40 results about "Low frequency modulation" patented technology

The invention belongs to the technical field of infrared thermal imaging defect detection, and particularly discloses an in-situ infrared thermal imaging detection device based on low-frequency modulation magnetic field excitation, which comprises a magnet yoke, an infrared thermal imager, a computer, a modulation power supply and an excitation coil group, the excitation coil group at least comprises a first excitation coil, a second excitation coil, a third excitation coil and a fourth excitation coil; the modulation power supply respectively introduces low-frequency alternating currents with different phases and direct currents with different directions into the first excitation coil, the second excitation coil, the third excitation coil and the fourth excitation coil; through composite excitation of an orthogonal direct-current magnetic field and a low-frequency rotating alternating-current magnetic field, the device can form a rotating low-frequency alternating-current magnetic field in a to-be-detected pipeline, the rotating magnetic field uniformly sweeps a detection area in a plurality of periods, the influence of eddy current distribution direction sensitivity is eliminated, and large-area uniform heating is realized; the problem of low efficiency of a traditional spot scanning or line scanning mode is avoided, and the coverage area of single detection is remarkably increased.

The invention relates to the technical field of vibration monitoring, and discloses a steam turbine cold end fault diagnosis method and system based on a fusion time sequence convolutional network, and the method comprises the steps: eliminating the frequency spectrum drift caused by the rotation speed fluctuation through band-limited filtering and order domain resampling, and automatically extracting the specific low-frequency modulation component of a cold end through the envelope square and a periodogram, and finally, the asymmetric dynamic response characteristics of the rotor system are quantified by third-order spectrum phase bias, and the phase change rule is adaptively learned by the pre-trained convolutional network. According to the method, the problem that traditional amplitude spectrum analysis is high in misjudgment rate under the strong noise, variable speed and unsteady environment is effectively solved, the fault features show higher stability and distinguishability in the phase domain, and therefore high-robustness and high-precision automatic diagnosis of the turbine cold end rotor faults is achieved.

The invention relates to the technical field of integrated photoelectron and electro-optical modulation, in particular to a thin-film lithium niobate electro-optical modulator structure and a preparation method of the thin-film lithium niobate electro-optical modulator structure. The buried layer is located on the upper surface of the substrate; the partially-etched thin film lithium niobate layer comprises a partially-etched thin film lithium niobate flat plate layer and a thin film lithium niobate ridge waveguide, the partially-etched thin film lithium niobate flat plate layer is located on the upper surface of the buried layer and exposes a part of the buried layer, and the thin film lithium niobate ridge waveguide is located on the partially-etched thin film lithium niobate flat plate layer; the partially-etched buffer layer is located on the partially-etched thin film lithium niobate layer, and the side wall of the partially-etched thin film lithium niobate flat plate layer is exposed; and the metal electrode is in electric contact with the side wall of the partially etched thin film lithium niobate flat plate layer. Therefore, the problems of low-frequency modulation waveform distortion, direct-current bias point drift and the like caused by electro-optical relaxation and electric field shielding of a related thin-film lithium niobate electro-optical modulator are solved.

The invention provides an intermediate-frequency carrier and low-frequency modulated wave composite output control method, which comprises the following steps of: acquiring spatial intensity change distribution of a composite waveform in optic nerve tissue, and acquiring an actual measurement value of a carrier intensity distribution field by combining a microtube skeleton polymerization rate and an extension orientation angle of growth cone propulsion, forming basic data of an initial distribution field; extracting candidate output of an optimal waveform modulation combination from the adjusted envelope gradual change speed control combination, comparing an actual path of directional extension with an expected damage repair track through track overlapping degree measurement, and determining a quantization result of the deviation degree of the extension path; and performing deviation degree classification processing on the extension path deviation degree quantification result, obtaining a high deviation subset in a classification result, generating a compensation signal in combination with an aggregation rate change development trend, and obtaining a compensated composite waveform output combination.

