A magnetic field and temperature sensing device based on a three-cell differential structure and a measurement method thereof

Abstract

The application discloses a kind of magnetic field and temperature sensing device based on three-unit differential structure and its measurement method, belong to magnetic field and temperature multi-physical quantity sensing technical field.Sensing device includes at least one sensitive unit and signal conditioning circuit;Each sensitive unit includes three subunits, each subunit includes diamond NV color center sensitive material, optical excitation source and photodetector;First, second subunit also includes microwave application structure, the frequency of the microwave excitation signal loaded is preselected, so that the response of the output electric signal of two subunits to magnetic field and temperature change one polarity is same, and the other polarity is opposite;Signal conditioning circuit is different to the output electric signal of third subunit respectively with the output electric signal of first, second subunit, and accordingly output magnetic field or temperature measurement result.The application solves the technical problems that magnetic field and temperature response signal coupling in prior art cannot distinguish the independent contribution of two physical quantities, and common mode noise is difficult to suppress.

Description

Technical Field

[0001] This invention relates to the field of multi-physical quantity sensing technology of magnetic field and temperature, specifically to a magnetic field and temperature sensing device based on a three-unit differential structure and its measurement method. Background Technology

[0002] Magnetic field and temperature, as two key physical quantities characterizing electromagnetic properties and thermal state, are of great significance in scenarios such as industrial equipment condition monitoring, electromagnetic environment detection, heat distribution analysis, and precision instrument operating status assessment. Changes in magnetic field can reflect current distribution, device operating status, and electromagnetic interference, while changes in temperature are directly related to material properties, energy loss, and system stability. In most applications, these two are coupled and jointly influence system behavior. Relying on a single physical quantity is often insufficient to comprehensively characterize the target state, thus necessitating the coordinated sensing of magnetic field and temperature within the same device.

[0003] However, in existing technologies, magnetic fields and temperatures are typically measured separately using different types of sensors. This not only increases the system's size and complexity but also introduces multi-source errors due to inconsistent spatial locations, making it difficult to meet the requirements of integrated sensing. Therefore, researchers have attempted to use a single sensing element to simultaneously sense multiple physical quantities. Among these, diamond nitrogen-vacancy (NV) centers are a widely studied class of solid-state quantum sensing elements, whose electronic spin states exhibit photodetector magnetic resonance (ODMR) characteristics. Specifically, the ground-state spin level of the diamond NV center exhibits zero-field splitting. An applied magnetic field causes symmetrical splitting of the ground-state spin level of the diamond NV center through the Zeeman effect, resulting in a linear shift in the ODMR resonance frequency. Changes in ambient temperature cause thermal expansion of the diamond lattice, and the lattice vibrations affect the ground-state spin level of the diamond NV center, also manifesting as a linear shift in the ODMR resonance frequency. Therefore, diamond NV centers possess the potential to collaboratively sense magnetic fields and temperatures within a single sensing element, making them an important research direction in this field.

[0004] However, in existing sensing studies based on diamond NV centers, both magnetic field and temperature variations cause shifts in the photodetector magnetic resonance frequency. Magnetic field variations primarily affect the Zeeman splitting of the ground-state spin level of the diamond NV center, while temperature variations influence the zero-field splitting parameter. Therefore, these two factors exhibit cross-sensitivity to the photodetector magnetic resonance signal. When both magnetic field and temperature change simultaneously, it becomes difficult to distinguish the independent contributions of the two physical quantities (magnetic field and temperature) in the output signal, leading to decreased measurement accuracy and stability. Furthermore, in diamond NV center sensing systems, fluctuations in optical excitation intensity and changes in ambient light cause overall drift in the fluorescence output signal. This drift, as common-mode noise, is superimposed on the response signal from the magnetic field or temperature, making effective separation of the common-mode noise from the response signal difficult and further reducing the measurement signal-to-noise ratio. Some studies have attempted to suppress common-mode noise through differential measurements, but these typically only address a single physical quantity and fail to simultaneously solve the problems of magneto-temperature coupling and common-mode noise suppression at the structural level.

[0005] Therefore, existing sensing schemes based on diamond NV centers cannot effectively decouple magnetic-temperature coupling, nor can they systematically suppress common-mode noise. How to achieve high signal-to-noise ratio and decoupled collaborative sensing of magnetic field and temperature at the device structure level has become a pressing technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a magnetic field and temperature sensing device and measurement method based on a three-unit differential structure, so as to solve the technical problems in the prior art where the coupling of magnetic field and temperature response signals makes it impossible to effectively distinguish the independent contributions of the two physical quantities, and the common mode noise is difficult to systematically suppress.

