Vibration real-time compensation device and method for cold atom gravimeter

Abstract

The present application relates to a kind of vibration real-time compensation device and method for cold atom gravimeter, the device includes Raman laser, rubidium atom group, reflector, accelerometer, optical phase-locked loop module, analog-digital converter, reference clock source, heteronuclear FPGA, direct frequency generation module, host computer.Two pairs of Raman laser in vertical direction relative to rubidium atom group, accelerometer and reflector are rigidly connected, the analog differential signal of accelerometer enters analog-digital converter, the digital signal converted enters heteronuclear FPGA and carries out digital calculation, reference clock source is as the clock signal of digital circuit.Signal calculated by heteronuclear FPGA enters direct frequency generation module and is output to the phase of optical phase-locked loop controlled Raman laser, and heteronuclear FPGA and host computer are communicated by TCP connection.The present application is a kind of digital, with large dynamic range, low noise, high-precision phase synchronization compensation capacity of vibration real-time compensation device for cold atom gravimeter.

Description

Technical Field

[0001] This invention relates to a vibration real-time compensation device and method for cold atom gravimeters. It is mainly used to eliminate the influence of carrier vibration on the frequency and phase of Raman light in an atomic interferometer in real time when a mobile platform (such as a ship or vehicle) is in operation, thereby ensuring the accuracy and stability of quantum gravity measurement in dynamic environments. Background Technology

[0002] Cold atom gravimeters, especially atomic interferometric gravimeters, have become a cutting-edge technology for achieving the highest precision in absolute gravity measurement. Their principle involves using laser-cooled atoms as near-ideal gravity testing masses. A laser pulse sequence (Raman or Bragg light) interferes with the atoms, and the gravitational acceleration value is ultimately inverted by detecting the phase of the interference fringes corresponding to the atomic population distribution. This phase is extremely sensitive to the frequency and phase of the laser acting on the atoms.

[0003] In dynamic measurement environments, such as when instruments are deployed on moving ships, vehicles, or aircraft, the vibration of the carrier itself causes complex relative motion between the reference mirror carrying the instrument and the freely falling atoms. This relative motion introduces an additional Doppler frequency shift, directly leading to frequency detuning of the Raman light and accumulating into a non-negligible interference phase error. In severe cases, this can reduce or even eliminate the contrast of the interference fringes, causing measurement failure. Therefore, real-time and accurate compensation for the frequency and phase of the Raman light caused by carrier vibration is a core technological bottleneck for achieving high-precision dynamic atomic gravity measurement.

[0004] Current mainstream solutions typically employ post-measurement data processing compensation: after measurement, acceleration and angular velocity data recorded by the onboard high-precision inertial measurement unit (IMU) are used to reconstruct the carrier's trajectory through post-processing algorithms, derive the theoretically required compensation amount, and then correct the gravity measurement results. However, this approach lacks real-time capability and is highly dependent on the accuracy of the motion model, limiting key performance aspects of its compensation system, such as dynamic range, noise level, long-term stability, and phase compensation accuracy. Furthermore, it lacks flexible algorithm reconstruction capabilities. This directly restricts the applicability and final measurement sensitivity of dynamic cold atom gravimeters in complex, high-vibration environments.

[0005] The closest invention patent to this application is titled "Vibration Compensation Method for an Atomic Absolute Gravimeter," application publication number CN 116449446 A. This is a vibration compensation method for an atomic absolute gravimeter. The implementation method involves: determining the optimization objective and constraints for vibration compensation of the atomic absolute gravimeter; solving for the optimal gain coefficient and optimal delay coefficient using an ergonomic method. The optimal gain coefficient and optimal delay coefficient are used to calculate the vibration of the Raman mirror during each atomic drop, obtaining the change in atomic interference phase caused by the vibration, and then correcting the Raman light frequency scanning rate to obtain the atomic interference fringe signal free from vibration effects, thus achieving vibration compensation for the atomic absolute gravimeter. However, the real-time performance of this method is still limited. The ergonomic optimization process involves a large amount of computation, making it difficult to achieve high-frequency real-time compensation. Furthermore, it depends on the fitting quality of the atomic interference fringes; under low signal-to-noise ratio or strong non-stationary vibration conditions, the optimization process may converge slowly or fail, and there is a trade-off between dynamic response speed and accuracy.

