Quantum sensor for current measurement

Abstract

The invention provides a quantum sensor for current measurement, comprising: an optical fiber having an annular structure, a plurality of light leakage areas arranged on a part between a light input end and a light output end of the optical fiber, each light leakage area being used for leaking a part of light transmitted in the optical fiber; the multiple quantum probes are arranged in the multiple light leakage areas in a one-to-one correspondence mode, and each quantum probe comprises a diamond containing a nitrogen vacancy color center and a microwave antenna; the laser source is used for inputting laser to the light input end of the optical fiber; the plurality of fluorescence detection modules are positioned on one sides of the plurality of diamonds in a one-to-one correspondence manner; the microwave source is used for transmitting modulated microwaves to the microwave antennas, and the modulation frequencies of the microwaves transmitted to the microwave antennas are different; and the processing module is used for receiving the fluorescent electric signal, demodulating the fluorescent electric signal by adopting a reference signal with a corresponding modulation frequency to obtain demodulation data, and calculating a magnetic field intensity value and / or a current value according to the demodulation data. Microwave mutual interference among a plurality of quantum probes at a short distance can be reduced, and the measurement accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of quantum sensing, and in particular to a quantum sensor for current measurement. Background Technology

[0002] Quantum sensors, when used for magnetic field measurements, offer advantages such as a wide temperature range, high precision, and large detection range, providing a new and effective approach to solving the current measurement challenges in power systems. Since the magnetic field generated by a current-carrying conductor runs along its circumference, multiple quantum probes are arranged along the circumference of the conductor during detection to improve accuracy.

[0003] To improve the signal-to-noise ratio and avoid 1 / f noise, existing quantum sensors employ a modulation signal of a certain frequency added to the microwave. Since the microwave frequency oscillates in a sinusoidal or square wave manner, the fluorescence generated by the NV color center near the resonance absorption peak will also oscillate at a corresponding frequency. After demodulation, the first-order differential spectrum, i.e., the demodulation curve, can be obtained. The modulated microwave frequency can be expressed by the following formula: ,in, It is an unmodulated frequency. It is the modulation depth. It is the modulation frequency. This is the modulation phase. The AC signal used for demodulation in the fluorescence signal generated by this modulated microwave is... , The oscillation amplitude of the fluorescence signal. For fluorescence phase. Using a reference signal. Mixing with the fluorescence signal, since the frequency of the reference signal is the same as that of the fluorescence signal, the result after mixing is: Then, through low-pass filtering, we can obtain: ,adjust , making ,get: ,because If it is known, then it can be extracted. .

[0004] In practical applications, because multiple quantum probes are located close together and operate simultaneously, the microwaves radiated by the antennas of adjacent probes can interfere with each other. For example... Figure 3 As shown, when the resonant frequency of quantum probe A is At that time, the microwaves generated by the adjacent quantum probe B... The oscillations occur in the vicinity, and the oscillation frequency is the modulation frequency. ,when and When the difference is not significant, such as Figure 3If both frequencies are within the same resonance peak, or within two different resonance peaks, the microwaves generated by the quantum probe B antenna will cause a change in the fluorescence signal on the quantum probe A. When the fluorescence signals are in phase, the AC signals used for demodulation in the fluorescence signal generated by the same quantum probe are superimposed. Finally, the demodulation result is obtained Mixed with Interference with other quantum probes can introduce more interference signals, leading to errors in the acquisition of the resonant frequency and consequently, in the measurement. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a quantum sensor for current measurement, which solves the problem that microwave interference occurs when multiple quantum probes are used to detect current simultaneously and the quantum probes are close together, thus introducing errors into the measurement.

[0006] To achieve the above and other related objectives, the present invention provides a quantum sensor for current measurement, comprising:

[0007] An optical fiber has a ring structure with multiple light leakage regions on the section between its optical input and optical output ends. Each light leakage region is used to leak out a portion of the light transmitted in the optical fiber. The middle part of the ring structure is used to place the conductor to be tested.

[0008] Multiple quantum probes are set in multiple light leakage areas in a one-to-one correspondence. Each quantum probe includes a diamond containing nitrogen vacancy color centers and a microwave antenna.

[0009] A laser source is used to input laser light into the optical input end of an optical fiber, and the laser light is used to excite the nitrogen vacancy centers in diamond to produce fluorescence.