[0007] To achieve the above objectives, the present invention provides a magnetic field and temperature sensing device based on a three-unit differential structure, comprising at least one sensing unit and a signal conditioning circuit;

[0008] Each sensitive unit includes a first sub-unit, a second sub-unit, and a third sub-unit;

[0009] Each subunit includes:

[0010] Diamond NV color center sensitive material, used to sense magnetic fields and temperature;

[0011] An optical excitation source is used to excite the diamond NV color center sensitive material to generate a fluorescence signal.

[0012] A photodetector is used to receive fluorescence signals and convert them into electrical signals.

[0013] Both the first and second subunits include a microwave application structure for applying microwave excitation signals to the diamond NV color center sensitive material.

[0014] The microwave application structure of the first subunit and the microwave application structure of the second subunit are respectively used to apply microwave excitation signals of different frequencies.

[0015] The signal conditioning circuit is used to: take the difference between the electrical signal output by the first subunit and the electrical signal output by the third subunit as the first differential signal, take the difference between the electrical signal output by the second subunit and the electrical signal output by the third subunit as the second differential signal, and perform differential processing based on the first differential signal and the second differential signal.

[0016] Furthermore, there are multiple sensitive units, which are arranged in an array to form a sensitive unit array. The electrical signals are converged in the interconnection structure of the sensitive unit array and then output to the signal conditioning circuit.

[0017] Furthermore, the signal conditioning circuit adjusts the microwave excitation frequency of the first subunit and the second subunit to output the magnetic field measurement result in the magnetic field measurement mode and the temperature measurement result in the temperature measurement mode.

[0018] In the magnetic field measurement mode, the electrical signal output by the first subunit and the electrical signal output by the second subunit have the same polarity in response to changes in the magnetic field and opposite polarity in response to changes in temperature.

[0019] In temperature measurement mode, the electrical signal output by the first subunit and the electrical signal output by the second subunit have the same polarity in response to temperature changes, but opposite polarity in response to magnetic field changes.

[0020] Furthermore, the sensitive unit array is a 10×10 pixel array.

[0021] Furthermore, the signal conditioning circuit is also used to regulate the power and on / off state of the optical excitation source.

[0022] Furthermore, each subunit also includes a filter element disposed between the diamond NV color center sensitive material and the photodetector. The filter element is used to filter out the emitted light from the optical excitation source and transmit the fluorescence signal.

[0023] Furthermore, the filter element is a 600-800nm ​​bandpass filter; the photodetector is a photodiode.

[0024] Furthermore, the optical excitation source is a laser; the microwave application structure is a microstrip antenna.

[0025] Furthermore, in each subunit, the optical excitation source is positioned to the side of the diamond NV color center sensitive material; the photodetector is positioned below the diamond NV color center sensitive material.

[0026] Another aspect of the present invention provides a method for measuring magnetic field and temperature sensing devices based on a three-unit differential structure, comprising:

[0027] Step S1: Turn on the optical excitation source to excite the diamond NV color center sensitive material, causing it to generate a fluorescence signal;

[0028] Step S2: Adjust the frequency of the microwave excitation signal of the first subunit and the second subunit through the signal conditioning circuit, select to enter the magnetic field measurement mode or the temperature measurement mode, and apply the microwave excitation signal of the structure loading frequency to the microwave of the first subunit and the second subunit. The third subunit is not loaded with a microwave excitation signal.

[0029] Step S3: Receive the fluorescence signal generated by the diamond NV color center sensitive material in each sub-unit using a photodetector, and convert it into an electrical signal. , , ;

[0030] Step S4: Convert the electrical signal output by the first sub-unit Electrical signal output from the third subunit The difference is used as the first differential signal. ,in, ;

[0031] The electrical signal output by the second subunit Electrical signal output from the third subunit The difference is used as the second differential signal. ;in, ;

[0032] Step S5: In magnetic field measurement mode, the signal conditioning circuit adjusts the signal according to the first differential signal. With the second differential signal Converted to the corresponding optically detected magnetic resonance frequency shifts , The magnetic field measurement results are output based on the magnetic field calculation formula.

[0033] The formula for calculating the magnetic field is: ;

[0034] in, This is the change in magnetic field. The gyromagnetic ratio of the diamond NV color center is 2.8 MHz / Gs;

[0035] In temperature measurement mode, the signal conditioning circuit uses the first differential signal. With the second differential signal Converted to the corresponding optically detected magnetic resonance frequency shifts , The temperature measurement result is output according to the temperature calculation formula;

[0036] The formula for temperature calculation is: ;

[0037] in, The change in temperature The temperature coefficient of the zero-field splitting frequency of the diamond NV color center. The typical value is -74kHz / ℃.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] First, by rationally configuring the frequencies of the microwave excitation signals of the first subunit and the second subunit, the present invention enables the invention to respond only to magnetic field changes and suppress temperature interference in magnetic field measurement mode, and to respond only to temperature changes and suppress magnetic field interference in temperature measurement mode. This achieves effective decoupling of magnetic field and temperature measurement at the device structure level, solving the technical problem that magnetic field and temperature signals cannot be effectively decoupled in the prior art.

