KR102104398B1 - An atomic spin gyroscope and a method for correcting a magnetic field gradient using the atomic spin gyroscope - Google Patents

Abstract

A task to be solved by the present invention is to provide a method of correcting a magnetic field gradient of an atomic spin gyroscope using a plurality of detection beams. The method of correcting the magnetic field gradient according to one embodiment of the present invention may comprise the following steps of: acquiring magnetic fields corresponding to each of the plurality of detection beams at each of a plurality of detection points through which each of the plurality of detection beams passes; obtaining the magnetic field gradient of an atomic spin gyroscope using the magnetic fields corresponding to each of the plurality of detection beams; and correcting the magnetic field gradient by controlling a current supplied to a gradient compensating coil.

Description

Atomic spin gyroscope and how to correct magnetic field gradient using it {AN ATOMIC SPIN GYROSCOPE AND A METHOD FOR CORRECTING A MAGNETIC FIELD GRADIENT USING THE ATOMIC SPIN GYROSCOPE}

The present invention relates to an atomic spin gyroscope and a method for correcting a magnetic field gradient using the same.

The atomic spin gyroscope is a sensor that measures the amount of rotation by measuring the frequency of the atomic precession of the atomic spin. Atomic spin gyroscopes are based on the Lamer precession, so they can react sensitively to the magnetic field. In the case of an atomic spin gyroscope, in general, the magnetic field shielding can be used to reduce the effect of the external magnetic field as much as possible, but the magnetic field gradient may be generated by the remaining magnetic field or various coils, and the magnetic field gradient may change with time. . The change in magnetic field gradient can inhibit the coherence of spin precession and reduce the time T ₂ for determining sensitivity. Therefore, there is a need for a method to keep the magnetic field gradient constant. Time T ₂ is determined using the collision frequency as shown in Equation 1 below.

At this time, the collision frequency due to the magnetic field gradient is determined as shown in Equation 2 below.

이고,

이고, R은 원자 셀의 반지름이고,

은 베셀 함수와 관계되는 공간 주파수 계수이다. B₀은 공통의 정적 자기장을 의미한다. 자기장 기울기를 만들어내는 자기장은

로 나타낼 수 있다. 자기장 기울기에 의한 충돌 빈도는 아래의 식 3과 같이 근사적으로 나타낼 수 있다.At this time, D is the diffusion coefficient,

ego,

, R is the radius of the atomic cell,

Is a spatial frequency coefficient related to the Bessel function. B ₀ means a common static magnetic field. The magnetic field that produces the magnetic field gradient

Can be represented as The collision frequency due to the magnetic field gradient can be approximated as in Equation 3 below.

The problem to be solved by the present invention is to provide a method of correcting the magnetic field gradient of an atomic spin gyroscope using a plurality of detection beams.

However, the problem to be solved by the present invention is not limited to those mentioned above, and another problem not to be solved can be clearly understood by those having ordinary knowledge to which the present invention belongs from the following description. will be.

A method of correcting a magnetic field gradient according to an embodiment of the present invention includes: determining magnetic field values for each of the plurality of detection beams at a plurality of detection points where each of the plurality of detection beams passes; Determining a magnetic field gradient of an atomic spin gyroscope using magnetic field values for each of the plurality of detection beams; And correcting the magnetic field gradient by controlling the current supplied to the gradient compensation coil.

The step of correcting the magnetic field gradient corrects the magnetic field gradient to be zero.

Determining magnetic field values for each of the plurality of detection beams includes: determining a first larmor frequency of a first detection beam among the plurality of detection beams; Determining a second rammer frequency of a second detection beam among the plurality of detection beams; And determining a first magnetic field value for the first detection beam and a second magnetic field value for the second detection beam, using the first and second second rammer frequencies.

The method of correcting the magnetic field gradient further includes measuring the intensity of each of the detection beams using a photodiode array.

The photodiode arrangement is one-dimensional or two-dimensional.

