46 results about "Frequency standard" patented technology

The invention provides a high-precision time-keeping low-phase-noise time synchronization device, and belongs to the technical field of time synchronization. The system comprises a power supply module, a satellite time service module, a frequency source module, a clock synchronization module, a frequency shunt module, a communication interface module and a Bluetooth module. Wherein the power supply module adopts a dual-power-supply redundant circuit design, and after one power supply breaks down, the other power supply can be automatically switched; the satellite time service module adopts a single Beidou signal baseband signal processing algorithm and an anti-cheating design, so that the safety of equipment is improved; the frequency source module comprises a constant-temperature crystal oscillator and a rubidium atomic clock, and high-time-keeping and low-phase-noise signal output is achieved in the mode that the crystal oscillator and the atomic clock are complementary. According to the invention, the problem that the conventional time synchronization equipment cannot have high time keeping precision and low phase noise of output signals at the same time is solved, a high-steady-state low-phase-noise 10MHz frequency standard signal, a 1PPS time service signal and an NTP network time service signal can be provided, and time service is provided for various terminals or servers.

This invention belongs to the field of time-frequency unification and relates to a fast discipline method and system based on a high-stability OCXO. The method includes selecting a primary reference source, inputting the reference signal into a phase-locked loop frequency multiplier for frequency multiplication, and inputting the processed high-frequency reference signal into a high-precision phase measurement module. A monitoring and processing platform controls two frequency standard signals output from the OCXO frequency standard source through a control word. The first frequency standard signal of the first channel is input into a phase-locked loop frequency divider, and the second frequency standard signal is output to the high-precision phase measurement module. The third frequency standard signal of the second channel is directly input into the high-precision phase measurement module to measure the phase difference between the high-frequency reference signal and the second frequency standard signal. The monitoring and processing platform outputs an updated control word through a fast discipline algorithm to correct the OCXO frequency standard source parameters. The fast discipline process continues until the OCXO frequency standard source stabilizes and the phase difference with the reference source converges, ending the fast discipline state.

The application discloses a full-range error live calibration device and method for a low-voltage current transformer, comprising: a current control unit for outputting full-range calibration current control signals of each frequency; a hetero-frequency calibration current source for outputting full-range hetero-frequency current signals based on the current control signals and injecting the signals into the measured current transformer and a standard current transformer; an open current sensor for measuring a background current signal in real time; a signal decoupling unit for acquiring a mixed-frequency error voltage signal, eliminating a voltage component generated by the background current signal in the mixed-frequency error voltage signal, and acquiring a hetero-frequency error voltage signal; an error measurement unit for calculating ratio error and phase error of the measured current transformer based on the hetero-frequency standard signal and the hetero-frequency error voltage signal; and a data processing unit for determining calibration error under a power frequency frequency mapping based on the ratio error and the phase error under each hetero-frequency frequency.

The invention discloses a multi-source heterogeneous clock group management system and method based on an ALGOS time scale algorithm. The method comprises the steps that an atomic clock group outputs multiple paths of radio frequency analog signals; the signal frequency discrimination comparison module is used for converting the radio frequency analog signal into a digital signal, measuring the frequency and calculating frequency difference data; the atomic time scale calculation module converts the frequency difference data into frequency difference data relative to the atomic time scale, predicts the clock face frequency reading, determines the weight of each atomic clock according to the forecast residual error, and calculates the atomic time correction through weighted average; the frequency scale control module calculates the frequency offset according to the atomic time correction, the crystal oscillator and the atomic clock signal, and generates control voltage; and the local voltage-controlled crystal oscillator receives the control voltage and reproduces a high-precision time-frequency reference signal synchronized with the atomic clock group. According to the invention, the operation state of the atomic clock is not adjusted, only discrete sampling is carried out, the advantages of the clock group are fused by utilizing the ALGOS algorithm, the long-term stability of the output signal is improved by controlling the high-reliability voltage-controlled crystal oscillator, and the influence of frequency drift, intermittent start and stop and noise interference is effectively inhibited.