[0006] Currently, the industrialization of cold atom gravimeters is gradually entering the dynamic measurement stage. Therefore, there is a need for a vibration compensation device and method with high integration, strong real-time performance, and suitability for highly dynamic vibration environments. This device and method should be able to achieve low-delay, high-precision real-time feedforward compensation of vibration phase during atomic interference, in order to support the reliable application of cold atom gravimeters in mobile platforms such as vehicle-mounted, ship-mounted, and airborne systems. Summary of the Invention

[0007] To address the aforementioned technical problems, the first objective of this invention is to provide a fully digital vibration real-time compensation device for cold atom gravimeters that combines a large dynamic range, low noise, and high-precision phase synchronization compensation capabilities. The second objective of this invention is to provide a vibration real-time compensation method for cold atom gravimeters.

[0008] To achieve the first objective of the invention, the present invention adopts the following technical solution:

[0009] A vibration real-time compensation device for a cold atom gravimeter includes an interferometric sequence excitation mechanism, a reflector, an accelerometer, an optical phase-locked loop, an analog-to-digital converter, a reference clock source, a heterogeneous FPGA, and a direct digital generation module.

[0010] The interference sequence excitation mechanism includes Raman light A, Raman light B, and rubidium atomic clusters. The two opposing Raman beams interact with the rubidium atomic clusters falling freely in the vacuum, and a three-pulse sequence based on light pulses is applied to cause population interference in the rubidium atomic clusters.

[0011] The accelerometer is rigidly connected to a mirror that shares the same path with one of the Raman beams. The analog differential signal output by the accelerometer is digitized by an analog-to-digital converter, and the digital signal stream is sent to a heterogeneous FPGA for real-time processing.

[0012] The velocity integration signal processing chain in the heterogeneous FPGA integrates and filters the accelerometer signal to obtain the instantaneous velocity of the reflector. The heterogeneous FPGA calculates in real time the Raman laser frequency correction required to compensate for the instantaneous velocity and generates the corresponding frequency word, which is then sent to the direct digital generation module.

[0013] Driven by a reference clock source, the direct digital generation module generates a microwave signal with precisely adjusted frequency to drive an optical phase-locked loop and control the frequencies of Raman light A and Raman light B in real time, thereby offsetting the phase error introduced by the vibration of the mirror in the optical domain and forming a closed-loop compensation.

[0014] As a preferred option, it also includes a host computer, which is connected to the heterogeneous FPGA via a TCP network interface for system status monitoring, parameter configuration, and data acquisition.

[0015] As a preferred embodiment: the heterogeneous FPGA includes an analog-to-digital converter driver module, an AXI-FIFO1 register, a velocity integral calculation module, a timer module, a frequency word calculation module, and a direct frequency generation driver module. The analog-to-digital converter driver module receives the data stream from the analog-to-digital converter; the data stream is connected to the AXI-FIFO1 register via the AXI bus. The real-time velocity value calculated by the velocity integral calculation module is connected to the frequency word calculation module. The timer module is implemented through high-level synthesis to precisely control the key pulse sequence timing signal of the cold atom interferometry. The pulse signal is connected to the frequency word calculation module. The frequency word calculation module is implemented through high-level synthesis to dynamically calculate and output the frequency word based on the atomic velocity measurement value and the interferometry sequence timing. The frequency word data stream is transmitted to the direct frequency generation driver module, which converts the frequency word into binary data received by the external module and then transmits it through a parallel interface.

[0016] As a preferred solution: the speed integral calculation module is implemented through high-level synthesis, and outputs the speed value through ADC data normalization and dimension conversion, 31st-order FIR digital filtering, 10x CIC downsampling and first-order IIR approximate integral operation; all processing units are transmitted in a pipeline, and can complete multi-level signal processing in parallel within a single clock cycle.

[0017] As a preferred option, the device employs a three-state finite state machine, responds to external pulse sequence control, and continuously outputs frequency word data streams through the AXI-Stream interface.

[0018] As a preferred embodiment: the device latches the initial velocity reference v0 when the magneto-optical trap is loaded. Then, triggered by the velocity change during the interference process, the Raman laser frequency is calculated in real time according to the Doppler frequency shift formula f = f0 + (v - v0)·k_eff, where f is the Raman light frequency that resonates with the atom, f0 is the reference Raman light frequency, v is the current velocity, v0 is the initial velocity, and k_eff is the effective wave vector of the Raman light. The frequency word output of the direct frequency generation driving module is converted into the frequency word output by the scaling factor.

