Magneto-optical crystal-based high-sensitivity reciprocal optical current sensor and working method thereof

Abstract

The invention belongs to the technical field of optical current sensors, and particularly relates to a high-sensitivity reciprocal optical current sensor based on a magneto-optical crystal and a working method of the high-sensitivity reciprocal optical current sensor. The broadband light source (1), the polarizer (2), the circulator (3), the 45-degree fusion welding point (4), the lambda / 4 wave plate (5) and the sensing head (6) are sequentially connected, the circulator (3) is connected with the beam splitter (7), and the beam splitter (7) is respectively connected with the first photoelectric detector (8) and the second photoelectric detector (9). The problem that a sensor in the prior art is poor in long-term use stability is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical current sensors, and in particular relates to a high-sensitivity reciprocal optical current sensor based on magneto-optical crystal and a working method thereof. Background Art

[0002] With the improvement of relay protection, automation degree of electrical equipment and insulation level of power system in large power systems (such as ships, power grids, railways, etc.), traditional electromagnetic current transformers can no longer meet the needs of power system development due to their principle defects, and are gradually replaced by optical current sensors. Magneto-optical crystal optical current sensors use magneto-optical crystals with small size and large Wildt constant as sensing elements, which have high sensitivity and no linear birefringence. According to the different optical path structures, magneto-optical crystal sensor heads can be divided into two types: transmission type and reflection type. Among them, the reflection type usually has a reflector at the end of the probe to reflect the incident light back. While eliminating the influence of the defects of the optical path itself, the Faraday rotation angle is also doubled, which improves the measurement sensitivity. However, in practical applications, such as ship environments, temperature, magnetic field, vibration and shock are inevitable, and with the launch of future high-energy weapons (such as electromagnetic guns, high-energy microwaves, laser systems, etc.), the short-term ultra-high power shock pulses and magnetic fields generated have a huge impact on the sensor output, which cannot meet the high stability requirements of the industry.

[0003] At present, in order to improve the sensitivity of the system to measure current and enhance the anti-interference ability and long-term stability of the sensor, most of the research work is to adopt algorithm compensation on the basis of adding optical devices. Therefore, these solutions are complex in structure, high in cost, and have limited effect, and cannot completely eliminate the errors caused by environmental factors. In addition, although the reflective structure increases the sensitivity, there are too many structured optical devices at present, which increases the complexity of the system and makes its stability unfavorable for the long-term use of the sensor. Summary of the invention

[0004] The present invention provides a high-sensitivity reciprocal optical current sensor based on magneto-optical crystal and a working method thereof, so as to solve the problem of poor stability of the sensor in the prior art during long-term use.

[0005] The present invention is achieved through the following technical solutions:

[0006] A high-sensitivity reciprocal optical current sensor based on magneto-optical crystal, the high-sensitivity reciprocal optical current sensor comprising a wide-spectrum light source 1, a polarizer 2, a circulator 3, a 45° fusion point 4, a λ / 4 wave plate 5, a sensor head 6, a beam splitter 7, a first photodetector 8, and a second photodetector 9;

[0007] The broadband light source 1, polarizer 2, circulator 3, 45° fusion point 4, λ / 4 wave plate 5 and sensor head 6 are connected in sequence, the circulator 3 is connected to the beam splitter 7, and the beam splitter 7 is respectively connected to the first photodetector 8 and the second photodetector 9.

[0008] Furthermore, the sensor head 6 includes a fiber collimator 10 and a BGO crystal 11 . The fiber collimator 10 and the BGO crystal 11 are spatially aligned, and the end surface of the BGO crystal 11 is configured as a reflection surface 12 .

[0009] Furthermore, the BGO crystal 11 is polished before use to increase light transmittance, and a dielectric film is plated on the crystal end reflection surface 12 of the BGO crystal 11, and the reflectivity of the dielectric film is 100%.

[0010] Furthermore, the length, width and height dimensions of the BGO crystal 11 are 10 mm×5 mm×5 mm.

