Magnetic field measurement method based on magnetic rotation effect and image analysis

Abstract

The invention discloses a magnetic field measurement method based on a magnetic rotation effect and image analysis. The method comprises the following steps: constructing a wedge device, and setting a magnetic field measurement device based on a magnetic rotation effect and image analysis by using the wedge device based on a magnetic field measurement method of a polarizer and an analyzer; the wedge device comprises a glass sheet and a magnetic rotation crystal which are equal in thickness; the glass sheet is connected with one end of the magnetic optical rotation crystal in parallel, and the other end of the glass sheet and the other end of the magnetic optical rotation crystal are provided with interval filaments, so that a wedge-shaped air film with an inclination angle is formed between the glass sheet and the magnetic optical rotation crystal; acquiring an image gray value of the wedge interference fringes by using a magnetic field measurement device based on a magnetic rotation effect and image analysis; and based on the image gray value of the wedge interference fringes, the magnetic field intensity is calculated by using a magnetic rotation effect principle. According to the invention, the fine change of the magnetic field in a small range can be accurately measured, the components are easy to combine and the light path is easy to build in the measurement process, and the measurement time is shortened.

Description

Technical Field

[0001] The invention relates to the field of magnetic field measurement, and in particular to a magnetic field measurement method based on magneto-optical rotation effect and image analysis. Background Art

[0002] Magnetic field measurement is very important for many scientific and engineering applications. However, existing magnetic field measurement methods have their own shortcomings. Magnetic field strength detectors can measure magnetic field strength, but have certain limitations on measurement accuracy and stability; magnetic field detection methods based on deep learning require a large data set; although the atomic spin magnetic field detection method without spin exchange relaxation has high measurement accuracy, it is sensitive to ambient temperature and vibration and requires complex isolation and stabilization devices; magnetic field sensors composed of Hall elements and iron core magnetic field detection methods based on excitation signals are sensitive to temperature and electromagnetic interference; although nuclear magnetic resonance magnetometers have high accuracy and sensitivity, they are large in size and are not conducive to use in small spaces. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a magnetic field measurement method based on magneto-optical rotation effect and image analysis.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0005] A magnetic field measurement method based on magneto-optical rotation effect and image analysis, characterized in that it comprises the following steps:

[0006] S1. construct a split-tip device, a magnetic field measurement method based on a polarizer and an analyzer, and use the split-tip device to set up a magnetic field measurement device based on magneto-optical rotation effect and image analysis;

[0007] The splitting device comprises a glass sheet and a magneto-optical rotatory crystal of equal thickness; one end of the glass sheet and the magneto-optical rotatory crystal are parallel to each other, and a spacer filament is arranged at the other end of the glass sheet and the magneto-optical rotatory crystal to form a split-shaped air film with an inclination angle between the glass sheet and the magneto-optical rotatory crystal;

[0008] S2, using the magnetic field measurement device based on magneto-optical rotation effect and image analysis in step S1 to obtain the image grayscale value of the wedge-tip interference fringes;

[0009] S3. Based on the grayscale value of the wedge-shaped interference fringe image in step S2, the magnetic field intensity is calculated using the principle of magneto-optical rotation effect.

[0010] Further, in step S1, a magnetic field measurement method based on a polarizer and an analyzer is used, and a magnetic field measurement device based on magneto-optical rotation effect and image analysis is set using a wedge device. The specific process is: a sodium lamp, a polarizer, a half-reflecting half-mirror, a wedge device, an electromagnet, an analyzer, a CCD camera and a microscope are set on an operating table; the polarizer and the half-reflecting half-mirror are set on the optical path axis of the sodium lamp, the arm of the microscope is connected to the lens base through a lens column, a CCD camera is set above the arm of the microscope, an analyzer is set below the arm of the microscope, a half-reflecting half-mirror is set directly below the analyzer, the middle part of the lens base of the microscope is hollowed out to place the electromagnet, and the wedge device is set above the electromagnet; the angle between the half-reflecting half-mirror and the horizontal plane is set to 45°; the CCD camera is connected to the display terminal.

[0011] Further, in step S2, the image grayscale value of the wedge interference fringes includes the image grayscale value of the wedge interference fringes at the first set detection angle when the electromagnet is not energized, the image grayscale value of the wedge interference fringes at the second set detection angle when the electromagnet is not energized, and the image grayscale value of the wedge interference fringes at the second set detection angle when the electromagnet is energized.

