A method for correcting coriolis force error of an atomic gravimeter

Abstract

This invention discloses a method for correcting the Coriolis force error in an atomic gravimeter, belonging to the fields of precision gravity measurement and quantum precision measurement. The method involves calibrating the atomic gravimeter to determine the parameter values ​​of the Coriolis force error function at the measured location. The Coriolis force sine function relationship is determined using the latitude of the current location and the azimuth angle of the atomic gravimeter. During the Coriolis force evaluation process, the atomic gravimeter is adjusted to a given reference angle, and the latitude of the current location and the reference angle of the gravimeter are recorded. Substituting the latitude of the current location and the reference angle of the gravimeter into the Coriolis force sine function relationship yields the Coriolis force error of the gravimeter at that moment, thus achieving the correction of the Coriolis force error. This invention eliminates the need for repeated rotational measurement corrections, offering advantages such as high correction efficiency, high accuracy, and ease of operation. This invention overcomes the limitation of Coriolis force error on portable atomic gravity measurements, making it suitable for dynamic applications.

Description

Technical Field

[0001] This invention relates to a method for correcting the Coriolis force error in an atomic gravimeter, belonging to the fields of precision gravity measurement and quantum precision measurement. Background Technology

[0002] Gravitational acceleration *g* is a key parameter describing the Earth's gravitational field. Achieving high-precision gravity measurements is of great significance and has broad application prospects in geophysics, resource exploration, fundamental physics research, and military defense. Compared to traditional laser interferometry gravimeters, gravity measurement devices based on the principle of atomic interferometry offer advantages such as higher measurement sensitivity and the ability to perform long-term, uninterrupted measurements. Their measurement uncertainty is also comparable to that of laser interferometry gravimeters. This represents a representative research direction in the field of quantum precision measurement and is a key development area for precision gravity measurement instruments. Currently, atomic gravimeters are gradually moving from the laboratory to engineering applications and have gained widespread attention from dozens of research institutions and companies both domestically and internationally.

[0003] An atomic gravimeter is an absolute gravitational acceleration measurement device. Several factors can affect the accuracy of gravitational acceleration measurements, including the Coriolis effect, wavefront distortion, optical frequency shift, tilt error, and self-gravity effect. Among these, the Coriolis effect causes a measurement deviation in gravitational acceleration ranging from 1E-8g to 1E-7g. This deviation primarily originates from the horizontal velocity of the atomic cluster in the east-west direction and the alignment of the detector with the center of the atomic cluster. It is one of the main factors limiting the practical application of atomic gravimeters. In contrast, the Coriolis effect in traditional laser interferometric gravimeters is negligible.

[0004] Existing methods for correcting Coriolis force errors and their problems are as follows:

[0005] 1. Rotational Measurement Correction Method: Based on the principle of the Coriolis effect, the gravimeter is rotated 180 degrees around the vertical axis. The average of the gravity measurements before and after the rotation is the gravity after correcting for the Coriolis error. The disadvantage of this method is that the gravimeter needs to repeat the rotation process for each measurement, and the rotation may cause other changes in the instrument's own state (such as changes in fiber optic coupling efficiency, leading to additional system errors, etc.). The rotational measurement correction method has high requirements for the stability of the device. More importantly, each measurement cycle, including rotation, adjustment, and measurement, takes a long time, which seriously affects the efficiency of online measurement.

[0006] 2. Rotating mirror method: The Raman laser mirror can be rotated in the opposite direction to the Earth's rotation to eliminate the Coriolis force error. The disadvantage is that rotating the mirror will cause translational motion of the mirror. While eliminating the Coriolis force error, it will introduce a deviation in the gravity measurement due to the translational motion of the mirror. The best international rotating mirror method has a correction effect at the 1E-8g level, which does not meet the requirements of 1E-9g gravimeters.

[0007] 3. Adjusting the laser power ratio: The Coriolis force error can be eliminated by adjusting the laser power ratio. However, whether the Coriolis force error has been eliminated needs to be determined by other correction methods. In addition, this method is only applicable to static measurements. Once the position of the gravimeter is changed, the laser power ratio needs to be readjusted. Summary of the Invention

[0008] To address the problem that correcting the Coriolis force error in an atomic interferometric gravimeter requires repeated rotational measurements, which is time-consuming, inefficient, and introduces additional systematic errors, this invention aims to provide a method for correcting the Coriolis force error in an atomic gravimeter. This method involves calibrating the parameter values ​​of the Coriolis force error function at the measurement location of the atomic gravimeter, and then using the calibrated sinusoidal function relationship of the Coriolis force to correct the error. This invention eliminates the need for repeated rotational measurements, offering advantages such as high correction efficiency, high accuracy, and ease of operation.