The application provides a frequency standard measurement method, device, computer equipment and storage medium, the method comprises: frequency source output measurement signal is carried out frequency division processing, obtains low frequency pulse signal; using high-precision time interval counter to low frequency pulse signal is carried out delay measurement and time interval counting, and is output in the form of time stamp; by setting a sliding window, using sliding average algorithm to time stamp is carried out sliding average filtering processing, all time stamps are carried out sliding difference to obtain time difference, time difference is grouped according to order and is taken average in group to obtain average time difference; by increasing the length of the sliding window, the number of samples is increased to reduce the statistical error; using average time difference, calculate frequency measurement value, relative frequency deviation and allan variance. The method of the application increases the sliding window, and the frequency measurement result obtained by the algorithm of grouping and averaging the time difference has higher measurement precision and stability.

The invention discloses an atomic optical frequency standard rapid self-locking system, which comprises a clock laser, and the output of the clock laser is divided into a first path of modulation laser and a second path of modulation laser after sequentially passing through an ultra-stable cavity system, a frequency power modulation optical system and a first spectroscope. The spectral data acquisition system acquires spectral data generated when a first path of modulation laser enters the atomic system physical system, the spectral data acquisition system is respectively connected with the servo feedback system and the integrated automatic control system, and the servo feedback system is connected with the frequency power modulation optical system; the output of the femtosecond optical comb and three paths of modulation laser divided from the second path of modulation laser are subjected to beat frequency to generate beat frequency signals which enter the photoelectric detector; and the laser, the ultra-stable cavity system, the frequency power modulation optical system, the laser frequency scanning system, the atomic system physical system and the femtosecond optical comb are respectively connected with the integrated automatic control system. The invention further discloses a rapid self-locking method for the atomic optical frequency standard, and rapid locking of the optical frequency standard is achieved.

The invention discloses a laser frequency stabilization electric control system based on a modulation transfer spectrum, and the system is constructed based on a ZYNQ7030 heterogeneous SoC platform, and integrates laser modulation, signal collection, error extraction, feedback control and man-machine interaction functions. Comprising a sinusoidal modulation chain driven by a high-speed DAC and an electro-optical modulator which are used for realizing laser frequency modulation; the MTS signal acquisition link consists of a photoelectric detector, a low-noise amplifier and a high-speed analog-to-digital converter; feedback control is carried out on the frequency of the laser through the precise digital-to-analog converter and the current source circuit. Meanwhile, the system integrates an air cavity temperature control module, a multi-channel communication interface and a man-machine interaction module, and frequency stabilization and system management are achieved. According to the invention, high-precision and high-stability laser frequency locking based on the rubidium atom absorption spectrum can be realized without depending on an external frequency standard, and reliable frequency reference is provided for applications such as high-precision atom physical experiments, quantum sensing, spectral measurement and the like.

The application relates to the technical field of signal processing, and provides a signal processing method and system of a rubidium atomic frequency standard, a main frequency standard adopts a double-threshold amplitude comparison circuit, a standby frequency standard adopts a single-threshold amplitude comparison circuit, and the existence of a signal, the validity of an amplitude and a locking state are synchronously monitored; double-threshold detection of the main frequency standard ensures reliability, single-threshold detection of the standby frequency standard ensures readiness for quick switching, and the reliability and switching efficiency are balanced; through preset logic rule fusion analysis, the validity is comprehensively judged in combination with a frequency standard locking signal. A control signal is generated based on a priority rule, the main frequency standard is kept when the main frequency standard is valid, a high-level pulse synchronized with a 10MHz signal zero-crossing point is generated when the main frequency standard is invalid and the standby is ready, an abnormal alarm is triggered when the double frequency standards fail, and the control signal is transmitted to a frequency standard switching circuit through a level conversion subunit, so that the trigger timing requirement of a high-speed switching module is met, quick response switching is ensured, the stability in the switching process is ensured, and the whole is reliable and stable.

