Absolute atomic time grating displacement sensor
By constructing a uniform motion reference frame and processing two-way probe light, the absolute atomic time grating displacement sensor solves the cumulative error problem of the incremental atomic time grating, realizes absolute angle measurement without reset, and improves the accuracy of measurement.
Patent Information
- Application Number
- CN202311776973.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2026-02-06
AI Technical Summary
Incremental atomic time gratings suffer from cumulative errors in quantum precision measurements, requiring a power-on reset after a power outage.
An absolute atomic time-grating displacement sensor is used. By constructing a uniform motion reference frame, two probe beams are used for signal acquisition and processing. The first beam is fixed, while the second beam rotates with the object being measured. The signal processing system performs filtering and phase comparison calculations to obtain the absolute angular displacement value.
It enables the acquisition of absolute angle information without powering on and resetting, eliminating accumulated errors and improving the accuracy and reliability of measurements.
Smart Images
Figure CN121474981A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of quantum precision measurement technology, specifically to an absolute atomic time-grating displacement sensor. Background Technology
[0002] Quantum precision measurement aims to utilize quantum resources and effects to achieve measurement accuracy that surpasses classical methods. It is a comprehensive technology that integrates multiple disciplines such as atomic physics, physical optics, electronic technology, and control technology.
[0003] In quantum precision measurement, incremental atomic time gratings are used. Although incremental atomic time gratings solve the problems of grating line characterization and uniform velocity reference frame construction, they still use incremental counting, which results in accumulated errors and the technical problem of needing to reset after power failure.
[0004] Therefore, a new solution is needed to address the above problems. Summary of the Invention
[0005] The purpose of this invention is to provide an absolute atomic time-grid displacement sensor.
[0006] To achieve the above objectives, the present invention provides the following technical solution: an absolute atomic time-grating displacement sensor, comprising an atomic processing system, wherein the atomic processing system is used to construct a uniform motion reference system, wherein the uniform motion reference system is composed of optically pumped atomic nuclei polarization, Larmor precession of atoms under the action of an external static magnetic field, and nuclear magnetic resonance generated by applying a radio frequency magnetic field;
[0007] It also includes a signal detection system, which includes a detection light generation module, a detection light adjustment module, and a detection light acquisition module. The detection light generation module is used to emit detection light, which is two-way detection light. The detection light adjustment module is used to adjust the two-way detection light. The detection light acquisition module is used to acquire signals from the two-way detection light after it has been adjusted by the detection light adjustment module.
[0008] It also includes a signal processing system, which is used to filter, compare phases, and calculate the output probe light signal to obtain the absolute angular displacement value.
[0009] The steps for calculating the angular displacement to be measured using the absolute reference frame measured by the absolute atomic time-grating displacement sensor are as follows:
[0010] S1: The probe light generation module generates the first probe light and the second probe light;
[0011] S2: The first probe beam remains stationary;
[0012] S3: The second detection light is used to rotate with the object being measured. The time before the rotation is the first moment T1. At moment T1, the detection light acquisition module acquires the signal output by the second detection light, denoted as U2; it also acquires the signal output by the first detection light, denoted as U1. The signal processing system amplifies and filters signals U2 and U1, and then performs phase comparison calculation to obtain the angle value θ1 of the two detection lights at the first moment.
[0013] S4: The second detection light is used to rotate with the object being measured, and the time after the rotation is the second moment T2; at moment T2, the detection light acquisition module acquires the signal output by the second detection light, which is denoted as U3; the signal processing system amplifies and filters the signal U3, and then compares it with U1 to calculate the angle value θ2 of the two detection lights at the second moment.
[0014] S5: Combine the angular displacement values at times T1 and T2 to obtain the absolute angular displacement value θ to be measured.