[0011] A working method of a high-sensitivity reciprocal optical current sensor based on a magneto-optical crystal, the working method uses the above-mentioned high-sensitivity reciprocal optical current sensor based on a magneto-optical crystal, the working method is:

[0012] The natural light emitted by the broadband light source 1 sends a light signal to the polarizer 2, which is converted into single polarized light after passing through the polarizer 2, and then transmitted to the 45° welding point 4 after passing through the circulator 3, and is divided into two polarized light beams perpendicular to each other by the 45° welding point 4. The two polarized light beams are converted into left-handed circularly polarized light and right-handed circularly polarized light after passing through the λ / 4 wave plate 5, and the two light beams are transmitted to the sensor head 6;

[0013] The left-handed circularly polarized light and the right-handed circularly polarized light are reflected and exchanged in the sensor head 6, and then pass through the λ / 4 wave plate 5, the 45° fusion point 4 and the circulator 3 in turn to enter the beam splitter 7. The beam splitter 7 separates the two beams of light and respectively enters the first photodetector 8 and the second photodetector 9. The first photodetector 8 and the second photodetector 9 calculate the obtained light intensity values ​​respectively, and finally obtain the light intensity change.

[0014] Furthermore, the fiber collimator 10 in the sensor head 6 receives the left-handed circularly polarized photosynthesis and the right-handed circularly polarized light and transmits them to the BGO crystal 11 until they are totally reflected by the reflection surface 12 at the end of the crystal. At this time, the handedness of the left-handed circularly polarized photosynthesis and the right-handed circularly polarized light is swapped, the optical rotation angle is doubled, and then returns to the light path through the fiber collimator 10.

[0015] Furthermore, the BGO crystal 11 is polished before use to increase light transmittance, and a dielectric film is plated on the crystal end reflection surface 12 of the BGO crystal 11, and the reflectivity of the dielectric film is 100%.

[0016] Furthermore, the optical signal is split into two beams with mutually perpendicular polarization planes by the beam splitter 7, and input into the first photodetector 8 and the second photodetector 9 respectively. The output light intensities can be expressed as:

[0017]

[0018] Where I0 is the total intensity of the two polarized lights; is the Faraday rotation angle.

[0019] Furthermore, the noise caused by the fluctuation of the two light intensities is eliminated, specifically:

[0020]

[0021] Wherein, P0 is the input power of the light source; k is the light response of the first photodetector 8 and the second photodetector 9.

[0022] A high-sensitivity reciprocal optical current sensor resistant to interference from environmental factors is implemented using the high-sensitivity reciprocal optical current sensor based on magneto-optical crystal as described above.

[0023] The beneficial effects of the present invention are:

[0024] The present invention utilizes a reflective structure to form optical path reciprocity, thereby achieving resistance to interference from environmental factors such as temperature, magnetic field, vibration, etc., and improving sensor sensitivity; a total reflection film is plated on the end of the crystal to reduce the number of devices in the reflective structure and reduce complexity; a two-path light intensity output cancellation algorithm is utilized to eliminate the impact of light intensity fluctuations and reduce noise.

[0025] In order to further promote the application of optical current sensors in power systems, the present invention proposes a high-sensitivity, reciprocal optical current sensor based on the working principle of optical current sensors of magneto-optical crystals, which can resist interference from environmental factors such as temperature, magnetic field, and vibration, thereby improving the stability of the sensor and expanding the application range of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the present invention.

[0027] Figure 2 It is a structural schematic diagram of the sensor head of the present invention;

[0028] Figure 3 It is a comparison diagram of the sensor input current and output current of the present invention.

[0029] Among them, 1 is a broadband light source, 2 is a polarizer, 3 is a circulator, 4 is a 45° fusion point, 5 is a λ / 4 wave plate, 6 is a sensor head, 7 is a beam splitter, 8 is a first photodetector, 9 is a second photodetector, 10 is a fiber collimator, 11 is a BGO crystal, and 12 is a reflection surface. DETAILED DESCRIPTION

[0030] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0031] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0032] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0033] The following is attached to this application specification Figure 1-3 , the technical solutions in the embodiments of the present application are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0035] Implementation Method 1

[0036] This embodiment provides a high-sensitivity reciprocal optical current sensor based on magneto-optical crystal, the high-sensitivity reciprocal optical current sensor comprising a wide-spectrum light source 1, a polarizer 2, a circulator 3, a 45° fusion point 4, a λ / 4 wave plate 5, a sensor head 6, a beam splitter 7, a first photodetector 8, and a second photodetector 9;

[0037] The broadband light source 1, polarizer 2, circulator 3, 45° fusion point 4, λ / 4 wave plate 5 and sensor head 6 are connected in sequence, the circulator 3 is connected to the beam splitter 7, and the beam splitter 7 is respectively connected to the first photodetector 8 and the second photodetector 9.