[0019] As a preferred embodiment, it also includes a phase-locked loop (PLL), which generates a 40 MHz system clock signal from a reference 280 MHz clock provided by a reference clock source through frequency division and phase locking; the system clock signal is distributed to the analog-to-digital conversion driver module, the speed integral calculation module, the timer module, the frequency word calculation module, and the direct frequency generation driver module.

[0020] As a preferred embodiment, it also includes an AXI-FIFO2 register and an on-chip system. The key parameters of the speed integral calculation module are configured online through the AXI-Lite interface, and a data stream for intermediate calculation variables is provided. The data stream is connected to the AXI-FIFO2 register, read in real time by the on-chip system, and transmitted via TCP network communication.

[0021] To achieve the second objective of the invention, the present invention adopts the following technical solution:

[0022] A vibration real-time compensation method for a cold atom gravimeter, employing any of the aforementioned devices, the core workflow of which is as follows:

[0023] 1. Interference sequence excitation: Two beams of Raman light from opposite directions interact with rubidium atoms falling freely in a vacuum, applying a "three-pulse" sequence based on light pulses to cause population interference of the atoms;

[0024] 2. Vibration signal acquisition: The vibration of the mirror that shares the same path with one of the Raman beams will be equivalent to the phase noise of the Raman laser. A high-sensitivity accelerometer installed close to the mirror measures its vibration acceleration signal in real time.

[0025] 3. Signal chain processing: The analog differential signal output by the accelerometer is digitized by a high-precision analog-to-digital converter, and the digital signal stream is sent to the heterogeneous FPGA for real-time processing.

[0026] 4. Real-time calculation and compensation: The velocity integration signal processing chain in the heterogeneous FPGA integrates and filters the acceleration signal to obtain the instantaneous velocity of the reflector. Combined with the precise timing of the interference sequence, the heterogeneous FPGA calculates the Raman laser frequency correction required to compensate for the velocity in real time and generates the corresponding frequency word.

[0027] 5. Closed-loop execution: The frequency word is sent to the direct digital generation module. Driven by the reference clock source, the direct digital generation module generates a microwave signal with precise frequency adjustment, drives the optical phase-locked loop, and finally controls the frequency of Raman light A and Raman light B in real time, thereby canceling the phase error introduced by the vibration of the mirror in the optical domain and forming closed-loop compensation.

[0028] As a preferred option, step 6, monitoring and configuration, is also included: the host computer connects to the heterogeneous FPGA via a TCP network interface for system status monitoring, parameter configuration, and data acquisition.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] This invention employs a heterogeneous FPGA as the core processing platform to construct a fully digital real-time processing device that integrates high-precision accelerometer data acquisition with DDS frequency compensation output, achieving low compensation delay and high bandwidth. The device utilizes a DC-drift-resistant finite-bandwidth integration algorithm, combined with configurable digital filtering and downsampling, effectively suppressing low-frequency noise and integration accumulation errors. By receiving a Raman optical pulse synchronous trigger signal, the device stores the velocity integral value at precise moments and calculates the high-precision frequency compensation, achieving real-time feedforward compensation for the vibration phase. The device adopts a modular hardware design, supporting adaptive configuration for various vibration environments, providing reliable technical support for high-precision measurements of cold atom gravimeters on dynamic platforms.

[0031] This invention directly calculates the compensation amount using a hardware-implemented deterministic algorithm, avoiding the computational delays and uncertainties caused by iterative optimization, and exhibits superior response characteristics in strong dynamic vibration environments. Compared to traditional DSP-based vibration compensation schemes, the all-digital processing architecture of this invention, through the parallel computing capabilities of heterogeneous FPGAs, extends the compensation bandwidth from the usual below 100Hz to above 500Hz, effectively compensating for higher frequency vibration components. Attached Figure Description

[0032] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute a limitation thereof.

[0033] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention;

[0034] Figure 2 This is a diagram of the heterogeneous FPGA system architecture of the present invention.