[0010] Multiple fluorescence detection modules are located on one side of multiple diamonds, one for each diamond. Each fluorescence detection module collects and detects the fluorescence generated by the corresponding diamond and outputs a fluorescence electrical signal.

[0011] A microwave source is used to transmit modulated microwaves to microwave antennas, and the modulation frequency of the microwaves transmitted to each microwave antenna is different.

[0012] The processing module is used to receive fluorescent electrical signals, process them, use them as detection signals, demodulate the AC signals in the detection signals using a reference signal with a corresponding modulation frequency to obtain demodulated data, calculate the magnetic field strength value and / or current value based on the demodulated data, and also transmit frequency modulation signals to the microwave source.

[0013] Furthermore, the modulation frequency difference between the microwaves transmitted to each of the two adjacent microwave antennas is not less than 1 kHz, and each modulation frequency is not greater than the maximum modulation frequency that the diamond NV color center can accept.

[0014] Furthermore, the distance between any two adjacent diamonds is no more than 10 cm.

[0015] Furthermore, the light leakage region is formed by changing the shape of the core layer and cladding interface, or by exposing at least a portion of the cross-section of the core layer to the outside.

[0016] Furthermore, a focusing structure is set between the diamond and the fluorescence detection module to focus the fluorescence generated by the diamond.

[0017] Furthermore, the light leakage area is filled with a filler having a set refractive index.

[0018] Furthermore, the processing module adjusts the frequency of the modulated microwave radiated by the microwave source according to the demodulated data and through a closed-loop control algorithm to obtain the resonant frequency corresponding to the magnetic field, and calculates the magnetic field strength value based on the resonant frequency.

[0019] Furthermore, a laser detection module is set at the optical output end of the optical fiber to collect the laser output from the detection optical output end and output the laser electrical signal to the processing module. The processing module processes the electrical signal and performs differential processing on each fluorescent electrical signal and the laser electrical signal to obtain a differential signal, which is then used as the detection signal for demodulation processing.

[0020] Furthermore, the processing module includes an analog circuit module, a digital-to-analog conversion module, and a demodulation module. The analog circuit module is used to receive fluorescent electrical signals and laser electrical signals, process the electrical signals and perform differential processing, and transmit the obtained differential electrical signals as detection signals to the digital-to-analog conversion module for digital-to-analog conversion, and then the demodulation module performs demodulation processing.

[0021] Furthermore, it also includes a control module connected to the analog circuit module, which transmits control signals to the analog circuit module based on the laser electrical signals transmitted to it; the analog circuit module is also connected to the laser source, which controls the driving of the laser source according to the control signals.

[0022] As described above, the quantum sensor for current measurement of the present invention has the following beneficial effects: By setting multiple light leakage regions between the optical input and output ends of a ring optical fiber, and placing multiple diamonds one-to-one in the multiple light leakage regions to receive the irradiation of the laser light leaking from the light leakage regions, and by using multiple microwave antennas one-to-one to radiate modulated microwaves to the multiple diamonds, with each microwave antenna transmitting a different modulation frequency of microwaves, the correct fluorescence signal can be demodulated during demodulation using a reference signal with the corresponding modulation frequency. This reduces microwave interference from other quantum probes at close range, thereby improving measurement accuracy. Furthermore, the ring optical fiber arrangement simplifies the light supply structure of the multiple diamonds, streamlines the layout, and reduces the number of laser sources. Attached Figure Description

[0023] Figure 1 The diagram shows a first structural schematic of a quantum sensor;

[0024] Figure 2 Displayed as Figure 1 Enlarged view of point A in the middle;

[0025] Figure 3 The diagram shows the fluorescence changes caused by microwave interference between two probes at close range;

[0026] Figure 4 The diagram shows a second structural representation of a quantum sensor.

[0027] Figure 5 Displayed as Figure 4 Enlarged view at point B in the middle;

[0028] Figure 6 The diagram shows a cross-sectional view of the optical fiber, magnetic shield, and housing.

[0029] Figure 7 Displayed as Figure 6 Enlarged view at point C;

[0030] Figure 8 The diagram shows the installation structure in a quantum sensor.

[0031] Figure 9 The graph shown is the demodulation curve obtained by microwave sweep frequency method for ODMR measurement of diamond NV color centers.