[0038] Furthermore, the sensor head 6 includes a fiber collimator 10 and a BGO crystal 11 . The fiber collimator 10 and the BGO crystal 11 are spatially aligned, and the end surface of the BGO crystal 11 is configured as a reflected surface 12 .

[0039] Furthermore, the BGO crystal 11 is polished before use to increase light transmittance, and a dielectric film is plated on the crystal end reflection surface 12 of the BGO crystal 11, and the reflectivity of the dielectric film is 100%.

[0040] The present invention adopts BGO crystal 11 as the magneto-optical material. The material has a large Verdet constant and can obtain a higher sensitivity.

[0041] Furthermore, the length, width and height dimensions of the BGO crystal 11 are 10 mm×5 mm×5 mm.

[0042] Implementation Method 2

[0043] This embodiment provides a working method of a high-sensitivity reciprocal optical current sensor based on a magneto-optical crystal. The working method uses a high-sensitivity reciprocal optical current sensor based on a magneto-optical crystal as described in Embodiment 1. The working method is:

[0044] The natural light emitted by the broadband light source 1 sends an optical signal to the polarizer 2, which is converted into single polarized light after passing through the polarizer 2, and then transmitted to the 45° fusion point 4 after passing through the circulator 3, and is divided into two polarized light beams perpendicular to each other by the 45° fusion point 4. The two polarized light beams are converted into left-handed circularly polarized light and right-handed circularly polarized light after passing through the λ / 4 wave plate 5, that is, the two polarized light beams are propagated on the fast and slow axes of the polarization-maintaining optical fiber, so they are all converted into left-handed circularly polarized light and right-handed circularly polarized light after passing through the λ / 4 wave plate, and then the two light beams are transmitted to the sensor head 6;

[0045] When an external current is applied, the Faraday effect causes the polarization angle of the light beam in the sensor head 6 to rotate. Since the rotation direction of the light polarization plane in the Faraday effect is determined by the direction of the magnetic field and has nothing to do with the light propagation direction, the optical rotation angle of the light beam reflected back from the sensor head 6 will be doubled, thereby amplifying its sensitivity. At the same time, due to the reflection, the rotation directions of the two circularly polarized lights are exchanged, forming a reciprocal optical path, so it can resist interference from environmental factors such as temperature, magnetic field, and vibration.

[0046] The left-handed circularly polarized light and the right-handed circularly polarized light are reflected and exchanged in the sensor head 6, and then pass through the λ / 4 wave plate 5, the 45° fusion point 4 and the circulator 3 in turn to enter the beam splitter 7. The beam splitter 7 separates the two beams of light and respectively enters the first photodetector 8 and the second photodetector 9. The first photodetector 8 and the second photodetector 9 calculate the obtained light intensity values ​​respectively, and finally obtain the light intensity change.

[0047] Furthermore, the fiber collimator 10 in the sensor head 6 receives the left-handed circularly polarized photosynthesis and the right-handed circularly polarized light and transmits them to the BGO crystal 11 until the end of the crystal is totally reflected by the reflection surface 12. At this time, the handedness of the left-handed circularly polarized photosynthesis and the right-handed circularly polarized light is swapped, the optical rotation angle is doubled, and then returns to the light path through the fiber collimator 10.

[0048] Furthermore, the BGO crystal 11 is polished before use to increase the transmittance, and a dielectric film is plated on the crystal end reflection surface 12 of the BGO crystal 11, and the reflectivity of the dielectric film is 100%. The present invention uses the BGO crystal 11 as a magneto-optical material, which has a large Verdet constant and can obtain a higher sensitivity. The length, width and height of the BGO crystal 11 are 10mm×5mm×5mm.

