Adjusting the reflection angle optical path mechanism and the rapid measurement method of the initial tilt angle of Raman light

Abstract

The present application belongs to the field of atomic interferometer gravimeters, and specifically discloses a rapid measurement method for adjusting the reflection angle optical path mechanism and the initial inclination of Raman light. By changing the inclination at the initial inclination of Raman light in the atomic interferometer gravimeter, the atomic transition probability is obtained, the cumulative change in angle is used as the independent variable, the atomic transition probability is used as the dependent variable, the atomic interference fringes are drawn, and the data is fitted to obtain the initial inclination of the reflected Raman light. Through the present application, there is no need to repeatedly change the Raman light sweep slope at each angle position to obtain the gravitational acceleration value, which simplifies the operation steps; there is no need to measure the acceleration at different positions first, but the initial inclination of the reflected Raman light is obtained directly by fitting the data with the cumulative change in angle as the independent variable and the atomic transition probability as the dependent variable, which shortens the measurement time; the fluctuations of each parameter caused by factors such as environmental influences are small, and at the same time, the interference of external interference factors on the measurement is reduced.

Description

Technical Field

[0001] The present application belongs to the field of atomic interferometer gravimeters, and more specifically, relates to a method for adjusting a reflection angle optical path mechanism and a rapid measurement method for the initial inclination angle of Raman light. Background Art

[0002] An atomic interferometer gravimeter is an instrument that measures the absolute value of gravitational acceleration based on the principle of atomic matter-wave interference. In atomic interferometer gravimeters, Raman light is often used to manipulate atomic wave packets to achieve the atomic interference process. Its related parameters are coupled into the final gravity measurement results, representing a significant source of error affecting the accuracy of atomic interferometer gravity measurements. The initial Raman light inclination, the angle between the Raman light direction and the direction of gravitational acceleration, is a significant systematic error that requires accurate measurement and evaluation.

[0003] "Performance Evaluation of the Portable Atomic Gravimeter HUST-QG" proposes mounting the reflector on a tilting stage, sequentially changing the Raman light sweep slope at that angle to obtain the corresponding transition probability, changing the free evolution time, and determining the center position of the interference fringes corresponding to different free evolution times. The acceleration is calculated using the corresponding sweep slope value at that position, and the reflector angle is continuously changed. Using the same operation, the corresponding acceleration values ​​are measured at different angles. Parabolic fitting is performed on the accelerations at different angles, and the inclination angle corresponding to the position of maximum acceleration is the initial inclination angle of the Raman light that needs to be determined.

[0004] However, this method has the following defects and shortcomings: (1) Since it is necessary to sweep the frequency to obtain the gravitational acceleration value at different inclination angles, the operation needs to be repeated many times, which is cumbersome; (2) Since it is necessary to first measure the acceleration at different inclination positions and then perform fitting to obtain the initial inclination angle of the Raman light, the measurement time is long; (3) Due to the long measurement time, the various parameters are greatly affected by factors such as environmental factors and fluctuate greatly. Summary of the Invention

[0005] In view of the defects of the existing technology, the purpose of this application is to provide a method for adjusting the reflection angle optical path mechanism and the rapid measurement of the initial tilt angle of Raman light, aiming to solve the problem that the existing Raman light initial tilt angle measurement is time-consuming.

[0006] To achieve the above objectives, in a first aspect, the present application provides a reflection angle adjustment optical path mechanism for an atomic gravimeter, comprising: a reflector, a displacement member, and a table level adjustment member;

[0007] The reflector is used to reflect the incident Raman light and then enter the vacuum system to interact with the atoms and the incident Raman light in the vacuum environment, generating a phase shift including gravitational acceleration, which is reflected in the atomic transition probability;

[0008] The displacement member is equipped with a reflector to adjust the angle between the main plane of the reflector and the horizontal plane, thereby changing the angle of the reflected Raman light;

[0009] The table top horizontal adjustment component is equipped with a displacement component for adjusting the displacement component so that the displacement component is parallel to the horizontal plane.

[0010] Preferably, the table level adjustment component comprises: an inclinometer, an adjustment frame and a tilting table;

[0011] Inclinometer, used to monitor table level;

[0012] The adjustment stand is equipped with an inclinometer for fine adjustment of the inclinometer level;

[0013] The tilting table is equipped with a displacement component and an adjustment frame for coarsely adjusting the table surface level.

[0014] To achieve the above-mentioned objectives, in a second aspect, the present application provides an atomic gravimeter, comprising the reflection angle adjustment optical path mechanism as described in the first aspect.

