A device and method for calibrating a pulsed magnetic field standard

Abstract

The application discloses a kind of to the device and calibration method of calibrating pulsed magnetic field standard device, the device includes: laser emitter, polarizer, optical path mirror, first optical rotatory crystal, second optical rotatory crystal, 1 ° mirror, beamsplitter and differential detector.Laser beam emitted by laser emitter passes through polarizer, is converted into linearly polarized light, linearly polarized light is obtained after the polarization of pure light by optical path mirror;The length ratio of first optical rotatory crystal located in the center of constant magnetic field coil and second optical rotatory crystal located in the middle of pulsed magnet is k;After the polarization of pure light, linearly polarized light passes through the first optical rotatory crystal and the second optical rotatory crystal in turn, and obtains mixed polarized light;Mixed polarized light is reflected by 1 ° mirror, enters the beamsplitter, and the beamsplitter divides mixed polarized light into two single polarized lights;The two single polarized lights are respectively incident to the differential detector, and the two single polarized lights are compared by the differential detector.

Description

Technical Field

[0001] This invention relates to the field of magnetic field tracing technology, specifically to a device and method for calibrating a pulsed magnetic field standard device. Background Technology

[0002] With the continuous development of modern metrology and testing needs, the demand for strong pulsed magnetic field detection is increasing. For example, in the testing of magnets made of highly coercive materials, there is an urgent need to measure and verify the parameters of strong pulsed magnetic fields. The measuring devices used for this purpose need to undergo metrological evaluation and periodic verification. Pulsed magnetic field standard devices are used to evaluate, verify, and calibrate these measuring devices. Currently, there is a lack of industrial instruments and precise, amplitude-stable single-pulse pulse generators capable of measuring single pulse amplitudes with pulse widths of 1–15 ms, measurement uncertainties of less than 1% (k=2), and peak values ​​of 0.3–10 T. Therefore, it is necessary to conduct overall metrological evaluation of the established pulsed magnetic field standard devices and to trace and calibrate the standard measuring instruments.

[0003] In existing technologies, there are two main methods for measuring strong pulsed magnetic fields: the differential loop method and the Faraday optical rotation effect method. The differential loop method uses a coaxial cable to lead the differential loop induced signal to a recording device such as an oscilloscope. Because the rise time of a strong pulsed magnetic field is very short, on the order of milliseconds, a very high voltage will be induced in the differential loop, which may endanger personnel and equipment.

[0004] Strong pulsed magnetic fields are generally characterized by steep rise, short pulse duration, and large amplitude. These electromagnetic signals usually exert a strong effect on instruments and equipment in the surrounding environment through conduction and radiation. They can interfere with the wires connected to the probe in the measuring equipment and may also transmit high voltage to the recording equipment, causing irreversible damage.

[0005] This invention employs the optical rotation effect method using a laser as the light source to measure strong pulsed magnetic fields. It eliminates the need for contact with the probe (magneto-optical medium) and allows for maintaining a certain distance from the strong pulsed magnetic field generator, making it a superior choice for measuring the amplitude of strong pulsed magnetic fields. This invention utilizes the optical rotation effect path ratio method, comparing the standard magnetic field strength generated by a calibrated magnetic field coil with the amplitude of the pulsed magnetic field generated by a pulsed magnetic field standard device. This allows for traceability and calibration of the pulsed magnetic field standard device while ensuring that the uncertainty requirements are met. Summary of the Invention

[0006] In view of this, the present invention provides an apparatus and a calibration method for calibrating a pulsed magnetic field standard device, which can solve the technical problem of calibrating the amplitude of the pulsed magnetic field generated by the existing pulsed magnetic field standard device.

[0007] To solve the above-mentioned technical problems, the present invention is implemented as follows.

[0008] A device for calibrating a pulsed magnetic field standard device, comprising:

[0009] Laser emitter, polarizer, optical path reflector, first optical rotator crystal, second optical rotator crystal, 1° reflector, beam splitter and differential detector.