[0049] When the current changes, the Faraday effect will be generated on the light in the BGO crystal 11, which will cause the light polarization plane to rotate. Since the rotation direction of the light polarization plane in the Faraday effect is only determined by the magnetic field direction and has nothing to do with the light propagation direction, the optical rotation angle of the light beam reflected back by the sensor head 6 will be doubled, and the sensitivity will be amplified. At the same time, since the light signal has undergone reflection, the rotation directions of the two circularly polarized lights are exchanged, forming a reciprocal optical path, so the sensor can resist interference from environmental factors such as temperature, magnetic field, and vibration.

[0050] Furthermore, the optical signal is split into two beams with mutually perpendicular polarization planes by the beam splitter 7, and input into the first photodetector 8 and the second photodetector 9 respectively. The output light intensity values ​​can be expressed as:

[0051]

[0052] In the formula, I0 is the total intensity of the two polarized lights, which can be 1; is the Faraday rotation angle, expressed as VLB, V is the Verdet constant of the BGO crystal 11, which is 18.4481rad / T·m, L is the length of the BGO crystal 11, which is 10mm, and B is the magnetic field generated by the current to be measured; if the current range to be measured is 5~10kA, the corresponding magnetic induction intensity B is about 30~60mT.

[0053] Furthermore, the two light intensity values ​​are calculated as follows to eliminate the noise caused by light intensity fluctuations, specifically:

[0054]

[0055] In the formula, P0 is the input power of the light source, which is set according to actual experience and is generally 1.5 mW; k is the light response of the first photodetector 8 and the second photodetector 9, which is set according to actual experience and is generally greater than 0.85 A / W.

[0056] After calculation, the sensor output and input current are obtained as follows Figure 3 As shown, under the same current change conditions, the reflective structure effectively increases the measurement sensitivity.

[0057] Implementation Method 3

[0058] This embodiment provides a high-sensitivity reciprocal optical current sensor that is resistant to interference from environmental factors. The high-sensitivity reciprocal optical current sensor that is resistant to interference from environmental factors is implemented using a high-sensitivity reciprocal optical current sensor based on a magneto-optical crystal as described in the first embodiment.

[0059] Implementation Method 4

[0060] An embodiment of the present invention provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the memory is used to store software programs and modules, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory and the processor are connected via a bus. Specifically, the processor implements any step in the first embodiment above by running the computer program stored in the memory.

[0061] It should be understood that in the embodiments of the present invention, the processor referred to may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0062] The memory may include a read-only memory, a flash memory, and a random access memory, and provides instructions and data to the processor. A part or all of the memory may also include a nonvolatile random access memory.

[0063] As can be seen from the above, the electronic device provided in the embodiment of the present invention can implement the working method of the high-sensitivity reciprocal optical current sensor as described in the second embodiment by running a computer program to calculate the light intensity and eliminate the noise generated by the light intensity.

[0064] It should be understood that if the above-mentioned integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the present invention implements all or part of the processes in the above-mentioned implementation method, and can also be completed by instructing the relevant hardware through a computer program. The above-mentioned computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method implementations when executed by the processor. Among them, the above-mentioned computer program includes computer program code, and the above-mentioned computer program code can be in source code form, object code form, executable file or some intermediate form. The above-mentioned computer-readable medium may include: any entity or device capable of carrying the above-mentioned computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the above-mentioned computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction.

[0065] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest range consistent with the principles and novel features disclosed herein.

[0066] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the above-mentioned device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the implementation method can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method implementation method, which will not be repeated here.

[0067] It should be noted that the methods and detailed examples provided in the above embodiments can be combined with the devices and equipment provided in the embodiments, and references can be made to each other, and no further details will be given.

[0068] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0069] In the embodiments provided by the present invention, it should be understood that the disclosed device / terminal equipment and method can be implemented in other ways. For example, the device / equipment implementation described above is only illustrative, for example, the division of the above modules or units is only a logical function division, and in actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0070] The above-mentioned embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above-mentioned embodiments, or replace some of the technical features therein by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A high-sensitivity reciprocal optical current sensor based on magneto-optical crystal, characterized in that: The high-sensitivity reciprocal optical current sensor comprises a wide-spectrum light source (1), a polarizer (2), a circulator (3), a 45° fusion point (4), a λ / 4 wave plate (5), a sensor head (6), a beam splitter (7), a first photodetector (8), and a second photodetector (9); The broadband light source (1), the polarizer (2), the circulator (3), the 45° fusion point (4), the λ / 4 wave plate (5) and the sensor head (6) are connected in sequence; the circulator (3) is connected to a beam splitter (7); and the beam splitter (7) is respectively connected to a first photodetector (8) and a second photodetector (9).