[0032] Component labeling: 1—Fiber optic cable; 11—Optical input end; 12—Optical output end; 13—Leakage area; 131—Filling material; 14—Core layer; 15—Cladding layer; 16—Coating layer; 17—Condenser lens; 2—Conductor under test; 3—Quantum probe; 31—Diamond; 32—Microwave antenna; 4—Laser source; 5—Fluorescence detection module; 51—First filter; 52—First photodetector; 6—Microwave source; 7—Processing module; 71—Analog circuit module; 72—Analog-to-digital conversion module; 73—Demodulation module; 8—Laser detection module; 81—Second filter; 82—Second photodetector; 9—Control module; 10—Magnetic shield; 20—Housing; 30—Channel; 40—Mounting structure; 401—First support; 402—Second support; 403—First groove; 404—Second groove; 50—Opening / closing point. Detailed Implementation

[0033] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0034] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0035] Example 1: As Figure 1 , Figure 2 As shown, this embodiment provides a quantum sensor for current measurement, including:

[0036] The optical fiber 1 has a ring structure, and multiple light leakage regions 13 are provided on the part between the optical input end 11 and the optical output end 12. Each light leakage region 13 is used to leak out a portion of the light transmitted in the optical fiber; the middle part of the ring structure is used to place the conductor to be tested 2.

[0037] Multiple quantum probes 3 are set in multiple light leakage areas 13 in a one-to-one correspondence. Each quantum probe 3 includes a diamond 31 containing nitrogen vacancy color centers and a microwave antenna 32.

[0038] Laser source 4 is used to input laser light into the optical input end 11 of optical fiber 1. The laser light is used to excite the diamond nitrogen vacancy color center to generate fluorescence.

[0039] Multiple fluorescence detection modules 5 are located on one side of multiple diamonds, one to one. Each fluorescence detection module 5 collects and detects the fluorescence generated by the corresponding diamond and outputs a fluorescence electrical signal.

[0040] Microwave source 6 is used to transmit modulated microwaves to microwave antenna 32, and the modulation frequency of the microwaves transmitted to each microwave antenna 32 is different.

[0041] The processing module 7 is used to receive the fluorescent electrical signal, process it, use it as a detection signal, demodulate the AC signal in the detection signal using a reference signal with a corresponding modulation frequency to obtain demodulated data, calculate the magnetic field strength value and / or current value based on the demodulated data, and also transmit the frequency modulation signal to the microwave source 6.

[0042] In this embodiment, modulated microwaves with different modulation frequencies are transmitted to multiple microwave antennas. Taking two diamonds as an example, the microwave frequencies applied through the corresponding microwave antennas are as follows: and In demodulation processing, the AC signals generated by two microwaves with different modulation frequencies on the same diamond are superimposed. For the superimposed signal generated by the first diamond, using Demodulating the signal as a reference signal can yield the demodulated signal. For the superimposed signal generated by the second diamond, use Demodulating the signal as a reference signal can yield the demodulated signal. Similarly, this can be applied to the superposition of AC signals generated by more than two microwaves with different modulation frequencies on the same diamond. Therefore, during demodulation, using a reference signal with the corresponding modulation frequency can demodulate the correct fluorescence signal, reduce microwave interference caused by multiple quantum probes operating simultaneously at close range, and thus improve measurement accuracy.

[0043] It is important to note that for modulated signals The fluorescence it produces can be expressed by the formula This indicates that, since demodulation is performed on AC signals and specifically on the first harmonic, the DC term V must be filtered out first during demodulation, which can be achieved, for example, through AC coupling. When performing low-pass filtering after mixing, multiple quantum probes can share a single filter, or filters with different cutoff frequencies can be set. The cutoff frequency is determined based on the minimum frequency of the AC term to be filtered out.

[0044] The modulation signal in this embodiment can be a sine, cosine, or square wave. Since the square wave signal can be expanded into a Fourier series, its principle is the same as that of sine modulation.

[0045] In this embodiment, the optical fiber can be bent into a loop. Within a certain bending diameter (generally a bending radius of not less than 1-5 cm), the propagation of light within the optical fiber remains unaffected. Optical fibers can be categorized into bare fibers and fibers with protective layers, as exemplified by... Figure 1 As shown, a bare optical fiber includes a core layer 14, a cladding layer 15, and a coating layer 16 from the inside out. An optical fiber with a protective layer has a protective layer added outside the cladding layer. Regardless of the type of optical fiber, the principle of light transmission in an optical fiber is the same: light propagates in the core layer and undergoes total internal reflection at the interface between the core layer and the cladding layer, so that the light propagating in the core layer does not leak out.