[0015] Preferably, the atomic processing system includes a uniform static magnetic field B0, a pump laser, an optical path adjustment module, and an atomic gas chamber module;
[0016] The atomic gas chamber module includes a magnetic field shielding cylinder, a non-magnetic heating device, and a glass gas chamber. The glass gas chamber is located inside the magnetic field shielding cylinder and is filled with saturated alkali metal atoms, inert gas, and buffer gas to enhance atomic polarization performance. The glass gas chamber is externally equipped with a non-magnetic heating device, which heats the glass gas chamber to vaporize the alkali metal. A magnetic field coil is provided on the outside of the non-magnetic heating device. The magnetic field coil generates a static magnetic field in the first direction and a radio frequency magnetic field in the second direction by energizing three sets of coils with a current source.
[0017] Preferably, the optical path adjustment module is located at one end of the glass gas chamber, and the optical path adjustment module consists of a quarter-wave plate, an optical fiber collimator, an optical fiber port coupler I, a polarization beam splitter prism, and a half-wave plate I from one end to the other.
[0018] The pump light emitted by the pump laser passes through a half-wave plate I and a polarizing beam splitter I, then through an optical fiber collimator and an optical fiber port coupler to adjust the pump light. Finally, a quarter-wave plate adjusts the linearly polarized light into circularly polarized light, which then enters the glass gas cell to excite alkali metal atoms.
[0019] Preferably, the atomic processing system is used to construct a uniformly moving reference frame, and the construction method includes at least the following steps:
[0020] The direction of the uniform static magnetic field B0 is defined as the first direction, and the direction of the radio frequency magnetic field is defined as the second direction. The first direction is perpendicular to the first plane formed by the direction of the probe light and the second direction.
[0021] When a uniform magnetic field B0 is applied along the first direction, the spin magnetic moment μ of the atom precesses around the magnetic field at a certain angular frequency under the action of the external magnetic field, i.e., Larmor precession.
[0022] Alkali metal atoms are pumped along the first direction using circularly polarized light of a specific wavelength. Through energy transfer between photons and alkali metal atoms, the alkali metal atoms are pumped to a specific magnetic energy level.
[0023] Under the combined action of pump light and external uniform magnetic field B0, a macroscopic nuclear spin magnetic moment M is formed. At this time, gas atoms in the glass chamber undergo Larmor precession along the first direction perpendicular to the first direction with the macroscopic nuclear spin magnetic moment M.
[0024] A radio frequency magnetic field is applied along the second direction, causing the precession frequency of the atomic spin magnetic moment to resonate with the radio frequency. At this time, the resonant macroscopic nuclear spin magnetic moment M is the largest, and its Larmor precession frequency is ω0.
[0025] Preferably, before the radio frequency magnetic field is introduced, the signal processing system needs to perform a radio frequency sweep in a direction perpendicular to the static magnetic field to determine the Larmor precession frequency ω0 of the gas atoms in the glass chamber.
[0026] Preferably, the probe light adjustment module includes at least an outgoing light adjustment module and an incoming light adjustment module. The incoming light adjustment module is used to introduce the adjusted two probe lights into the atomic gas chamber module, and the outgoing light adjustment module is used to transmit the adjusted two probe lights from the atomic gas chamber module to the probe light acquisition module.
[0027] Preferably, the detection light generating module includes at least a laser, and the detection light acquisition module includes at least a photodetector.
[0028] Preferably, the incident light adjustment module includes at least a half-wave plate II, a polarizing beam splitter II, and a fiber optic port coupler II. A laser, a half-wave plate II, and a polarizing beam splitter II are arranged on one side of the atomic gas cell module. A fiber optic port coupler II is arranged at one end of the polarizing beam splitter II. The probe light emitted from the laser passes through the half-wave plate II and the polarizing beam splitter II. The polarizing beam splitter II separates the emitted probe light into two polarized paths. The first polarized path enters the atomic gas cell module, and the second polarized path passes through the fiber optic port coupler II and then enters the atomic gas cell module through an optical fiber.
[0029] Preferably, the emitted light adjustment module includes at least a half-wave plate III and a Wollaston prism. After the two probe beams pass through the atomic gas cell module, they are adjusted by the half-wave plate III and the Wollaston prism. The first emitted linearly polarized beam is split into two beams of unequal power after passing through the Wollaston prism. The two beams of unequal power are collected by a photodetector, and the difference is calculated to output a sinusoidal signal U1. Similarly, the second linearly polarized beam is split into two beams of unequal power after passing through the Wollaston prism. The two beams of unequal power are collected by a photodetector, and the difference is calculated to output sinusoidal signals U2 and U3.