[0012] Furthermore, the image grayscale value of the wedge interference fringe at the second set detection angle when the electromagnet is not energized is expressed as:

[0013]

[0014] Where: I a2 is the image grayscale value of the second set detection angle wedge interference fringe when the electromagnet is not energized, I a1 is the image grayscale value of the wedge interference fringe at the first set detection angle when the electromagnet is not energized, I1 is the image grayscale value of the first wedge interference light, and I2 is the image grayscale value of the second wedge interference light. is the phase difference between the first wedge interference light and the second wedge interference light, and θ is the second set detection angle.

[0015] Furthermore, the image grayscale value of the wedge interference fringe at the second set detection angle when the electromagnet is energized is expressed as:

[0016]

[0017] Where: I b2 is the image grayscale value of the second set detection angle wedge interference fringe when the electromagnet is energized, I a1 is the image grayscale value of the wedge interference fringe at the first set detection angle when the electromagnet is not energized, I1 is the image grayscale value of the first wedge interference light, and I2 is the image grayscale value of the second wedge interference light. is the phase difference between the first wedge interference light and the second wedge interference light, θ is the second set detection angle, θ Fis the optical rotation angle produced by the magneto-optical crystal.

[0018] Further, step S3 includes the following steps:

[0019] S31, calculating the optical rotation angle generated by the magneto-optical rotation crystal based on the image grayscale value of the wedge-shaped interference fringes in step S2;

[0020] S32, based on the optical rotation angle generated by the magneto-optical rotation crystal in step S31, the magnetic field intensity is calculated using the magneto-optical rotation effect principle.

[0021] Further, in step S31, based on the image grayscale value of the wedge-shaped interference fringes in step S2, the optical rotation angle generated by the magneto-optical rotation crystal is calculated, which is expressed as:

[0022]

[0023] Where: θ F is the optical rotation angle produced by the magneto-optical crystal, I b2 is the image grayscale value of the second set detection angle wedge interference fringe when the electromagnet is energized, I a1 is the image grayscale value of the wedge interference fringe at the first set detection angle when the electromagnet is not energized, I a2 is the image grayscale value of the wedge-shaped interference fringes at the second set detection angle when the electromagnet is not energized, and θ is the second set detection angle.

[0024] The present invention has the following beneficial effects:

[0025] (1) The present invention constructs a wedge-tip device, a magnetic field measurement method based on a polarizer and an analyzer, and uses the wedge-tip device to set up a magnetic field measurement device based on magneto-optical rotation effect and image analysis, which can accurately measure subtle changes in the magnetic field within a small range. In addition, during the measurement process, each component is easy to combine and the optical path is easy to build, thereby shortening the measurement time.

[0026] (2) The magnetic field measurement device of the present invention, based on the magneto-optical effect and image analysis, obtains the image grayscale value of the wedge-shaped interference fringes, and can obtain a large amount of data in a single picture in data processing. At the same time, the use of image analysis technology is conducive to data analysis in the entire picture, and the change trend of the magnetic field in the entire picture range can be clearly seen;

[0027] (3) The present invention uses wedge-interference to measure the magnetic field, thereby reducing the interference of stray light in the environment on the measurement process and the impact of the measurement environment. In addition, the data points of the wedge-interference fringes are highly regular and easy to analyze, and the requirements for the stability of the operating environment are relatively low. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1The figure is a flow chart of a magnetic field measurement method based on magneto-optical rotation effect and image analysis;

[0029] Figure 2 It is a schematic diagram of the structure of the splitting device;

[0030] Figure 3 This is the wedge-tip interferogram taken when there is no magnetic field and the angle between the polarizer and the analyzer is 90°;

[0031] Figure 4 This is the wedge-tip interferogram taken when there is no magnetic field and the angle between the polarizer and the analyzer is 45°;

[0032] Figure 5 This is the wedge-tip interferogram taken when the angle between the polarizer and the analyzer is 45° and there is a magnetic field;

[0033] Figure 6 The intensity variation curve of the wedge-tip interference light with and without a magnetic field when the angle between the polarizer and the analyzer is 45°;

[0034] Among them: 1. Glass sheet; 2. Magneto-optical crystal; 3. Spacer filaments. DETAILED DESCRIPTION

[0035] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0036] like Figure 1 As shown, a magnetic field measurement method based on magneto-optical rotation effect and image analysis is characterized by comprising steps S1-S3, which are specifically as follows:

[0037] S1. Construct a wedge-tip device, a magnetic field measurement method based on a polarizer and an analyzer, and use the wedge-tip device to set up a magnetic field measurement device based on magneto-optical rotation effect and image analysis.