[0009] The objective of this invention is achieved through the following technical solution.

[0010] This invention discloses a method for correcting the Coriolis force error of an atomic gravimeter. It employs the parameter values ​​of the Coriolis force error function at the measured location of the atomic gravimeter, and determines the Coriolis force sine function relationship using the latitude of the current location and the azimuth angle of the atomic gravimeter. In subsequent Coriolis force evaluation of the atomic gravimeter, the gravimeter is adjusted to a given reference angle, and the latitude of the current location and the reference angle of the gravimeter are recorded. Substituting the latitude of the current location and the reference angle of the gravimeter into the Coriolis force sine function relationship yields the Coriolis force error of the gravimeter at that moment, thus achieving the correction of the Coriolis force error of the atomic gravimeter.

[0011] This invention discloses a method for correcting the Coriolis force error in an atomic gravimeter, comprising the following steps:

[0012] Step 1: Power on the atomic gravimeter under stable experimental conditions and measure the latitude of the location. AAfter the device stabilizes, gravity measurement is performed. The tilt sensor value α0 in the pitch direction of the gravimeter is read and recorded. The angle θ of the north finder fixed to the gravimeter is also read. The actual gravity value g is calculated based on the absolute gravity value g0 measured by the gravimeter, which has been corrected for other systematic errors. m

[0013] g m =g cor +g0

[0014] Wherein: g cor Indicates the magnitude of the Coriolis force gravity correction value.

[0015] g cor =g A sin(θ+θ0)

[0016] Wherein: g A The amplitude of the fitted sine curve is represented by θ, the angle of the north-finding instrument is represented by θ0, and the tilt compensation of the north-finding instrument is represented by θ0. A set of points f(g, θ, lat) is obtained to represent the Coriolis force error function f(g, θ, lat). A ,θ,lat A );

[0017] Step 2: Rotate the atomic gravimeter by a predetermined angle, adjust the tilt sensor reading in the pitch direction of the gravimeter to maintain α0, and after the device stabilizes, repeat Step 1 to obtain the second set of points, and record the new absolute gravity value g2 measured by the gravimeter after correcting for other systematic errors. Calculate the actual gravity value based on g2, and then obtain a new set of points for the Coriolis force error function; repeat the above steps until the angle is θ+360°; rotate N times to obtain N+1 sets of data points;

[0018] Step 3: Maintain the tilt sensor reading of the gravimeter at α0 in the pitch direction and obtain the absolute gravity value after correcting for other system errors. Fit the sine function curve of the Coriolis force error based on N+1 sets of data points, and obtain the functional relationship of the sine function, thus achieving the calibration of the Coriolis force error function. After calibration, obtain θ0 and the amplitude g of the sine curve. A .

[0019] Step 4: When the environment of the gravimeter changes, adjust the gravimeter pitch to the previously given angle α0. After the device stabilizes, measure the absolute gravity value after correcting for other systematic errors. There is no need to rotate the entire atomic interferometer gravimeter. Read the current latitude lat and the north-finding instrument reading θ, and substitute them into the Coriolis force sine function formula:

[0020]

[0021]

[0022] Where g A θ represents the amplitude of the fitted Coriolis force error function sine curve, and θ0 represents the tilt angle compensation of the calibrated north finder. These two values ​​have been obtained in step three.

[0023] The Coriolis force error value g at the current position is obtained based on the aforementioned Coriolis force sine function formula. cor (θ, lat) and the actual gravity value g m (θ, lat), where g t This is the absolute gravity value measured in real time by the gravimeter at the current moment, after correction of other systematic errors, thus realizing the Coriolis force error correction of the atomic gravimeter.

[0024] Beneficial effects:

[0025] 1. This invention discloses a method for correcting the Coriolis force error of an atomic gravimeter. Only one parameter calibration is required. Subsequent measurements can then yield the Coriolis force error based on latitude and azimuth, eliminating the need for complex operations such as 180-degree rotation, significantly simplifying the process. During use, regardless of the gravimeter's orientation, the Coriolis force error can be quickly obtained by substituting the north-finding instrument reading into the sine function formula for the Coriolis force, saving time and providing convenience.