[0035] The labels in the attached diagram are as follows: 101, Phase-Locked Loop; 102, Analog-to-Digital Converter Driver Module; 103, AXI-FIFO1 Register; 104, Velocity Integrator Calculation Module; 105, AXI-FIFO2 Register; 106, System-on-Chip; 107, Timer Module; 108, Frequency Word Calculation Module; 109, Direct Frequency Generation Driver Module; 201, Raman Beam A; 202, Rubidium Atom Cluster; 203, Raman Beam B; 204, Mirror; 205, Accelerometer; 206, Optical Phase-Locked Loop; 207, Analog-to-Digital Converter; 208, Reference Clock Source; 209, Heterogeneous FPGA; 210, Direct Digital Generation Module; 211, Host Computer. Detailed Implementation

[0036] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0037] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] Furthermore, in the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless explicitly defined otherwise.

[0040] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0043] like Figure 1 As shown, a vibration real-time compensation device for a cold atom gravimeter includes an interference sequence excitation mechanism, a reflector 204, an accelerometer 205, an optical phase-locked loop 206, an analog-to-digital converter 207, a reference clock source 208, a heterogeneous FPGA 209, and a direct digital generation module 210. The interference sequence excitation mechanism includes Raman beams A201, Raman beams B203, and rubidium atom clusters 202. Two opposing Raman beams interact with the rubidium atom clusters 202 falling freely in a vacuum, applying a three-pulse sequence based on light pulses to cause population interference in the rubidium atom clusters 202.

[0044] The accelerometer 205 is rigidly connected to a mirror 204 that shares a path with one of the Raman beams. The analog differential signal output by the accelerometer 205 is digitized by an analog-to-digital converter 207, and the digital signal stream is sent to a heterogeneous FPGA 209 for real-time processing.

[0045] The velocity integration signal processing chain in the heterogeneous FPGA 209 integrates and filters the accelerometer signal to obtain the instantaneous velocity of the reflector 204. The heterogeneous FPGA 209 calculates in real time the Raman laser frequency correction required to compensate for the instantaneous velocity and generates the corresponding frequency word, which is sent to the direct digital generation module 210.

[0046] Driven by the reference clock source 208, the direct digital generation module 210 generates a microwave signal with precisely adjusted frequency to drive the optical phase-locked loop 206 and control the frequencies of Raman light A201 and Raman light B203 in real time, thereby canceling the phase error introduced by the vibration of the mirror in the optical domain and forming a closed-loop compensation.

[0047] The heterogeneous FPGA system architecture diagram of this invention is shown below. Figure 2 As shown, it mainly consists of a phase-locked loop 101, an analog-to-digital conversion driver module 102, an AXI-FIFO1 register 103, a speed integral calculation module 104, an AXI-FIFO2 register 105, an on-chip system 106, a timer module 107, a frequency word calculation module 108, and a direct frequency generation driver module 109.

[0048] The phase-locked loop (PLL) described in this invention is an IP core from Xilinx, which generates a 40 MHz system clock signal from an external 280 MHz reference clock through frequency division and PLL. This clock signal is then distributed to the analog-to-digital converter (ADC) driver module, speed integral calculation module, timer module, frequency word calculation module, and direct frequency generation module. The ADC driver module, implemented using a hardware description language, receives the data stream from the ADC. The data stream is connected to the AXI-FIFO1 register via the AXI bus, serving as a data buffer. The speed integral calculation module, implemented through high-level synthesis, outputs the speed value through ADC data normalization and dimension conversion, 31st-order FIR digital filtering, 10x CIC downsampling, and first-order IIR approximate integration. All processing modules achieve low latency through pipelined execution, enabling parallel computation of multiple signal processing stages within a single clock cycle. Key parameters can be configured online via the AXI-Lite interface, and an intermediate calculation variable data stream is provided. This data stream is connected to the AXI-FIFO2 register and can be read in real-time by the on-chip system and transmitted via TCP network communication. The real-time speed value calculated by this module is connected to the frequency word calculation module. The timer module, implemented through high-level synthesis, precisely controls the timing signals of the key pulse sequences for four cold atom interferometry measurements. These pulse signals are connected to the frequency word calculation module. The frequency word calculation module, also implemented through high-level synthesis, dynamically calculates and outputs the DDS frequency tuning word based on the atomic velocity measurements and the interferometric sequence timing. The system latches the initial velocity reference v0 at the moment the magneto-optical trap is loaded. Subsequently, triggered by velocity changes during the interferometry process, it calculates the Raman laser frequency in real time according to the Doppler frequency shift formula f = f0 + (v - v0)·k_eff (where f is the Raman light frequency resonating with the atom, f0 is the reference Raman light frequency, v is the current velocity, v0 is the initial velocity, and k_eff is the effective wave vector of the Raman light). This frequency word is then converted into a 48-bit DDS frequency word output using a scaling factor. The design employs a three-state finite state machine to respond to external pulse sequence control. It continuously outputs a frequency word data stream through the AXI-Stream interface. This data stream is transmitted to the direct frequency generation driver module, which, implemented using a hardware description language, converts the frequency word into binary data received by the external module and then transmits it through a parallel interface.