[0046] In this embodiment, the shape of the core-cladding interface in the leakage region is altered by processing the optical fiber, thereby changing the incident angle of light at this interface and thus changing the total internal reflection condition, allowing light to leak out from the cladding. In this embodiment, the outer layer of the optical fiber, such as a coating or protective layer, is removed to expose the cladding. Removal methods include scraping, stripping, polishing, or heating. The exposed cladding is then heated and stretched to change the incident angle of light at the core-cladding interface, thereby changing the total internal reflection condition and allowing light to leak out from the cladding. When a laser is input into the optical fiber, the diamond located in the leakage region is irradiated by the leaked laser, resulting in a photoluminescence effect. Figures 1-2 After being stretched, the optical fiber in the middle forms an hourglass-shaped leakage area. Different leakage intensities can be obtained by selecting different stretching lengths. Furthermore, after the optical fiber is stretched in multiple places to form multiple leakage areas, it is easier to bend into a ring structure, ensuring that the propagation of light in the non-leakage areas is not affected. For current measurement, since the radius of the cable is generally at least several centimeters, the bending radius of the outer optical fiber will be larger, which can fully meet the minimum bending radius requirement. Figure 1 , Figure 4 The bending radii of the optical input and output ends are also within the allowable range. The figure is only an example and does not represent the actual bending radius.

[0047] This embodiment uses only a single ring optical fiber to achieve laser irradiation and fluorescence detection of multiple diamonds. The fluorescence detection module 5 is located on one side of the diamond 31, and the two are integrated in close proximity. Compared with the multi-fiber light supply in the prior art, the structure is simple and occupies less space, which can realize the simplification of spatial layout. Moreover, only one laser source is needed to meet the irradiation needs of multiple diamonds, which can further simplify the light source structure and thus simplify the sensor structure. The fluorescence generated by the diamond 31 is directly collected by the fluorescence detection module 5, which can reduce the light loss caused by optical fiber transmission.

[0048] To increase the collection of light leakage in the light-leaking area and minimize its size, for example, in this embodiment, a stretching method is used to allow light to leak out and obtain the required light leakage intensity. This places certain requirements on the stretching length; a larger stretching length is needed for a higher light intensity, but since optical fibers are thin, excessive stretching can easily lead to breakage. Therefore, a filler 131 can be filled into the light-leaking area. The filler has a set refractive index to change the original refractive index, increasing the collection efficiency of the leaked light or improving the light emission ratio. Furthermore, by adjusting the size of the filler, the size of the light-leaking area and the light leakage efficiency can be flexibly controlled. The formation of the filler acts similarly to an optical lens. Different refractive indices of the filler result in different light collection effects or light emission ratios. Fillers with higher refractive indices can be selected, such as optical adhesives, UV-curable adhesives, or PDMS (polydimethylsiloxane). The shape of the filler is configured to converge light, for example, as a lens structure with a convex surface. Diamond can also be fixed to the light-leaking area using optical adhesives or PDMS.

[0049] Microwave interference occurs when the distance between two adjacent diamonds is no more than 10cm. Here, the distance refers to the straight-line distance between the opposite surfaces of the two diamonds. Using the quantum sensor of this embodiment, even if two adjacent probes are brought close to each other with a distance of 1cm, the mutual interference of microwaves can be reduced. Figure 1 The example given has four quantum probes 31, but other numbers are also possible, preferably 2n, where n is an integer. The microwave antenna 32 can be selected from, for example... Figure 2 The spiral antenna shown is fitted over the outside of the diamond. Alternatively, a microstrip antenna can be used, which is placed on one side of the diamond to radiate microwaves to it.

[0050] Microwave source 6 transmits modulated microwaves to multiple microwave antennas 32. After receiving the frequency modulation signal transmitted by processing module 7, it modulates the microwave frequency and then transmits the modulated microwaves to the microwave antennas. The frequency modulation signal includes multiple different modulation frequencies, each corresponding to a different microwave antenna. During demodulation, processing module 7 uses a reference signal of the same frequency to demodulate the signal according to the modulation frequency corresponding to each antenna. Microwave source 6 includes the generation and processing of microwave signals, such as amplification and isolation of reflected signals. Microwave source 6 can be configured as multiple sources corresponding one-to-one with microwave antennas, or it can be a single source with multiple channels, each channel corresponding to one of the microwave antennas.

[0051] Laser source 4 is a laser that generates laser light to excite color centers, such as a 532nm laser.