[0026] 2. This invention discloses a method for correcting the Coriolis force error of an atomic gravimeter. It fits calibration parameters based on multiple sets of azimuth / gravity measurements, achieving high accuracy. Compared to the method of rotating the gravimeter device 180°, the measurement results are more precise, and the obtained Coriolis force error is more accurate. Furthermore, the calibration of the Coriolis force error function involves a large amount of data, resulting in a more accurate function, which in turn leads to more accurate calculations when measuring the Coriolis force error.

[0027] 3. The Coriolis force error correction method for atomic gravimeters disclosed in this invention solves the limitation of Coriolis force error on the measurement of portable atomic gravity. It is suitable for dynamic applications. In the case of inconvenient rotation of the gravimeter device or insufficient testing time during field testing, the Coriolis force error of the gravimeter can be obtained conveniently and quickly by applying the Coriolis force error function calibration method of this patent. Therefore, it is more convenient to test in complex dynamic environments. Attached Figure Description

[0028] Figure 1 This is a flowchart of a method for correcting the Coriolis force error in an atomic gravimeter, as disclosed in this invention.

[0029] Figure 2 The graph shows the sinusoidal function of gravity error caused by Coriolis force at different calibration angles of the gravimeter.

[0030] Among them, 1-turntable; 2-gravimeter sensing unit; 3-north-finding instrument. Detailed Implementation

[0031] To better illustrate the purpose and advantages of the present invention, the invention will be further described below in conjunction with the accompanying drawings and examples.

[0032] Example 1:

[0033] like Figure 1 As shown in this embodiment, a method for correcting the Coriolis force error in an atomic gravimeter is disclosed. The specific implementation steps are as follows:

[0034] Step 1: Power on the atomic gravimeter under stable experimental conditions and measure the latitude of the location. A After the device stabilizes, gravity measurement is performed. The tilt sensor value α0 in the pitch direction of the gravimeter is read and recorded. The angle θ of the north finder fixed to the gravimeter is also read. The actual gravity value g is calculated based on the absolute gravity value g0 measured by the gravimeter, which has been corrected for other systematic errors. m

[0035] g m =g cor +g0

[0036] Wherein: g cor Indicates the magnitude of the Coriolis force gravity correction value.

[0037] g cor =g A sin(θ+θ0)

[0038] Wherein: g A The amplitude of the fitted sine curve is represented by θ, the angle of the north-finding instrument is represented by θ0, and the tilt compensation of the north-finding instrument is represented by θ0. A set of points f(g, θ, lat) is obtained to represent the Coriolis force error function f(g, θ, lat). A ,θ,lat A );

[0039] Step 2: Rotate the atomic gravimeter by a predetermined angle, adjust the tilt sensor reading in the pitch direction of the gravimeter to maintain α0, and after the device stabilizes, repeat Step 1 to obtain the second set of points, and record the new absolute gravity value g2 measured by the gravimeter after correcting for other systematic errors. Calculate the actual gravity value based on g2, and then obtain a new set of points for the Coriolis force error function; repeat the above steps until the angle is θ+360°; rotate N times to obtain N+1 sets of data points;

[0040] Step 3: Maintain the tilt sensor reading of the gravimeter at α0 in the pitch direction and obtain the absolute gravity value after correcting for other system errors. Fit the sine function curve of the Coriolis force error based on N+1 sets of data points, and obtain the functional relationship of the sine function, thus achieving the calibration of the Coriolis force error function. After calibration, obtain θ0 and the amplitude g of the sine curve. A .

[0041] Step 4: When the environment of the gravimeter changes, adjust the gravimeter pitch to the previously given angle α0. After the device stabilizes, measure the absolute gravity value after correcting for other systematic errors. There is no need to rotate the entire atomic interferometer gravimeter. Read the current latitude lat and the north-finding instrument reading θ, and substitute them into the Coriolis force sine function formula:

[0042]

[0043]

[0044] Where g A θ represents the amplitude of the fitted Coriolis force error function sine curve, and θ0 represents the tilt angle compensation of the calibrated north finder. These two values ​​have been obtained in step three.