The invention discloses an error calculation method based on a pulse sequence with a time scale, and belongs to the technical field of electric power measurement testing. The standard time-frequency signal, a high-frequency standard pulse output by the standard electric energy meter and a detected pulse output by the detected electric energy meter are connected to an acquisition processor; the acquisition processor detects a jump edge of the detected pulse in real time based on a clock provided by the standard time frequency signal, and records moments corresponding to a rising edge and a falling edge of the detected pulse; counting the standard pulse in real time, and recording the current count value of the standard pulse at the corresponding moment; combining the moment information with the count value to form an original sampling sequence with a time mark; the calculation processor reads the stored original sampling sequence with the time scale, and calculates the power value, the error value, the waveform characteristic and the jitter index of the detected electric energy meter according to the edge moment of the detected pulse and the corresponding standard pulse count value; and according to the error distribution condition, the stable state of the verification system is monitored in real time, and an alarm is dynamically triggered.

This invention relates to a method for identifying abnormal waveforms of partial discharge pulse groups based on a trigger threshold moving window, comprising: Step 1, calculating the average amplitude of a points at the beginning and b points at the end of the recorded waveform to obtain the reference offset value of the recorded waveform; Step 2, removing the reference offset value from the recorded waveform to form a processed waveform; Step 3, establishing an adjustable-duration trigger threshold moving window based on the trigger threshold Yz, and calculating the time standard deviation T and frequency standard deviation B of the data within the moving window when the absolute amplitude within the moving window is greater than or equal to Yz / m, and recording the extreme values ​​and corresponding positions when T×B≥1; Step 4, when the number of extreme values ​​k... j When the value is greater than 1, the time-domain waveform of the currently recorded single pulse is judged as an abnormal waveform; when the number of extreme values ​​k j When the value equals 1, the time-domain waveform of the currently recorded single pulse is determined to be a normal waveform. Compared with the prior art, the present invention has advantages such as good robustness.

This invention relates to the field of intelligent surveillance technology, and more particularly to an image data retrieval method and system based on surveillance big data. The method includes: extracting the visibility and color features of pedestrian key points from surveillance trajectory segments; calculating viewpoint similarity using the cosine similarity of visibility vectors combined with the ratio of frequency standard deviations; selecting comparable key points and weighting them by the minimum visible frequency; calculating appearance similarity by combining color differences; introducing time constraint parameters to optimize the initial clustering distance to obtain a significant clustering distance; clustering matching for the same pedestrian trajectory; and finally establishing a retrieval index to complete image data retrieval. This invention improves pedestrian information retrieval performance by extracting key point visibility and color information, fusing optimized viewpoint and appearance similarity to construct an initial clustering distance, and optimizing with time constraint parameters to avoid interference from multi-camera scenes.

The invention provides an ultra-narrow linewidth laser frequency time-varying testing device and method. The device comprises a first 1 * 2 coupler, a self-heterodyne structure, a frequency etalon structure, a frequency drift signal processing module and a frequency noise signal processing module. A short-length delay optical fiber is adopted to form a self-heterodyne structure, and the self-heterodyne structure is matched with a frequency drift signal processing circuit to realize laser frequency drift (less than 100Hz) measurement; meanwhile, a photonic crystal resonant cavity is adopted as a frequency reference and is matched with a frequency noise signal processing circuit to realize laser frequency noise (greater than or equal to 100Hz) measurement. According to the invention, the rapid measurement of the optical frequency drift / noise of different frequency components can be realized, the test device is simple, the measurement precision is high, the measurement range is wide, and a foundation is laid for the frequency characteristic evaluation of the ultra-narrow linewidth laser.