Atomic spin gyroscope according to another embodiment of the present invention includes a memory for storing information about at least one program; And a processor that controls the memory to execute the at least one program, wherein the processor determines magnetic field values for each of the plurality of detection beams at a plurality of detection points where each of the plurality of detection beams passes. ; Determining a magnetic field gradient using magnetic field values for each of the plurality of detection beams; The magnetic field slope is corrected by controlling the current supplied to the slope compensation coil.

The processor corrects the magnetic field gradient to be zero.

The processor determines a first larmor frequency of a first detection beam among the plurality of detection beams; Determine a second rammer frequency of a second detection beam among the plurality of detection beams; And a first magnetic field value for the first detection beam and a second magnetic field value for the second detection beam by using the first and second second rammer frequencies.

The processor measures the intensity of each of the detection beams using a photodiode arrangement.

According to another embodiment of the present invention, a computer-readable recording medium includes determining magnetic field values for each of the plurality of detection beams at a plurality of detection points where each of the plurality of detection beams passes; Determining a magnetic field gradient of an atomic spin gyroscope using magnetic field values for each of the plurality of detection beams; And correcting the magnetic field gradient by controlling the current supplied to the gradient compensation coil.

According to an embodiment of the present invention, by providing an atomic spin gyroscope using a plurality of detection beams, the magnetic field gradient can be kept constant.

1 shows an atomic spin gyroscope according to an embodiment of the present invention.
2 shows an example of the slope of the frequency / voltage conversion signal.
3 shows an example of a two-dimensional detection beam.
4 shows a detection beam mask when the detection beam is two-dimensional.
5 shows an example of the form of a coil.
6 shows another example of the form of a coil.
7 shows a tilt correction method according to an embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims.

In describing embodiments of the present invention, when it is determined that a detailed description of known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. In addition, terms to be described later are terms defined in consideration of functions in an embodiment of the present invention, which may vary according to a user's or operator's intention or practice. Therefore, the definition should be made based on the contents throughout this specification.

1 shows an atomic spin gyroscope according to an embodiment of the present invention, and FIG. 2 shows an example of a slope of a frequency / voltage conversion signal.

Referring to FIG. 1, the atomic spin gyroscope 1 irradiates two probe beams pl1 and pl2, and measures the amount of rotation using two detection beams pl1 and pl2 can do. For convenience of description, in the present specification, the detection beams pl1 and pl2 are assumed to travel in the x direction, but are not limited thereto. That is, the traveling directions of the detection beams pl1 and pl2 may be freely set according to an embodiment, and the features of the present invention to be described herein are not limited to the traveling directions of the detection beams.

Each of the detection beams pl1 and pl2 may pass through the first point z1 and the second point z2 in the atomic gas shell 20. The detection beams pl1 and pl2 pass through a first point z1 and a second point z2, and then a half-wave plate 30 and a polarization beam splitter 40 ).

The atomic spin gyroscope 1 may measure the Faraday rotation to measure the larmor frequency of the detection beams pl1 and pl2 that have passed through the half-wave plate and the polarization beam splitter. When the linearly polarized detection beams pl1 and pl2 are incident on the atomic cell 10, the left and right circularly polarized detection beams sense different phases, thereby causing the linear polarization of the detection beams pl1 and pl2 to rotate. However, the Faraday rotation is a method of measuring the intensity change of the detection beam passing through the polarization beam splitter 40 using the change in polarization. If the spin of the alkali atom is precessing, the degree of polarization change varies depending on the spin direction of the alkali atom. Therefore, the rammer frequency can be detected by finding the frequency of the degree of polarization change.

The atomic spin gyroscope 1 may measure the intensity of each of the detection beams pl1 and pl2 using a photodiode array and perform balanced detection. At this time, the atomic spin gyroscope 1 may calculate the magnitude of the magnetic field at the first point z1 and the second point z2.

주파수로 진동하는 제1 신호와

주파수로 진동하는 제2 신호가 섞여 있다. 상기 제1 신호와 상기 제2 신호는 락-인-증폭기(lock-in-amplifier)를 이용하여 전압 신호로 변환될 수 있다. 이때, 주파수/전압 환산 비율(기울기)은 이미 알고 있다고 가정한다.The magnitude of the magnetic field can be calculated through heteroatomic motion. The signal measured in the photodiode array and the balance detection

The first signal vibrating at frequency

The second signal vibrating at the frequency is mixed. The first signal and the second signal may be converted into a voltage signal using a lock-in-amplifier. At this time, it is assumed that the frequency / voltage conversion ratio (slope) is already known.