[0010] A laser emitter emits a highly collimated laser beam, which is converted into linearly polarized light by the polarizer. The linearly polarized light is then directed by the optical path reflector, which further purifies the polarization of the linearly polarized light to obtain purified polarized light. The length ratio of the first optically rotating crystal to the second optically rotating crystal is k. The first optically rotating crystal is located at the center of the constant magnetic field coil, and the second optically rotating crystal is located in the middle of the pulse magnet. The purified polarized light passes through the first and second optically rotating crystals sequentially to obtain mixed polarized light. The mixed polarized light is reflected by the 1° reflector and enters the beam splitter, which splits the mixed polarized light into two single-polarized beams. The two single-polarized beams are then incident on the differential detector, which compares the two single-polarized beams.

[0011] Preferably, the laser emitter, polarizer, optical path reflector, first optical rotator, second optical rotator, 1° reflector, beam splitter, and differential detector are fixed on the optical platform.

[0012] Preferably, the differential detector converts the optical signal into an electrical signal. Utilizing Malus's law and the Faraday optical rotation effect, based on the length ratio k of the first and second optical rotating crystals and the constant magnetic field strength generated by the constant magnetic field coil, the pulse magnetic field amplitude can be obtained.

[0013] Preferably, based on the length ratio k of the first optically active crystal and the second optically active crystal, and the constant magnetic field strength generated by the constant magnetic field coil, the correspondence between the constant magnetic field strength and the pulse magnetic field amplitude is determined, thereby completing the calibration and traceability of the pulse magnetic field standard device.

[0014] Preferably, the optical path reflector is a Green Taylor prism or other reflector, the first optical rotator crystal and the second optical rotator crystal are both TGG crystals, the differential detector is a balanced photodetector, and the beam splitter is a Wollaston prism.

[0015] A method for calibrating a pulsed magnetic field standard device, using the apparatus for calibrating a pulsed magnetic field standard device as described above, the calibration method comprising the following steps:

[0016] Step S1: Obtain a first optically active crystal and a second optically active crystal with a length ratio of k. Place the first optically active crystal at the center of the constant magnetic field coil and place the second optically active crystal in the middle of the pulse magnet.

[0017] Step S2: The laser emitter emits a highly collimated laser beam, which is processed by the device that calibrates the pulse magnetic field standard device to obtain a mixed polarized light beam that has been deflected twice by passing through a constant magnetic field coil and a pulse magnetic field coil. The intensity of the two polarized beams contained in the mixed polarized light is obtained by a differential detector.

[0018] Step S3: Based on the magnetic field strength corresponding to the constant magnetic field coil and the length ratio k, the ratio between the intensity of the two single-polarized light beams and Malus's law is used to obtain the ratio between the constant magnetic field strength and the amplitude of the pulsed magnetic field, thereby realizing the traceability of the amplitude of the pulsed magnetic field.

[0019] Beneficial effects:

[0020] This invention employs two optically rotating modules with a defined length ratio, located in a constant magnetic field and a pulsed magnetic field, respectively. This ensures that the ratio of the optical path length (optical path length) of the generated polarized light passing through the constant and pulsed magnetic fields remains constant. By measuring the angles through which the polarization plane of the light waves rotates twice, the correspondence between the constant magnetic field strength and the pulsed magnetic field amplitude can be obtained, thereby enabling the calibration of the pulsed magnetic field standard device. This invention achieves traceability of the values ​​of strong pulsed magnetic fields.

[0021] It has the following technical effects:

[0022] (1) This invention enables operators to accurately measure the strong pulsed magnetic field generated by a standard device without having to be in close contact with the strong magnetic field area.

[0023] (2) In the calibration process of the pulsed magnetic field standard device, this invention only introduces uncertainty components such as the length of the optical rotation module and the frequency of the light source. This makes the measurement uncertainty of the calibration method less than 1% (k=2).

