Confocal optical path system based on diamond NV color center and current detection method

Abstract

The invention discloses a confocal light path system based on a diamond NV color center and a current detection method, and belongs to the technical field of quantum measurement, the confocal light path system comprises a main control module, an excitation light path module, a microwave driving module, a fluorescence collection module, a fluorescence processing module, an environment adaptive control module, an active feedback regulation and control module and a signal processing module, wherein the main control module is used for generating a synchronous time sequence control signal; the excitation light path module is used for generating, regulating and controlling excitation laser and guiding the excitation laser to the diamond NV color center sample; the microwave driving module is used for generating and applying a microwave field and a magnetic field to the diamond NV color center sample; and the active feedback regulation and control module is used for dynamically generating an optimization parameter instruction according to the preprocessed electric signal and the magnetic field information, and dynamically adjusting the working parameters of the excitation light path module and the microwave driving module. Through full-link modular integration and cooperative intelligent regulation and control, the NV color center current detection precision, stability and applicability are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of quantum measurement technology, and more specifically, relates to a confocal optical path system based on diamond NV color centers and a current detection method. Background Technology

[0002] Currently, the current sensors used in power grids are mainly traditional electromagnetic current transformers. Due to limitations imposed by their magnetization curve characteristics, the linearity of these sensors remains good only within a certain range. In the extreme regions of the measurement range, especially in the low-current range, the measurement accuracy often falls short of optimal levels. This results in current sensors being unable to simultaneously monitor both high-current and low-current-to-ground faults caused by insulation and grounding faults in power grid online safety monitoring systems.

[0003] Traditional power system voltage measurement methods utilize potential transformers (PTs). The size, insulation complexity, and manufacturing and installation costs of PTs increase with voltage levels. Electromagnetic voltage transformers are prone to ferromagnetic saturation, leading to a reduction in their dynamic range and, in more severe cases, ferroresonance, which is more pronounced in lower voltage distribution networks. Capacitive voltage transformers, due to their capacitive inertial elements, exhibit poor transient characteristics and may experience high-frequency oscillations on their secondary side under high-frequency overvoltage conditions. Contact-type voltage measurement terminals used for inspection require disruption of their original electrical structure and power outages, making them inconvenient to use.

[0004] With the construction of new power systems, on the one hand, the large-scale grid connection of new energy power generation and the continuous increase of nonlinear power equipment are increasing. The new power systems exhibit characteristics such as wide dynamics, fast time-varying, and strong randomness, and are accompanied by extreme quantities such as instantaneous impacts and harmonic over-limits, which puts forward higher requirements for the accuracy and rapid response capability of measurement technology.

[0005] In the field of quantum sensing, magnetic detection technology based on diamond NV centers has shown great potential, but existing measurement schemes still have significant shortcomings. While some integrated schemes have achieved system miniaturization, their fixed structure, non-replaceable core components, and lack of environmental disturbance compensation and optical path coordination mechanisms lead to insufficient measurement stability in complex environments. Typical confocal optical path schemes, although providing a complete optical path structure, have limited microwave control capabilities, simplistic filtering designs, and a decentralized layout of system links, failing to achieve timing synchronization and closed-loop control, thus hindering improvements in system coordination efficiency and detection accuracy.

[0006] Therefore, there is an urgent need in this field for a high-performance confocal optical path system that can achieve full-link coordinated control and has environmental adaptability. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a confocal optical path system and current detection method based on diamond NV centers, so as to achieve accurate excitation of NV centers, high spatial resolution acquisition of fluorescence signals and efficient suppression of stray light, thereby improving the signal quality and stability of NV center optical detection magnetic resonance experiments.

[0008] The present invention adopts the following technical solution.

[0009] A first aspect of the present invention provides a confocal optical path system based on diamond NV color centers, comprising: The system comprises a main control module, an excitation optical path module, a microwave drive module, a fluorescence collection module, a fluorescence processing module, an environmental adaptive control module 26, an active feedback modulation module 28, and a signal processing module 27, wherein: The main control module is connected to the excitation optical path module, microwave drive module, fluorescence processing module, active feedback control module 28 and signal processing module 27 to generate synchronous timing control signals; The excitation optical path module is used to generate and regulate the excitation laser according to the synchronous timing control signal, and guide the excitation laser to the diamond NV color center sample 10; The microwave drive module is used to generate and apply microwave and magnetic fields to the diamond NV color center sample 10 according to the synchronous timing control signal, so as to coordinately control its spin state. The fluorescence collection module is used to collect the fluorescence signal generated by the diamond NV color center sample 10 after excitation; The fluorescence processing module is signal-connected to the fluorescence collection module and is used to convert fluorescence signals into electrical signals and perform preprocessing. The signal processing module 27 is connected to the fluorescence processing module and is used to perform calculations and noise suppression on the preprocessed electrical signal in order to extract magnetic field information. The active feedback control module 28 is connected to the fluorescence processing module, the signal processing module 27, the excitation optical path module and the microwave drive module. It is used to dynamically generate optimization parameter instructions based on the pre-processed electrical signal and magnetic field information, and dynamically adjust the working parameters of the excitation optical path module and the microwave drive module. The environmental adaptive control module 26 is used to provide stability support for the signals of the excitation optical path module and the microwave drive module.

[0010] Optionally, the main control module sends TTL signals to the excitation optical path module, microwave drive module, and fluorescence processing module via a TTL control link to achieve timing synchronization of the excitation optical path module, microwave drive module, and fluorescence processing module.