Referring to FIG. 2, FIG. 2 (a) shows a frequency / voltage conversion slope of ¹²⁹ Xe, and FIG. 2 (b) shows a frequency / voltage conversion slope of ¹³¹ Xe. For example, if the first signal consists of ¹²⁹ Xe, and the frequency of the first signal is approximately 118.0 Hz, the first signal can be converted into a voltage signal having a voltage of approximately -0.5 V using a lock-in-amplifier. . Further, if the second signal consists of ¹³¹ Xe, and the frequency of the second signal is approximately 34.8 Hz, the second signal may be converted into a voltage signal having a voltage of approximately 1 V using a lock-in-amplifier.

In addition, if the signal of the first atom is called p ₁₁ and the signal of the second atom passing through the second point z2 is called p ₁₂ , the atom's lamer frequency may be determined as shown in Equation 4 below.

At this time, f ₁₀ means the frequency of the magnetic field applied to the magnetic field coil in the x-direction to induce the spin precession motion of the first atom, and f ₂₀ is the x-direction to induce spin precession motion of the second atom. It means the frequency applied to the magnetic field coil.

In addition, p _11,0 means a voltage signal obtained by converting the first atom pre-moved at a frequency of f ₁₀ using a lock-in-amplifier, and p _12,0 is a second atom pre-moved at a frequency of f ₂₀ Denotes a voltage signal converted using a lock-in-amplifier. S ₁ means the frequency / voltage conversion slope for the first atom, and S ₂ means the frequency / voltage conversion slope for the second atom.

When there is rotation in the precessional atom, the atom's lamer frequency may be determined as shown in Equation 5 below.

The first magnetic field B _z1 of the first atom passing through the first point z1 may be determined using Equation 6 below.

The second magnetic field B z2 of the second atom passing through the second point _z2 may also be determined through the same method as the method for determining the first magnetic field B _z1 .

When the distance between the first point z1 and the second point z2 is sufficiently close, the magnetic field gradient may be calculated using Equation 7 below.

By applying a specific current to the z-axis gradient magnetic coil so that the magnetic field gradient becomes 0, one of the primary magnetic field gradient components can be compensated. The z-axis gradient magnetic field coil may be subject to anti-helmholtz conditions. At this time, the output of the gyroscope can be determined by the average of the angular velocity obtained at each point.

That is, the operation for determining the output of the atomic spin gyroscope may be as follows.

(1) Determine the rammer frequency of the first detection beam passing through the first point (z1) and the second detection beam passing through the second point (z2), and using the determined rammer frequency, the first point (z1) and The magnetic field and angular velocity at the second point z2 are determined.

(2) A magnetic field gradient is determined by dividing the determined magnetic field value at the first point z1 by the magnetic field value at the second point z2 by the distance between the first point z1 and the second point z2.

(3) According to the determined magnetic field gradient, the current flowing through the z-axis gradient magnetic field coil is controlled using a Proportional-Integral-Differential (PID) method. At this time, the output angular velocity of the gyroscope may be an average of the angular velocity determined in step (1).

3 shows a two-dimensional detection beam, FIG. 4 shows a detection beam mask when the detection beam is two-dimensional, and FIGS. 5 and 6 show an example of the form of a coil.

Referring to FIG. 3, the present invention can be applied not only when the detection beam is transmitted in one dimension, but also when it is transmitted in two dimensions.

기울기는 도 3에 도시된 (y₁, z₂), (y₁, z₁)(또는 (y₂, z₂), (y₂, z₁)) 빔 조합을 통하여 알아낼 수 있고,

기울기는 (y₁, z₂), (y₂, z₂)(또는 (y₁, z₁), (y₂, z₁)) 빔 조합을 통하여 알아낼 수 있다.