[0024] (3) This invention establishes a connection between the pulsed magnetic field coil and the constant magnetic field coil through an optical rotation system, enabling the pulsed magnetic field standard device to be traced back to the constant magnetic field coil. This solves the problem of traceability of measurement values ​​during metrological verification. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the device for calibrating a pulsed magnetic field standard device provided by the present invention.

[0026] Figure 2 This is a top view of the apparatus for calibrating a pulsed magnetic field standard device provided by the present invention.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1: Optical platform;

[0029] 2: Laser emitter;

[0030] 3: Polarizing filter;

[0031] 4: Optical path reflector;

[0032] 5: Optical crystals;

[0033] 6:1° reflector;

[0034] 7: Beam splitter;

[0035] 8: Differential detector. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] like Figures 1-2 As shown, the present invention proposes a device for calibrating a pulsed magnetic field standard device, the calibration device comprising:

[0038] 2. Laser emitter, 3. Polarizer, 4. Optical path reflector, 5. First optical rotator, 6. Second optical rotator, 7. 1° reflector, 8. Beam splitter and differential detector.

[0039] Laser emitter 2 emits a highly collimated laser beam, which is converted into linearly polarized light by polarizer 3. The linearly polarized light is then directed by optical path reflector 4, which further purifies the polarization of the linearly polarized light to obtain purified polarized light. The length ratio of the first optical rotator crystal to the second optical rotator crystal is k. The first optical rotator crystal is located at the center of the constant magnetic field coil, and the second optical rotator crystal is located in the middle of the pulse magnet. The purified polarized light passes through the first optical rotator crystal and the second optical rotator crystal successively to obtain mixed polarized light. The mixed polarized light is reflected by 1° reflector 6 and enters beam splitter 7, which splits the mixed polarized light into two single-polarized beams. The two single-polarized beams are then incident on differential detector 8, which compares the two single-polarized beams.

[0040] Furthermore, the calibration device includes an optical platform 1, and the laser emitter 2, polarizer 3, optical path reflector 4, first optical rotator crystal, second optical rotator crystal, 1° reflector 6, beam splitter 7 and differential detector 8 are fixed on the optical platform 1.

[0041] Furthermore, the differential detector 8 converts the optical signal into an electrical signal. Utilizing Malus's law and the Faraday optical rotation effect, based on the length ratio k of the first and second optical rotating crystals and the constant magnetic field strength generated by the constant magnetic field coil, the amplitude of the pulsed magnetic field can be obtained.

[0042] Furthermore, based on the length ratio k of the first optically active crystal and the second optically active crystal, and the constant magnetic field strength generated by the constant magnetic field coil, the correspondence between the constant magnetic field strength and the amplitude of the pulsed magnetic field is determined, thereby completing the calibration and traceability of the pulsed magnetic field standard device.

[0043] The optical emission module and polarization module generate a beam of polarized light. After two optical rotation effects, the constant magnetic field strength and the pulsed magnetic field amplitude are correlated. A standard magnetic field generated by a constant magnetic field coil is compared with the pulsed magnetic field generated by a pulsed magnetic field standard device. By controlling the length ratio (optical path ratio) of the optically rotating crystals in the two magnetic fields, the correspondence between the constant magnetic field strength and the pulsed magnetic field amplitude is determined, thus completing the calibration and traceability of the pulsed magnetic field standard device. Specifically, the single beam of polarized light generated by the laser emitter, polarizer, and optical path mirror passes through the optically rotating crystal between the constant magnetic field coil and the pulsed magnet. The optical rotation phenomenon occurs due to the change in the refractive index of the medium caused by the magnetic field. The magneto-optical rotation angle is proportional to the length of the light traveling through the medium and the component of the magnetic induction intensity in the medium along the direction of light propagation. By controlling the length ratio of the two optically rotating crystals, i.e., the optical path ratio, a correspondence between the magnetic field generated by the constant magnetic field coil and the pulsed magnetic field amplitude can be established.

