119 results about "Colour centre" patented technology

The invention discloses a detection method of an ocean magnetic field sensor based on a diamond NV color center. The detection method comprises the following steps: S1, calibrating a base line; s2, alternately measuring fluorescence between two single quantum resonance frequencies, and obtaining a difference to realize DQ reading; s3, three-axis compensation current is adjusted based on closed-loop control, and the NV working point is maintained at zero magnetization bias; s4, obtaining background magnetic field change through digital demodulation and adaptive filtering; and S5, calculating a gradient based on the spatial difference of the multi-point light spots, judging the existence and trajectory of the underwater vehicle in combination with a threshold value and a spectrum matching method, calibrating the threshold value according to the magnetic field characteristics of the existing underwater vehicle, adopting short-time Fourier transform signal spectrum, comparing the threshold value with known submarine characteristic spectrum data, and prompting if the similarity exceeds a set threshold value. According to the detection method, the measurement precision and the anti-interference capability can be improved, and the method is suitable for real-time monitoring of weak magnetic anomalies (such as magnetic moment disturbance of an underwater vehicle).

The invention discloses an underwater magnetic field measuring device based on a diamond NV color center. The underwater magnetic field measuring device comprises a diamond NV color center module, an incident laser excitation module, a multi-path optical coupling module, a microwave excitation module, a fluorescence acquisition and photoelectric conversion module, a signal processing and control module and a magnetic field module, the multi-path optical coupling module is used for dividing an optical fiber into multiple paths and collecting fluorescence generated by the diamond block; the microwave excitation module is used for switching between two single-quantum resonance frequencies to drive an NV color center to realize double-quantum DQ reading; and the signal processing and control module comprises an FPGA (Field Programmable Gate Array) processing unit of a field programmable logic array chip. According to the invention, a dual-quantum DQ working point of a diamond NV color center is used as a measurement channel, common-mode influence of D is removed through differential measurement, the problem of D drift caused by temperature drift, stress and material aging is physically and obviously inhibited, and the device can still realize ultrahigh-sensitivity measurement in a complex underwater environment.

The invention discloses a quantum magnetometer device based on a diamond nitrogen-vacancy color center. The quantum magnetometer device comprises a laser emission unit used for generating a 532nm laser beam based on a laser trigger signal; the beam shaping unit is used for focusing the laser beam to the diamond sample; the diamond sample comprises an NV color center array with specific depth on the surface or in the diamond sample, and electrons in NV color centers are excited based on laser beams to transition and generate fluorescence; the fluorescence collection unit is used for separating exciting light from 650-800nm fluorescence signals and converting the fluorescence signals into multi-channel electric signals; the microwave radiation unit is distributed around a diamond sample space and emits three independently regulated microwave frequencies at the same time; and the control and processing unit is used for receiving and processing the multi-channel electric signals in real time and analyzing magnetic field parameters based on the optical detection magnetic resonance spectral line. Synchronous measurement of a three-dimensional magnetic field is realized, and the limitation of single-axis measurement of a traditional NV magnetometer is broken through.

The invention provides a high-sensitivity superconducting magnetic detection device and method based on an NV color center under high pressure and low temperature. The high-sensitivity superconducting magnetic detection device comprises a microwave emission module, an optical excitation module, an imaging module, a fluorescence collection module, a data collection and control module, a diamond anvil cell, a low-temperature test module and a magnet module. The method has the beneficial effects that the diamond injected with the NV color center serves as the anvil cell of the diamond anvil cell, and high-pressure and low-temperature conditions are synchronously obtained in liquid helium and liquid nitrogen temperature zones; according to the invention, in-situ pressure measurement can be realized under high pressure, and ruby or Raman standard pressure is not needed; a sample is placed in the diamond anvil cell, the diamond anvil cell is placed in the low-temperature cavity, the lowest temperature of 4K and in-situ pressurization can be realized by using the low-temperature test module, and the quality of a microwave signal transmitted by the low-temperature semi-steel cable is higher and the loss is smaller by using the low-temperature semi-steel cable. And the superconducting property of the material at low temperature and high pressure is quantitatively tested under the condition of high integration.