[0011] Optionally, the microwave drive module includes a signal generator 13, two microwave sources, a combiner 16, a microwave antenna 12, and a triaxial magnetic field coil 11; Signal generator 13 is controlled by the main control module and is used to generate synchronous TTL timing signals; Two microwave sources respond to the synchronous TTL timing signal to generate two microwave signals. The two microwave signals are combined by the combiner 16, selected by the microwave switch 17 and transmitted to the microwave antenna 12. Microwave antenna 12 radiates a microwave field to diamond NV color center sample 10 according to the selected microwave signal; The triaxial magnetic field coil 11 is used to generate a three-dimensional compensating magnetic field that works in conjunction with the microwave field to initialize or modulate the spin energy level of the NV color center.

[0012] Optionally, the excitation optical path module includes a laser excitation unit, a polarization control unit, and a pulse modulation and beam shaping unit, wherein: The laser excitation unit, polarization control unit, and pulse modulation and beam shaping unit are arranged sequentially along the optical path; The laser excitation unit is used to emit linearly polarized laser light of a specific wavelength. The polarization control unit is used to receive the laser emitted from the laser excitation unit and control its polarization state and intensity. The pulse modulation and beam shaping unit is used to receive the synchronous TTL timing signal, modulate the continuous laser after polarization control unit into pulse laser and shape the laser beam, and guide the shaped laser to the diamond NV color center sample 10.

[0013] Optionally, the pulse modulation and beam shaping unit includes a first lens 4, an acousto-optic modulator 5, a second lens 6, an aperture 7, a dichroic mirror 8, and an objective lens 9; The first lens 4 is used to focus the laser beam, which has been modulated by the polarization control unit, onto the modulation area of ​​the acousto-optic modulator 5. The acousto-optic modulator 5 is used to receive the synchronous TTL timing signal and modulate the incident continuous laser into pulsed laser. The second lens 6 is disposed on the light-emitting side of the acousto-optic modulator 5 and is used to collimate the modulated pulsed laser. The aperture 7 is set in the collimating optical path of the second lens 6 and is used to filter the target diffraction order of the pulsed laser; Dichroic mirror 8 is set at a preset tilt angle on the light-emitting side of aperture 7 to reflect the filtered pulsed laser to objective lens 9; Objective lens 9 is used to focus the incident pulsed laser onto the diamond NV color center sample 10.

[0014] Optionally, the fluorescence collection module includes a reflector 18, a first filter 19, a second filter 20, and a third lens 21; The fluorescence signal generated by the diamond NV color center sample 10 after being excited is transmitted through the dichroic mirror 8 and then incident on the reflecting mirror 18. After being reflected by mirror 18, the fluorescence signal passes sequentially through first filter 19, second filter 20 and third lens 21 before being transmitted to the fluorescence processing module.

[0015] Optionally, the signal processing module 27 is configured to perform: The preprocessed electrical signal is solved to reconstruct the optically detected magnetic resonance spectrum; The spin resonance characteristic parameters of the NV color center are extracted from the optically detected magnetic resonance spectrum. The resonance characteristic parameters include resonance frequency, spectral line contrast and spectral linewidth. Based on the physical relationship between resonance characteristic parameters and magnetic field, the intensity information of the magnetic field to be measured is calculated and output.

[0016] Optionally, the active feedback control module 28 is used to perform first feedback control and second feedback control, wherein: The first feedback regulation includes: Based on the fluorescence intensity and signal-to-noise ratio output by the fluorescence processing module, adjust the laser power and aperture 7 of the excitation optical path module; The second feedback regulation includes: Based on the resonance characteristic parameters calculated by the signal processing module 27, adjust the microwave frequency, microwave power, microwave operating mode, or compensation magnetic field of the microwave drive module.

[0017] Optionally, the environmental adaptive control module 26 includes a vibration-resistant unit and a temperature control unit; The vibration-resistant unit is used to support and stabilize the optical components in the excitation optical path module; The temperature control unit is used to maintain the temperature stability of the sample area in the microwave driving module.

[0018] A second aspect of the present invention provides a current detection method based on diamond NV centers, and a confocal optical path system based on diamond NV centers as described in the first aspect of the present invention, characterized in that it includes: The excitation laser is generated and controlled, and then directed to the diamond NV color center sample 10 carrying the current to be measured. A microwave field and a compensating magnetic field are generated and applied to the diamond NV color center sample 10 to synergistically regulate its spin state; Collect the fluorescence signal generated by the diamond NV color center sample 10 after it is stimulated; The fluorescence signal is converted into an electrical signal and preprocessed. The preprocessed electrical signal is solved and noise is suppressed to extract the magnetic field information generated by the current under test; Based on the extracted magnetic field information, and according to the correspondence between the magnetic field and the current, the final value of the current to be measured is calculated. During the detection process, the following coordinated control is executed: Based on the preprocessed electrical signal and magnetic field information, control commands are dynamically generated to collaboratively optimize the parameters of the excitation laser, microwave field, and compensation magnetic field. Generate system synchronization timing signals to coordinate the timing of excitation laser application, microwave field application, fluorescence signal preprocessing, and control command generation; The system monitors and compensates for the excitation and magnetic field environments to maintain system stability.

[0019] Compared with the prior art, the beneficial effects of the present invention include at least the following: 1. To address the problem of low excitation efficiency caused by insufficient focusing accuracy of excitation light in existing technologies, this invention designs a precise focusing structure including an achromatic lens group, an adjustable aperture, and a high numerical aperture objective lens, and combines it with a polarization synergistic control mechanism to achieve precise convergence and energy concentration of the excitation spot in the target region of the NV color center, thereby significantly improving the excitation efficiency of the NV color center.

[0020] 2. To address the problem of low signal-to-noise ratio caused by weak stray light suppression capability in existing technologies, this invention constructs a multi-layered collaborative filtering system consisting of a dichroic mirror, a long-pass filter, and a band-pass filter. Combined with the spatial filtering characteristics of a confocal structure, it achieves comprehensive suppression of residual excitation light, ambient stray light, and non-target wavelength light, effectively improving the purity and signal-to-noise ratio of the fluorescence signal and making the extraction of weak quantum signals clearer and more reliable.