[0015] To achieve the above objectives, in a third aspect, the present application provides a method for rapidly measuring the initial tilt angle of Raman light for an atomic gravimeter, comprising:

[0016] S1. Level the table of the displacement component;

[0017] S2. Continuously changing the angle between the principal plane of the reflector and the horizontal plane by means of a displacement member, and measuring the atomic transition probability each time the angle is changed;

[0018] S3. Using the cumulative change in angle as the independent variable and the atomic transition probability as the dependent variable, perform data fitting to obtain the initial inclination angle of the reflected Raman light.

[0019] Preferably, when leveling the table of the displacement component, the table is first roughly leveled by the tilting table, and then the inclinometer is finely leveled by the adjustment frame.

[0020] Preferably, the angle between the main plane of the reflector and the horizontal plane varies in the range of -1.4 mrad to 1.4 mrad.

[0021] Preferably, 13 to 26 points are selected, and the angles are changed in sequence, with the angles changed each time being the same or different.

[0022] Preferably, the transition probability is detected by a time-of-flight signal.

[0023] Preferably, four parameters are obtained by fitting two variables, wherein the two fitted variables are the difference between the transformed angle and the initial tilt angle and the atomic transition probability, and the parameters obtained by fitting are the offset, fringe contrast, local gravitational acceleration, and the initial tilt angle of Raman light.

[0024] Preferably, the solution is obtained by particle swarm optimization.

[0025] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies:

[0026] (1) The present application provides a mechanism for adjusting the reflection angle optical path of an atomic gravimeter, comprising: a reflector for reflecting incident Raman light and then allowing it to enter a vacuum system, thereby interacting with atoms and the incident Raman light in a vacuum environment, generating a phase shift including gravitational acceleration, which is reflected in the atomic transition probability; a displacement member equipped with a reflector for adjusting the angle between the principal plane of the reflector and the horizontal plane, thereby changing the angle of the reflected Raman light; and a table-level adjustment member equipped with a displacement member for adjusting the displacement member so that it is parallel to the horizontal plane. The mechanism has a simple structure, uses a small number of components, and can flexibly adjust the angle of the reflected Raman light.

[0027] (2) This application proposes a method for quickly measuring the initial tilt angle of Raman light for an atomic gravimeter. By changing the tilt angle at the initial tilt angle of Raman light in the atomic interferometer gravimeter, the atomic transition probability is obtained, and the cumulative change in angle is used as the independent variable, the atomic transition probability is used as the dependent variable, and the atomic interference fringes are drawn. Data fitting is performed to obtain the initial tilt angle of the reflected Raman light. 1) By determining the initial tilt angle of Raman light by scanning fringes in this way, there is no need to repeatedly change the Raman light sweep slope at each angle position to obtain the gravitational acceleration value, which simplifies the operation steps; 2) This application does not need to measure the acceleration at different positions first, but directly obtains the initial tilt angle of the reflected Raman light by fitting the data with the cumulative change in angle as the independent variable and the atomic transition probability as the dependent variable, thus shortening the measurement time; 3) This application has a short measurement time, and the various parameters are relatively less affected by factors such as environmental factors. At the same time, the interference of external interference factors on the measurement is reduced. There is no need to replace experimental components before and after the experiment, and the operation is quick. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of a partial structure of the atomic gravity interferometer provided in an embodiment of the present application.

[0029] Figure 2 This is a schematic diagram of the process of adjusting the angle of the reflector provided in an embodiment of the present application.

[0030] Figure 3 This is a schematic diagram of obtaining corresponding interference fringes by changing the angle provided in an embodiment of the present application.

[0031] Figure 4 The embodiment of the present application provides an interference fringe effect diagram obtained by changing the angle through actual experimental data.

[0032] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0033] 1-incident position; 2-incident Raman light; 3-atomic cluster; 4-reflected Raman light; 5-reflection position; 6-tiltmeter; 7-adjustment frame; 8-reflector; 9-displacement component; 10-tilt stage. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0035] The term "and / or" as used herein describes an association between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. The symbol " / " as used herein indicates that the related objects are in an "or" relationship, for example, A / B means either A or B.

[0036] The terms "first" and "second" in this specification and claims are used to distinguish different objects rather than to describe a specific order of objects. For example, "first response message" and "second response message" are used to distinguish different response messages rather than to describe a specific order of response messages.

[0037] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0038] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more, for example, multiple processing units means two or more processing units, etc.; multiple elements means two or more elements, etc.

[0039] Next, the technical solutions provided in the embodiments of this application are introduced.

[0040] like Figure 1 As shown, the atomic gravity interferometer partially comprises: an optical system (not shown), a vacuum system and a detection system (not shown).

[0041] The optical path system includes an incident optical path part and a reflection angle adjustment optical path mechanism, wherein the incident optical path part is used to generate Raman light, enter the vacuum system and the reflection angle adjustment optical path mechanism; the reflection angle adjustment optical path mechanism is used to reflect the incident Raman light and can change the direction of the reflected Raman light.