[0040] Second, in this invention, the third subunit is not subjected to microwave excitation, and its fluorescence output does not contain response information of magnetic field or temperature, but only reflects the changes in optical excitation intensity and ambient light. By subtracting the fluorescence output of the third subunit from the output of the first and second subunits respectively through differential operation, the background interference commonly experienced by the three subunits cancels each other out, thus solving the technical problem that common mode noise is difficult to systematically suppress in the prior art. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the overall structure of a magnetic field and temperature sensing device based on a three-unit differential structure in an embodiment of the present invention;

[0042] Figure 2 This is a side view of a magnetic field and temperature sensing device based on a three-unit differential structure in an embodiment of the present invention;

[0043] Figure 3 This is a schematic diagram of the structure of the sensitive unit in an embodiment of the present invention;

[0044] Figure 4 This is a schematic diagram of the optical detection magnetic resonance curve of the sensitive unit array in an embodiment of the present invention;

[0045] Figure 5 This is a graph showing the photodetector magnetic resonance curves of the sensitive unit array under different applied magnetic fields in an embodiment of the present invention.

[0046] Figure 6 The graphs shown are optical detection magnetic resonance curves of the sensitive unit array under different temperature conditions in the embodiments of the present invention.

[0047] In the figure: 1—Sensitive unit; 11—First sub-unit; 12—Second sub-unit; 13—Third sub-unit; 101—Diamond NV color center sensitive material; 102—Microwave application structure; 103—Optical excitation source; 104—Filter element; 105—Photodetector; 2—Signal conditioning circuit. Detailed Implementation

[0048] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0049] refer to Figure 1 , Figure 2 , Figure 3 One embodiment of the present invention provides a magnetic field and temperature sensing device based on a three-unit differential structure, which mainly includes a sensing unit 1 and a signal conditioning circuit 2.

[0050] In a preferred embodiment, multiple independent sensing units 1 are arranged in a two-dimensional array to form a sensing unit array. Each sensing unit 1 is an independent pixel unit and can selectively operate in magnetic field measurement mode or temperature measurement mode to sense magnetic field or temperature.

[0051] In a preferred embodiment, the sensitive cell array is a 10×10 pixel array.

[0052] refer to Figure 3 Each sensitive unit 1 includes a first subunit 11, a second subunit 12, and a third subunit 13, which together form a three-unit differential structure.

[0053] The first subunit 11 and the second subunit 12 have the same structure, both including: a diamond NV color center sensitive material 101, an optical excitation source 103, a microwave application structure 102, a filter element 104, and a photodetector 105. The third subunit 13 includes: a diamond NV color center sensitive material 101, an optical excitation source 103, a filter element 104, and a photodetector 105, but does not include the microwave application structure 102.

[0054] The diamond NV center sensitive material 101 is used to sense magnetic fields and temperature; in a preferred embodiment, the diamond NV center sensitive material 101 is irradiated with a 10MeV high-energy electron beam for 4 hours and annealed at 850 degrees Celsius for 2 hours to make the concentration of nitrogen vacancy (NV) centers in diamond reach about 0.8ppm.

[0055] An optical excitation source 103 is used to excite the diamond NV color center sensitive material 101 to generate a fluorescence signal. In a preferred embodiment, a laser with a wavelength of 532 nm is used.

[0056] The microwave application structure 102 is used to apply a microwave excitation signal of a specific frequency to the diamond NV center sensitive material 101. When the microwave frequency of the applied microwave excitation signal matches the resonance frequency of the photodetector magnetic resonance of the NV center in the diamond NV center sensitive material 101, it drives the spin state of the NV center electrons to transition, causing a change in the intensity of the fluorescence signal output, thus forming a photodetector magnetic resonance response. In a preferred embodiment, the microwave application structure 102 is a microstrip antenna.

[0057] A filter element 104 is disposed between the diamond NV color center sensitive material 101 and the photodetector 105 to filter out the emitted light from the optical excitation source 103, while allowing the fluorescence signal emitted by the diamond NV color center sensitive material 101 to pass through and be incident on the photodetector 105. In a preferred embodiment, the filter element 104 is a 600-800nm ​​bandpass filter with an optical density of 3.

[0058] The photodetector 105 is used to receive the fluorescence signal filtered by the filter element 104 and convert it into an electrical signal output. In a preferred embodiment, the photodetector 105 is a photodiode.

