frequency shift caused by the electromagnetic environment noise in deep space between interstellar spaces. Then, through the data processing unit, the optical frequency ratio data of time and frequency satellites from different planets is uniformly processed, and the dynamic environmental compensation data of optical clocks and lasers is corrected to obtain the gravitational potential difference between any interstellar space.

[0093] The embodiments of the present invention are based on the reference optical clock module, optical frequency comb module, time-frequency comparison link, satellite orbit determination module and ground data processing system equipped on the planet to measure the gravitational potential difference between stars, forming an integrated interstellar gravitational potential difference measurement system that integrates data acquisition, processing and output.

[0094] In summary, this invention, through the deployment of high-precision optical clocks on Earth, the Moon, and / or Mars (planetary systems in the solar system), establishes interstellar connections via optical frequency signals. Utilizing the principles of general relativity, it converts the frequency difference of the interstellar optical clocks into gravitational potential difference, achieving high-precision, high-spatial-resolution interstellar gravitational potential difference measurement and joint determination of interstellar gravitational fields. This invention is primarily applied in research fields such as planetary gravitational field modeling, interstellar gravitational field modeling, gravitational wave detection, and interstellar navigation. In this invention, different planets require the deployment of clocks with long-term stability better than 10... -19 This invention utilizes a high-precision optical clock and femtosecond optical comb, signal receiving and transmitting devices, and signal reflecting devices. The optical frequency signal from the planetary optical clock is down-converted via the femtosecond optical comb, making the hundreds of THz optical frequency signal generated by the optical clock suitable for interstellar propagation. Through a three-frequency combination time-frequency link between planets, various errors in the optical frequency link propagation process are eliminated, accurately extracting the interplanetary gravitational frequency signals and determining the interstellar gravitational potential difference. This invention combines the rapidly developing optical clock technology with an optical clock, optical comb, and frequency-stabilized laser to construct a system for measuring interstellar gravitational potential difference. By constructing an interstellar optical frequency comparison link, it achieves the extraction of interstellar gravitational frequency shift signals and the measurement of gravitational potential difference. This method, aided by a high-precision optical clock mounted on a time-frequency planet, can sense centimeter-level changes in gravitational potential difference, playing a crucial role in planetary gravitational field modeling, interstellar gravitational potential difference determination, gravitational wave detection, and interstellar satellite navigation.

[0095] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring interstellar gravitational potential difference using optical frequency signals, characterized in that, include: Optical clock and optical frequency comparison systems were established on two planets where gravitational potential differences needed to be measured, in order to construct a planet-to-planet three-frequency combined optical frequency comparison link; Based on the constructed planet-to-planet three-frequency optical frequency comparison link, bidirectional optical frequency signal transmission, reception, and reflection are performed between the two planets, and the transmission frequencies of the links from planet one to planet two to planet one are recorded respectively. Reflection frequency and receiving frequency and the transmission frequency of the Planet 2 to Planet 1 link. and receiving frequency ; Based on the interstellar one-way frequency transfer model and combined with the recorded frequencies, the gravitational redshift frequency shift between the two planets is extracted; the interstellar one-way frequency transfer model is expressed as: ， Where K represents the downconversion coefficient of the femtosecond optical comb. This represents the frequency difference between two clocks in a relativistic reference frame. This indicates the nominal frequency of an atomic clock within a relativistic reference frame. This indicates the transmission frequency of one of the planetary ends. This indicates the receiving frequency at the other planetary end. This indicates the frequency shift caused by the gravitational redshift effect. This indicates that relativistic effects cause a transverse Doppler frequency shift. This indicates the frequency shift caused by the deep space interplanetary environment between planets. and This indicates the frequency shift caused by the atmospheric environments of the two planets. Indicates the nominal frequency of the optical signal; Based on the relationship between gravitational redshift frequency shift and gravitational potential difference, the gravitational potential difference between the two planets is calculated.

2. The method for measuring interstellar gravitational potential difference using optical frequency signals according to claim 1, characterized in that, Based on the constructed planet-to-planet three-frequency combined optical frequency comparison link, bidirectional optical frequency signal transmission, reception, and reflection are performed between the two planets, including: By using optical clocks positioned on two planets, simultaneously generating signals with an accuracy better than 10... -19 Optical frequency signals of magnitude; The generated optical frequency signal is down-converted to a frequency suitable for spatial transmission. Each planetary station simultaneously receives optical frequency signals from the other and extracts the frequency signals.