[0049] The core workflow of the device system structure of the present invention is as follows:

[0050] 1. Interference sequence excitation: Two opposing Raman beams A201 and B203 interact with rubidium atom cluster 202 falling freely in vacuum, applying a "three-pulse" (π / 2-π-π / 2) sequence based on light pulses, causing population interference of the atoms.

[0051] 2. Vibration Signal Acquisition: The vibration of the mirror 204, which shares a path with one of the Raman beams, is equivalent to the phase noise of the Raman laser. A high-sensitivity accelerometer 205, mounted close to the mirror, measures its vibration acceleration signal in real time.

[0052] 3. Signal chain processing: The analog differential signal output by the accelerometer 205 is digitized by a high-precision analog-to-digital converter 207. The analog-to-digital converter 207 uses the AD7762 chip, and the digital signal stream is sent to the heterogeneous FPGA 209 for real-time processing.

[0053] 4. Real-time Calculation and Compensation: The velocity integration signal processing chain within the heterogeneous FPGA209 integrates and filters the acceleration signal to obtain the instantaneous velocity of the reflector. Combined with precise interference sequence timing, the heterogeneous FPGA calculates in real time the Raman laser frequency correction required to compensate for this velocity and generates the corresponding frequency word.

[0054] 5. Closed-loop execution: The frequency word is sent to the direct digital generation module 210. Driven by the reference clock source 208, the direct digital generation module 210 generates a microwave signal with precise frequency adjustment, drives the optical phase-locked loop 206, and finally controls the frequency of Raman light A201 and Raman light B203 in real time, thereby canceling the phase error introduced by the vibration of the reflector in the optical domain and forming closed-loop compensation.

[0055] The device of the present invention also includes a host computer 211, which is connected to the heterogeneous FPGA 209 via a TCP network interface and is used for system status monitoring, parameter configuration and data acquisition.

[0056] This invention has the following outstanding advantages: It achieves a fully hardware-based vibration compensation loop with microsecond-level delay through a heterogeneous FPGA, solidifying acceleration signal acquisition, digital integration, timing control, and frequency calculation into a parallel hardware circuit, fundamentally solving the bottlenecks of high latency and large jitter in traditional software solutions; it innovatively adopts a feedforward compensation architecture based on a physical model, generating compensation signals in real time according to a precise "acceleration-velocity-Doppler frequency shift" chain model, avoiding the stability problem of closed-loop feedback; more importantly, by synchronously locking the precise timing of the interference sequence with velocity measurement, it ensures a strict spatiotemporal match between laser phase compensation and the atomic interference process, giving the system high bandwidth, high precision, and strong robustness, providing a hardware-level reliable guarantee for achieving extreme measurement accuracy in dynamic environments for cold atom interferometers.

[0057] This invention employs a heterogeneous FPGA to construct a fully hardware-based processing chain and incorporates real-time vibration signals provided by a high-precision ADC and accelerometer. The acceleration signal physically directly characterizes the vibration disturbance of the reflector, and its measurement itself has no cumulative error. Through a hardware-implemented signal processing chain (scaling-filtering-integration), the acceleration signal can be converted into precise instantaneous velocity information within microsecond delays. This process solves the problem of mismatch between the compensation signal and the interference sequence caused by software processing delays and timing jitter in traditional vibration compensation schemes. This mismatch directly translates into inseparable phase noise, which is a major bottleneck limiting the accuracy of interference in dynamic environments.