The inclination can be found through the (y ₁ , z ₂ ), (y ₁ , z ₁ ) (or (y ₂ , z ₂ ), (y ₂ , z ₁ )) beam combinations illustrated in FIG. 3,

The inclination can be determined through a combination of (y ₁ , z ₂ ), (y ₂ , z ₂ ) (or (y ₁ , z ₁ ), (y ₂ , z ₁ )) beams.

가 0이 되도록

코일에 전류를 가하는 경우, z-축 경사자장 코일은 도 5의 왼쪽과 같이 제작한 코일을 도 5의 오른쪽과 같이 실린더 형으로 둥글게 말아놓은 형태를 가질 수 있다.To achieve the object of the present invention, the magnetic field gradient

So that 0

When applying a current to the coil, the z-axis gradient magnetic field coil may have a form in which the coil produced as shown in the left side of FIG. 5 is rolled in a cylindrical shape as shown in the right side of FIG. 5.

가 0이 되도록

코일에 전류를 가하는 경우, z-축 경사자장 코일은 도 6의 왼쪽과 같은 고레이 코일(Golay coil)을 도 6의 오른 쪽과 같이 실린더 형으로 둥글게 말아놓은 형태를 가질 수 있다. Also, the magnetic field gradient

So that 0

When applying a current to the coil, the z-axis gradient magnetic field coil may have a form in which a Golay coil as shown in the left side of FIG. 6 is rolled in a cylinder shape as shown in the right side of FIG. 6.

Referring to FIG. 6, in the high-ray coil, the current directions of the first portions are opposite to each other to cancel the magnetic field effect, and the current directions of the second portions composed of four loops are the same, thereby maximizing the coil effect. have. That is, the first parts are composed of currents whose directions are opposite to each other, thereby canceling the effect, and the second parts are composed of currents having the same directions, thereby contributing to the formation of a magnetic field.

값이 주어지지 않을 수 있다.

값을 결정하기 위해, y-방향으로의 검출 빔을 이용할 수 있다. y-방향으로 진행하는 빔의 마스크는 도 4와 같을 수 있다.

코일은

코일과 패턴은 같으나,

코일로부터 90도 회전된 코일일 수 있다.In the two-dimensional detection beam arrangement

Values may not be given.

To determine the value, a detection beam in the y-direction can be used. The mask of the beam traveling in the y-direction may be as shown in FIG. 4.

Coils

Same pattern as coil,

It may be a coil rotated 90 degrees from the coil.

코일,

코일 및

코일을 겹칠 후, 실린더 형태로 말아서 구현될 수 있다.Each coil is in a z-direction coil

coil,

Coil and

After overlapping the coil, it can be implemented by rolling in the form of a cylinder.

7 shows a tilt correction method according to an embodiment of the present invention.

Referring to FIG. 7, the atomic spin gyroscope may obtain magnetic fields corresponding to each of the plurality of detection beams at a plurality of detection points through a plurality of detection beams (S700). For example, the atomic spin gyroscope determines the first larmor frequency for the first detection beam pl1 through the first detection point z1, and the second detection beam through the second detection point z2 A first magnetic field for the first detection beam pl1 and the second detection beam pl2 are determined by determining a second rammer frequency for (pl2) and using the first and second rammer frequencies ) Can determine a second magnetic field. The first magnetic field and the second magnetic field may be determined using Equations 4 to 6 described above.

The atomic spin gyroscope may determine the magnetic field gradient of the atomic spin gyroscope using the obtained magnetic fields (S710). For example, the atomic spin gyroscope may determine the magnetic field gradients for the first magnetic field and the second magnetic field using the first magnetic field and the second magnetic field. The magnetic field gradient may be determined using Equation 7 described above.

The atomic spin gyroscope may correct the magnetic field gradient by controlling the current supplied to the z-axis gradient compensation coil (S720). At this time, the atomic spin gyroscope can control the current so that the magnetic field gradient is zero.