[0052] Each fluorescence detection module 5 includes a first filter 51 and a first photodetector 52. The fluorescence generated by the diamond 31 is filtered out by the first filter 51 and collected by the first photodetector 52, and converted into a fluorescence electrical signal. Each first filter 51 is attached to the light-receiving surface of the corresponding first photodetector 52, although they can also be spaced apart.

[0053] For a fixed sensor system, different modulation frequencies will result in a corresponding fixed phase in the fluorescence response. This phase can be obtained experimentally under the influence of a single modulation frequency. This embodiment uses biphase demodulation technology, employing two reference signals, namely... , After mixing the two reference signals with the fluorescence signal and performing low-pass filtering, two components can be obtained. , By adjusting the phase so that one component, for example X, approaches zero, the other component Y becomes the desired value. Figure 9 The demodulation curves shown are for the case of the eight resonant frequencies of the diamond NV color center.

[0054] Processing module 7 can be exemplarily as follows: Figure 1 As shown, the system includes an analog circuit module 71, an analog-to-digital converter module 72, and a demodulation module 73. The analog circuit module 71 processes the received electrical signal and transmits the processed signal as a probe signal to the analog-to-digital converter module 72. The processing of the electrical signal can, for example, include signal conditioning. The circuit used for conditioning includes one or more of a transimpedance amplifier, a voltage amplifier, and a filter. This is a commonly used circuit in the field and will not be described in detail here. After the analog-to-digital converter module 72 performs analog-to-digital conversion on the probe signal, it transmits it to the demodulation module 73, which demodulates the signal to obtain demodulated data. The magnetic field strength value is calculated based on the demodulated data. Specifically, this includes first obtaining the resonant frequency from the demodulated data, then calculating the magnetic field strength value based on the resonant frequency, and further calculating the current value in the conductor 2 under test using the Biot-Savart formula. The current vector can also be obtained based on the current direction.

[0055] One method to obtain the resonant frequency is to plot the demodulated data as a function of frequency by sweeping the frequency curve and finding the resonant frequency point on the curve. Another method is to use a closed-loop control algorithm to adjust the frequency of the modulated microwave radiated by the microwave source after obtaining the resonant frequency point through the first frequency sweep, in order to obtain the resonant frequency corresponding to the magnetic field. This method is called frequency tracking, which can improve efficiency. The closed-loop control algorithm used is, for example, the PID algorithm. When using the frequency sweep method, if there are errors in the demodulated data, it may lead to the absence of a zero-crossing point or an incorrect zero-crossing point in the demodulation curve, resulting in an incorrect resonant frequency. It should be noted that if multiple probes operating simultaneously have the same microwave frequency, the multiple probes will affect the fluorescence in terms of microwave power. Whether the superimposed power weakens or enhances is uncertain, which may also lead to errors in the obtained zero-crossing point. When using the PID algorithm for control, for each demodulated data, the slope of the curve segment where the zero-crossing point is located in the initial demodulation curve is usually used to calculate the microwave offset to be adjusted each time, in order to calculate the new resonant frequency. If there are errors in the demodulated data, the calculated resonant frequency will be incorrect. In this embodiment, after demodulating the correct fluorescence signal, the above-mentioned errors can be reduced.

[0056] The demodulation module 73 can be programmed for demodulation, for example, using FPGA programming, or it can be demodulated and transmitted to the microwave source via a quadrature digital lock-in amplifier. Since there are multiple fluorescence detection modules 5, the output detection signals are multiplexed. The analog circuit module 71 can include multiple processing circuits or multiplexed circuits. The analog-to-digital conversion module 72 can include multiple analog-to-digital converters or a single analog-to-digital converter with multiple channels.

[0057] The modulation frequency difference between the microwaves transmitted to each pair of adjacent microwave antennas is no less than 1 kHz, ensuring efficient low-pass filtering during demodulation and improving the signal-to-noise ratio. Furthermore, each modulation frequency is no greater than the maximum modulation frequency acceptable to the diamond NV color center, achieving optimal color center response. The maximum modulation frequency can be determined experimentally; the acceptable modulation frequency for the diamond NV color center is between 10 and 100 kHz.