[0030] Compared with the prior art, the beneficial effects of the present invention are:
[0031] This invention employs a dual-path detection method, using the first detection light as a stationary reference while the second detection light rotates with the object being measured. It offers advantages such as no need for a reset upon power-on, immediate acquisition of absolute angle information, and no cumulative error. This solves the problem that incremental atomic time gratings still use incremental counting, resulting in cumulative errors and the need for a power-on reset after a power failure. Attached Figure Description
[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0033] Figure 1 This is a schematic diagram of the overall structure of the present invention;
[0034] Figure 2 This is a partial schematic diagram of the detection light of the present invention;
[0035] Figure 3 This is a schematic diagram of the dual-optical-path absolute atomic time grating of the present invention;
[0036] Figure 4 This is a schematic diagram showing the spin state of the atoms in their natural state according to the present invention;
[0037] Figure 5 This is a schematic diagram of the atomic state after applying a static magnetic field to the present invention.
[0038] Figure 6 This is a schematic diagram of the state of atoms after optical pumping according to the present invention;
[0039] Figure 7 This is a schematic diagram of the nuclear magnetic resonance principle after applying a radio frequency magnetic field to this invention;
[0040] Figure 8 This is a schematic diagram illustrating the working principle of the atomic time grating of the present invention. Detailed Implementation
[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0042] Example 1:
[0043] See Figure 1 - Figure 8 An absolute atomic time-grating displacement sensor includes an atomic processing system. The atomic processing system is used to construct a uniform motion reference system, which is composed of optically pumped atomic nuclei polarization, Larmor precession of atoms under the action of an external static magnetic field, and nuclear magnetic resonance generated by applying a radio frequency magnetic field.
[0044] It also includes a signal detection system, which includes a detection light generation module, a detection light adjustment module, and a detection light acquisition module. The detection light generation module is used to emit detection light, which consists of two detection lights. The detection light adjustment module is used to adjust the two detection lights. The detection light acquisition module is used to acquire the signals of the two detection lights after they have been adjusted by the detection light adjustment module.
[0045] It also includes a signal processing system, which is used to filter, compare phases, and calculate the angular displacement value of the output probe light signal.
[0046] The atomic processing system includes a uniform static magnetic field B0, a pump laser, an optical path adjustment module, and an atomic gas cell module;
[0047] An optical path adjustment module and a pump laser are sequentially arranged at one end of the atomic gas cell module. The pump laser is used to emit pump light to the atomic gas cell module, and the optical path adjustment module is used to adjust the pump light irradiating the atomic gas cell module.
[0048] The pump laser emits a pump light with a wavelength of 795 nm, which is consistent with the D1 characteristic spectral line of rubidium atoms, causing electrons to rapidly transition from the ground state to the excited state. The main function of the pump light injected into the glass gas cell is to achieve optical pump hyperpolarization. Optical pump hyperpolarization refers to the gradual polarization of alkali metal atoms in the atomic gas cell under the action of circularly polarized pump light and an external static magnetic field, and the formation of macroscopic magnetic moments under the action of the static magnetic field.
[0049] A quarter-wave plate converts linearly polarized light into circularly polarized light, while a half-wave plate I and a beam expander are used to continuously adjust the intensity of the pump light. To achieve better polarization, the beam expander is used to increase the diameter of the pump light spot, thereby allowing the rubidium atoms to be fully polarized.
[0050] The atomic gas chamber module includes a magnetic field shielding cylinder, a non-magnetic heating device, and a glass gas chamber. The glass gas chamber is located inside the magnetic field shielding cylinder and is filled with saturated rubidium atoms, inert gas, and buffer gas to enhance the polarization performance of the atoms. The glass gas chamber is equipped with a non-magnetic heating device, which heats the glass gas chamber to vaporize the rubidium atoms. A magnetic field coil is set on the outside of the non-magnetic heating device. The magnetic field coil generates a static magnetic field in the first direction and a radio frequency magnetic field in the second direction by energizing the three sets of coils with a current source.