[0021] 3. To address the issues of low integration, complex debugging, and poor adaptability in existing technologies, this invention integrates functions such as laser excitation, polarization control, pulse modulation, and beam shaping into independent collaborative modules through a full-link modular integration scheme and a replaceable core optical component design. This significantly simplifies the optical path calibration process, reduces debugging difficulty and time consumption, and enables the system to flexibly adapt to the detection needs of diamond samples of different sizes, thus significantly enhancing its versatility and practicality. Attached Figure Description

[0022] Figure 1 The energy level structure and Zeeman effect of the NV color center provided in accordance with the embodiments of the present invention; Figure 2 The excitation optical path module provided according to the embodiments of the present invention includes: 1-532nm laser, 2-half-wave plate, 3-polarizing beam splitter, 4-first lens, 5-acoustic-optic modulator (AOM), 6-second lens, and 7-aperture.

[0023] Figure 3In the microwave driving module provided according to the embodiments of the present invention, 9-objective lens, 10-diamond sample, 11-triaxial magnetic field coil, 12-microwave antenna, 13-signal generator, 14-first microwave source, 15-second microwave source, 16-combiner, 17-microwave switch, 24-lock-in amplifier, 25-computer.

[0024] Figure 4 In the fluorescence collection module provided according to the embodiments of the present invention, 18-reflector, 19-long-pass filter, 20-band-pass filter, 21-third lens.

[0025] Figure 5 In the fluorescence processing module provided according to the embodiments of the present invention, 22-photodetector, 23-IV conversion circuit, 24-lock-in amplifier, 25-computer, 27-signal processing module.

[0026] Figure 6 This is a schematic diagram of the confocal optical path platform structure based on diamond NV color centers according to the present invention. In the figure: 1-532nm laser, 2-half-wave plate, 3-polarizing beam splitter, 4-first lens, 5-acoustic-optic modulator (AOM), 6-second lens, 7-aperture, 8-dichroic mirror, 9-objective lens, 10-diamond sample, 11-triaxial magnetic field coil, 12-microwave antenna, 13-signal generator, 14-microwave source 1, 15-microwave source 2, 16-combiner, 17-microwave switch, 18-reflector, 19-first filter, 20-second filter, 21-third lens, 22-photodetector, 23-IV conversion circuit, 24-lock-in amplifier, 25-computer, 26-environmental adaptive control module, 27-signal processing module, 28-active feedback control module. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0028] In Embodiment 1, this invention provides a confocal optical path system based on diamond NV color centers, such as... Figure 6 As shown, it includes: The system comprises a main control module, an excitation optical path module, a microwave drive module, a fluorescence collection module, a fluorescence processing module, an environmental adaptive control module 26, an active feedback modulation module 28, and a signal processing module 27, wherein: The main control module is connected to the excitation optical path module, microwave drive module, fluorescence processing module, active feedback control module 28 and signal processing module 27 to generate synchronous timing control signals; The excitation optical path module is used to generate and regulate the excitation laser according to the synchronous timing control signal, and guide the excitation laser to the diamond NV color center sample 10; The microwave drive module is used to generate and apply microwave and magnetic fields to the diamond NV color center sample 10 according to the synchronous timing control signal, so as to coordinately control its spin state. The fluorescence collection module is used to collect the fluorescence signal generated by the diamond NV color center sample 10 after excitation; The fluorescence processing module is signal-connected to the fluorescence collection module and is used to convert fluorescence signals into electrical signals and perform preprocessing. The signal processing module 27 is connected to the fluorescence processing module and is used to perform calculations and noise suppression on the preprocessed electrical signal in order to extract magnetic field information. The active feedback control module 28 is connected to the fluorescence processing module, the signal processing module 27, the excitation optical path module and the microwave drive module. It is used to dynamically generate optimization parameter instructions based on the pre-processed electrical signal and magnetic field information, and dynamically adjust the working parameters of the excitation optical path module and the microwave drive module. The environmental adaptive control module 26 is used to provide stability support for the signals of the excitation optical path module and the microwave drive module.

[0029] Preferably, the main control module sends TTL signals to the excitation optical path module, the microwave drive module, and the fluorescence processing module via a TTL control link to achieve timing synchronization of the excitation optical path module, the microwave drive module, and the fluorescence processing module.

[0030] Preferably, such as Figure 3 As shown, the microwave driving module includes a signal generator 13, a first microwave source 14, a second microwave source 15, a combiner 16, a microwave antenna 12, and a triaxial magnetic field coil 11. Signal generator 13 is controlled by the main control module and is used to generate synchronous TTL timing signals; The first microwave source 14 and the second microwave source 15 generate two microwave signals in response to the synchronous TTL timing signal. After the two microwave signals are combined by the combiner 16, they are selected by the microwave switch 17 and transmitted to the microwave antenna 12. Microwave antenna 12 radiates a microwave field to diamond NV color center sample 10 according to the selected microwave signal; The triaxial magnetic field coil 11 is used to generate a three-dimensional compensating magnetic field that works in conjunction with the microwave field to initialize or modulate the spin energy level of the NV color center.

[0031] Specifically, the microwave driving module includes a signal generator 13, a diamond NV color center sample 10, a triaxial magnetic field coil 11, a microwave antenna 12, a signal generator 13, a first microwave source 14, a second microwave source 15, a combiner 16, and a microwave switch 17. A three-dimensional uniform magnetic field is generated by a triaxial magnetic field coil 11 surrounding the diamond to modulate the spin energy level of the NV color center; Microwave antenna 12 transmits microwave signals, and signal generator 13 synchronously triggers first microwave source 14, second microwave source 15 and AOM; The microwave signals generated by the first microwave source 14 and the second microwave source 15 are combined by the combiner 16 and selected by the microwave switch 17 before being transmitted to the microwave antenna 12, thereby realizing the microwave control of the spin state of the NV color center.