[0058] This invention introduces a precise hardware timing and velocity measurement synchronization mechanism for the interference sequence. The innermost timing generator enables nanosecond-level precise control of each stage of atomic interference (atomic trapping, Raman π / 2 pulse, Raman π pulse); the outer frequency calculator calculates the compensation frequency in real time based on the latched initial velocity v0 and the Doppler model. Therefore, this architecture endows the compensation loop with extremely high timing determinism and model fidelity, ensuring that the compensation phase and the vibration phase sensed by the atomic wave packet are strictly synchronized in time and space, achieving effective cancellation of phase noise.

[0059] This invention implements a complete digital signal processing and frequency calculation pipeline within an FPGA and designs an observable system with multi-level debugging interfaces and configurable parameters. This enables the system to monitor intermediate data processing results in real time and dynamically adjust compensation parameters during operation, achieving full-chain transparency and optimization from data acquisition to frequency generation. This provides a hardware foundation for maintaining system performance and diagnosing faults in complex working environments.

[0060] Compared to DSP or MCU-based processing solutions, this invention leverages the parallel computing capabilities of FPGAs to achieve a fully pipelined processing of acceleration signal acquisition, filtering, integration, and compensation calculations. This avoids data processing bottlenecks in traditional architectures, significantly improving the system's real-time performance and determinism. The invention employs a finite-bandwidth anti-drift integration algorithm. Compared to traditional direct integration methods, it effectively suppresses sensor DC drift and low-frequency noise accumulation through second-order filtering design, improving the long-term stability of velocity integration. The system incorporates a configurable digital filter and downsampling module. Compared to fixed-parameter filters, it can dynamically adjust processing parameters according to the vibration environment, maintaining signal integrity under strong vibration conditions and optimizing noise suppression under weak vibration conditions. In summary, this invention provides a high-real-time, wide-bandwidth, configurable vibration compensation solution, significantly improving the measurement stability and accuracy of cold atom gravimeters in dynamic environments such as vehicle-mounted and ship-mounted systems.

[0061] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A vibration real-time compensation device for a cold atom gravimeter, characterized in that: It includes an interference sequence excitation mechanism, a reflector (204), an accelerometer (205), an optical phase-locked loop (206), an analog-to-digital converter (207), a reference clock source (208), a heterogeneous FPGA (209), and a direct digital generation module (210). The interference sequence excitation mechanism includes Raman light A (201), Raman light B (203) and rubidium atom cluster (202). The two opposing Raman beams interact with the rubidium atom cluster (202) falling freely in the vacuum, and a three-pulse sequence based on light pulses is applied to cause population interference in the rubidium atom cluster (202). The accelerometer (205) is rigidly connected to a mirror (204) that shares a path with one of the Raman beams. The analog differential signal output by the accelerometer (205) is digitized by an analog-to-digital converter (207), and the digital signal stream is sent to a heterogeneous FPGA (209) for real-time processing. The velocity integration signal processing chain in the heterogeneous FPGA (209) integrates and filters the accelerometer signal to obtain the instantaneous velocity of the reflector (204). The heterogeneous FPGA (209) calculates the Raman laser frequency correction required to compensate for the instantaneous velocity in real time and generates the corresponding frequency word. The frequency word is sent to the direct digital generation module (210). Driven by a reference clock source (208), the direct digital generation module (210) generates a microwave signal with a precisely adjusted frequency, drives the optical phase-locked loop (206), and controls the frequency of Raman light A (201) and Raman light B (203) in real time, thereby canceling the phase error introduced by the vibration of the mirror in the optical domain and forming a closed-loop compensation. The heterogeneous FPGA (209) includes an analog-to-digital converter driver module (102), an AXI-FIFO1 register (103), a velocity integral calculation module (104), a timer module (107), a frequency word calculation module (108), and a direct frequency generation driver module (109). The analog-to-digital converter driver module (102) is used to receive the data stream from the analog-to-digital converter (207). The data stream is connected to the AXI-FIFO1 register (103) via the AXI bus. The real-time velocity value calculated by the velocity integral calculation module (104) is connected to the frequency word calculation module (108). The timer module (107) is implemented through high-level synthesis to precisely control the key pulse sequence timing signal of cold atom interferometry. The key pulse sequence timing signal is connected to the frequency word calculation module (108). The frequency word calculation module (108) is implemented through high-level synthesis to dynamically calculate and output the frequency word based on the atomic velocity measurement value and the interferometry sequence timing. The frequency word data stream is transmitted to the direct frequency generation driver module (109), which converts the frequency word into binary data received by the external module and then transmits it through the parallel interface. The device latches the initial velocity reference v0 when the magneto-optical trap is loaded. Then, triggered by the velocity change during the interference process, it calculates the Raman laser frequency in real time according to the Doppler frequency shift formula f = f0 + (v - v0)·k_eff, where f is the Raman light frequency that resonates with the atom, f0 is the reference Raman light frequency, v is the current velocity, v0 is the initial velocity, and k_eff is the effective wave vector of the Raman light. The frequency word output of the direct frequency generation driving module (109) is converted into a frequency word output by a scaling factor.