[0051] The optical path adjustment module is located at one end of the glass gas chamber. The optical path adjustment module consists of a quarter-wave plate, an optical fiber collimator, an optical fiber port coupler I, a polarization beam splitter, and a half-wave plate I, from one end to the other.
[0052] The pump light emitted by the pump laser passes through a half-wave plate I and a polarizing beam splitter I, then through an optical fiber collimator and an optical fiber port coupler to adjust the pump light. Finally, a quarter-wave plate adjusts the linearly polarized light into circularly polarized light, which then enters the glass gas cell to excite rubidium atoms.
[0053] An atomic processing system is used to construct a uniformly moving reference frame, and its construction method includes at least the following steps:
[0054] The direction of the uniform static magnetic field B0 is defined as the first direction, and the direction of the radio frequency magnetic field is defined as the second direction. The first direction is perpendicular to the first plane formed by the direction of the probe light and the second direction.
[0055] When a uniform magnetic field B0 is applied along the first direction, the spin magnetic moment μ of the atom precesses around the magnetic field at a certain angular frequency under the action of the external magnetic field, i.e., Larmor precession.
[0056] Alkali metal atoms are pumped along the first direction using circularly polarized light of a specific wavelength. Through energy transfer between photons and rubidium atoms, the rubidium atoms are pumped to a specific magnetic energy level.
[0057] Under the combined action of pump light and external uniform magnetic field B0, a macroscopic nuclear spin magnetic moment M is formed. At this time, rubidium atoms in the glass chamber undergo Larmor precession along the first direction perpendicular to the first direction with the macroscopic nuclear spin magnetic moment M.
[0058] A radio frequency magnetic field is applied along the second direction, causing the precession frequency of the atomic spin magnetic moment to resonate with the radio frequency. At this time, the resonant macroscopic nuclear spin magnetic moment M is the largest, and its Larmor precession frequency is ω0.
[0059] The signal detection system is located on both sides of the atomic gas chamber module;
[0060] The probe light generation module is located on one side of the atomic gas cell module;
[0061] The probe light adjustment module includes at least an output light adjustment module and an incident light adjustment module. The incident light adjustment module is used to input the two adjusted probe lights into the atomic gas cell module, and the output light adjustment module is used to transmit the two probe lights that have passed through the atomic gas cell module to the probe light acquisition module after adjustment.
[0062] The detection light generation module includes at least a laser, and the detection light acquisition module includes at least a photodetector.
[0063] The incident light conditioning module includes at least a half-wave plate II, a polarizing beam splitter II, and a fiber optic port coupler II. A laser, half-wave plate II, and polarizing beam splitter II are arranged on one side of the atomic gas cell module. A fiber optic port coupler II is arranged at one end of the polarizing beam splitter II. The laser emits a probe light with a wavelength of 795nm, which passes through the half-wave plate II and the polarizing beam splitter II. The polarizing beam splitter II polarizes the light into two paths. The first path of polarized light is incident into the atomic gas cell module, and the second path of polarized light passes through the fiber optic port coupler II and then enters the atomic gas cell module through an optical fiber.
[0064] The output light adjustment module includes at least a half-wave plate III and a Wollaston prism. The two probe beams pass through the atomic gas cell module and are then adjusted by the half-wave plate III and the Wollaston prism. The first output linearly polarized beam is split into two beams of unequal power after passing through the Wollaston prism. The two beams of unequal power are collected by a photodetector, and the difference is calculated to output a sinusoidal signal U1. Similarly, the second linearly polarized beam is split into two beams of unequal power after passing through the Wollaston prism. The two beams of unequal power are collected by a photodetector, and the difference is calculated to output sinusoidal signals U2 and U3.
[0065] Before the radio frequency magnetic field is introduced, the signal processing system needs to perform a radio frequency sweep in a direction perpendicular to the static magnetic field in order to determine the Larmor precession frequency ω0 of the gas atoms in the glass chamber.