[0032] It should be noted that the microwave drive module is mainly used to provide the microwave field required to change the electron configuration of the NV color center in the ms=0 and ms=±1 states, such as... Figure 1 As shown, the high-frequency signal generator 13 first acts on the structure of the microwave antenna 12, and then the microwave antenna 12 radiates high-frequency microwaves outward, thereby acting on the diamond NV color center.

[0033] Preferably, such as Figure 2 As shown, the excitation optical path module includes a laser excitation unit, a polarization control unit, and a pulse modulation and beam shaping unit, wherein: The laser excitation unit, polarization control unit, and pulse modulation and beam shaping unit are arranged sequentially along the optical path; The laser excitation unit is used to emit linearly polarized laser light of a specific wavelength. The polarization control unit is used to receive the laser emitted from the laser excitation unit and control its polarization state and intensity. The pulse modulation and beam shaping unit is used to receive the synchronous TTL timing signal, modulate the continuous laser after polarization control unit into pulse laser and shape the laser beam, and guide the shaped laser to the diamond NV color center sample 10.

[0034] Specifically, the laser excitation unit is a 532nm solid-state linearly polarized laser used to emit linearly polarized laser light, with an adjustable output power range of 10mW-200mW to meet the excitation requirements of different concentrations of NV color centers.

[0035] Specifically, the polarization control unit includes a half-wave plate 2 and a polarization beam splitter 3; the half-wave plate 2 is disposed in the laser output path and is used to adjust the laser linear polarization angle. The polarizing beam splitter 3 is positioned on the light-emitting side of the half-wave plate 2, separating P / S polarized light and allowing only P-polarized light to pass through; by adjusting the rotation angle of the half-wave plate 2, the intensity of the emitted laser can be continuously controlled. The half-wave plate 2 and the polarizing beam splitter prism 3 (PBS) work together to form a polarization control unit. The half-wave plate 2 can rotate around the optical axis to adjust the polarization angle of the incident laser; the PBS separates the P-polarized light from the S-polarized light, allowing only the P-polarized light to pass through. By adjusting the rotation angle of the half-wave plate 2 to change the angle between the polarization direction and the transmission direction of the PBS, the intensity of the emitted laser can be continuously controlled to adapt to the excitation requirements of different concentrations of NV centers, while ensuring the consistency of the laser polarization state.

[0036] Specifically, the laser is used to emit highly stable linearly polarized lasers, providing an efficient photoexcitation source for NV color centers. It adapts to the differentiated needs of low-concentration (requiring high-power excitation) and high-concentration (requiring low-power to avoid saturation) NV color centers. With good laser stability and noise level, the signal-to-noise ratio of the system can be effectively improved.

[0037] Specifically, the excitation optical path module is designed with a combination structure of an achromatic lens group, an adjustable aperture 7, and a high numerical aperture objective lens 9. The combination structure of the achromatic lens group (focal length f=20mm, model AC254-020-A-ML) made of crown glass and flint glass composite, the adjustable aperture 7, and the high numerical aperture objective lens 9 (NA=0.95) is as follows: the achromatic lens group is specifically designed to correct the chromatic aberration between the 532nm excitation laser and the characteristic fluorescence of the NV color center (637nm), and with the coordinated control mechanism of the half-wave plate 2 and the polarizing beam splitter 3, the precise focusing of the excitation spot and the continuous adaptation of the laser intensity are achieved. The adjustable aperture 7 is installed on the light-emitting side of the acousto-optic modulator 5 and in the optical path behind the second achromatic lens. The specific purpose of adjusting its aperture is: when the aperture is small (≤1mm), the first-order diffraction laser of the acousto-optic modulator 5 is screened, stray diffraction orders are filtered out, and the purity of the laser pulse is improved; when the aperture is increased (1-3mm), it can be adapted to the excitation requirements of diamond samples of different sizes and expand the effective excitation area.

[0038] More preferably, the pulse modulation and beam shaping unit includes a first lens 4, an acousto-optic modulator 5 (AOM), a second lens 6, an aperture 7, a dichroic mirror 8, and an objective lens 9; The first lens 4 is used to focus the laser beam, which has been modulated by the polarization control unit, onto the modulation area of ​​the acousto-optic modulator 5. The acousto-optic modulator 5 is used to receive the synchronous TTL timing signal and modulate the incident continuous laser into pulsed laser. The second lens 6 is disposed on the light-emitting side of the acousto-optic modulator 5 and is used to collimate the modulated pulsed laser. The aperture 7 is set in the collimating optical path of the second lens 6 and is used to filter the target diffraction order of the pulsed laser; Dichroic mirror 8 is set at a preset tilt angle on the light-emitting side of aperture 7 to reflect the filtered pulsed laser to objective lens 9; Objective lens 9 is used to focus the incident pulsed laser onto the diamond NV color center sample 10.

[0039] Specifically, the acousto-optic modulator 5, as the core device for pulse modulation, can receive TTL signals to control the laser diffraction state, converting continuous laser light into nanosecond-level pulses. This allows for precise control of the laser's action time and suppression of the photobleaching effect of the NV color centers. Simultaneously, by synchronizing the pulse timing with subsequent microwave and magnetic field modulation, time-resolved excitation of the spin state of the NV color centers can be achieved.