[0038] like Figure 2As shown, the wedge device comprises a glass sheet 1 of equal thickness and a magneto-optical rotatory crystal 2; one end of the glass sheet and the magneto-optical rotatory crystal are parallel to each other, and a spacer filament 3 is arranged at the other end of the glass sheet and the magneto-optical rotatory crystal to form a wedge-shaped air film with an inclination angle between the glass sheet and the magneto-optical rotatory crystal. The present invention replaces the upper surface glass sheet in the traditional wedge interference with the magneto-optical rotatory crystal, places the device on the magnetic field to be measured, generates wedge interference fringes on the wedge device using linearly polarized light, and compares the light intensity changes of the wedge interference fringes image under no magnetic field and the wedge interference fringes image under magnetic field, so as to obtain the optical rotation angle generated by the magneto-optical rotatory crystal.

[0039] In an optional embodiment of the present invention, the present invention is based on a magnetic field measurement method of a polarizer and an analyzer, and uses a wedge device to set up a magnetic field measurement device based on magneto-optical rotation effect and image analysis. The specific process is: a sodium lamp, a polarizer, a half-reflecting half-mirror, a wedge device, an electromagnet, an analyzer, a CCD camera and a microscope are set on an operating table; the polarizer and the half-reflecting half-mirror are set on the optical path axis of the sodium lamp, the arm of the microscope is connected to the lens base through a lens column, a CCD camera is set above the arm of the microscope, an analyzer is set below the arm of the microscope, a half-reflecting half-mirror is set directly below the analyzer, the middle part of the lens base of the microscope is hollowed out to place the electromagnet, and the wedge device is set above the electromagnet; the angle between the half-reflecting half-mirror and the horizontal plane is set to 45°; the CCD camera is connected to the display terminal.

[0040] S2. Using the magnetic field measurement device based on magneto-optical rotation effect and image analysis in step S1, the grayscale value of the image of the wedge-tip interference fringe is obtained.

[0041] In an optional embodiment of the present invention, the image grayscale value of the wedge interference fringes includes the image grayscale value of the wedge interference fringes at the first set detection angle when the electromagnet is not energized, the image grayscale value of the wedge interference fringes at the second set detection angle when the electromagnet is not energized, and the image grayscale value of the wedge interference fringes at the second set detection angle when the electromagnet is energized.

[0042] Specifically, the first set detection angle of the present invention is to set the included angle between the polarizer and the analyzer to be 90°, and the second set detection angle is to set the included angle between the polarizer and the analyzer to be 45°.

[0043] The present invention uses the magnetic field measuring device based on magneto-optical rotation effect and image analysis in step S1 to obtain the image grayscale value of the wedge interference fringes. The specific process is: turn on the sodium light lamp for preheating, set the angle between the polarizer and the analyzer to 90 degrees, let the reflected sodium light lamp emit linear polarized light through the polarizer so that it can be vertically incident on the wedge device, adjust the CCD camera lens for focusing, so that clear wedge interference fringes can be observed on the display terminal, and then use the CCD camera to shoot the light spot interference fringes image when the angle between the polarizer and the analyzer is 90 degrees when the electromagnet is not energized, so as to obtain the image grayscale value of the wedge interference fringes at the first set detection angle when the electromagnet is not energized, change the angle between the polarizer and the analyzer to 45 degrees, shoot the wedge interference fringes image again, so as to obtain the image grayscale value of the wedge interference fringes at the second set detection angle when the electromagnet is not energized, and then energize the electromagnet, and use the CCD camera to shoot the wedge interference fringes image under the condition of strong magnetic field again, so as to obtain the image grayscale value of the wedge interference fringes at the second set detection angle when the electromagnet is energized.