The invention provides a light source multiplexing diamond NV color center wide field detection system and an illumination detection method. The system comprises a diamond containing an NV color center, an exciting light module, a first double-color sheet, an objective lens, a second double-color sheet, a wide field imaging module, an illumination imaging module and a microwave module, exciting light generated by the exciting light module irradiates the first double-color piece, is guided to the objective lens, and irradiates the diamond after being transmitted by the objective lens so as to excite the NV color center of the diamond to generate fluorescent light; the objective lens is of an infinity type; the exciting light is irradiated to a sample to be detected after being transmitted by the diamond; fluorescent light and exciting light from a sample to be detected are collected by the objective lens, then transmitted to the first double-color piece and guided to the second double-color piece through the first double-color piece, the second double-color piece guides the fluorescent light to the wide-field imaging module for imaging, and the exciting light in the second double-color piece is guided to the illumination imaging module for imaging. Illumination can be achieved in the exciting light working state, exciting light switching operation in the prior art is avoided, and efficiency can be remarkably improved.

In a general aspect, orientation information is used to generate a unique code. In some aspects, orientation information is extracted from an object. The object includes multiple elements, and the orientation information indicates the relative spatial orientations of the respective elements. The orientation information can be extracted, for instance, by a scanner system that detects the elements. A unique code is generated for the object based on the orientation information. In some examples, the elements are diamond particles that each have one or more color centers, and the orientation information is extracted by detecting the color centers.

The invention provides an imaging device and method based on a diamond NV color center, and the device comprises a diamond containing the NV color center, an objective lens assembly, an optical detection module, a displacement platform, and a microwave module. The objective lens assembly comprises an objective lens turntable, and an objective lens and a suction tube which are mounted on the objective lens turntable, the objective lens turntable can switch the objective lens or the suction tube to a working position, and the suction tube is used for introducing negative pressure; the displacement platform is located below the objective lens assembly, and the upper surface of the displacement platform is used for placing a to-be-tested piece and can regulate and control the position of the to-be-tested piece; the diamond is used for being placed on a to-be-tested piece and located below the working position of the objective lens assembly, when the suction pipe is switched to the working position, an opening in the lower end of the suction pipe faces the diamond, and the diamond can be adsorbed or released through negative pressure in the control pipe. And the implementation mode is simple and convenient, the use of other auxiliary equipment is reduced, the occupied space is simplified, and accurate and efficient operation of adsorbing and releasing the diamond can be ensured. By using the device, multiple times of imaging scanning of a large-size to-be-measured piece can be realized.

In one form of the present disclosure, a quantum sensor comprises a quantum device. The quantum device comprises gallium nitride (GaN) with a color center with a zero-phonon line (ZPL) between about 900 nanometers (nm) and about 990 nm. The GaN can be doped with silicon (Si) and have low carbon (C) and oxygen (O) impurities. In one example, the quantum device is GaN doped with about 1016 atoms of Si per cm3, having less than about 8×1015 C atoms per cm3 and less than about 6×1015 O atoms per cm3, and a Ga vacancy density less than about 1016 vacancies per cm3.

The invention provides a polarization selectivity all-dielectric high-saturation structural color metasurface with a maintainable color center. The metasurface sequentially comprises a SiO2 semi-ellipsoid layer, a GaN elliptic cylinder array and a PDMS flexible substrate from top to bottom, wherein the SiO2 semi-ellipsoid layer and the GaN elliptic cylinder array form a periodically arranged double-layer all-dielectric nanostructure unit. Under the condition of x polarization incidence, the structure generates a narrow-band high-reflection structural color in a visible light wave band, the full width at half maximum of a main reflection peak is about 9 nm, the peak reflectivity can reach 99.8% or above, and the reflectivity of a secondary reflection peak on the short wave side is lower than 0.01; and under the y polarization incidence condition orthogonal to the light source, the reflectivity near the corresponding wavelength is lower than 2%, and the light source shows remarkable polarization selectivity. The inventor further finds that when the equivalent radius change of the nano unit causes the reduction of the reflection efficiency, the reflectivity of the main peak can be recovered by adjusting the long-short axis ratio of the GaN elliptic cylinder and the SiO2 semi-ellipsoid, and the central wavelength of the main formant is basically kept unchanged, so that the brightness adjustment is realized on the premise that the color center is basically constant. The structure is suitable for flexible or wearable optical devices, polarization-related structural color display and other applications.

