A full-vector fiber optic magnetic field sensor

Abstract

This invention discloses a full-vector fiber optic magnetic field sensor, comprising a fiber optic magnetic sensor, an additional magnetic field, and a base. The fiber optic magnetic sensor has unidirectional sensitivity and is fixed on the base. The additional magnetic field is also fixed on the base, and its direction is the same as the sensitive direction of the fiber optic magnetic sensor. This ensures that during measurement, the component of the resultant magnetic field experienced by the fiber optic magnetic sensor in its sensitive direction only changes in magnitude, not in direction, thus achieving the ability to distinguish the north and south poles of the magnetic field. This invention overcomes the problem of existing fiber optic vector magnetic field sensors being unable to distinguish the north and south poles of the measured magnetic field, achieving full-vector measurement of the magnetic field.

Description

Technical Field

[0001] This invention relates to the field of fiber optic magnetic field sensor technology, and in particular to a full-vector fiber optic magnetic field sensor. Background Technology

[0002] Magnetic fields, as one of the fundamental physical quantities, are closely related to various human activities and are important physical parameters in industrial, medical, military, and aerospace fields. Magnetic field sensors can be divided into optical and electrical types based on their measurement principles. Most electrical magnetic field sensors, such as Hall effect magnetometers, magnetoresistive magnetometers, and fluxgate magnetometers, while technologically mature, still require active metal cables for signal transmission, which can interfere with the distribution of the measured magnetic field itself. Furthermore, the electrical signal is susceptible to external electromagnetic noise, leading to erroneous measurement results. Fiber optic sensors, using light waves as the signal carrier and optical fibers as the signal transmission medium, are characterized by being non-energized, resistant to electromagnetic interference, small in size, and highly sensitive. They are a powerful complement to electrical magnetic field sensors and have enormous application potential in wearable safety environmental monitoring devices, navigation equipment, and other fields.

[0003] Fiber optic vector magnetic field sensors can be classified into magnetostrictive, magnetohydrodynamic, and Faraday rotator effect types according to their sensing mechanisms. Magnetostrictive fiber optic magnetic field sensors measure the magnetic field by modulating the phase, wavelength, and refractive index of an optical signal based on the change in length of the magnetostrictive material under a magnetic field. Magnetohydrodynamic fiber optic magnetic field sensors measure the magnetic field by detecting changes in the refractive index, based on the sensitivity of the refractive index of a magnetohydrodynamic material to magnetic fields. Faraday rotator effect fiber optic magnetic field sensors measure the magnetic field by measuring changes in the polarization angle, based on the Faraday rotator effect of magneto-optical fibers.

[0004] Magnetostrictive and magnetohydrodynamic fiber optic magnetic field sensors exhibit the same response to magnetic fields of equal magnitude but opposite directions. While Faraday rotation-type fiber optic magnetic field sensors show a polarization angle change related to the magnetic field's orientation, this change is typically measured by measuring the resulting change in light intensity, which is insensitive to the magnetic field's sign. Therefore, fiber optic vector magnetic field sensors, formed by combining the aforementioned sensors in orthogonal configurations, can only measure the magnetic field deflection angle and cannot determine whether that angle points to the North or South poles or to port or starboard. Summary of the Invention

[0005] The purpose of this invention is to provide a full-vector fiber optic magnetic field sensor that overcomes the problems of north-south ambiguity and port-side ambiguity in magnetic field direction measurement by adding an additional magnetic field.

[0006] A full-vector fiber optic magnetic field sensor includes a fiber optic magnetic sensor, an additional magnetic field, and a base. The fiber optic magnetic sensor has unidirectional sensitivity and is fixed on the base. The additional magnetic field is also fixed on the base, and its direction is the same as the sensitive direction of the fiber optic magnetic sensor. This ensures that the component of the resultant magnetic field experienced by the fiber optic magnetic sensor in the sensitive direction changes only in magnitude, not in direction, during the measurement process, thus enabling the differentiation of the north and south poles of the magnetic field.

[0007] The additional magnetic field is added by a permanent magnet, magnetic material, or energized coil;

[0008] The magnitude of the additional magnetic field acting on the position of the fiber optic magnetic sensor is greater than that of the magnetic field to be measured, and remains constant.

[0009] The working principle of this invention is as follows: Traditional fiber optic magnetic sensors have the same response to magnetic fields of the same magnitude but opposite directions, thus failing to distinguish between the north and south poles. This invention adds an auxiliary magnetic field, oriented in the same direction as the sensing direction of the fiber optic magnetic sensor and larger in magnitude than the magnetic field being measured. This ensures that the component of the resultant magnetic field experienced by the fiber optic magnetic sensor in its sensing direction changes only in magnitude, not in direction, thus achieving the ability to distinguish between the north and south poles of the magnetic field.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0011] This invention overcomes the shortcomings of general fiber optic vector magnetic field sensors that cannot distinguish between the positive and negative directions of the measured magnetic field by adding an additional magnetic field, and achieves accurate measurement of the magnetic field direction. Attached Figure Description

[0012] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In the drawings, the elements or parts are not necessarily drawn to scale.