2. The high-sensitivity reciprocal optical current sensor according to claim 1, characterized in that: The sensor head (6) comprises a fiber collimator (10) and a BGO crystal (11); the fiber collimator (10) and the BGO crystal (11) are spatially aligned, and the end surface of the BGO crystal (11) is configured as a reflection surface (12).

3. The high-sensitivity reciprocal optical current sensor according to claim 2, characterized in that: The BGO crystal (11) is polished before use to increase light transmittance, and a dielectric film is plated on the crystal end reflection surface (12) of the BGO crystal (11), and the reflectivity of the dielectric film is 100%.

4. The high-sensitivity reciprocal optical current sensor according to claim 2, characterized in that: The length, width and height dimensions of the BGO crystal (11) are 10 mm×5 mm×5 mm.

5. A working method of a high-sensitivity reciprocal optical current sensor based on magneto-optical crystal, characterized in that: The working method uses a high-sensitivity reciprocal optical current sensor based on a magneto-optical crystal as described in any one of claims 1 to 4, and the working method is: The natural light emitted by the wide-spectrum light source (1) emits a light signal to the polarizer (2), which is converted into single polarized light after passing through the polarizer (2), and then transmitted to the 45° fusion point (4) after passing through the circulator (3), and is divided into two mutually perpendicular polarized light beams by the 45° fusion point (4). The two polarized light beams are converted into left-handed circularly polarized light and right-handed circularly polarized light after passing through the λ / 4 wave plate (5), and the two light beams are transmitted to the sensor head (6); The left-handed circularly polarized light and the right-handed circularly polarized light are reflected and rotated in the sensor head (6) and sequentially pass through a λ / 4 wave plate (5), a 45° fusion point (4) and a circulator (3) to enter a beam splitter (7). The beam splitter (7) separates the two beams of light and respectively enters a first photodetector (8) and a second photodetector (9). The first photodetector (8) and the second photodetector (9) respectively calculate the obtained light intensity values ​​to finally obtain a light intensity variation.

6. The working method of the high-sensitivity reciprocal optical current sensor according to claim 5, characterized in that: The optical fiber collimator (10) in the sensor head (6) receives left-handed circularly polarized light and right-handed circularly polarized light and transmits them to the BGO crystal (11) until the end of the crystal is totally reflected by the reflection surface (12). At this time, the rotation directions of the left-handed circularly polarized light and the right-handed circularly polarized light are exchanged, the optical rotation angle is doubled, and then they return to the optical path through the optical fiber collimator (10).

7. The working method of the high-sensitivity reciprocal optical current sensor according to claim 6, characterized in that: The BGO crystal (11) is polished before use to increase light transmittance, and a dielectric film is plated on the crystal end reflection surface (12) of the BGO crystal (11), and the reflectivity of the dielectric film is 100%.

8. The working method of the high-sensitivity reciprocal optical current sensor according to claim 5, characterized in that: The optical signal is split into two light beams with mutually perpendicular polarization planes by a beam splitter (7), and input into a first photodetector (8) and a second photodetector (9) respectively. The output light intensity values ​​can be expressed as: Where I0 is the total intensity of the two polarized lights; φ is the Faraday rotation angle.

9. The working method of the high-sensitivity reciprocal optical current sensor according to claim 8, characterized in that: Eliminate the noise caused by the fluctuation of the two light intensities, specifically: In the formula, P0 is the input power of the light source; k is the light response of the first photodetector (8) and the second photodetector (9).

10. A highly sensitive reciprocal optical current sensor resistant to environmental interference, characterized in that: The high-sensitivity reciprocal optical current sensor is implemented using a high-sensitivity reciprocal optical current sensor based on a magneto-optical crystal as described in any one of claims 1-3.

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