[0059] refer to Figure 2 , Figure 3 In each subunit, an optical excitation source 103 is disposed to the side of the diamond NV center sensitive material 101 to provide lateral optical excitation; a photodetector 105 is disposed below the diamond NV center sensitive material 101; the diamond NV center sensitive material 101, the filter element 104, and the photodetector 105 are stacked sequentially in the vertical direction to form a compact integrated structure, thereby improving fluorescence collection efficiency and device integration. In the first subunit 11 and the second subunit 12, a microwave application structure 102 is disposed above the diamond NV center sensitive material 101.

[0060] Working principle of the invention:

[0061] Under the excitation of the optical excitation source 103, the diamond NV center sensitive material 101 absorbs the excitation light and generates a red fluorescence signal. The intensity of the fluorescence signal is closely related to the spin state of the NV center electrons in the diamond NV center sensitive material 101. When a microwave excitation of a specific frequency is applied to the diamond NV center sensitive material 101, the spin state of the NV center electrons in the diamond NV center sensitive material 101 undergoes a transition when the microwave frequency coincides with the resonance frequency. The fluorescence signal intensity then decreases significantly, forming a resonance dip on the photodetector magnetic resonance curve.

[0062] The NV centers in the diamond NV center sensitive material 101 possess an inherent zero-field splitting frequency. An applied magnetic field, through the Zeeman effect, splits this zero-field splitting frequency into two resonant frequencies: a low-frequency and a high-frequency frequency. These result in two corresponding resonant depressions on the photodetector magnetic resonance curve, and the depression positions shift with changes in the applied magnetic field. Changes in ambient temperature cause an overall drift in the zero-field splitting frequency, leading to the two resonant depressions shifting in the same direction. These characteristics enable the diamond NV center sensitive material 101 to produce distinguishable responses to magnetic fields and temperature within the same sensitive element. This is the physical basis for the present invention's ability to sense both magnetic fields and temperature.

[0063] refer to Figure 4 In this embodiment of the invention, a working frequency point is selected on each of the four linear ramps of the two resonance depressions in the photodetector magnetic resonance curve of the sensitive unit array, and these are denoted as frequency points ①②③④. At each frequency point, the fluorescence output intensity responds linearly to changes in magnetic field or temperature. Since the low-frequency depression shifts to lower frequencies and the high-frequency depression shifts to higher frequencies when the applied magnetic field increases, and both depressions shift to lower frequencies when the ambient temperature increases, the magnetic field response polarity and temperature response polarity of the four frequency points can be obtained as follows, based on the position of each frequency point on the ramp:

[0064] Frequency point ① is located on the left slope of the low-frequency depression. When the magnetic field increases, the low-frequency depression moves towards lower frequencies, the center of the depression moves closer to frequency point ①, fluorescence decreases, and the magnetic field response polarity is negative. When the temperature increases, the low-frequency depression also moves towards lower frequencies, and the temperature response polarity is also negative. Frequency point ② is located on the right slope of the low-frequency depression, with the response polarity opposite to that of frequency point ①; both the magnetic field and temperature responses are positive. Frequency point ③ is located on the left slope of the high-frequency depression. When the magnetic field increases, the high-frequency depression moves towards higher frequencies, the center of the depression moves away from frequency point ③, fluorescence increases, and the magnetic field response polarity is positive. When the temperature increases, the high-frequency depression moves towards lower frequencies, the center of the depression moves closer to frequency point ③, fluorescence decreases, and the temperature response polarity is negative. Frequency point ④ is located on the right slope of the high-frequency depression, with the response polarity opposite to that of frequency point ③; both the magnetic field and temperature responses are negative. This constitutes a working frequency point matrix covering four polarity combinations, providing a frequency selection basis for the decoupled measurement of magnetic field and temperature.

[0065] Signal conditioning circuit 2 performs the following functions:

[0066] Firstly, according to the mode selection command, the frequency of the microwave excitation signal of the first subunit 11 and the second subunit 12 is adjusted to achieve selective switching between magnetic field measurement mode and temperature measurement mode.

[0067] Specifically, the signal conditioning circuit 2 includes a mode selection interface for receiving external control signals (such as mode selection instructions issued by the host computer). The microcontroller or digital signal processor built into the signal conditioning circuit 2 automatically sets the frequency of the microwave excitation signals of the first subunit 11 and the second subunit 12 to the frequency value required for the corresponding mode according to the mode selection instruction, thereby realizing the selective switching between the magnetic field measurement mode and the temperature measurement mode.