[0044] This invention utilizes the principle of magneto-optical modulation to achieve a design method for the overall metrological traceability and calibration of a pulsed magnetic field standard device by comparing the amplitude of a constant magnetic field strength with that of a pulsed magnetic field. This solves the problem of a lack of metrological standards for measuring and verifying strong pulsed magnetic fields in electron accelerators and other fields, enabling traceability of strong pulsed magnetic field values. Light emitted from a laser passes through a polarizer, a constant magnetic field coil, and a pulsed magnet. When passing through a magneto-optical medium placed in a magnetic field, the polarized light is deflected. A balanced photodetector receives the optical signal and converts it into an electrical signal. Using Malus's law and the Faraday effect, the measured magnetic field value can be obtained. The pulsed magnetic field standard device designed in this invention is used to generate pulsed magnetic fields with high accuracy and a large number of values. It is suitable for measuring magnetic properties under strong pulsed magnetic fields and serves as a standard metrological instrument to reproduce standard pulsed magnetic fields, enabling the verification and calibration of instruments and equipment based on strong pulsed magnetic field parameters.

[0045] Furthermore, the optical path reflector 4 is a Green Taylor prism or other reflector, the first optical rotator crystal and the second optical rotator crystal are both TGG crystals, the differential detector 8 is a balanced photodetector, and the beam splitter 7 is a Wollaston prism.

[0046] The present invention provides an embodiment for calibrating a device for calibrating a pulsed magnetic field standard device.

[0047] The calibration device for the pulsed magnetic field standard device includes: a laser, a polarization and optical path module, an optical rotation module, and a balanced photodetector. The specific implementation steps are described below:

[0048] Step 1: The light-emitting module emits a highly collimated, low-noise laser beam. After passing through the polarization module, the laser light is converted from free-space light to linearly polarized light. Then, the beam's propagation direction is adjusted by a reflector, causing the laser to be incident on a Green Taylor prism for further purification of the laser's polarization.

[0049] Step 2: Adjust the optical path so that the polarized light passes through the TGG crystals (optical rotation modules) located in two magnetic fields, and the ratio of the optical path lengths of the polarized light passing through the two optical rotation crystals is constant.

[0050] Step 3: After undergoing two magneto-optical rotations, the mixed polarized light enters the beam splitting module via the optical path reflection module, splitting the mixed light into two single-polarized beams. The two single-polarized beams are then incident on the differential detection module for signal processing.

[0051] Step 4: Compare the standard magnetic field generated by the constant magnetic field coil with the pulsed magnetic field generated by the pulsed magnetic field standard device. By measuring the intensity of polarized light passing through the two magnetic fields, determine the correspondence between the constant magnetic field strength and the pulsed magnetic field amplitude, thereby achieving traceability of the strong pulsed magnetic field value.

[0052] A method for calibrating a pulsed magnetic field standard device, using the apparatus for calibrating a pulsed magnetic field standard device as described above, the calibration method comprising the following steps:

[0053] Step S1: Obtain a first optically active crystal and a second optically active crystal with a length ratio of k. Place the first optically active crystal at the center of the constant magnetic field coil and place the second optically active crystal in the middle of the pulse magnet.

[0054] Step S2: The laser emitter emits a highly collimated laser beam, which is processed by the device that calibrates the pulse magnetic field standard device to obtain a mixed polarized light beam that has been deflected twice by passing through a constant magnetic field coil and a pulse magnetic field coil. The intensity of the two polarized beams contained in the mixed polarized light is obtained by a differential detector.

[0055] Step S3: Based on the magnetic field strength corresponding to the constant magnetic field coil and the length ratio k, the ratio between the intensity of the two single-polarized light beams and Malus's law is used to obtain the ratio between the constant magnetic field strength and the amplitude of the pulsed magnetic field, thereby realizing the traceability of the amplitude of the pulsed magnetic field.