[0044] like Figure 3 As shown, when the angle between the polarizer and the analyzer is 90°, the present invention obtains the wedge-tip interferogram when there is no magnetic field. Figure 4 As shown, when the angle between the polarizer and the analyzer is 45°, the present invention obtains the wedge-tip interference pattern when there is no magnetic field. Figure 5 As shown, when the angle between the polarizer and the analyzer is 45°, the present invention obtains the wedge-tip interferogram in the presence of a magnetic field. Then the present invention deducts the background light intensity of the wedge-tip interferogram when the angle between the polarizer and the analyzer is 45°, as shown in FIG. Figure 6 As shown, there is a clear difference between the blue and orange interference fringe light intensities, which represent the distribution of interference fringe light intensities on the same horizontal line in the absence of a magnetic field and in the presence of a magnetic field. Therefore, the present invention can obtain all light intensity changes in the entire bright spot image, and then obtain the magnetic field distribution in the entire bright spot image.

[0045] The image grayscale value of the wedge interference fringe at the second set detection angle when the electromagnet is not energized is expressed as:

[0046]

[0047] Where: I a2 is the image grayscale value of the second set detection angle wedge interference fringe when the electromagnet is not energized, I a1 is the image grayscale value of the wedge interference fringe at the first set detection angle when the electromagnet is not energized, I1 is the image grayscale value of the first wedge interference light, and I2 is the image grayscale value of the second wedge interference light. is the phase difference between the first wedge interference light and the second wedge interference light, and θ is the second set detection angle.

[0048] The image grayscale value of the second set detection angle wedge interference fringe when the electromagnet is energized is expressed as:

[0049]

[0050] Where: I b2 is the image grayscale value of the second set detection angle wedge interference fringe when the electromagnet is energized, I a1 is the image grayscale value of the wedge interference fringe at the first set detection angle when the electromagnet is not energized, I1 is the image grayscale value of the first wedge interference light, and I2 is the image grayscale value of the second wedge interference light. is the phase difference between the first wedge interference light and the second wedge interference light, θ is the second set detection angle, θ F is the optical rotation angle produced by the magneto-optical crystal.

[0051] S3. Based on the grayscale value of the wedge-shaped interference fringe image in step S2, the magnetic field intensity is calculated using the principle of magneto-optical rotation effect.

[0052] In an optional embodiment of the present invention, the present invention calculates the optical rotation angle generated by the magneto-optical rotation crystal based on the image grayscale value of the wedge-tip interference fringe, and then calculates the magnetic field strength based on the optical rotation angle generated by the magneto-optical rotation crystal using the magneto-optical rotation effect principle.

[0053] Step S3 includes the following steps:

[0054] S31, based on the image grayscale value of the wedge-shaped interference fringes in step S2, calculate the optical rotation angle generated by the magneto-optical rotation crystal, expressed as:

[0055]

[0056] Where: θ F is the optical rotation angle produced by the magneto-optical crystal, I b2 is the image grayscale value of the second set detection angle wedge interference fringe when the electromagnet is energized, I a1 is the image grayscale value of the wedge interference fringe at the first set detection angle when the electromagnet is not energized, I a2 is the image grayscale value of the wedge-shaped interference fringes at the second set detection angle when the electromagnet is not energized, and θ is the second set detection angle.

[0057] S32, based on the optical rotation angle generated by the magneto-optical rotation crystal in step S31, the magnetic field strength is calculated using the magneto-optical rotation effect principle, expressed as:

[0058]

[0059] Where: B is the magnetic field strength, θ F is the optical rotation angle produced by the magneto-optical crystal, V is the Field constant, and D is the thickness of the magneto-optical crystal.

[0060] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0061] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0062] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0063] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0064] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A magnetic field measurement method based on magneto-optical effect and image analysis, characterized in that: The following steps are involved: S1. construct a split-tip device, a magnetic field measurement method based on a polarizer and an analyzer, and use the split-tip device to set up a magnetic field measurement device based on magneto-optical rotation effect and image analysis; The splitting device comprises a glass sheet and a magneto-optical rotatory crystal of equal thickness; one end of the glass sheet and the magneto-optical rotatory crystal are parallel to each other, and a spacer filament is arranged at the other end of the glass sheet and the magneto-optical rotatory crystal to form a split-shaped air film with an inclination angle between the glass sheet and the magneto-optical rotatory crystal; S2, using the magnetic field measurement device based on magneto-optical rotation effect and image analysis in step S1 to obtain the image grayscale value of the wedge-tip interference fringes; S3. Based on the grayscale value of the wedge-shaped interference fringe image in step S2, the magnetic field intensity is calculated using the principle of magneto-optical rotation effect.