Combinations of each block in the block diagrams and respective steps in the flow diagrams attached to the present invention may be performed by computer program instructions. These computer program instructions may be mounted on an encoding processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, so that the instructions performed through the encoding processor of a computer or other programmable data processing equipment may include each block in the block diagram or In each step of the flowchart, means are created to perform the functions described. These computer program instructions can also be stored in computer readable or computer readable memory that can be oriented to a computer or other programmable data processing equipment to implement a function in a particular way, so that computer readable or computer readable memory The instructions stored in it are also possible to produce an article of manufacture containing instructions means for performing the functions described in each block or flowchart step of the block diagram. Since computer program instructions may be mounted on a computer or other programmable data processing equipment, a series of operational steps are performed on the computer or other programmable data processing equipment to create a process that is executed by the computer to generate a computer or other programmable data. It is also possible for instructions to perform processing equipment to provide steps for executing the functions described in each block of the block diagram and in each step of the flowchart.

Further, each block or each step may represent a module, segment, or portion of code that includes one or more executable instructions for executing the specified logical function (s). It should also be noted that in some alternative embodiments it is also possible that the functions mentioned in blocks or steps occur out of order. For example, two blocks or steps shown in succession may in fact be executed substantially simultaneously, or it is also possible that the blocks or steps are sometimes performed in reverse order depending on the corresponding function.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains may make various modifications and variations without departing from the essential quality of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

1: Atomic spin gyroscope device
10: atomic cell
20: atomic gas shell
30: half-wave plate
40: polarized beam splitter

Claims (11)

Determining magnetic field values for each of the plurality of detection beams at a plurality of detection points where each of the plurality of detection beams passes;
Determining a magnetic field gradient of an atomic spin gyroscope using magnetic field values for each of the plurality of detection beams; And
Comprising the step of correcting the magnetic field gradient by controlling the current supplied to the gradient compensation coil
How to correct the magnetic field gradient. According to claim 1,
The step of correcting the gradient of the magnetic field corrects the gradient of the magnetic field to be 0
How to correct the magnetic field gradient. According to claim 1,
Determining the magnetic field values for each of the plurality of detection beams,
Determining a first larmor frequency of a first detection beam among the plurality of detection beams;
Determining a second rammer frequency of a second detection beam among the plurality of detection beams; And
And determining a first magnetic field value for the first detection beam and a second magnetic field value for the second detection beam by using the first and second second rammer frequencies.
How to correct the magnetic field gradient. According to claim 1,
And measuring the intensity of each of the detection beams using a photodiode array.
How to correct the magnetic field gradient. According to claim 4,
The photodiode array is one-dimensional or two-dimensional
How to correct the magnetic field gradient. A memory for storing information about at least one program; And
And a processor that controls the memory to execute the at least one program,
The processor,
Determining magnetic field values for each of the plurality of detection beams at a plurality of detection points where each of the plurality of detection beams passes;
Determining a magnetic field gradient using magnetic field values for each of the plurality of detection beams;
Correcting the magnetic field slope by controlling the current supplied to the slope compensation coil
Atomic spin gyroscope. The method of claim 6,
The processor corrects the magnetic field gradient to be zero.
Atomic spin gyroscope. The method of claim 6,
The processor,
Determining a first larmor frequency of a first detection beam among the plurality of detection beams;
Determine a second rammer frequency of a second detection beam among the plurality of detection beams; And
Determining a first magnetic field value for the first detection beam and a second magnetic field value for the second detection beam using the first rammer frequency and the second rammer frequency
Atomic spin gyroscope. The method of claim 6,
The processor measures the intensity of each of the detection beams using a photodiode array
Atomic spin gyroscope. The method of claim 9,
The photodiode array is one-dimensional or two-dimensional
Atomic spin gyroscope. Determining magnetic field values for each of the plurality of detection beams at a plurality of detection points where each of the plurality of detection beams passes;
Determining a magnetic field gradient of an atomic spin gyroscope using magnetic field values for each of the plurality of detection beams; And
Comprising the step of correcting the magnetic field gradient by controlling the current supplied to the gradient compensation coil
A program has been written to implement a method to correct the magnetic field gradient.
Computer-readable recording media.

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