[0056] The specific embodiments described above only illustrate the design principles of the present invention. The shapes and names of the components in this description may differ and are not limited. Therefore, those skilled in the art can modify or make equivalent substitutions to the technical solutions described in the foregoing embodiments; and these modifications and substitutions do not depart from the inventive spirit and technical solutions of the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A device for calibrating a pulsed magnetic field standard device, characterized in that, The device includes: Laser emitter (2), polarizer (3), optical path reflector (4), first optical rotator crystal, second optical rotator crystal, 1° reflector (6), beam splitter (7) and differential detector (8); The laser emitter (2) emits a highly collimated laser beam. The laser beam passes through the polarizer (3) and is converted into linearly polarized light. The linearly polarized light is adjusted in the transmission direction by the optical path reflector (4) so ​​that the linearly polarized light is incident on the optical path reflector (4). The optical path reflector (4) further purifies the polarization degree of the linearly polarized light to obtain purified polarized light. The length ratio of the first optical rotator crystal and the second optical rotator crystal is k. The first optical rotator crystal is located at the center of the constant magnetic field coil, and the second optical rotator crystal is located in the middle of the pulse magnet. The purified polarized light passes through the first optical rotator crystal and the second optical rotator crystal in turn to obtain mixed polarized light. The mixed polarized light is reflected by the 1° reflector (6) and enters the beam splitter (7). The beam splitter (7) splits the mixed polarized light into two single polarized beams. The two single polarized beams are incident on the differential detector (8) respectively, and the differential detector (8) compares the two single polarized beams.

2. The apparatus as claimed in claim 1, characterized in that, The laser emitter (2), polarizer (3), optical path reflector (4), first optical rotator crystal, second optical rotator crystal, 1° reflector (6), beam splitter (7) and differential detector (8) are fixed on the optical platform (1).

3. The apparatus as described in claim 1, characterized in that, The differential detector (8) converts the optical signal into an electrical signal. Using Malus's law and the Faraday optical rotation effect, based on the length ratio k of the first optically rotating crystal and the second optically rotating crystal, and the constant magnetic field strength generated by the constant magnetic field coil, the amplitude of the pulsed magnetic field can be obtained.

4. The apparatus as claimed in claim 1, characterized in that, Based on the length ratio k of the first optically active crystal and the second optically active crystal, and the constant magnetic field strength generated by the constant magnetic field coil, the correspondence between the constant magnetic field strength and the amplitude of the pulsed magnetic field is determined, thereby completing the calibration and traceability of the pulsed magnetic field standard device.

5. The apparatus as described in any one of claims 1-4, characterized in that, The optical path reflector (4) is a Green Taylor prism or other reflector, the first optical rotator crystal and the second optical rotator crystal are both TGG crystals, the differential detector (8) is a balanced photodetector, and the beam splitter (7) is a Wollaston prism.

6. A method for calibrating a pulsed magnetic field standard device, using the apparatus for calibrating a pulsed magnetic field standard device as described in any one of claims 1-5, characterized in that, The calibration method includes the following steps: Step S1: Obtain a first optically active crystal and a second optically active crystal with a length ratio of k. Place the first optically active crystal at the center of the constant magnetic field coil and place the second optically active crystal in the middle of the pulse magnet. Step S2: The laser emitter emits a highly collimated laser beam, which is processed by the device that calibrates the pulse magnetic field standard device to obtain a mixed polarized light beam that has been deflected twice by passing through a constant magnetic field coil and a pulse magnetic field coil. The intensity of the two polarized beams contained in the mixed polarized light is obtained by a differential detector. Step S3: Based on the magnetic field strength corresponding to the constant magnetic field coil and the length ratio k, the ratio between the intensity of the two single-polarized light beams and Malus's law is used to obtain the ratio between the constant magnetic field strength and the amplitude of the pulsed magnetic field, thereby realizing the traceability of the amplitude of the pulsed magnetic field.

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