2. The magnetic field measurement method based on magneto-optical rotation effect and image analysis according to claim 1, characterized in that: In step S1, a magnetic field measurement method based on a polarizer and an analyzer is used, and a magnetic field measurement device based on magneto-optical rotation effect and image analysis is set using a wedge device. The specific process is: a sodium lamp, a polarizer, a half-reflecting half-mirror, a wedge device, an electromagnet, an analyzer, a CCD camera and a microscope are set on an operating table; the polarizer and the half-reflecting half-mirror are set on the optical path axis of the sodium lamp, the arm of the microscope is connected to the lens base through a lens column, a CCD camera is set above the arm of the microscope, an analyzer is set below the arm of the microscope, a half-reflecting half-mirror is set directly below the analyzer, the middle of the lens base of the microscope is hollowed out to place an electromagnet, and a wedge device is set above the electromagnet; the angle between the half-reflecting half-mirror and the horizontal plane is set to 45°; the CCD camera is connected to a display terminal.

3. The magnetic field measurement method based on magneto-optical rotation effect and image analysis according to claim 1, characterized in that: In step S2, the image grayscale value of the wedge interference fringes includes the image grayscale value of the wedge interference fringes at the first set detection angle when the electromagnet is not energized, the image grayscale value of the wedge interference fringes at the second set detection angle when the electromagnet is not energized, and the image grayscale value of the wedge interference fringes at the second set detection angle when the electromagnet is energized.

4. The magnetic field measurement method based on magneto-optical rotation effect and image analysis according to claim 3, characterized in that: The image grayscale value of the wedge interference fringe at the second set detection angle when the electromagnet is not energized is expressed as: Where: I aW is the image grayscale value of the second set detection angle wedge interference fringe when the electromagnet is not energized, I a1 is the image grayscale value of the wedge interference fringe at the first set detection angle when the electromagnet is not energized, I1 is the image grayscale value of the first wedge interference light, and I2 is the image grayscale value of the second wedge interference light. is the phase difference between the first wedge interference light and the second wedge interference light, and θ is the second set detection angle.

5. The magnetic field measurement method based on magneto-optical rotation effect and image analysis according to claim 3, characterized in that: The image grayscale value of the second set detection angle wedge interference fringe when the electromagnet is energized is expressed as: Where: I b2 is the image grayscale value of the second set detection angle wedge interference fringe when the electromagnet is energized, I a1 is the image grayscale value of the interference fringes at the first set detection angle wedge when the electromagnet is not energized, I1 is the interference light intensity reflected by the glass sheet to the lower surface of the magneto-optical rotatory crystal after passing through the magneto-optical rotatory crystal, I2 is the interference light intensity passing through the magneto-optical rotatory crystal, is the phase difference between the first wedge interference light and the second wedge interference light, θ is the second set detection angle, θ F is the optical rotation angle produced by the magneto-optical crystal.

6. The magnetic field measurement method based on magneto-optical rotation effect and image analysis according to claim 1, characterized in that: Step S3 includes the following steps: S31, calculating the optical rotation angle generated by the magneto-optical rotation crystal based on the image grayscale value of the wedge-shaped interference fringes in step S2; S32, based on the optical rotation angle generated by the magneto-optical rotation crystal in step S31, the magnetic field intensity is calculated using the magneto-optical rotation effect principle.

7. The magnetic field measurement method based on magneto-optical rotation effect and image analysis according to claim 6, characterized in that: In step S31, based on the image grayscale value of the wedge-shaped interference fringes in step S2, the optical rotation angle generated by the magneto-optical rotation crystal is calculated, which is expressed as: Where: θ F is the optical rotation angle produced by the magneto-optical crystal, I b2 is the image grayscale value of the second set detection angle wedge interference fringe when the electromagnet is energized, I a1 is the image grayscale value of the wedge interference fringe at the first set detection angle when the electromagnet is not energized, I a2 is the image grayscale value of the wedge-shaped interference fringes at the second set detection angle when the electromagnet is not energized, and θ is the second set detection angle.

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