A diamond magneto-optical sensor includes: a diamond that includes a color center with an electronic spin and is irradiated with excitation light, and an irradiation unit that irradiates the diamond with the excitation light of the color center and electromagnetic waves for magnetic resonance, wherein the irradiation unit receives modulated light having been subjected to amplitude modulation, and a modulation frequency of the modulated light is included in a microwave frequency band.

The invention provides an angular displacement measurement method and system based on diamond quantum sensing, and relates to the field of quantum sensing, and the method comprises the steps: taking a diamond NV color center as a probe, placing the probe in a magnetic field and a static magnetic field which rotate at a constant speed, and carrying out the coaxial rotation with a to-be-measured object, the diamond NV color center of the system is measured by adopting continuous light excitation and microwave radiation based on diamond quantum sensing angular displacement; acquiring a first fluorescence signal emitted by the diamond NV color center at a first moment, and outputting a corresponding first traveling wave signal; acquiring a second fluorescence signal emitted by the diamond NV color center at a second moment, and outputting a corresponding second traveling wave signal; and based on the phase difference between the first traveling wave signal and the second traveling wave signal, determining the angular displacement value of the rotation of the object to be measured of the angular displacement measurement system based on diamond quantum sensing. According to the embodiment of the invention, the diamond NV color center is highly sensitive to the change of the magnetic field, and the measurement precision of angular displacement can be improved.

A magnetometer includes a resonant atomic medium, a photonic crystal surface emitting laser (PCSEL), and a light detector. The resonant atomic medium includes color centers or other dopants that form vacancies that fluoresce light when excited by an excitation light having an excitation wavelength. Characteristics of the fluoresced light are dependent upon a magnetic field applied to the resonant atomic medium. The PCSEL is configured to develop the excitation light having the excitation wavelength of the vacancies and direct the excitation light into the resonant atomic medium. The light detector is configured to receive the fluoresced light and generate a measurement signal indicative of the fluoresced light and the magnetic field applied to the resonant atomic medium.

A nanoscale temperature detector comprising a diamond sensing probe (1) having a lateral dimension of at least 200 nanometers and having a sensing tip (2) with a radius of curvature (R) of less than 100 nanometers, less than 10 nanometers or less than 1 nanometer and a plurality of color centers (5) showing temperature sensitive features in the emission count rate. The diamond sensing probe (1) has a lateral dimension of at least 200 nanometers and is connected to a detector system (13) by a mounting structure (6). A thermal isolation barrier (3) thermally separates the sensing probe (1) from the detector system (13).

The application discloses a two-dimensional magnetic field imaging method based on diamond NV color centers, comprising the following steps: generating a rough scanning path according to a region to be measured, controlling a displacement scanning unit to drive a diamond NV color center detection unit to move point by point, locking and triggering collection after reaching a position; obtaining the light detection magnetic resonance spectrum of each measuring point through light excitation and microwave sweep, and calculating the magnetic field information; identifying an abnormal region according to the rough scanning result and generating a fine scanning path, and performing fine scanning on the abnormal region; periodically returning to a reference point to collect a reference spectrum line during the scanning process, and compensating for the drift of the current batch of measuring points, and finally matching the compensated magnetic field information with coordinate information to generate a two-dimensional magnetic field distribution map. The application can improve the positioning accuracy, measurement stability and imaging reliability of two-dimensional magnetic field imaging.