[0045] The Coriolis force error value g at the current position is obtained based on the aforementioned Coriolis force sine function formula. cor (θ, lat) and the actual gravity value g m (θ, lat), where g t This is the absolute gravity value measured in real time by the gravimeter at the current moment, after correction of other systematic errors, thus realizing the Coriolis force error correction of the atomic gravimeter.

[0046] Compared to other methods for measuring the Coriolis force error of gravimeters, this patent has the advantages of simple process and convenient operation. When conducting gravity tests in complex outdoor fields, it eliminates the need to rotate the entire gravimeter device 180° and repeatedly measure gravity values ​​to obtain the Coriolis force error. Instead, the required Coriolis force error is calculated on-site based on a pre-calibrated Coriolis force error function. This patent can perform calculations effectively even in harsh environments or dynamic environments such as airplanes and ships. Furthermore, if a large amount of data is collected during the calibration of the Coriolis force error function, and the function is accurate, the calculated Coriolis force error will be more accurate, resulting in higher precision compared to current methods for calculating the Coriolis force error of gravimeters.

[0047] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for correcting the Coriolis force error in an atomic gravimeter, characterized in that: The parameter values ​​of the Coriolis force error function at the current location are measured using a calibrated atomic gravimeter, and the relationship of the Coriolis force sinusoidal function is determined by the latitude of the current location and the azimuth of the atomic gravimeter. In the subsequent evaluation of the Coriolis force of the atomic gravimeter, the pitch of the atomic gravimeter is adjusted to a given reference angle, the latitude of the location and the reference angle of the gravimeter are recorded, and the latitude of the location and the reference angle of the gravimeter are substituted into the Coriolis force sine function relationship to obtain the Coriolis force error of the gravimeter at this time, thus realizing the correction of the Coriolis force error of the atomic gravimeter. The method for correcting the Coriolis force error of the atomic gravimeter includes the following steps. Step 1: Power on the atomic gravimeter under stable experimental conditions and measure the latitude of the location. A After the device stabilizes, gravity measurement is performed. The tilt sensor value α0 in the pitch direction of the gravimeter is read and recorded. The angle θ of the north finder fixed to the gravimeter is also read. The actual gravity value g is calculated based on the absolute gravity value g0 measured by the gravimeter, which has been corrected for other systematic errors. m : g m =g cor +g0 Wherein: g cor Indicates the magnitude of the Coriolis force gravity correction value; g cor =g A sin(θ+θ0) Wherein: g A Let θ represent the amplitude of the fitted sine curve, θ represent the angle of the north-finding instrument, and θ0 represent the tilt compensation of the north-finding instrument; a set of points f(g, θ, lat) is obtained for the Coriolis force error function f(g, θ, lat). A ,θ,lat A ); Step 2: Rotate the atomic gravimeter by a predetermined angle, adjust the tilt sensor reading in the pitch direction of the gravimeter to maintain α0, and after the device stabilizes, repeat Step 1 to obtain the second set of points, and record the new absolute gravity value g2 measured by the gravimeter after correcting for other systematic errors. Calculate the actual gravity value based on g2, and then obtain a new set of points for the Coriolis force error function; repeat the above steps until the angle is θ+360°; rotate N times to obtain N+1 sets of data points; Step 3: Maintain the tilt sensor reading of the gravimeter at α0 in the pitch direction and obtain the absolute gravity value after correcting for other system errors. Fit the sine function curve of the Coriolis force error based on N+1 sets of data points, and obtain the functional relationship of the sine function, thus achieving the calibration of the Coriolis force error function. After calibration, obtain θ0 and the amplitude g of the sine curve. A ; Step 4: When the environment of the gravimeter changes, adjust the gravimeter pitch to the previously given angle α0. After the device stabilizes, measure the absolute gravity value after correcting for other systematic errors. There is no need to rotate the entire atomic interferometer gravimeter. Read the current latitude lat and the north-finding instrument reading θ, and substitute them into the Coriolis force sine function formula: Where g A θ0 represents the amplitude of the fitted Coriolis force error function sine curve, and θ0 represents the tilt angle compensation of the calibrated north finder. These two values ​​have been obtained in step three. The Coriolis force error value g at the current position is obtained based on the aforementioned Coriolis force sine function formula. cor (θ,lat) and the actual gravity value g m (θ,lat), where g t This is the absolute gravity value measured in real time by the gravimeter at the current moment, after correction of other systematic errors, thus realizing the Coriolis force error correction of the atomic gravimeter.

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