The invention discloses an industrial steam extraction combined heat and power generation frequency modulation system and an industrial steam extraction combined heat and power generation frequency modulation method adapting to a variable load condition, and relates to the technical field of combined heat and power generation. The problems that the heat storage capacity is limited and the frequency modulation capacity is low due to the fact that only reheating hot section steam is utilized at the present stage are abandoned, and in the sliding temperature operation mode, due to the fact that the temperature of main steam and the temperature of reheating steam can be changed by unit variable loads, the change trend of the steam extraction amount is completely opposite to the steam extraction temperature in the frequency modulation process, and the heat storage capacity is limited. Therefore, the outlet temperature of the heated molten salt is controlled by changing the sensible heat exchange amount of the main steam superheating heat exchanger and the reheating hot section steam superheating heat exchanger, and through the control strategy that the temperature is dynamically adjusted to be stable through the flow branches and the molten salt flow distribution of the main steam superheating heat exchanger and the reheating hot section steam superheating heat exchanger, the heat exchange efficiency of the molten salt is improved. The stability of the temperature of the heat storage medium in the heat storage process is greatly improved, and finally efficient operation of the system is achieved.

The application provides a kind of dual-channel low-frequency modulation intermediate frequency bipolar pulse signal generation system, it is related to integrated circuit technical field, including: power supply and signal isolation circuit, signal generation master module and signal generation slave module respectively connected with power supply and signal isolation circuit;The circuit structure in signal generation master module and signal generation slave module is identical;Signal generation master module includes the first step-down power supply circuit connected in turn, first MCU controller circuit, first intermediate frequency bipolar pulse signal generation circuit and first signal output interface, it also includes the first output current detection circuit and the first low-frequency current signal generation circuit connected with first MCU controller circuit, and first low-frequency current signal generation circuit is also connected with first intermediate frequency bipolar pulse signal generation circuit.The technical scheme of the application overcomes the problem that the medical device in the prior art cannot stimulate multiple acupoints simultaneously.

The invention discloses an underwater image enhancement and restoration method based on a double-domain adaptive fusion module. The method comprises the following steps: feature extraction; replacing the module; performing frequency decomposition; performing high-frequency treatment; performing low-frequency modulation; reconstructing a frequency domain; performing normalization processing; performing statistical enhancement; performing nonlinear enhancement; carrying out double-source gating fusion; performing multi-scale enhancement; and network backflow and image restoration. The method has remarkable innovation points in network structure position selection, frequency modeling branch processing strategies, normalized branch modeling modes and fusion mechanism design, and can effectively improve the fineness, stability and robustness of underwater image restoration.

The application discloses a method and system for primary frequency modulation optimization based on reinforcement learning, and relates to the technical field of power dispatching and power generation. The method comprises the following steps: constructing a hierarchical reinforcement learning framework, taking system frequency deviation, frequency modulation demand prediction and unit operation state as input based on a high-level policy network, and outputting a dynamic frequency modulation weight vector; taking the dynamic frequency modulation weight vector and real-time frequency deviation as input based on a bottom-level policy network, outputting output adjustment instructions of each frequency modulation unit, and performing real-time verification; if the verification fails, triggering a strategy re-planning mechanism to iteratively calculate new instructions. The application solves the technical problem that the existing frequency modulation method cannot effectively respond to the frequency fluctuation caused by large-scale renewable energy access, resulting in slow response speed and low frequency modulation accuracy. The application achieves the technical effect of optimizing through hierarchical reinforcement learning, realizing efficient power grid frequency regulation under renewable energy access, and improving the efficiency and accuracy of primary frequency modulation.

Embodiments of the present disclosure provide a method and system for detecting abnormal instructions in a hardware device, which is applied to the technical field of network security. The method comprises receiving a mixed signal sent by a DCS device, wherein the mixed signal is obtained by mixing a side phase waveform and a low-frequency modulation signal by the DCS device, the side phase waveform is obtained by executing a DCS instruction by the DCS device, and the low-frequency modulation signal is obtained by a control device according to a first signature value corresponding to the DCS instruction; extracting a second signature value according to the mixed signal; verifying the second signature value according to the first signature value, and sending a verification result to the control device, wherein the verification result comprises a legal instruction or an illegal instruction. In this way, the identifiable execution of abnormal instructions can be realized without modifying the control device.

The invention discloses a speaker recognition model frequency modulation trigger injection method, particularly relates to the technical field of voice signal processing and artificial intelligence safety, and is used for solving the problems that an existing speaker recognition model back door injection method is insufficient in concealment, poor in black box environment adaptability, prone to distortion of trigger characteristics in the physical transmission process and poor in safety. And mainstream defense strategies such as model fine tuning, pruning and spectrum detection are difficult to resist. The method comprises the following steps: constructing a piecewise linear periodic low-frequency modulation curve for original voice, generating a smooth phase track according to a frequency and phase relationship, constructing a sinusoidal modulator to generate a hidden sample, mixing normal samples in proportion and uniformly marking, training a model by a black box, testing reproduction modulation and inputting the model; according to the method, the defects of insufficient concealment, black box adaptability, physical robustness and defensive resistance of an existing method are overcome, high-concealment, high-robustness and wide-application backdoor injection is realized, and reliable support is provided for security evaluation of a speaker recognition system.