The application relates to the technical field of signal processing, and provides a signal processing method and system of a rubidium atomic frequency standard, a main frequency standard adopts a double-threshold amplitude comparison circuit, a standby frequency standard adopts a single-threshold amplitude comparison circuit, and the existence of a signal, the validity of an amplitude and a locking state are synchronously monitored; double-threshold detection of the main frequency standard ensures reliability, single-threshold detection of the standby frequency standard ensures readiness for quick switching, and the reliability and switching efficiency are balanced; through preset logic rule fusion analysis, the validity is comprehensively judged in combination with a frequency standard locking signal. A control signal is generated based on a priority rule, the main frequency standard is kept when the main frequency standard is valid, a high-level pulse synchronized with a 10MHz signal zero-crossing point is generated when the main frequency standard is invalid and the standby is ready, an abnormal alarm is triggered when the double frequency standards fail, and the control signal is transmitted to a frequency standard switching circuit through a level conversion subunit, so that the trigger timing requirement of a high-speed switching module is met, quick response switching is ensured, the stability in the switching process is ensured, and the whole is reliable and stable.

The invention discloses an integrated Michelson optical frequency scale and displacement measurement system based on pyramid array feedback. The device comprises a Michelson optical frequency standard system (optical frequency standard system for short) and a Michelson displacement measurement system (displacement measurement system for short), and the optical frequency standard system and the displacement measurement system share the same reference arm. According to the invention, quantum spectral lines are used as absolute frequency reference to generate stable and accurate optical frequency standard signals, and the optical frequency standard signals are used as the reference of displacement measurement to realize organic unification of time frequency and displacement measurement; an optical frequency signal output by the optical frequency standard system has a relatively strong anti-interference capability to an external environment, and the resolution of the displacement measurement system can be improved; in order to solve the interference problem of the pitching inclination angle of a measuring arm cavity mirror in displacement measurement and tiny movement in the non-displacement measurement direction, the invention provides a reflecting mirror adopting an integrated pyramid array as a composite cavity, so that the stability and the robustness of a displacement measurement system can be improved, and the measurement range and the measurement resolution are optimized.

This invention relates to a method for detecting the time-frequency fingerprint characteristics of a frequency source, belonging to the field of frequency detection technology. The method acquires the clock signal of a frequency standard source, extracts a time-frequency fingerprint feature region from the curve of the clock signal's frequency stability changing with sampling time, and obtains the time-frequency fingerprint characteristics of the frequency source by detecting the time-frequency characteristics of this region. This fingerprint is then compared with the original, inherent time-frequency fingerprint characteristics to identify the type of the frequency standard source and the individual frequency source. This invention creatively proposes using the detection of a specific curve characteristic within the frequency source's stability changing with sampling time as a unique time-frequency fingerprint feature region to identify the type and individual characteristics of the frequency source. This achieves the application objective of uniquely identifying and determining the health status of a specific electronic device by detecting the time-frequency fingerprint characteristics of the frequency source. The method is unique and has good market application prospects.

The invention discloses a device and method for improving stability and output phase noise of a broadband frequency-mixing phase-locked loop, and belongs to the technical field of electronic integration, and the device comprises a crystal oscillator, a power divider, an FPGA controller, a frequency-mixing phase-locked loop and a frequency scale phase-locked loop. A plurality of narrowband voltage-controlled oscillators are adopted to replace a traditional broadband voltage-controlled oscillator, and a radio frequency one-out-of-N switch selection mechanism is combined, so that the problem of phase noise deterioration caused by a DAC (Digital-to-Analog Converter) capture mode is avoided, and meanwhile, the stability of a phase-locked loop and the quality of an output signal are improved. According to the invention, the output phase noise can be obviously reduced, the requirement of a complex system for a wide-band signal is met, and the method has important application value.

The technology described herein is directed towards a capacitor with a modified design (relative to standard capacitors), in which a first conductor is coupled to a second conductor via a distributed array of conducting interconnects through a dielectric that separates the conductors. The array of interconnects facilitates electrical surface current flow between the first conductor and the second conductor, and determines the self-resonant frequency of the capacitor. The array (or enlarged area) of conducting interconnects, not present in standard capacitors, results in capacitors with larger self-resonant frequency, e.g., having a substantially stable capacitance over a range of high radio frequencies, including millimeter wave frequencies. This further provides an improved quality factor. The improvements resulting from the technology described herein facilitate more optimal surface current density. The modified capacitor provides benefits in various circuits, e.g., in an impedance or a millimeter wave frequency phase shifter for antenna elements.