[0066] The signal processing system amplifies, filters, compares, and performs equal calculations on the signal U3 output by the probe light acquisition module at the second moment and the signal U1 output at the first moment to calculate the absolute angular displacement of the measured object.
[0067] Example 2:
[0068] The steps for calculating the angular displacement to be measured using the absolute reference frame measured by the absolute atomic time-grating displacement sensor are as follows:
[0069] S1: The probe light generation module generates the first probe light and the second probe light;
[0070] S2: The first probe beam remains stationary;
[0071] S3: The second detection light is used to rotate with the object being measured. The time before the rotation is the first moment T1. At moment T1, the detection light acquisition module acquires the signal output by the second detection light, denoted as U2; it also acquires the signal output by the first detection light, denoted as U1. The signal processing system amplifies and filters signals U2 and U1, and then performs phase comparison calculation to obtain the angle value θ1 of the two detection lights at the first moment.
[0072] S4: The second detection light is used to rotate with the object being measured, and the time after the rotation is the second moment T2; at moment T2, the detection light acquisition module acquires the signal output by the second detection light, which is denoted as U3; the signal processing system amplifies and filters the signal U3, and then compares it with U1 to calculate the angle value θ2 of the two detection lights at the second moment.
[0073] S5: The angular displacement values at times T1 and T2 are combined to obtain the absolute angular displacement value θ to be measured. It will be apparent to those skilled in the art that this invention is not limited to the details of the above exemplary embodiments, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Therefore, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
Claims
1. An absolute atomic time-grating displacement sensor, characterized in that: The system includes an atomic processing system for constructing a uniform motion reference frame, which is composed of optically pumped atomic nuclei polarization, Larmor precession of atoms under the action of an external static magnetic field, and nuclear magnetic resonance generated by applying a radio frequency magnetic field. It also includes a signal detection system, which includes a detection light generation module, a detection light adjustment module, and a detection light acquisition module. The detection light generation module is used to emit detection light, which is two-way detection light. The detection light adjustment module is used to adjust the two-way detection light. The detection light acquisition module is used to acquire signals from the two-way detection light after it has been adjusted by the detection light adjustment module. It also includes a signal processing system, which is used to filter, compare phases, and calculate the angular displacement value of the output probe light signal. The steps for calculating the angular displacement to be measured using the absolute reference frame measured by the absolute atomic time-grating displacement sensor are as follows: S1: The probe light generation module generates the first probe light and the second probe light; S2: The first probe beam remains stationary; S3: The second detection light is used to rotate with the object being measured. The time before the rotation is the first moment T1. At moment T1, the detection light acquisition module acquires the signal output by the second detection light, denoted as U2; it also acquires the signal output by the first detection light, denoted as U1. The signal processing system amplifies and filters signals U2 and U1, and then performs phase comparison calculation to obtain the angle value θ1 of the two detection lights at the first moment. S4: The second detection light is used to rotate with the object being measured, and the time after the rotation is the second moment T2; at moment T2, the detection light acquisition module acquires the signal output by the second detection light, which is denoted as U3; the signal processing system amplifies and filters the signal U3, and then compares it with U1 to calculate the angle value θ2 of the two detection lights at the second moment. S5: Combine the angular displacement values at times T1 and T2 to obtain the absolute angular displacement value θ to be measured.
2. The absolute atomic time-grating displacement sensor according to claim 1, characterized in that: The atomic processing system includes a uniform static magnetic field B0, a pump laser, an optical path adjustment module, and an atomic gas cell module. The atomic gas chamber module includes a magnetic field shielding cylinder, a non-magnetic heating device, and a glass gas chamber. The glass gas chamber is located inside the magnetic field shielding cylinder and is filled with saturated alkali metal atoms, inert gas, and buffer gas to enhance atomic polarization performance. The glass gas chamber is externally equipped with a non-magnetic heating device, which heats the glass gas chamber to vaporize the alkali metal. A magnetic field coil is provided on the outside of the non-magnetic heating device. The magnetic field coil generates a static magnetic field in the first direction and a radio frequency magnetic field in the second direction by energizing three sets of coils with a current source.