[0068] Secondly, the signal conditioning circuit 2 synchronously acquires the output electrical signals of the three sub-units through a built-in analog-to-digital converter or analog sampling circuit. , , The first differential signal is obtained by performing differential operations by a microcontroller or digital signal processor. Second differential signal ;

[0069] Third, the microcontroller or digital signal processor built into the signal conditioning circuit 2, based on the slope of the photodetector magnetic resonance curve at each operating frequency (this slope has been pre-calibrated and stored in the memory of the signal conditioning circuit 2), processes the first differential signal... Converted to the optical detection magnetic resonance frequency offset at the operating frequency of the first sub-unit 11 The second differential signal Converted to the optical probe magnetic resonance frequency offset at the operating frequency of the second subunit 12 ;

[0070] Fourth, in the corresponding measurement mode, the microcontroller or digital signal processor calculates the optical detection magnetic resonance frequency shift according to the corresponding formula. and Perform the corresponding calculations and output the magnetic field measurement results or temperature measurement results.

[0071] Fifth, the signal conditioning circuit 2 regulates the power and on / off state of the optical excitation source 103 through the built-in laser driving circuit to ensure stable optical excitation conditions.

[0072] It should be noted that the third subunit 13 is not subjected to microwave excitation; its fluorescence output only reflects fluctuations in optical excitation intensity and changes in ambient light, and does not contain response information from magnetic fields or temperature. Experiments show that, under the same optical excitation conditions, the common noise component output by the third subunit 13 is highly correlated with the common noise components in the first subunit 11 and the second subunit 12. Therefore, through... and The differential operation can effectively cancel common mode noise.

[0073] The following is the principle of decoupling in magnetic field measurement:

[0074] refer to Figure 4 , Figure 5 The magnetic field measurement mode achieves decoupling between the magnetic field and temperature by selecting frequency combinations with the same magnetic field response polarity and opposite temperature response polarity. This invention provides two frequency combinations:

[0075] Frequency combination 1: The first subunit 11 operates at frequency ①, and the second subunit 12 operates at frequency ④. The signal conditioning circuit 2, based on the slope of the photodetector magnetic resonance curve at each frequency point, modulates the first differential signal... Converted to the optically detected magnetic resonance frequency shift at frequency point ① The second differential signal Converted to the optical probe magnetic resonance frequency shift at frequency point ④ Since the magnetic field responses at frequencies ① and ④ are both negative, when the applied magnetic field changes, and The directions are consistent, and the sum of the two increases the amplitude to twice that of a single channel; since the temperature response of frequency point ① is negative and the temperature response of frequency point ④ is positive, when the ambient temperature changes... and Since they are in opposite directions, their addition cancels each other out, thus eliminating the interference of temperature changes on the magnetic field measurement. The change in magnetic field is calculated using the following formula:

[0076] ;

[0077] in, To determine the magnetic field change when frequency points ① and ④ are selected as the frequency point combination, The gyromagnetic ratio of the diamond NV color center is 2.8 MHz / Gs.

[0078] Frequency combination two: The first subunit 11 operates at frequency point ②, and the second subunit 12 operates at frequency point ③. The signal conditioning circuit 2 will... Converted to the optical probe magnetic resonance frequency shift at frequency point ② ,Will Converted to the optical probe magnetic resonance frequency shift at frequency point ③ Since the magnetic field responses at frequencies ② and ③ are both positive, when the applied magnetic field changes, and The directions are consistent, and the sum of the two increases the amplitude to twice that of a single channel; since the temperature response of frequency point ② is positive and the temperature response of frequency point ③ is negative, when the ambient temperature changes... and Since they are in opposite directions, their addition cancels each other out. The change in magnetic field is calculated using the following formula:

[0079] ;in, The change in magnetic field when frequency points ② and ③ are selected as the combination of frequency points.

[0080] The two frequency combinations can be flexibly selected according to actual application requirements.

[0081] like Figure 5 As shown, under different applied magnetic field conditions (0Gs, 1.67Gs and 3.42Gs), the position of the resonance depression in the photodetector magnetic resonance curve (current-microwave frequency response curve) of the sensitive unit array shifts linearly with the increase of the magnetic field, indicating that the electrical signal output by the embodiment of the present invention has good linear response characteristics to changes in the magnetic field, and the experiment verifies the effectiveness of the above-mentioned magnetic field measurement decoupling principle.