The application discloses an underwater image enhancement and restoration method based on a dual-domain adaptive fusion module, and comprises the following steps: feature extraction, module replacement, frequency decomposition, high-frequency processing, low-frequency modulation, frequency domain reconstruction, normalization processing, statistical enhancement, nonlinear enhancement, dual-source gate fusion, multi-scale enhancement, network backflow and image restoration. The application has significant innovation points in network structure position selection, frequency modeling branch processing strategy, normalization branch modeling mode and fusion mechanism design, and can effectively improve the fineness, stability and robustness of underwater image restoration.

The application relates to the technical field of signal processing and brain wave synchronization, and provides a brain wave induction signal synthesis and modulation method and system.The method comprises the following steps: receiving user configuration, wherein the configuration at least specifies a target brain wave frequency and a modulation topology type; in response to user selection, generating a harmonic waveform synthesized based on a golden ratio constant as a carrier or a low-frequency modulation signal; applying the waveform signal to audio processing according to the selected topology type, wherein the topology type comprises binaural beat, monaural beat, isochronous tone sequence, Shepard ascending sequence and external audio modulation; enabling a smooth interpolation mechanism for real-time parameter changes of the user during the processing; and finally outputting a processed audio signal.The application solves the problems of single function, monotonous listening feeling and harsh switching in the prior art, and significantly enhances the flexibility, comfort and application range of the brain wave synchronization audio.

The invention relates to an M3C low-frequency port modeling method, device, equipment and medium based on multi-frequency coupling, and the method comprises the steps: carrying out the non-single frequency multiplication sequence decomposition of voltage, current and modulation signals in an M3C bridge arm loop under a static coordinate system, extracting the steady-state component of each frequency component, and constructing an M3C steady-state frequency domain model; based on the model, analyzing frequency coupling characteristics of the power frequency component, the low frequency component and the circulating current component in the bridge arm current, and establishing a frequency-crossing conversion relation between the bridge arm current and the power frequency current, and between the bridge arm current and the low frequency current and the circulating current; based on the cross-frequency conversion relation, performing frequency domain modeling on the low-frequency side control signal, and establishing a low-frequency modulation small signal model; the modulation effect of a control loop is introduced, a bridge arm modulation small signal comprehensive model is established, equivalent coupling factors of power frequency power grid impedance and a low-frequency transformer are considered, and an admittance model of an M3C low-frequency port is deduced. The method has the effect of improving the judgment accuracy of the dynamic relation between the bridge arm current and the port voltage under the low-frequency and frequency doubling coupling condition.

The application discloses a multi-frequency fusion ranging method and system based on echo quality adaptive control, relates to the field of multi-frequency ranging, and comprises the following steps: high and low frequency modulated light signals are transmitted to a target and echoes are received, echo signal characteristics of each frequency are obtained through demodulation, multi-frame echo quality evaluation quantities are calculated, and a hysteresis-continuous multi-frame judgment mechanism is adopted to identify that the current ranging state is normal or weak light. In the normal state, a high frequency dominant ranging strategy is executed; in the weak light state, the configuration parameters of the receiving front end are adjusted, and the judgment mechanism is used to adaptively switch to a low frequency dominant ranging strategy. According to the single frequency distance value of each frequency and the multi-frequency fusion weight corresponding to the selected strategy, the final ranging result is calculated. The application combines the hysteresis and continuous multi-frame judgment with the low frequency dominant mode, constructs a state machine cooperative link under weak light, realizes the stable linkage of the front end parameters, phase processing and multi-frequency fusion, realizes the smooth switching of the ranging strategy, and improves the ranging stability and accuracy under weak light.