[0058] Example 2: In this example, the light leakage area is configured to be formed by exposing a portion of the core layer to the outside. Specifically, it can be done as follows: Figure 4 , Figure 5 As shown, a notch is formed radially from the outermost layer of the optical fiber towards the core layer, exposing part of the core layer to the outside. Or as... Figure 6 , Figure 7As shown, each light leakage area is groove-shaped, with at least part of the groove bottom located in the core layer. This is achieved by polishing the light leakage area of ​​the optical fiber using a polishing machine or scraping it with a tool, creating the groove. At least part of the groove bottom exposes the core layer to the outside, allowing some light propagating in the core layer to leak out. After multiple local cuts or grooves, the optical fiber is easier to bend into a ring structure, ensuring that the propagation of light in non-leakage areas is not affected.

[0059] like Figure 4 , Figure 5 As shown, a condenser lens 17 is also provided between each diamond 31 and the fluorescence detection module 5 to collect light from the diamond 31. The condenser lens can be a TIR lens (i.e., a total internal reflection lens). The incident surface of the TIR lens is a groove recessed into the lens body, allowing the diamond to be placed inside the groove of the TIR lens, or as shown in the diagram. Figure 4 The lens shown is external. The TIR lens focuses light through total internal reflection. Other lenses, such as hemispherical lenses, compound parabolic condensers, and aspherical lenses, can also be used to collect light. A slot or perforation can also be made in the lens body to place a diamond inside.

[0060] like Figure 4 As shown, it also includes a laser detection module 8, located at the optical output end 12 of the optical fiber, used to detect the laser emitted from the optical output end and output a laser electrical signal. The laser detection module 8 includes a second filter 81 and a second photodetector 82. The second filter 81 filters out the laser emitted from the optical output end 12, and the second photodetector 82 collects the detected laser signal. The processing module 7 also receives the laser electrical signal, processes the signal, and differentially processes each fluorescent electrical signal with the excitation photoelectric signal to obtain a differential signal. This differential signal is then used as the detection signal for demodulation. Differential processing reduces common-mode noise and improves measurement accuracy. Specifically, the analog circuit module 71 receives the laser electrical signal, processes it, differentially processes it with each fluorescent electrical signal, and then transmits the resulting differential signal as the detection signal to the analog-to-digital converter 72 for analog-to-digital conversion. Finally, the demodulation module 73 performs demodulation processing.

[0061] like Figure 4 As shown, it also includes a control module 9 connected to the analog circuit module 71, which transmits a control signal to the analog circuit module 71 based on the laser electrical signal transmitted to it. The analog circuit module 71 is also connected to the laser source 4 and controls the driving of the laser source according to the control signal, for example, by controlling the current to drive the laser source circuit.

[0062] like Figure 6As shown, a magnetic shield 10 is provided around the optical fiber 1 to shield the influence of the external magnetic field on the magnetic field generated by the conductor under test 2. The magnetic shield 10 has through holes at both ends for the conductor under test 2 to pass through, making the end faces annular. Furthermore, a housing 20 is also provided, with annular end faces, extending from the periphery of the magnetic shield 10 to the middle of the annular structure of the optical fiber 1, and extending along the axial direction of the magnetic shield 10 to form a channel 30 for placing the conductor under test 2, making the housing 20 a hollow annular cylindrical structure.

[0063] like Figure 6 , Figure 8 As shown, optical fibers, detection modules, etc., are installed via the mounting structure 40. The mounting structure is mounted on the housing portion between the magnetic shielding cover 10 and the channel 30 where the conductor to be tested is placed. Figure 8 (Only this part of the housing is shown). The mounting structure 40 is a frame structure, including a first support 401 for supporting the optical fiber 1 and a second support 402 (only one is shown in the figure) for supporting optical components such as lenses, filters, and photodetectors. The first support 401 is an annular body surrounding the inner housing, with a first groove 403 for placing the optical fiber 1. The second support 402 is a block-shaped body with a second groove 404 for placing optical components such as condenser lenses, filters, and photodetectors. The diamond 31 is placed inside the lens or pressed between the lens and the light leakage area of ​​the optical fiber. After the optical fiber, diamond, filter, and photodetector are installed on the two supports, the contact surfaces of the two supports are connected to achieve installation on the inner housing. The mounting structure 40 can also be filled with soft materials, such as sponge or rubber.