[0082] The following is the principle of temperature measurement decoupling:

[0083] refer to Figure 4 , Figure 6 The temperature measurement mode achieves decoupling between temperature and magnetic field by selecting frequency point combinations with the same temperature response polarity and opposite magnetic field response polarity. This invention also provides two frequency point combinations:

[0084] Frequency combination 1: The first subunit 11 operates at frequency point ①, and the second subunit 12 operates at frequency point ③. The signal conditioning circuit 2 will... Converted to the optically detected magnetic resonance frequency shift at frequency point ① ,Will Converted to the optical probe magnetic resonance frequency shift at frequency point ③ Since the temperature response polarities of frequency points ① and ③ are both negative, when the ambient temperature changes, and The directions are consistent, and the sum of the two increases the amplitude to twice that of a single channel; since the magnetic field response at frequency ① is negative and the magnetic field response at frequency ③ is positive, when the applied magnetic field changes, and Since they are in opposite directions, their addition cancels each other out, thus eliminating the interference of the external magnetic field change on the temperature measurement. The temperature change is calculated using the following formula:

[0085] ;

[0086] in, To determine the temperature change when frequency points ① and ③ are selected as the frequency point combination, The temperature coefficient of the zero-field splitting frequency of the diamond NV color center. The typical value is -74kHz / ℃.

[0087] Frequency combination two: The first subunit 11 operates at frequency point ②, and the second subunit 12 operates at frequency point ④. Signal conditioning circuit 2 will... Converted to the optical probe magnetic resonance frequency shift at frequency point ② ,Will Converted to the optical probe magnetic resonance frequency shift at frequency point ④ Since the temperature response polarities of frequencies ② and ④ are both positive, when the ambient temperature changes, and The directions are consistent, and the sum of the two increases the amplitude to twice that of a single channel; since the magnetic field response at frequency ② is positive and the magnetic field response at frequency ④ is negative, when the applied magnetic field changes, and Since they are in opposite directions, their addition cancels each other out. The temperature change is calculated using the following formula:

[0088] ;in, The temperature change when frequency points ② and ④ are selected as the combination of frequency points.

[0089] The two frequency combinations can be flexibly selected according to actual application requirements.

[0090] like Figure 6 As shown, under different temperature conditions (48.8℃, 54.2℃ and 58.6℃), the resonance depression position in the photodetector magnetic resonance curve (current-microwave frequency response curve) of the sensitive unit array shows a linear shift towards the lower frequency direction as the temperature increases. This indicates that the electrical signal output by the embodiment of the present invention has good linear response characteristics to temperature changes, and the experiment verifies the effectiveness of the above-mentioned temperature measurement decoupling principle.

[0091] This invention also provides a magnetic field measurement method based on the above-mentioned magnetic field and temperature sensing device with a three-unit differential structure. Taking frequency point combination one (frequency point ① and frequency point ④) as an example, the method includes the following steps:

[0092] S1: Turn on the optical excitation source 103 to excite the diamond NV color center sensitive material 101, causing it to generate a fluorescent signal;

[0093] S2: According to the mode selection instruction, the frequency of the microwave excitation signal of the first subunit 11 is adjusted to frequency point ① by the microcontroller or digital signal processor built into the signal conditioning circuit 2, and the frequency of the microwave excitation signal of the second subunit 12 is adjusted to frequency point ④, and the magnetic field measurement mode is entered; the third subunit 13 is not loaded with a microwave excitation signal.

[0094] S3: After the fluorescence signal of each sub-unit is filtered by the filter element 104 to remove the emitted light from the optical excitation source 103, it is received by the photodetector 105 and converted into an electrical signal. , , .

[0095] S4: The built-in microcontroller or digital signal processor in the signal conditioning circuit 2 processes electrical signals. , , Differential processing is performed to obtain the first differential signal. Second differential signal This eliminates background interference caused by fluctuations in optical excitation intensity and changes in ambient light.

[0096] S5: The microcontroller or digital signal processor built into the signal conditioning circuit 2, based on the slope of the photodetector magnetic resonance curve at frequency point ①, modulates the first differential signal... Converted to the optically detected magnetic resonance frequency shift at frequency point ① The second differential signal Converted to the optical probe magnetic resonance frequency shift at frequency point ④ Since the magnetic field responses at frequency points ① and ④ have the same polarity, and When added in the same direction, the magnetic field response amplitude is increased to twice that of a single channel; since the temperature response at frequency ① is negative and the temperature response at frequency ④ is positive, when the ambient temperature changes... and Since they are in opposite directions, their addition cancels each other out, thus eliminating the interference of temperature changes on the magnetic field measurement. The microcontroller or digital signal processor built into the signal conditioning circuit 2 calculates the change in magnetic field according to the following formula:

[0097] ;

[0098] in, To determine the magnetic field change when frequency points ① and ④ are selected as the frequency point combination, The gyromagnetic ratio of the diamond NV color center is 2.8 MHz / Gs.

[0099] refer to Figure 5 Under different applied magnetic field conditions, the position of the resonance depression in the optical detection magnetic resonance curve (current-microwave frequency response curve) shifts linearly with the increase of the magnetic field, verifying the feasibility of the magnetic field detection method of the magnetic field and temperature sensing device based on the three-unit differential structure in the embodiments of the present invention.