[0042] The vacuum system includes an interference cavity for causing atoms, incident Raman light and reflected Raman light to interact in a vacuum environment, thereby generating a phase shift including gravitational acceleration, which is reflected in the atomic transition probability.

[0043] The detection system is used to measure atomic transition probability.

[0044] The present application proposes a reflection angle adjustment optical path mechanism for an atomic gravimeter, comprising: a reflector 8, a displacement member 9, and a table level adjustment member;

[0045] The reflector 8 is used to reflect the incident Raman light and then enter the vacuum system to interact with the atoms and the incident Raman light in the vacuum environment, thereby generating a phase shift including gravitational acceleration, which is reflected in the atomic transition probability;

[0046] The displacement member 9 is equipped with a reflector 8, which is used to adjust the angle between the main plane of the reflector 8 and the horizontal plane, thereby changing the angle of the reflected Raman light;

[0047] The table level adjustment member is equipped with a displacement member 9 for adjusting the displacement member 9 so as to make it parallel to the horizontal plane.

[0048] The displacement member 9 may be a tilting displacement stage.

[0049] Specifically, the table level adjustment component includes: an inclinometer 6, an adjustment frame 7 and a tilting table 10;

[0050] Inclinometer 6, used to monitor the level of the table;

[0051] The adjustment frame 7 carries the inclinometer 6 for fine-tuning the level of the inclinometer 6;

[0052] The tilting table 10 is equipped with a displacement member 9 and an adjustment frame 7 for coarsely adjusting the table surface level.

[0053] The working process of the entire device is as follows: Raman light is generated from the optical path system, enters the vacuum system through position 1, and is reflected at position 5. Light 2 with wave vector k1 is the incident Raman light, and light 4 with wave vector k2 is the reflected Raman light. The two interact at atomic cluster 3.

[0054] This application is approved Figure 1The displacement structure 9 changes the angle between the main plane of the reflector 8 and the horizontal plane, further changing the direction of the reflected Raman light, wherein the angle between the main plane of the reflector and the horizontal plane is twice the angle formed by the reflected Raman light and the direction of gravity acceleration.

[0055] Correspondingly, the present application proposes a method for quickly measuring the initial tilt angle of Raman light, comprising:

[0056] S1. Level the displacement member (9) on the table.

[0057] By leveling the table, it is ensured that the Raman light can be reflected back into the interference cavity and interact with the atoms.

[0058] S2. The angle between the main plane of the reflector (8) and the horizontal plane is continuously changed by the displacement member (9), and the transition probability of the atom is measured each time the angle is changed.

[0059] S3. Using the cumulative change in angle as the independent variable and the atomic transition probability as the dependent variable, perform data fitting to obtain the initial inclination angle of the reflected Raman light.

[0060] like Figure 2 As shown in the figure, the Raman light is tilted slightly and continuously at a certain initial tilt angle θ0. To ensure the smooth progress of the interference process, the adjusted angle needs to be as small as possible, so that the interference phase change caused by the angle varies within the range of 2π, corresponding to an angle range of approximately 0 to 1.4 mrad, or the angle change range can be appropriately expanded to -1.4 mrad to 1.4 mrad. The range of angle change should not be too large. On the one hand, it is necessary to ensure that the Raman light can be reflected back into the interferometer cavity during the angle change process. On the other hand, the interference phase shift must be within the range of 2π, which is sufficient to last for one cycle of the trigonometric function.

[0061] 13 to 26 points are selected and the angles are changed in sequence. By changing a set of Raman light inclination angles, corresponding transition probabilities P are obtained at different inclination angles. In this embodiment, the transition probability is detected by TOF (Time of Flight) signal.

[0062] like Figure 3 As shown, at an inclination angle, the corresponding transition probability value P is obtained. Due to the even function relationship between the angle and the transition probability, when the angle scanning range is -1.4mrad to 1.4mrad, "M"-shaped stripes will appear.

[0063] Four parameters are obtained by program fitting two variables: the changed angle value θ and the transition probability P. The obtained parameters are the offset a, the fringe contrast b, the local gravitational acceleration g, and the initial Raman light inclination angle θ0. This embodiment uses the solver in MATLAB, taking the particle swarm algorithm as an example, to set the target function, the number of fitting parameters and their corresponding initial values, upper and lower limits, the number of particles, the function tolerance, the number of iterations, the optimization options, and the inertia weight. The initial Raman light inclination angle θ0 is directly obtained through the fitting program. The algorithm has good solution speed and accuracy.