The invention relates to an optical accelerometer control method based on nonlinear optical coupling, and the method comprises the steps: building a nonlinear optical coupling module, carrying out the laser initial calibration, and obtaining system parameters; and establishing a blue detuning light field to drive the mechanical oscillator to enter a pre-oscillation-starting state. During operation, the output optical power spectrum of the resonant cavity is acquired in real time, and the laser wavelength and the coupling spacing are dynamically adjusted by using a PID feedback algorithm, so that dynamic optimization adaptation of optical coupling is realized. The system monitors laser input power in real time and intelligently switches working modes according to the laser input power, parameter optical mechanical oscillation is started in a low-power interval to improve sensitivity, and the risk of mode interlocking is avoided by reducing power or adjusting coupling in a high-power interval. And finally, establishing a linear relation between the amplitude of a low-frequency modulation sideband signal generated by a mechanical oscillator in an output optical power spectrum and the external acceleration by resolving the low-frequency modulation sideband signal, so as to accurately calculate the magnitude and the direction of the acceleration. Dynamic adaptation, wide-power-range noise suppression and high-precision segmented solution are effectively realized, and the measurement accuracy is remarkably improved.

The application discloses a kind of wind generating set fault early warning method and system, comprising: S1: collecting vibration waveform original data and temperature original data, and respectively pre-processing;S2: design isomorphic double-flow network respectively extracts high-frequency impact feature and low-frequency modulation feature;S3: according to high-frequency impact feature and low-frequency modulation feature, calculate vibration feature;S4: extract temperature rate of change sequence and temperature time series feature;S5: generate vibration on temperature attention weight matrix, temperature on vibration attention weight matrix, calculate fault sensitive mask, and generate fault sensitive feature;S6: to fault sensitive feature is compressed, again calculate three-stage early warning probability vector, unit fault early warning class, and issue alarm.The application can solve the problem of early warning lag caused by the dependence of traditional wind generating set fault early warning method on fixed threshold alarm.

The invention discloses a wearable periocular muscle electrical stimulation system and method for a facial paralysis patient, which are specially designed for eyelid closure dysfunction of the facial paralysis patient, adopt a wearable design, enable the patient to be treated anytime and anywhere, do not need to stay in hospital or frequently go to hospital, and are convenient and easy to use. The real-time eye movement signal provided by the eye movement tracking device is used as a control trigger source, and real-time closed-loop control that the uninjured side eyelid action triggers the affected side synchronous electrical stimulation is achieved. Meanwhile, a double-channel control strategy of high-frequency chopping boosting and low-frequency PWM modulation is introduced, the lepidomelaei muscle or the orbiculus ocularis muscle on the affected side is stimulated through the electrical stimulation technology, and the patient is effectively helped to recover the eyelid closing function. Through the signal cascading mode, the intermediate processing link of image acquisition and recognition is omitted, the control process is more direct, and real-time response and synchronous stimulation of eyelid movement can be achieved conveniently.

The invention discloses a dual-channel modulation and demodulation method based on an EIT signal, and relates to the technical field of atomic physics, and the method comprises the steps: loading different low-frequency modulation signals for 852 nm laser and 509 nm laser; according to a Rydberg EIT signal generated by the same cesium gas chamber, an error signal related to frequency deviation of 852 nm laser and 509 nm laser is extracted; demodulating the modulation signals of the 852 nm laser and the 509 nm laser by using a lock-in amplifier to generate error signals related to the detuning amount of each laser frequency; generated error signals are fed back to a 852 nm laser device and a 509 nm laser device respectively, and driving current of the laser devices or an external modulator is adjusted through a PID (Proportion Integration Differentiation) controller. EIT signals generated by the same cesium gas chamber are utilized, frequency error signals of 852 nm laser and 509 nm laser are obtained at the same time, the frequency error signals are demodulated through the lock-in amplifier and fed back through the PID controller, the frequencies of the two laser beams are independently adjusted, dependence on an extra saturated absorption light path and an external optical cavity is greatly reduced, and the overall cost is reduced.

The application belongs to the technical field of infrared thermal imaging defect detection, and specifically discloses an in-situ infrared thermal imaging detection device based on low-frequency modulation magnetic field excitation, which comprises a magnetic yoke, an infrared thermal imager, a computer, a modulation power supply and an excitation coil group, and the excitation coil group at least comprises a first excitation coil, a second excitation coil, a third excitation coil and a fourth excitation coil; the modulation power supply respectively inputs low-frequency alternating current with different phases and direct current with different directions into the first excitation coil, the second excitation coil, the third excitation coil and the fourth excitation coil; the device can form a rotating low-frequency alternating magnetic field in the pipeline to be detected through the composite excitation of the orthogonal direct-current magnetic field and the low-frequency rotating alternating magnetic field, the rotating magnetic field uniformly sweeps the detection area in multiple cycles, the influence of the eddy current distribution direction sensitivity is eliminated, large-area uniform heating is realized, the problem of low efficiency of the traditional point scanning or line scanning mode is avoided, and the single detection coverage area is significantly improved.