The invention discloses a solid-state spin quantum nondestructive detector, which comprises a laser module used for outputting excitation light, and an NV color center generates photoluminescence under the irradiation of the excitation light; the microwave module is used for outputting and modulating a microwave signal; the sensor is used for detecting an external leakage magnetic field and comprises an optical fiber with one side end face being an inclined plane and a diamond which is arranged below the inclined plane and contains an NV color center, and the excitation light is transmitted through the optical fiber and then forms reflection excitation light and transmission excitation light through the inclined plane; according to the invention, a part of split excitation light is used as reference light to carry out differential noise reduction processing, so that the measurement precision is improved, and the surface crack of the to-be-measured object can be accurately measured; the beveled optical fiber is combined with the diamond containing the ensemble NV color center, the beveled optical fiber is used for replacing a traditional optical prism or an optical fiber beam splitter to achieve laser beam splitting, and the beveled optical fiber beam splitter has the advantage of being small and exquisite and can be conveniently integrated on a microstrip antenna.

The application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical field.The present application discloses a kind of defect detection method and equipment based on NV color center, it is related to nondestructive testing technical

The invention discloses an insulation defect detection method based on a quantum color center technology, and belongs to the field of state monitoring. Comprising the steps that a quantum sensing module and an excitation and signal acquisition module are adopted to detect the insulation defect of the electrical equipment, the quantum sensing module adopts a silicon carbide color center chip, a double-vacancy defect is prepared through an ion implantation and annealing process, a substrate material adopts AlN ceramic, and a protective layer adopts an aerogel composite structure; a DPSS laser is adopted as a light source of a laser excitation chain of an excitation and signal acquisition module, and a single-photon avalanche diode array is adopted as a detector of a fluorescence acquisition chain; a signal processing flow is based on silicon carbide double-vacancy color center fluorescence lifetime attenuation characteristics, partial discharge detection is carried out, dynamic change and frequency spectrum characteristics of a color center fluorescence lifetime tau value are analyzed, a multi-physics field decoupling algorithm combining time domain fluorescence lifetime analysis, frequency domain vibration spectrum extraction and a machine learning classification model is adopted, and a silicon carbide double-vacancy color center fluorescence lifetime tau value is analyzed. And high-precision identification and positioning of discharge types such as corona discharge and creeping discharge are realized.

The invention discloses a preparation method and application of a directional NV color center diamond layer for vector magnetic field measurement, and aims to solve the technical problems of measurement signal anisotropy attenuation, sensitivity reduction and the like caused by a randomly oriented NV color center in a diamond quantum magnetic sensing system based on the NV color center. The preparation method comprises the following steps: 1, pre-treating a seed wafer in mixed acid; 2, carrying out etching treatment by using hydrogen plasma; 3, introducing nitrogen, methane, oxygen and hydrogen into the vacuum cavity, controlling process parameters such as gas concentration, growth temperature and pressure intensity, and carrying out microwave plasma chemical vapor deposition growth; 4, cooling; 5, cutting off polycrystals; and 6, annealing treatment. According to the NV color center coherence time field grown by the preparation method, the orientation rate can reach more than 80%, the orientation high-sensitivity measurement of the vector magnetic field can be realized by accurately controlling the spatial orientation distribution of the NV color center, and the detection performance of the quantum sensor is remarkably improved.

The application relates to the technical field of quantum sensing and smart grid monitoring, in particular to a current detection method and device integrating sensing and communication and a current detection system; the method is applied to a control module in a current detection system, and the method comprises the following steps: in response to triggering of a sensing mode, a light excitation and detection module is controlled to apply excitation laser to an NV color center probe, and an antenna module is controlled to apply a microwave signal to the NV color center probe; a fluorescence intensity signal is acquired; according to the fluorescence intensity signal, the frequency of the microwave signal and the positional relationship between the NV color center probe and a to-be-detected transmission line, an induced magnetic field signal of an environmental magnetic field is determined, and a target current value in the to-be-detected transmission line is determined according to the induced magnetic field signal; in response to triggering of a communication mode, detection information containing the target current value is generated, and the antenna module is controlled to send the detection information. The scheme of the application can reduce the power consumption of the system.