[0100] This invention also provides a temperature measurement method based on the above-mentioned magnetic field and temperature sensing device with a three-unit differential structure. Taking frequency point combination one (frequency point ① and frequency point ③) as an example, the method includes the following steps:

[0101] S1: Turn on the optical excitation source 103 to excite the diamond NV color center sensitive material 101, causing it to generate a fluorescent signal;

[0102] S2: According to the mode selection instruction, the frequency of the microwave excitation signal of the first subunit 11 is adjusted to frequency point ① by the microcontroller or digital signal processor built into the signal conditioning circuit 2, and the frequency of the microwave excitation signal of the second subunit 12 is adjusted to frequency point ③, and the temperature measurement mode is entered; the third subunit 13 is not loaded with a microwave excitation signal.

[0103] S3: The fluorescence signals generated by each subunit are filtered by the filter element 104 to remove the emitted light from the optical excitation source 103, and then received by the photodetector 105 and converted into electrical signals. , , .

[0104] S4: The built-in microcontroller or digital signal processor in the signal conditioning circuit 2 processes electrical signals. , , Differential processing is performed to obtain the first differential signal. Second differential signal This eliminates background interference caused by fluctuations in optical excitation intensity and changes in ambient light.

[0105] S5: The microcontroller or digital signal processor built into the signal conditioning circuit 2, based on the slope of the photodetector magnetic resonance curve at frequency point ①, modulates the first differential signal... Converted to the optically detected magnetic resonance frequency shift at frequency point ① Based on the slope of the optically detected magnetic resonance curve at frequency point ③, the second differential signal... Converted to the optical probe magnetic resonance frequency shift at frequency point ③ Since the temperature response polarities of frequency points ① and ③ are the same, and When the signals are added in the same direction, the temperature response amplitude is increased to twice that of a single channel; since the magnetic field responses at the two frequencies have opposite polarities, the frequency shifts caused by the magnetic fields cancel each other out. The microcontroller or digital signal processor built into signal conditioning circuit 2 calculates the temperature change according to the following formula:

[0106] ;

[0107] in, To determine the temperature change when frequency points ① and ③ are selected as the frequency point combination, The temperature coefficient of the zero-field splitting frequency of the diamond NV color center. The typical value is -74kHz / ℃.

[0108] refer to Figure 6Under different temperature conditions, the position of the resonance depression in the optical detection magnetic resonance curve (current-microwave frequency response curve) shifts linearly towards the lower frequency direction as the temperature increases, verifying the feasibility of the temperature detection method of the magnetic field and temperature sensing device based on the three-unit differential structure in the embodiments of the present invention.

[0109] It should be noted that in this embodiment, the signal conditioning circuit 2 can use a microcontroller or digital signal processor as the core operation and control unit, and is implemented in conjunction with an analog-to-digital converter (or analog sampling circuit) and a laser driving circuit. The analog-to-digital converter (or analog sampling circuit) is used to synchronously acquire the output electrical signals of the three sub-units, the laser driving circuit is used to regulate the power and on / off state of the optical excitation source 103, and the microcontroller or digital signal processor is responsible for switching the (magnetic field and temperature) measurement modes, differential processing, conversion of the optically detected magnetic resonance frequency offset, and calculation of the magnetic temperature change (magnetic field change and temperature change). The selection and programming of the above-mentioned devices are conventional techniques in this field. Those skilled in the art can reasonably select the appropriate devices and write corresponding programs to implement them based on the functional descriptions in this specification, without requiring any creative effort.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the embodiments of the present invention have been described in detail, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of protection of the claims of the present invention.