The invention discloses a frequency modulation system of a fused salt energy storage coupling thermal power generating unit, belongs to the technical field of frequency modulation of power systems, and aims to solve the problems of low frequency modulation response speed, low energy storage efficiency and insufficient system coordination of the conventional thermal power generating unit. The system comprises a fused salt energy storage subsystem, a thermal power generating unit main system, a coupling heat exchange device, a power grid frequency monitoring module and a frequency modulation coordination control system, wherein the fused salt energy storage subsystem realizes efficient heat energy storage and release through a layered fused salt storage tank, a fused salt circulating pump, a heat exchanger and an auxiliary electric heating device; the thermal power generating unit main system is responsible for conventional power generation; the coupling heat exchange device injects fused salt heat energy into the main steam pipeline, and the steam enthalpy value is increased; the power grid frequency monitoring module collects frequency data in real time and calculates deviation; the frequency modulation coordination control system dynamically adjusts the fused salt flow and the operation mode through a fuzzy self-tuning PID unit, a heat exchange optimization distribution unit and a state judgment module, and three modes of quick response, combined frequency modulation and conventional stability are achieved.

An LED driver, an LED lighting system and an operating method thereof are provided. The LED driver is for driving an LED light source and includes a strobe circuit and a DC-DC converter. The strobe circuit generates a low-frequency modulation signal. The DC-DC converter is coupled to the strobe circuit and is configured to provide an adjustable operating current to the LED light source according to a DC signal and the low-frequency modulation signal. The operating current includes a DC current signal and a low-frequency AC current signal corresponding to the DC signal and the low-frequency modulation signal respectively. A frequency of the low-frequency AC current signal is between 25 Hz and 100 Hz, and a current ripple factor, equaling a difference of a maximum value and a minimum value of the operating current divided by a sum of the maximum value and the minimum value, is less than 8%.

The invention provides an efficient ozone generation system based on pulse modulation surface dielectric barrier discharge, which mainly comprises a power supply module, a pulse modulation module, a surface dielectric barrier discharge chamber, a spectral measurement module, a computer, an oscilloscope, a voltage probe, an air source, a gas flow control module and a mercury lamp light source, all the modules form a complete ozone generation and detection system through circuits, light paths and gas paths, so that efficient generation and real-time monitoring of ozone and intelligent regulation and control of parameters are realized. Through a double-layer modulation structure of'high-frequency continuous discharge + low-frequency pulse envelope ', electron energy enhancement and heat input decoupling are realized, so that the oxygen molecule dissociation efficiency is obviously improved, and the ozone concentration is obviously improved. The system can automatically adjust the pulse duty ratio and low-frequency modulation parameters according to temperature and humidity changes, inhibit temperature rise and compensate the influence of humidity on ozone generation, so that the stability of ozone concentration under different environmental conditions is ensured.

The invention belongs to the technical field of lithium ion battery electrochemical impedance spectroscopy measurement, and discloses a battery impedance spectroscopy online measurement method based on a random low-frequency modulation simplified multi-sinusoidal signal and a DAB converter, and the method comprises the steps: designing a simplified multi-sinusoidal signal of modulation wave optimization + random low-frequency carrier; building a current excitation measurement system based on a DAB converter; a battery pack is connected to a current excitation measurement system based on a DAB converter, and a complete battery impedance spectrum is generated based on simplified multi-sinusoidal signals of modulation wave optimization and random low-frequency carrier waves. The method is easy to implement, high in measurement precision, wide in scene adaptation and high in measurement efficiency.

The invention relates to an efficient nerve regulation and control device based on variable modulation high-frequency signals, and the device comprises a stimulation signal output electrode which is used for intermittently outputting stimulation current signals to regulate and control nerves; the high-frequency modulation electric signal generation module is used for generating a composite stimulation current signal formed by combining a high-frequency carrier signal and a low-frequency modulation signal; the power amplification and safety isolation module is used for amplifying the signal output by the high-frequency modulation electric signal generation module and controlling the output voltage within a human body safety voltage range; the signal input end of the power amplification and safety isolation module is connected with the signal output end of the high-frequency modulation electric signal generation module, and the signal output end of the power amplification and safety isolation module is connected with the stimulation signal output electrode. According to the invention, nerve regulation and control can be realized more efficiently.