The invention discloses an NV color center excitation laser adjusting method, a medium, a control device and measurement equipment, and relates to the technical field of quantum measurement. The method is used for the NV color center excitation laser debugging system. The system comprises a laser used for emitting target laser, at least two adjusting lenses used for expanding the target laser, and a focusing lens used for focusing the expanded target laser to generate laser spots. The method comprises the following steps: adjusting an adjusting lens according to a laser spot, so that the laser spot is matched with a laser incident surface of a target diamond; the adjusting lens is adjusted according to the fluorescence brightness generated when the NV color center in the target diamond is excited by the laser spot, so that the area of the laser spot is reduced, the position of the laser spot on the laser incident plane is adjusted, and the fluorescence brightness meets the target excitation requirement. Therefore, the NV color center position can be quickly positioned, the concentration ratio of the laser is enhanced, the laser intensity and the effective utilization rate are improved, and the accuracy and the sensitivity of measuring equipment are improved.

The invention relates to the technical field of radio frequency circuits and quantum sensing, and discloses an NV color center-oriented hybrid neural network adaptive pre-distortion system and method, a storage medium and electronic equipment, and the system comprises a main signal path, a feedback observation path and a hybrid neural network pre-distortion controller; a digital predistorter in the main signal channel receives an original digital signal, predistorts the original digital signal to generate a predistorted signal, and outputs an amplified signal after the predistorted signal passes through a power amplifier; a coupler of the feedback observation path receives an amplified signal, and the amplified signal passes through an attenuator and an analog-to-digital converter and then outputs a digital feedback signal; and the hybrid neural network predistortion controller receives the original digital signal and a digital feedback signal output by the analog-to-digital converter, outputs a calibration signal required by the digital predistorter through a neural network model based on the original digital signal and the digital feedback signal, and controls the digital predistorter based on the calibration signal.

The invention relates to the technical field of temperature control, in particular to a temperature control system and method based on an NV color center, and the system comprises a diamond NV color center temperature sensing module which is used for sensing the temperature change of a target area in real time and generating a corresponding fluorescence signal; the dual-channel demodulation and signal processing module is connected with the diamond NV color center temperature sensing module and is used for extracting an actual temperature value from the fluorescence signal; the PID temperature control module is connected with the dual-channel demodulation and signal processing module and is used for generating a control signal according to the deviation between the actual temperature value and the target temperature value; and the adjustment execution module is connected with the PID temperature control module and is used for adjusting the temperature of the target area according to the control signal. The high-stability temperature control system has the beneficial effects that diamond NV color center quantum sensing, two-channel demodulation and PID closed-loop control technologies are fused, and high-stability temperature control of milliKelvin-level precision and microsecond-level response under the micro-nano scale is realized.

The invention belongs to the technical field of radioactive element detection, and discloses a radioactive element content detection method and system and application, and the detection method comprises the following steps: carrying out quantum state initialization on a diamond nitrogen vacancy color center; converting gamma ray radiation of the to-be-detected sample into an optical signal; converting and amplifying the optical signal and driving a micro coil to obtain an electromagnetic signal; receiving the electric signal through the diamond nitrogen vacancy color center, and outputting a response light signal; converting the response optical signal into a response electric signal; and calculating to obtain the radioactive element content of the to-be-detected sample. According to the method, the detection lower limit of a traditional method is broken through by utilizing the high sensitivity characteristic of quantum sensing, and the content detection of trace radioactive elements is realized; gamma ray radiation is converted and amplified into electric signals which can be received by a diamond nitrogen vacancy color center, so that the coupling difficulty of quantum sensing and radioactive element signals is solved; and a novel high-sensitivity detection means is provided for the fields of environmental safety, food safety and nuclear emergency.

This solid quantum sensor module is provided with: a substrate having a first main surface and a second main surface on the opposite side from the first main surface; a solid element located on the first main surface side of the substrate and having a color center; a light guide plate located between the substrate and the solid element; an antenna for microwave field transmission; a light source that is positioned on the first main surface side of the substrate and emits light having a first wavelength that excites the color center from a ground state to an excited state; and a photodetector that is positioned on the first main surface side of the substrate and detects photoluminescence including a second wavelength emitted from the solid element, the solid element overlapping the microwave field transmission antenna when viewed along the normal direction of the first main surface of the substrate. The light detector does not overlap with the microwave field transmission antenna when viewed along the normal direction of the first main surface of the substrate.