[0040] Specifically, the first lens 4 focuses the laser onto the center of the AOM aperture, and the AOM receives the TTL signal to modulate the continuous laser into nanosecond-level pulses; the second lens 6 collimates the diffracted laser, and the aperture 7 filters the diffraction order to ensure the purity of the laser pulse.

[0041] Specifically, the objective lens 9 is positioned on the transmission path of the excitation laser and the collection path of the fluorescence, and is used to focus the excitation laser onto the diamond NV center sample 10 and collect the fluorescence signal generated by the diamond NV center sample 10 after excitation. Objective 9 focuses the laser onto the diamond NV color center region with a focused spot diameter ≤1μm, ensuring spatial accuracy of excitation. On the other hand, as a key element for fluorescence collection, its high numerical aperture design can efficiently capture the 600nm-800nm ​​fluorescence generated by the NV color center. Combined with the confocal structure, it suppresses off-focal plane signals, laying the foundation for high spatial resolution detection.

[0042] Specifically, the dichroic mirror 8 is tilted on the light-emitting side of the objective lens 9, reflecting the 532nm excitation laser to the objective lens 9, while transmitting 600nm-800nm ​​NV color center fluorescence; When the laser is incident on the dichroic mirror (8) at a preset tilt angle (45° angle), the laser will be reflected at a 45° angle onto the objective lens 9, and after being focused by the objective lens 9, it will irradiate the diamond.

[0043] Preferably, such as Figure 4 As shown, the fluorescence collection module includes a reflector 18, a first filter 19, a second filter 20, and a third lens 21; The fluorescence signal generated by the diamond NV color center sample 10 after being excited is transmitted through the dichroic mirror 8 and then incident on the reflecting mirror 18. After being reflected by mirror 18, the fluorescence signal passes sequentially through first filter 19, second filter 20 and third lens 21 before being transmitted to the fluorescence processing module.

[0044] Specifically, the first filter 19 and the second filter 20 work together to filter out stray light in the fluorescence and select the target wavelength.

[0045] Specifically, the fluorescence collection module includes a reflector 18, a first filter 19, a second filter 20, and a third lens 21; the first and second filters 20 are sequentially disposed on the fluorescence emitting side of the dichroic mirror 8 to filter out residual excitation light and stray light, retaining only the target fluorescence band; the third lens 21 focuses the fluorescence onto the subsequent detection element; The first filter 19 is a long-pass filter, and the second filter 20 is a band-pass filter. The long-pass filter and the band-pass filter are combined. The long-pass filter is used to filter out residual 532nm excitation light and short-wavelength environmental stray light that are not completely reflected by the dichroic mirror 8. The band-pass filter further selects the characteristic fluorescence band of the NV color center to improve the suppression rate of stray light in non-target bands.

[0046] It should be noted that the fluorescence collection module employs a multi-layered collaborative filtering design consisting of an 8-dichroic mirror, a long-pass filter, and a band-pass filter. Combined with the inherent spatial filtering characteristics of the confocal optical path, this constructs a multi-dimensional stray light suppression link. This design overcomes the limitations of existing single-filtering methods, efficiently separating excitation light and fluorescence, and comprehensively filtering out various types of stray light, significantly improving the purity of the fluorescence signal.

[0047] Preferably, such as Figure 5 As shown, the fluorescence processing module includes a photoelectric conversion unit and a signal preprocessing unit; The photoelectric conversion unit is used to convert fluorescence signals into electrical signals; The signal preprocessing unit is connected to the photoelectric conversion unit and is used to amplify and filter the electrical signal.

[0048] Specifically, the fluorescence processing module includes a photodetector 22, an IV conversion circuit 23, and a lock-in amplifier 24, which are used to convert fluorescence signals into voltage signals; The photoelectric conversion unit includes a photodetector 22, which converts the fluorescence signal into an electrical signal; The signal preprocessing unit includes an IV conversion circuit 23 and a lock-in amplifier 24. The IV conversion circuit 23 accurately converts the weak photocurrent output by the photodetector 22 into a voltage signal, and the lock-in amplifier 24 performs lock-in amplification on the electrical signal to extract the weak fluorescence modulation signal.

[0049] Specifically, photodetector 22 is a single-photon photodetector, serving as the terminal device for fluorescence signal detection. It converts the weak fluorescent photons emitted by the NV color center (wavelength range of 600-800nm) into electrical signals. The single-photon counter directly quantifies the fluorescence intensity of the NV color center by measuring the number of fluorescent photons in this wavelength range. Its high sensitivity allows the experimenter to acquire high-quality measurement data in a short time, improving the efficiency of quantum measurement. Combined with the signal amplification and extraction by lock-in amplifier 24, it can capture weak fluorescence modulation signals at the single NV color center level, which is key to realizing quantum state detection.

[0050] Preferably, the signal processing module 27 is used to perform: The preprocessed electrical signal is solved to reconstruct the optically detected magnetic resonance spectrum; Extracting spin resonance characteristic parameters of NV color centers from optically detected magnetic resonance spectra; Based on the physical relationship between resonance characteristic parameters and magnetic field, the intensity information of the magnetic field to be measured is calculated and output.

[0051] Specifically, the signal processing module 27 receives the raw electrical signals from the photodetector 22, lock-in amplifier 24, etc. in the fluorescence processing module, and performs in-depth calculation and noise suppression of the electrical signals through a dedicated signal purification algorithm.

[0052] Preferably, the active feedback control module 28 is used to perform the first feedback control and the second feedback control, wherein: The first feedback regulation includes: Based on the fluorescence intensity and signal-to-noise ratio output by the fluorescence processing module, adjust the laser power and aperture 7 of the excitation optical path module; The second feedback regulation includes: Based on the magnetic field information characteristic parameters calculated by the signal processing module 27, adjust the microwave frequency, microwave power, microwave operating mode, or compensate the magnetic field of the microwave drive module.