The invention discloses an underwater flexible compressed air energy storage primary frequency modulation control method, and belongs to the technical field of power system frequency control, and the method comprises the following steps: S1, constructing an underwater compressed air energy storage frequency modulation model; s2, constructing a comprehensive optimization model according to the underwater compressed air energy storage frequency modulation model; and S3, solving the comprehensive optimization model, calling an explicit analytic function generated by solving, and completing frequency modulation control. The method solves the problems of low frequency modulation speed and low efficiency of traditional compressed air energy storage, and is suitable for improving the stability of a high-proportion renewable energy power grid.

Examples include spatially positioning, in a three-dimensional (3D) space, a conductive coil and a living subject in a 3D spatial relation in which a target 3D region of the living subject's tissue is within a designated 3D electric field formation region for the conductive coil. An energizing source feeds a low frequency (LF) modulated high frequency (HF) carrier voltage to terminals of the conductive coil. This urges a corresponding LF modulated HF coil current, of maximum magnitude MA, through the conductive coil. The HF frequency of the HF coil current produces a magnetic flux with a corresponding HF related rate of change. Optionally, a secondary coil feeds an unmodulated HF signal that spatially overlaps the modulated HF signals.

The application discloses a phased array antenna for simultaneous same-frequency full-duplex communication and relates to the technical field of phased array antennas.The phased array antenna comprises, from top to bottom, a radio frequency feeding structure, a dielectric substrate and a modulation feeding structure, wherein the modulation feeding structure is further connected with the radio frequency feeding structure; the radio frequency feeding structure is used for receiving a radio frequency signal; and the modulation feeding structure is used for receiving a low-frequency modulation signal.The phased array antenna for simultaneous same-frequency full-duplex communication can realize the non-reciprocity of the transmitting pattern and the receiving pattern of the phased array antenna in the spatial domain by adjusting the phase of the radio frequency signal and the phase of the low-frequency modulation signal, and the independent transmitting pattern and receiving pattern of the phased array antenna can prevent the transmitting signal and the receiving signal from interfering with each other, so that the phased array antenna can realize the simultaneous same-frequency full-duplex communication.

This invention relates to an in-situ electrochemical testing method and application for solid-liquid interfaces, belonging to the field of in-situ electrochemical technology. The method utilizes a combined electrochemical reaction device and an amplitude-modulated electrostatic force microscope (AFM). The testing method includes: applying a high-frequency excitation voltage to a probe via an external signal source, and modulating the excitation voltage with a low-frequency modulation voltage applied via an atomic force microscope; the high-frequency excitation voltage is a sine wave with a frequency >1 MHz, and the low-frequency modulation voltage is a sine wave with a frequency of 5-10 kHz; constructing an electrochemical reaction device based on the sample to be tested and connecting it to an electrochemical workstation; performing dielectric imaging on the surface of the sample to be tested in an electrolyte environment, demodulating the image using a lock-in amplifier, and outputting the local capacitance gradient at the probe tip according to an equivalent circuit model. Compared with existing technologies, this invention overcomes the incompatibility between the probe and the electrolyte solution environment upon which the electrochemical reaction depends. This solution achieves dielectric imaging with nanometer-level spatial resolution in an electrolyte environment.

The invention relates to the technical field of preparation of optical dielectric film materials, and discloses a preparation method of a dielectric film material of a high-performance achromatic light splitting element, which comprises the following steps of: applying a low-frequency modulation formula to reaction gas to regulate and control an equivalent optical constant in reactive sputtering by adopting a single metal target material; meanwhile, plasma impedance characteristic signals in the process are monitored in real time and compared with reference impedance characteristics, a feedback control loop is established to automatically adjust a low-frequency modulation formula, and in-situ allocation of equivalent optical constants is achieved through low-frequency modulation; and furthermore, a plasma impedance signal associated with the modulation process is used as an endogenous probe to construct closed-loop feedback, so that the process drift is actively compensated, and the high consistency of the performance of the optical element in batch preparation is ensured.