Claims

1. A magnetic field and temperature sensing device based on a three-unit differential structure, characterized in that, include: At least one sensitive unit (1) and a signal conditioning circuit (2); Each of the aforementioned sensitive units (1) includes a first subunit (11), a second subunit (12), and a third subunit (13), each subunit comprising: Diamond NV color center sensitive material (101) for sensing magnetic fields and temperature; An optical excitation source (103) is used to excite the diamond NV color center sensitive material (101) to generate a fluorescence signal; A photodetector (105) is used to receive the fluorescence signal and convert it into an electrical signal; Both the first subunit (11) and the second subunit (12) include a microwave application structure (102) for applying a microwave excitation signal to the diamond NV color center sensitive material (101); The microwave application structures (102) of the first subunit (11) and the second subunit (12) are respectively used to load microwave excitation signals of different frequencies; The signal conditioning circuit (2) adjusts the frequency of the microwave excitation signal of the first subunit (11) and the second subunit (12) to output the magnetic field measurement result in the magnetic field measurement mode and the temperature measurement result in the temperature measurement mode. In the magnetic field measurement mode, the electrical signal output by the first subunit (11) and the electrical signal output by the second subunit (12) have the same response polarity to changes in magnetic field and opposite response polarity to changes in temperature. In temperature measurement mode, the electrical signal output by the first subunit (11) and the electrical signal output by the second subunit (12) have the same polarity in response to temperature changes and opposite polarity in response to magnetic field changes. The signal conditioning circuit (2) is used to: take the difference between the electrical signal output by the first subunit (11) and the electrical signal output by the third subunit (13) as a first differential signal, and take the difference between the electrical signal output by the second subunit (12) and the electrical signal output by the third subunit (13) as a second differential signal; and convert the first differential signal into the optical detection magnetic resonance frequency offset at the operating frequency of the first subunit (11). The second differential signal is converted into the optical detection magnetic resonance frequency offset at the operating frequency of the second subunit (12). and according to the and stated It outputs the magnetic field measurement results or temperature measurement results.

2. The magnetic field and temperature sensing device based on a three-unit differential structure according to claim 1, characterized in that, There are multiple sensitive units (1), and the multiple sensitive units (1) are arranged in an array to form a sensitive unit array. The electrical signals of each unit are converged in the interconnection structure of the sensitive unit array and then output to the signal conditioning circuit (2).

3. The magnetic field and temperature sensing device based on a three-unit differential structure according to claim 2, characterized in that, The sensitive unit array is a 10×10 pixel array.

4. The magnetic field and temperature sensing device based on a three-unit differential structure according to claim 1, characterized in that, The signal conditioning circuit (2) is also used to regulate the power and on / off state of the optical excitation source (103).

5. The magnetic field and temperature sensing device based on a three-unit differential structure according to claim 1, characterized in that, Each subunit also includes a filter element (104) disposed between the diamond NV color center sensitive material (101) and the photodetector (105), the filter element (104) being used to filter out the emitted light from the optical excitation source (103) and transmit the fluorescence signal.

6. The magnetic field and temperature sensing device based on a three-unit differential structure according to claim 5, characterized in that, The filter element (104) is a 600-800nm ​​bandpass filter; the photodetector (105) is a photodiode.

7. The magnetic field and temperature sensing device based on a three-unit differential structure according to claim 1, characterized in that, The optical excitation source (103) is a laser; the microwave application structure (102) is a microstrip antenna.

8. The magnetic field and temperature sensing device based on a three-unit differential structure according to claim 1, characterized in that, In each subunit, the optical excitation source (103) is disposed to the side of the diamond NV center sensitive material (101); the photodetector (105) is disposed below the diamond NV center sensitive material (101).

9. A measurement method based on a magnetic field and temperature sensing device with a three-unit differential structure as described in any one of claims 1 to 8, characterized in that, include: Step S1: Turn on the optical excitation source (103) to excite the diamond NV color center sensitive material (101) and make it generate a fluorescence signal; Step S2: The frequency of the microwave excitation signal of the first subunit (11) and the second subunit (12) is adjusted by the signal conditioning circuit (2), and the magnetic field measurement mode or temperature measurement mode is selected. The microwave excitation signal of the corresponding frequency is loaded onto the microwave application structure (102) of the first subunit (11) and the second subunit (12). The third subunit (13) does not load the microwave excitation signal. Step S3: Receive the fluorescence signal generated by the diamond NV color center sensitive material (101) in each subunit through the photodetector (105) and convert it into an electrical signal. , , ; Step S4: Convert the electrical signal output by the first subunit (11) The electrical signal output by the third subunit (13) The difference is used as the first differential signal. ,in, ; The electrical signal output by the second subunit (12) The electrical signal output by the third subunit (13) The difference is used as the second differential signal. ;in, ; Step S5: In the magnetic field measurement mode, the signal conditioning circuit (2) adjusts the signal according to the first differential signal. With the second differential signal Converted to the corresponding optically detected magnetic resonance frequency shifts , The magnetic field measurement results are output based on the magnetic field calculation formula. The formula for calculating the magnetic field is: ; in, This is the change in magnetic field. The gyromagnetic ratio of the diamond NV color center is 2.8 MHz / Gs; In temperature measurement mode, the signal conditioning circuit (2) adjusts the signal according to the first differential signal. With the second differential signal Converted to the corresponding optically detected magnetic resonance frequency shifts , The temperature measurement result is output according to the temperature calculation formula; The formula for temperature calculation is: ; in, The change in temperature The temperature coefficient of the zero-field splitting frequency of the diamond NV color center. The typical value is -74kHz / ℃.

Images