3. The absolute atomic time-grating displacement sensor according to claim 2, characterized in that: The optical path adjustment module is located at one end of the glass gas chamber. From one end to the other end, the optical path adjustment module consists of a quarter-wave plate, an optical fiber collimator, an optical fiber port coupler I, a polarization beam splitter prism, and a half-wave plate I. The pump light emitted by the pump laser passes through a half-wave plate I and a polarizing beam splitter I, then through an optical fiber collimator and an optical fiber port coupler to adjust the pump light. Finally, a quarter-wave plate adjusts the linearly polarized light into circularly polarized light, which then enters the glass gas cell to excite alkali metal atoms.
4. An absolute atomic time-grating displacement sensor according to claim 3, characterized in that: The atomic processing system is used to construct a uniformly moving reference frame, and its construction method includes at least the following steps: The direction of the uniform static magnetic field B0 is defined as the first direction, and the direction of the radio frequency magnetic field is defined as the second direction. The first direction is perpendicular to the first plane formed by the direction of the probe light and the second direction. When a uniform magnetic field B0 is applied along the first direction, the spin magnetic moment μ of the atom precesses around the magnetic field at a certain angular frequency under the action of the external magnetic field, i.e., Larmor precession. Alkali metal atoms are pumped along the first direction using circularly polarized light of a specific wavelength. Through energy transfer between photons and alkali metal atoms, the alkali metal atoms are pumped to a specific magnetic energy level. Under the combined action of pump light and external uniform magnetic field B0, a macroscopic nuclear spin magnetic moment M is formed. At this time, gas atoms in the glass chamber undergo Larmor precession along the first direction perpendicular to the first direction with the macroscopic nuclear spin magnetic moment M. A radio frequency magnetic field is applied along the second direction, causing the precession frequency of the atomic spin magnetic moment to resonate with the radio frequency. At this time, the resonant macroscopic nuclear spin magnetic moment M is the largest, and its Larmor precession frequency is ω0.
5. An absolute atomic time-grating displacement sensor according to claim 4, characterized in that: Before the radio frequency magnetic field is introduced, the signal processing system needs to perform a radio frequency sweep in a direction perpendicular to the static magnetic field to determine the Larmor precession frequency ω0 of the gas atoms in the glass chamber.
6. An absolute atomic time-grating displacement sensor according to claim 1, characterized in that: The probe light adjustment module includes at least an output light adjustment module and an incident light adjustment module. The incident light adjustment module is used to input the two adjusted probe lights into the atomic gas chamber module, and the output light adjustment module is used to transmit the two probe lights that have passed through the atomic gas chamber module to the probe light acquisition module after adjustment.
7. An absolute atomic time-grating displacement sensor according to claim 6, characterized in that: The detection light generating module includes at least a laser, and the detection light acquisition module includes at least a photodetector.
8. An absolute atomic time-grating displacement sensor according to claim 7, characterized in that: The incident light adjustment module includes at least a half-wave plate II, a polarizing beam splitter II, and a fiber optic port coupler II. A laser, a half-wave plate II, and a polarizing beam splitter II are arranged on one side of the atomic gas cell module. A fiber optic port coupler II is arranged at one end of the polarizing beam splitter II. The probe light emitted from the laser passes through the half-wave plate II and the polarizing beam splitter II. The polarizing beam splitter II separates the probe light into two polarized paths. The first polarized path enters the atomic gas cell module, and the second polarized path passes through the fiber optic port coupler II and then enters the atomic gas cell module through an optical fiber.
9. An absolute atomic time-grating displacement sensor according to claim 8, characterized in that: The emitted light adjustment module includes at least a half-wave plate III and a Wollaston prism. After passing through the atomic gas cell module, the two probe beams are adjusted by the half-wave plate III and the Wollaston prism. The first emitted linearly polarized beam is split into two beams of unequal power after passing through the Wollaston prism. The two beams of unequal power are collected by a photodetector, and the difference is calculated to output a sinusoidal signal U1. Similarly, the second linearly polarized beam is split into two beams of unequal power after passing through the Wollaston prism. The two beams of unequal power are collected by a photodetector, and the difference is calculated to output sinusoidal signals U2 and U3.