[0053] More preferably, the first feedback control includes: Monitor the fluorescence intensity and signal-to-noise ratio of the output signal from the fluorescence processing module; when the fluorescence intensity is lower than the first preset threshold, increase the laser power of the excitation optical path module; When the fluorescence intensity is higher than the second preset threshold, the laser power of the excitation optical path module is reduced; When the signal-to-noise ratio is lower than the set value, the aperture of aperture 7 in the excitation optical path module is reduced; Specifically, the decision-making logic adopts a PID closed-loop control algorithm: when the fluorescence intensity is lower than the preset threshold, the laser power is automatically increased; when the fluorescence intensity is higher than the saturation threshold, the laser power is gradually reduced; when the signal-to-noise ratio is lower than the set value, the aperture of the adjustable aperture 7 is reduced to reduce stray light interference.

[0054] More preferably, the second feedback control includes: The resonance peak position, peak width, and peak depth of the ODMR spectral line are calculated by the monitoring signal processing module 27. When the resonance peak position deviates from the target frequency, the output frequency of the microwave source in the microwave drive module is dynamically adjusted, and the compensation magnetic field of the triaxial magnetic field coil 11 is adjusted synchronously. When the peak width is greater than the threshold, reduce the microwave power of the microwave drive module; When the peak depth is insufficient, the control microwave drive module switches to the dual microwave source combining mode.

[0055] Specifically, the second feedback control uses signal processing module 27 to analyze three parameters of the ODMR spectrum: resonance peak position, peak width, and peak depth. The decision logic is based on a resonance locking algorithm: when the resonance peak position deviates from the target frequency, the output frequency of the dual microwave sources is dynamically fine-tuned, and the magnetic field gradient is compensated by a triaxial Helmholtz coil to bring the peak position back to the target value; when the peak width is greater than the threshold, the microwave power is reduced and the timing synchronization phase is optimized to reduce the control error caused by microwave field inhomogeneity; when the peak depth is insufficient, the microwave signal superposition mode (dual-source signal combining) is switched to enhance the effect of the microwave field on the NV color center and ensure efficient spin state flipping.

[0056] In addition, the active feedback control module 28 can further improve signal quality by optimizing the detection gain of the fluorescence processing module and the filtering parameters of the lock-in amplifier 24, thereby strengthening stray light suppression from the hardware end and ultimately achieving an overall improvement in the fluorescence signal-to-noise ratio and system calculation accuracy.

[0057] Preferably, the environmental adaptive control module 26 includes a vibration-resistant unit and a temperature control unit; The vibration-resistant unit is used to support and stabilize the optical components in the excitation optical path module; The temperature control unit is used to maintain the temperature stability of the sample area in the microwave driving module.

[0058] Specifically, the vibration-resistant unit is applied to the excitation optical path module to provide vibration-resistant bases for key optical path components such as lasers, lenses, and objective lenses to ensure the stability of the optical path; The temperature control unit is applied to the microwave drive module. The temperature control components are integrated in the diamond sample stage (around the microwave antenna 12 and the triaxial magnetic field coil 11) to stabilize the energy level environment of the NV color center.

[0059] Preferably, the modules of the system are modularly integrated, and the core optical and electronic components are replaceable.

[0060] Preferably, the main control module is a computer 25, which serves as the control and information center of the system. In addition to generating synchronous timing signals, it is also electrically connected to a lock-in amplifier 24, a signal processing module 27, etc., to receive data and perform final analysis, storage, and graphical display.

[0061] The system adopts a full-link modular integrated architecture, which mainly includes an excitation optical path module, a microwave drive module, a fluorescence collection module, a fluorescence processing module, a signal processing module 27, an environmental adaptive control module 26, and an active feedback control module 28.

[0062] It should be noted that the core of this invention lies in achieving a comprehensive improvement in system performance through the following design and synergy: The excitation optical path module is configured with a polarization-pulse-focusing coordinated control mechanism to achieve dynamic matching of excitation parameters and efficient excitation.

[0063] The microwave drive module adopts a multi-source coupling and magnetic field compensation structure, which greatly improves the flexibility and precision of quantum state control.

[0064] The fluorescence collection module constructs a multi-dimensional filtering system to enhance stray light suppression from both spectral and spatial dimensions.

[0065] The signal processing module 27 is equipped with a dedicated signal processing and noise suppression algorithm, which aims to improve the accuracy of extracting weak magnetic field information.

[0066] The environmental adaptive control module 26 integrates sample environment regulation and optical path stability assurance functions to compensate for external environmental disturbances and maintain system baseline stability.

[0067] The active feedback control module 28 relies on the real-time monitoring data of the fluorescence processing module and the signal processing module 27 to dynamically adjust the excitation and microwave control parameters, thereby achieving adaptive optimization and closed-loop control of quantum state regulation.

[0068] The above modules work together in a deep synergy to form a high-precision, highly stable quantum sensing system with self-optimization capabilities.

[0069] In a preferred embodiment of the present invention, the system adopts a full-link modular integration scheme. Functions such as laser excitation, polarization control, pulse modulation and beam shaping, and confocal excitation are integrated into independent collaborative modules. These modules are connected via precision optical adjustment frames, and the core optical components are designed to be replaceable. This scheme significantly reduces the system's debugging difficulty and complexity, while also giving it excellent versatility and adaptability.