2. The vibration real-time compensation device for a cold atom gravimeter according to claim 1, characterized in that: It also includes a host computer (211), which is connected to the heterogeneous FPGA (209) via a TCP network interface for system status monitoring, parameter configuration and data acquisition.

3. The vibration real-time compensation device for a cold atom gravimeter according to claim 1, characterized in that: The speed integral calculation module (104) is implemented through high-level synthesis. It outputs the speed value through ADC data normalization and dimension conversion, 31st-order FIR digital filtering, 10x CIC downsampling and first-order IIR approximate integral operation. All processing units are transmitted in a pipeline and can complete multi-level signal processing in parallel within a single clock cycle.

4. The vibration real-time compensation device for a cold atom gravimeter according to claim 1, characterized in that: The device employs a three-state finite state machine, responds to external pulse sequence control, and continuously outputs frequency word data streams through the AXI-Stream interface.

5. A vibration real-time compensation device for a cold atom gravimeter according to claim 1, characterized in that: It also includes a phase-locked loop (101), which generates a 40 MHz system clock signal by dividing and locking the reference 280 MHz clock provided by the reference clock source (208); the system clock signal is distributed to the analog-to-digital conversion driver module (102), the speed integral calculation module (104), the timer module (107), the frequency word calculation module (108), and the direct frequency generation driver module (109).

6. A vibration real-time compensation device for a cold atom gravimeter according to claim 1, characterized in that: It also includes an AXI-FIFO2 register (105) and a system-on-a-chip (106). The key parameters of the speed integral calculation module are configured online through the AXI-Lite interface, and there is a data stream for intermediate calculation variables. The data stream is connected to the AXI-FIFO2 register (105), and is read in real time through the system-on-a-chip (106) and transmitted through TCP network communication.

7. A method for real-time vibration compensation in a cold atom gravimeter, characterized in that: The core working process of the apparatus described in any one of claims 2 to 6 is as follows:

1. Interference sequence excitation: Two beams of Raman light from opposite directions interact with rubidium atoms (202) falling freely in a vacuum, applying a "three-pulse" sequence based on light pulses to cause population interference of the atoms; 2. Vibration signal acquisition: The vibration of the mirror (204) that shares the same path with one of the Raman beams will be equivalent to the phase noise of the Raman laser. A high-sensitivity accelerometer (205) installed close to the mirror measures its vibration acceleration signal in real time.

3. Signal chain processing: The analog differential signal output by the accelerometer (205) is digitized by a high-precision analog-to-digital converter (207), and the digital signal stream is sent to the heterogeneous FPGA (209) for real-time processing; 4. Real-time calculation and compensation: The velocity integration signal processing chain in the heterogeneous FPGA (209) integrates and filters the acceleration signal to obtain the instantaneous velocity of the reflector. Combined with the precise interference sequence timing, the heterogeneous FPGA (209) calculates the Raman laser frequency correction required to compensate for the velocity in real time and generates the corresponding frequency word.

5. Closed-loop execution: The frequency word is sent to the direct digital generation module (210). Under the drive of the reference clock source (208), the direct digital generation module (210) generates a microwave signal with precise frequency adjustment, drives the optical phase-locked loop (206), and finally controls the frequency of Raman light A (201) and Raman light B (203) in real time, thereby canceling the phase error introduced by the vibration of the reflector in the optical domain and forming closed-loop compensation.

8. A real-time vibration compensation method for a cold atom gravimeter according to claim 7, characterized in that: It also includes step 6, monitoring and configuration: the host computer (211) is connected to the heterogeneous FPGA (209) through the TCP network interface for system status monitoring, parameter configuration and data acquisition.

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