[0064] In an atomic interferometer gravimeter, atoms interact with Raman light, and the atomic clusters complete the atomic interference process through beam splitting, reflection, and beam combining. After supplementing the Doppler frequency shift, the following formula is obtained under the gravitational field:

[0065] P=a+bcos(k1gT 2 +k2gT 2 cos(θ+θ0)-2παT 2 )

[0066] Where a represents the offset, b represents the fringe contrast, k1 represents the wave vector size k1 of the incident Raman light, k2 represents the wave vector size of the reflected Raman light, g represents the acceleration of gravity, α represents the sweep slope, which is used to compensate for the Doppler shift, T is the free evolution time, θ represents the angle of change, and θ0 represents the initial inclination angle of the Raman light.

[0067] In the experiment, the initial Raman light inclination angle θ0 is set. By changing the angle of the reflector, θ is additionally introduced to change the Raman light reflection direction, that is, the angle between it and the direction of gravitational acceleration. By fitting the transition probability P and the changed angle, the initial Raman light inclination angle value is obtained, as shown in the following example: Figure 4 shown.

[0068] In this embodiment, the angle is changed and the corresponding interference fringe effect is obtained by experimental actual data. Figure 4 As shown, the fitted initial tilt angle of Raman light is θ0 = 947 ± 7 μrad.

[0069] It is understandable that the detailed functional implementation of each of the above units / modules can be found in the introduction of the aforementioned method embodiment, and will not be repeated here.

[0070] It should be understood that the above-mentioned device is used to execute the method in the above-mentioned embodiment. The implementation principle and technical effect of the corresponding program module in the device are similar to those described in the above-mentioned method. The working process of the device can refer to the corresponding process in the above-mentioned method and will not be repeated here.

[0071] Based on the methods in the above embodiments, embodiments of the present application provide an electronic device that may include: a processor, a communications interface, a memory, and a communication bus, wherein the processor, the communications interface, and the memory communicate with each other via the communication bus. The processor may invoke logic instructions in the memory to execute the methods in the above embodiments.

[0072] In addition, the logical instructions in the above-mentioned memory can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application.

[0073] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method in the above embodiment.

[0074] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method in the above embodiment.

[0075] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0076] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0077] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted via the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid state drive (SSD)).

[0078] It will be understood that the various numerical numbers involved in the embodiments of the present application are merely distinctions for the convenience of description and are not intended to limit the scope of the embodiments of the present application.

[0079] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for rapidly measuring the initial inclination angle of Raman light for an atomic gravimeter, characterized in that: include: S1. Level the table of the displacement component; S2. Continuously changing the angle between the principal plane of the reflector and the horizontal plane by means of a displacement member, and measuring the atomic transition probability each time the angle is changed; S3. Using the cumulative change in angle as the independent variable and the atomic transition probability as the dependent variable, perform data fitting to obtain the initial tilt angle of the reflected Raman light; The atomic gravimeter comprises a reflection angle adjustment optical path mechanism, which comprises: a reflector (8), a displacement component (9) and a table level adjustment component; the reflector (8) is used to reflect the incident Raman light and then enter the vacuum system to interact with atoms and the incident Raman light in the vacuum environment, thereby generating a phase shift including gravitational acceleration, and the phase shift is reflected in the atomic transition probability; the displacement component (9) is equipped with the reflector (8) and is used to adjust the angle between the main plane of the reflector (8) and the horizontal plane, thereby changing the angle of the reflected Raman light; the table level adjustment component is equipped with the displacement component (9) and is used to adjust the displacement component (9) so that it is parallel to the horizontal plane.

2. The measuring method according to claim 1, wherein The table top level adjustment component comprises: an inclinometer (6), an adjustment frame (7) and a tilting platform (10); the inclinometer (6) is used to monitor the level of the table top; the adjustment frame (7) carries the inclinometer (6) for fine-tuning the level of the inclinometer (6); and the tilting platform (10) carries a displacement component (9) and the adjustment frame (7) for coarse-tuning the level of the table top.

3. The measuring method according to claim 1, wherein: When leveling the table of a displacement component, first adjust the table surface roughly using the tilt table, and then fine-tune the inclinometer level using the adjustment frame.

4. The measuring method according to claim 1, wherein The angle between the main plane of the reflector and the horizontal plane varies from -1.4 ~1.4 .

5. The measuring method according to claim 4, wherein: Select 13 to 26 points and change the angle in sequence, with the angle changed the same or different each time.

6. The measuring method according to claim 1, wherein: The transition probability is detected by the time-of-flight signal.

7. The measuring method according to claim 1, wherein: Four parameters are obtained by fitting two variables. The two fitted variables are the difference of the transformed angle relative to the initial tilt angle and the atomic transition probability. The parameters obtained by fitting are offset, fringe contrast, local gravitational acceleration, and initial tilt angle of Raman light.

8. The measuring method according to claim 7, wherein: Solved by particle swarm algorithm.

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