[0070] In Embodiment 2, this invention provides a current detection method based on diamond NV centers, which is based on the confocal optical path system based on diamond NV centers described in Embodiment 1, comprising: The excitation laser is generated and controlled, and then directed to the diamond NV color center sample 10 carrying the current to be measured. A microwave field and a compensating magnetic field are generated and applied to the diamond NV color center sample 10 to synergistically regulate its spin state; Collect the fluorescence signal generated by the diamond NV color center sample 10 after it is stimulated; The fluorescence signal is converted into an electrical signal and preprocessed. The preprocessed electrical signal is solved and noise is suppressed to extract the magnetic field information generated by the current under test; Based on the extracted magnetic field information, and according to the correspondence between the magnetic field and the current, the final value of the current to be measured is calculated. During the detection process, the following coordinated control is executed: Based on the preprocessed electrical signal and magnetic field information, control commands are dynamically generated to collaboratively optimize the parameters of the excitation laser, microwave field, and compensation magnetic field. Generate system synchronization timing signals to coordinate the timing of excitation laser application, microwave field application, fluorescence signal preprocessing, and control command generation; The system monitors and compensates for the excitation and magnetic field environments to maintain system stability.

[0071] In Embodiment 3, the present invention provides an application example of current detection for high-voltage transmission lines in smart grids. The application scenario of this example is an outdoor high-voltage transmission environment with strong electromagnetic interference and complex stray light.

[0072] In this application example, the preferred technical solution is a combination of multi-layer collaborative filtering design, full-link modular integration, and precise focusing control mechanism.

[0073] Specifically, a complete multi-layer filtering chain consisting of a dichroic mirror, a long-pass filter, and a bandpass filter is employed to suppress strong environmental interference. Modularly integrated excitation and collection optical path components are used, enabling rapid outdoor installation and calibration via standard interfaces. Furthermore, a high numerical aperture objective lens and achromatic lens group are utilized to precisely focus the excitation spot onto the diamond NV color center. This solution effectively achieves high-precision detection with high voltage and high current.

[0074] In contrast, if a simplified filtering method with a single bandpass filter, a distributed optical path layout, or an alternative with a common objective lens is used, the signal-to-noise ratio of the system under strong interference will decrease significantly, the debugging time will increase dramatically, and sufficient excitation efficiency cannot be guaranteed to meet the detection requirements.

[0075] In Embodiment 4, the present invention provides an application example of DC current detection in industrial equipment. The application scenario of this example is an industrial site that requires cost control, compatibility with various size sensor chips, and variable current range.

[0076] In this application example, a simplified multilayer filter design, a replaceable core optical component, and a polarization control mechanism are preferred technical solutions.

[0077] Specifically, a simplified filtering combination of "dichroic mirror + long-pass filter" is adopted to balance cost and performance; the objective lens is designed with a quick-change structure to adapt to diamond sensor chips of different thicknesses; and the incident laser power is continuously adjusted by rotating a half-wave plate to match different DC current ranges.

[0078] This solution significantly improves the system's economy and adaptability while ensuring the accuracy of industrial environmental monitoring.

[0079] In contrast, if a single long-pass filter, fixed optical components, or alternatives without polarization control are used, there will be significant residual excitation light interference, making it unsuitable for different chips. Furthermore, the optical path needs to be readjusted when the current range changes, resulting in poor adaptability.

[0080] In Embodiment 5, the present invention provides an application example of weak current detection in microelectronic devices. The application scenario of this application example is the internal current detection of microelectronic devices with limited space and extremely weak signals.

[0081] In this application example, a preferred technical solution is a fully configured multi-layer collaborative filtering system, a high-precision focusing combination, and a compact modular integration. Specifically, a fully configured filtering link is enabled to ensure that weak fluorescence is not overwhelmed; a combination of a high-precision achromatic lens group and a high numerical aperture objective lens is used to maximize the excitation light energy density; and all optical modules are compactly integrated to accommodate the installation space limitations of a miniature detection platform. This solution achieves highly sensitive detection of weak currents.

[0082] In contrast, if alternative solutions such as a two-layer filter without a bandpass filter, a focusing structure without an achromatic lens group, or a non-modular integrated design are adopted, stray light in non-target bands cannot be effectively filtered out, the light spot dispersion leads to insufficient excitation efficiency, and the optical path cannot be adjusted according to the needs of micro-devices, severely limiting the scope of application.

[0083] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A confocal optical path system based on diamond NV color centers, characterized in that, include: The main control module, excitation optical path module, microwave drive module, fluorescence collection module, fluorescence processing module, environmental adaptive control module (26), active feedback modulation module (28), and signal processing module (27) are as follows: The main control module is connected to the excitation optical path module, microwave drive module, fluorescence processing module, active feedback control module (28) and signal processing module (27) to generate synchronous timing control signals; The excitation optical path module is used to generate and regulate the excitation laser according to the synchronous timing control signal, and guide the excitation laser to the diamond NV color center sample (10). The microwave driving module is used to generate and apply microwave and magnetic fields to the diamond NV color center sample (10) according to the synchronous timing control signal, so as to coordinately control its spin state; The fluorescence collection module is used to collect the fluorescence signal generated by the diamond NV color center sample (10) after it is stimulated; The fluorescence processing module is signal-connected to the fluorescence collection module and is used to convert fluorescence signals into electrical signals and perform preprocessing. The signal processing module (27) is connected to the fluorescence processing module and is used to perform calculation and noise suppression on the preprocessed electrical signal in order to extract magnetic field information. The active feedback control module (28) is connected to the fluorescence processing module, the signal processing module (27), the excitation optical path module and the microwave drive module. It is used to dynamically generate optimization parameter instructions based on the pre-processed electrical signal and magnetic field information, and dynamically adjust the working parameters of the excitation optical path module and the microwave drive module. The environmental adaptive control module (26) is used to provide stability support for the signals of the excitation optical path module and the microwave drive module.