[0013] Figure 1 This is a schematic diagram of a full-vector fiber optic magnetic field sensor according to the present invention;

[0014] Wherein, 1 is a general fiber optic vector magnetic field sensor, including but not limited to magnetostrictive type, magnetohydrodynamic refractive index modulated type, Faraday rotation effect type, and Ampere force hybrid photoelectric type fiber optic vector magnetic field sensor; 2 is a sub-fiber optic magnetic field sensor in fiber optic vector magnetic field sensor 1 that is parallel to the X-axis of the orthogonal X and Y coordinate system shown in the figure; 3 is a sub-fiber optic magnetic field sensor in fiber optic vector magnetic field sensor 1 that is parallel to the Y-axis of the orthogonal X and Y coordinate system shown in the figure; 4-7 are magnets, the positions of which can be moved, thereby adjusting the magnitude and direction of the total magnetic field formed.

[0015] Figure 2 This is a fiber optic magnetic sensor, showing the change of its surrounding magnetic field with and without an additional magnetic field;

[0016] Figure 3 This represents the response of the fiber optic magnetic sensor with and without an additional magnetic field. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are protected by the present invention.

[0018] A full-vector fiber optic magnetic field sensor comprises three parts: a fiber optic magnetic sensor, an auxiliary magnetic field, and a base. The fiber optic magnetic sensor is fixed to the base, and the auxiliary magnetic field, which is in the same direction as the sensing direction of the fiber optic magnetic sensor, is also fixed to the base.

[0019] Specifically, the fiber optic magnetic field sensor exhibits unidirectional sensitivity, meaning it is most sensitive to one direction and very weakly sensitive to the other two orthogonal directions. The direction of strongest sensitivity is defined as the sensitive direction.

[0020] Specifically, the direction of the additional magnetic field can be added using permanent magnets, magnetic materials, energized coils, etc. The magnitude of the additional magnetic field acting on the location of the fiber optic magnetic sensor should be greater than the magnetic field to be measured, and should remain constant.

[0021] Specifically, the fiber optic magnetic sensor and the additional magnetic field are fixed to the base and change only with the base, without relative movement between them.

[0022] Furthermore, two or three fiber optic magnetic sensors with added magnetic fields can be orthogonalized in two or three dimensions to achieve vector magnetic field testing.

[0023] An improved method for measuring the magnetic field direction of a fiber optic vector magnetic field sensor involves arranging four magnets (magnets 4-7) within the original two-dimensional fiber optic vector magnetic field sensor 1. The distance and position of the magnets are adjustable, forming an average equivalent magnetic field Hc in the XY direction for the fiber optic magnetic field sensor. This magnetic field is greater than the magnetic field to be measured. After adjustment, the fiber optic magnetic field sensor and the magnets are fixed as a single unit, forming a two-dimensional fiber optic vector magnetic field sensor. This two-dimensional fiber optic vector magnetic field sensor is then placed into the magnetic field H to be measured. For one of the fiber optic magnetic sensors, the change in the surrounding magnetic field with and without an additional magnetic field is as follows: Figure 2 As shown, the response of the fiber optic magnetic sensor with and without an additional magnetic field is as follows: Figure 3 As shown.

[0024] The magnitudes of the magnetic field components Hx and Hy measured by fiber optic magnetic field sensor 2 and fiber optic magnetic field sensor 3, respectively, are then used to determine the angle between the X-axis and the magnetic field being measured. can be Formula 1 calculation:

[0025]

[0026] The above description is a further detailed explanation of the present invention in conjunction with specific embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of patent protection determined by the submitted claims.

Claims

1. A full-vector fiber optic magnetic field sensor, characterized in that, It includes an optical fiber magnetic sensor, an additional magnetic field, and a base; the optical fiber magnetic sensor has unidirectional sensitivity and is fixed on the base, and the additional magnetic field is also fixed on the base. The direction of the additional magnetic field is the same as the sensitive direction of the optical fiber magnetic sensor, so that the component of the resultant magnetic field experienced by the optical fiber magnetic sensor in the sensitive direction of the optical fiber magnetic sensor only changes in magnitude and does not change in direction during the measurement process, thereby realizing the differentiation of the north and south poles of the magnetic field. The additional magnetic field is added by a permanent magnet, magnetic material, or energized coil; The magnitude of the additional magnetic field acting on the position of the fiber optic magnetic sensor is greater than that of the magnetic field to be measured, and remains constant.

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