[0064] During current measurement, the conductor under test 2 can be inserted into channel 30 before being connected to the power supply for measurement, or the conductor under test can be a device that can be directly fitted into channel 30. To facilitate current measurement of conductors that cannot be fitted into channel 30, both the magnetic shield 10 and the housing 20 can be designed as openable / closable structures. The opening / closing point is located between the optical input and output ends of the optical fiber, and can be directly snapped onto the outside of the conductor under test during detection. The opening / closing point 50 is as follows: Figure 6 As shown by the thick lines, it is located between the optical input and output ends of the optical fiber. To achieve opening and closing, a connecting rod is also provided in the gap between the housing 20 and the magnetic shield 10 to connect the two, so that when opened, the parts that are separated can become a whole structure. Figure 8 As shown, the mounting structure 40 is disconnected at the opening / closing point 50 to facilitate the opening and closing operation of the housing. Except for the separation of the input and output ends of the optical fiber, the rest is continuous. Based on the flexibility of the optical fiber, opening and closing operations of a certain degree will not affect the performance of the optical fiber.

[0065] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A quantum sensor for current measurement, characterized in that, The sensor includes: An optical fiber has a ring structure with multiple light leakage regions on the section between its optical input and optical output ends. Each light leakage region is used to leak out a portion of the light transmitted in the optical fiber. The middle part of the ring structure is used to place the conductor to be tested. Multiple quantum probes are set in multiple light leakage areas in a one-to-one correspondence. Each quantum probe includes a diamond containing nitrogen vacancy color centers and a microwave antenna. A laser source is used to input laser light into the optical input end of an optical fiber, and the laser light is used to excite the nitrogen vacancy centers in diamond to produce fluorescence. Multiple fluorescence detection modules are located on one side of multiple diamonds, one for each diamond. Each fluorescence detection module collects and detects the fluorescence generated by the corresponding diamond and outputs a fluorescence electrical signal. A microwave source is used to transmit modulated microwaves to microwave antennas, and the modulation frequency of the microwaves transmitted to each microwave antenna is different. The processing module is used to receive fluorescent electrical signals, process them, use them as detection signals, demodulate the AC signals in the detection signals using a reference signal with a corresponding modulation frequency to obtain demodulated data, calculate the magnetic field strength value and / or current value based on the demodulated data, and also transmit frequency modulation signals to the microwave source.

2. The quantum sensor for current measurement according to claim 1, characterized in that: The modulation frequency difference between the microwaves transmitted to each of the two adjacent microwave antennas is not less than 1 kHz, and each modulation frequency is not greater than the maximum modulation frequency that the diamond NV color center can accept.

3. The quantum sensor for current measurement according to claim 1, characterized in that: The distance between any two adjacent diamonds shall not exceed 10cm.

4. The quantum sensor for current measurement according to claim 1, characterized in that: The light leakage area is formed by changing the shape of the core layer and cladding interface, or by exposing at least a portion of the cross-section of the core layer to the outside.

5. The quantum sensor for current measurement according to claim 1, characterized in that: A focusing structure is placed between the diamond and the fluorescence detection module to focus the fluorescence generated by the diamond.

6. The quantum sensor for current measurement according to claim 1, characterized in that: The light leakage area is filled with a filler having a set refractive index.

7. The quantum sensor for current measurement according to claim 1, characterized in that: The processing module adjusts the frequency of the modulated microwave radiated by the microwave source according to the demodulated data and through a closed-loop control algorithm to obtain the resonant frequency corresponding to the magnetic field, and calculates the magnetic field strength value based on the resonant frequency.

8. The quantum sensor for current measurement according to any one of claims 1-7, characterized in that: A laser detection module is also set at the optical output end of the optical fiber to collect the laser output from the detection optical output end and output the laser electrical signal to the processing module. The processing module processes the electrical signal and performs differential processing on each fluorescent electrical signal and the laser electrical signal to obtain a differential signal, which is then used as the detection signal for demodulation processing.

9. The quantum sensor for current measurement according to claim 8, characterized in that: The processing module includes an analog circuit module, a digital-to-analog conversion module, and a demodulation module. The analog circuit module is used to receive fluorescent electrical signals and laser electrical signals, process the electrical signals and perform differential processing, and transmit the obtained differential electrical signals as detection signals to the digital-to-analog conversion module for digital-to-analog conversion, and then the demodulation module performs demodulation processing.

10. The quantum sensor for current measurement according to claim 9, characterized in that: It also includes a control module connected to the analog circuit module, which transmits control signals to the analog circuit module based on the laser electrical signals transmitted to it; the analog circuit module is also connected to the laser source, which controls the driving of the laser source based on the control signals.

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