2. The confocal optical path system based on diamond NV color centers according to claim 1, characterized in that: The main control module sends TTL signals to the excitation optical path module, microwave drive module, and fluorescence processing module via a TTL control link to achieve timing synchronization of the excitation optical path module, microwave drive module, and fluorescence processing module.

3. The confocal optical path system based on diamond NV color centers according to claim 2, characterized in that: The microwave drive module includes a signal generator (13), two microwave sources, a combiner (16), a microwave antenna (12), and a triaxial magnetic field coil (11). The signal generator (13) is controlled by the main control module and is used to generate synchronous TTL timing signals; Two microwave sources respond to the synchronous TTL timing signal to generate two microwave signals. After the two microwave signals are combined by the combiner (16), they are selected by the microwave switch (17) and transmitted to the microwave antenna (12). The microwave antenna (12) radiates a microwave field to the diamond NV color center sample (10) according to the selected microwave signal; The triaxial magnetic field coil (11) is used to generate a three-dimensional compensating magnetic field that works in conjunction with the microwave field to initialize or modulate the spin energy level of the NV color center.

4. A confocal optical path system based on diamond NV color centers according to claim 3, characterized in that: The excitation optical path module includes a laser excitation unit, a polarization control unit, and a pulse modulation and beam shaping unit, wherein: The laser excitation unit, polarization control unit, and pulse modulation and beam shaping unit are arranged sequentially along the optical path; The laser excitation unit is used to emit linearly polarized laser light of a specific wavelength. The polarization control unit is used to receive the laser emitted from the laser excitation unit and control its polarization state and intensity. The pulse modulation and beam shaping unit is used to receive the synchronous TTL timing signal, modulate the continuous laser after the polarization control unit into a pulse laser and shape the laser beam, and guide the shaped laser to the diamond NV color center sample (10).

5. A confocal optical path system based on diamond NV color centers according to claim 4, characterized in that: The pulse modulation and beam shaping unit includes a first lens (4), an acousto-optic modulator (5), a second lens (6), an aperture (7), a dichroic mirror (8), and an objective lens (9). The first lens (4) is used to focus the laser after it has been modulated by the polarization control unit onto the modulation area of ​​the acousto-optic modulator (5); The acousto-optic modulator (5) is used to receive the synchronous TTL timing signal and modulate the incident continuous laser into a pulsed laser. The second lens (6) is set on the light-emitting side of the acousto-optic modulator (5) and is used to collimate the modulated pulsed laser. The aperture (7) is set in the collimating optical path of the second lens (6) to filter the target diffraction order of the pulsed laser; The dichroic mirror (8) is set at a preset tilt angle on the light-emitting side of the aperture (7) to reflect the filtered pulsed laser to the objective lens (9). Objective (9) is used to focus the incident pulsed laser onto the diamond NV color center sample (10).

6. A confocal optical path system based on diamond NV color centers according to claim 5, characterized in that: The fluorescence collection module includes a reflector (18), a first filter (19), a second filter (20), and a third lens (21). The fluorescence signal generated by the diamond NV color center sample (10) after being excited is transmitted through the dichroic mirror (8) and then incident on the reflecting mirror (18). After being reflected by the mirror (18), the fluorescence signal passes through the first filter (19), the second filter (20) and the third lens (21) in sequence and is transmitted to the fluorescence processing module.

7. A confocal optical path system based on diamond NV color centers according to claim 1, characterized in that: The signal processing module (27) is used to perform: The preprocessed electrical signal is solved to reconstruct the optically detected magnetic resonance spectrum; The spin resonance characteristic parameters of the NV color center are extracted from the optically detected magnetic resonance spectrum. The resonance characteristic parameters include resonance frequency, spectral line contrast and spectral linewidth. Based on the physical relationship between resonance characteristic parameters and magnetic field, the intensity information of the magnetic field to be measured is calculated and output.

8. A confocal optical path system based on diamond NV color centers according to claim 7, characterized in that: The active feedback control module (28) is used to perform the first feedback control and the second feedback control, wherein: The first feedback regulation includes: Based on the fluorescence intensity and signal-to-noise ratio output by the fluorescence processing module, adjust the laser power and aperture (7) of the excitation optical path module; The second feedback regulation includes: Based on the resonance characteristic parameters calculated by the signal processing module (27), adjust the microwave frequency, microwave power, microwave action mode, or compensation magnetic field of the microwave drive module.

9. A confocal optical path system based on diamond NV color centers according to claim 1, characterized in that: The environmental adaptive control module (26) includes an anti-vibration unit and a temperature control unit; The vibration-resistant unit is used to support and stabilize the optical components in the excitation optical path module; The temperature control unit is used to maintain the temperature stability of the sample area in the microwave driving module.

10. A current detection method based on diamond NV centers, based on the confocal optical path system based on diamond NV centers as described in any one of claims 1-9, characterized in that, include: The excitation laser is generated and modulated to be directed to the diamond NV color center sample (10) carrying the current to be measured. A microwave field and a compensating magnetic field are generated and applied to the diamond NV color center sample (10) to synergistically modulate its spin state; The fluorescence signal generated by the diamond NV color center sample (10) after stimulation was collected; The fluorescence signal is converted into an electrical signal and preprocessed. The preprocessed electrical signal is solved and noise is suppressed to extract the magnetic field information generated by the current under test; Based on the extracted magnetic field information, and according to the correspondence between the magnetic field and the current, the final value of the current to be measured is calculated. During the detection process, the following coordinated control is executed: Based on the preprocessed electrical signal and magnetic field information, control commands are dynamically generated to collaboratively optimize the parameters of the excitation laser, microwave field, and compensation magnetic field. Generate system synchronization timing signals to coordinate the timing of excitation laser application, microwave field application, fluorescence signal preprocessing, and control command generation; The system monitors and compensates for the excitation and magnetic field environments to maintain system stability.

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