3. The method for measuring interstellar gravitational potential difference using optical frequency signals according to claim 1, characterized in that, The method further includes: Based on the interstellar one-way frequency transfer model, frequency shift equations are obtained for the links from Planet 1 to Planet 2 to Planet 1 and from Planet 2 to Planet 1, respectively. Based on the frequency shift equations, the gravitational redshift frequency shift is extracted.

4. The method for measuring interstellar gravitational potential difference using optical frequency signals according to claim 3, characterized in that, The extracted gravitational redshift frequency shift is expressed as: ， This represents the residual frequency shift related to the propagation frequency caused by different factors, where i represents the different factors.

5. The method for measuring interstellar gravitational potential difference using optical frequency signals according to claim 4, characterized in that, The relationship between gravitational redshift frequency shift and gravitational potential difference is expressed as: ， in, The measured gravitational redshift frequency shift is given by c, where c is the speed of light. For higher-order terms, Let be the gravitational potential difference between the two planets.

6. The method for measuring interstellar gravitational potential difference using optical frequency signals according to claim 1, characterized in that, The process involves bidirectional optical signal transmission between the two planets, recording the signals at each frequency, and includes: At each planetary station, the received optical frequency signal from the other side is optically coherently heterodyned or optically phase-locked with the optical frequency reference signal generated by the local optical clock to generate a beat frequency signal, and the frequency of the beat frequency signal is measured. Measure the bidirectional distance and relative velocity between two planets; The frequency, bidirectional distance, relative speed, and recorded timestamps of the beat frequency signal are packaged into raw measurement data.

7. The method for measuring interstellar gravitational potential difference using optical frequency signals according to claim 6, characterized in that, After obtaining the raw measurement data, the following is also included: Using the measured relative velocity, the first-order Doppler frequency shift caused by the relative motion of the satellite is calculated and eliminated; Based on the principles of general relativity, an accuracy to c is established. -4 A high-order gravity frequency shift model of magnitude 1.5 is used, and based on the high-order gravity frequency shift model, combined with bidirectional distance and orbital data, the second-order Doppler effect and dispersive frequency shift are calculated and eliminated; Based on the mechanism by which planetary atmospheres affect the frequency of optical signals, a system accurate to c is established. -18 An environmental noise frequency shift correction model of magnitude is developed, and the frequency shift caused by environmental noise between time-frequency satellites and planets is corrected based on the environmental noise frequency shift correction model.

8. An optical frequency signal interstellar gravity difference measurement device, characterized in that, include: An optical clock-frequency comparison system is established on two planets where gravitational potential differences need to be measured, to construct a planet-to-planet three-frequency combined optical frequency comparison link. Based on the constructed planet-to-planet three-frequency combined optical frequency comparison link, bidirectional optical frequency signal transmission, reception, and reflection are performed between the two planets, and the transmission frequency f1 and reflection frequency of the link from planet one to planet two to planet one are recorded respectively. and receiving frequency The transmit frequency f2 and receive frequency of the planet-to-planet link. ; The data processing system is used to extract the gravitational redshift frequency between two planets based on a one-way frequency transfer model between interstellar space and the recorded frequencies; and to calculate the gravitational potential difference between the two planets based on the relationship between the gravitational redshift frequency transfer and the gravitational potential difference; wherein, the one-way frequency transfer model between interstellar space is expressed as: ， Where K represents the downconversion coefficient of the femtosecond optical comb. This represents the frequency difference between two clocks in a relativistic reference frame. This indicates the nominal frequency of an atomic clock within a relativistic reference frame. This indicates the transmission frequency of one of the planetary ends. This indicates the receiving frequency at the other planetary end. This indicates the frequency shift caused by the gravitational redshift effect. This indicates that relativistic effects cause a transverse Doppler frequency shift. This indicates the frequency shift caused by the deep space interplanetary environment between planets. and This indicates the frequency shift caused by the atmospheric environments of the two planets. Indicates the nominal frequency of the optical signal.

9. The optical frequency signal interstellar gravity difference measuring device according to claim 8, characterized in that, The optical clock-frequency comparison system integrates an atomically stabilized laser and monitors the operating environment of the optical clock, optical comb, and laser in real time. It also establishes an environmental noise frequency drift correction model for the optical clock-frequency comparison system to provide real-time dynamic compensation and correction for frequency shifts caused by environmental noise.

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