The application discloses a method for testing anti-radiation damage performance of calcium fluoride crystal. The method adopts X-ray radiation to irradiate calcium fluoride crystal, and judges the anti-radiation damage performance of the crystal according to an X-ray radiation dose for inducing color center absorption peak of the calcium fluoride crystal and a color center absorption coefficient of a characteristic absorption peak induced by radiation.

A vector microwave detection device comprises a detection mechanism which is provided with a microwave plate for transmitting to-be-measured microwaves and an NV color center probe, and the detection mechanism is configured to enable the NV color center probe to move along a preset path in a microwave field of the to-be-measured vector microwaves; the microscope lens is mounted above the detection mechanism, is suitable for focusing the laser onto the NV color center probe so as to enable the NV color center to emit fluorescence under the action of the laser, and is suitable for collecting the fluorescence emitted by the NV color center under the action of the laser; the counting mechanism is suitable for counting the fluorescence collected by the microscope lens; and the calculation mechanism is suitable for obtaining the polarization direction of the vector microwave field to be measured according to the projection relationship between the first and second Labir oscillation frequencies of the NV color center probe in each strong effective field and the vector microwave to be measured in the direction of each strong effective field.

This invention provides a magnetic detection device based on diamond NV centers and the Kerr effect. It achieves the sharing of light sources and optical paths between magnetic detection technologies based on the magneto-optical Kerr effect and those based on NV centers, combining the two technologies and greatly simplifying the device structure. This increases the intensity of the optical signal received by the detection module, reduces noise interference in the signal, and thus improves the accuracy of magnetic detection. It can simultaneously meet the requirements of rapid and high-resolution detection, and improve the overall detection speed while ensuring detection accuracy.

This invention belongs to the field of current measurement and signal processing technology, specifically disclosing a method and system for extracting the amplitude of the flipped magnetic field of a nitrogen-vacancy color center quantum sensor. The method includes: acquiring the raw signal output by the nitrogen-vacancy color center quantum sensor and preprocessing it; detecting the minimum point of the preprocessed signal, setting a minimum interval and amplitude threshold to eliminate false boundaries, and forming a stable half-cycle segment; constructing two sets of complementary sequences based on the half-cycle segment to achieve the retention of the first half-cycle and zeroing of the second half-cycle, and the retention of the second half-cycle and zeroing of the first half-cycle, respectively, within each cycle; performing fundamental frequency phase-locked demodulation on the two sets of complementary sequences to obtain two fundamental amplitude components; fusing the two fundamental amplitude components to obtain a nitrogen-vacancy fundamental amplitude monitoring quantity that is proportional to the amplitude of the measured current. This invention effectively eliminates the measurement error caused by the asymmetry of the positive and negative half-cycles of the original current and achieves stable extraction of the fundamental amplitude.

The application discloses a method for measuring color center density in a BBO crystal, comprising the following steps: building a measurement system containing the measured BBO crystal; calculating the total loss of the optical system corresponding to different input pump powers of the measurement system at different temperatures based on the optical characteristic parameters of the optical system in the measurement system; and calculating the color center density of the measured BBO crystal corresponding to different pump powers at different temperatures according to the total loss and the optical characteristic parameters of the optical system. The application calculates the color center density of the BBO crystal based on the optical characteristic parameters and the total loss of the measurement system by constructing a simple measurement system, and the measurement equipment and method are simple and fast, the measurement cost is greatly reduced, and the influence factors are less, so that a good foundation is provided for the accuracy of the measurement result.

The application relates to the field of quantum precision measurement, and discloses a fluorescence data noise reduction demodulation method and a related device, which are applied to a process of sensing based on a diamond NV color center and using a photodetection magnetic resonance method. The fluorescence data noise reduction demodulation method provided by the scheme can move the center line of fluorescence digital signal data under different carrier frequencies to the vicinity of a zero axis, effectively reduces data offset, ensures the accuracy of quantum precision measurement, and the data used for calculating the zero axis offset value and the data used for filtering demodulation are fluorescence digital signal data under the same carrier frequency, so that the calculated zero axis offset value is very accurate and is not easily affected by external environment.