The present application relates to the technical field of power system, and more particularly to a kind of power system inertia distribution evaluation method, system and storage medium, method includes: the active power and frequency measurement data of power system power source side grid-connected node are collected, and measurement data is filtered and cleaned, bad data is rejected and interpolation reconstruction, and normalization processing is carried out, form active power standard data sequence and frequency standard data sequence;Combining sliding window technology and using detrended fluctuation analysis active power standard data sequence and frequency standard data sequence, identify the initial time of system disturbance occurrence;Based on generator group power frequency response characteristics, construct inertia evaluation analytical model from energy point of view;Through the continuous input of real-time measurement data and model iterative calculation, dynamically update inertia evaluation result, and determine final inertia evaluation value according to quasi-steady state result.The present application can realize the real-time perception of inertia distribution in power grid, and does not need excessive dependence on existing high-precision model.

The invention discloses a measurement type picometer-level displacement resolution generation method based on twin double cavities, and the method comprises the steps: employing a group of twin Fabry-Perot cavities with matched parameters, and the twin Fabry-Perot cavities comprise a measurement cavity and a reference cavity; based on the PDH technology, the lasers of the two lasers are locked to harmonic peaks of the measuring cavity and the reference cavity respectively, and then the resonant frequency is measured through an optical frequency comb to represent the displacement amount; a set frequency stepping signal is output through an optical phase-locked loop, the frequency stepping signal is converted into a voltage control signal to be loaded to a PZT of a measurement cavity, the PZT is driven to drive a reflector to move so as to change the cavity length, and a controllable picometer-scale standard displacement step is generated. According to the invention, on the basis of twin Fabry-Perot cavity resonant frequency differential mode detection, a common mode signal caused by Fabry-Perot cavity environment noise can be suppressed, the cavity length displacement is directly traced to an optical frequency standard, and absolute traceability and high-resolution measurement of a picometer-level displacement signal are realized.

This invention discloses a stabilized optical clock system and its implementation method based on a dual-microcavity optical comb and two-photon transitions. The system includes a microcavity optical comb section, a locking section, and a photodetector. The microcavity optical comb section contains two SiO2 microchip ring cavity optical comb oscillators, with center wavelengths matched to the two-photon transition lines of rubidium and cesium atoms, respectively. The locking section provides an atomic reference frequency through a two-photon transition generator, and combines a six-way phase-locked loop, an acousto-optic modulator, and a phase modulator to achieve initial frequency locking of the optical comb, interlocking of the repetition frequency, and suppression of thermally induced detuning. The photodetector converts the stabilized optical comb repetition frequency into an RF frequency standard output. This invention solves the problems of complex system design, large integrated size, cumbersome locking structure, and wavelength mismatch in existing ultra-high frequency stabilized atomic clock technologies.

The application discloses a multi-source heterogeneous fusion distributed layered time scale system construction method, system, equipment and storage medium, and relates to the technical field of time frequency standard and time reference construction. The method comprises the following steps: a distributed layered framework containing a plurality of parallel first-level units in a first layer and one second-level unit in a second layer is constructed, and space, type and affiliation information of time frequency sources are collected; the time frequency sources are grouped according to a grouping strategy, each unit is arranged in different data centers, and a distributed first-level time scale is generated through differential processing; the first-level time scale is represented as a virtual time frequency source and participates in comparison, and is input into the second-level unit; a second-level time scale is generated through virtual comparison; and based on a layered time scale algorithm and an elastic strategy, a final time scale output is dynamically updated and generated. The application can continuously output a time scale meeting stability and continuity requirements, and improves the expandability and elasticity of a time reference system.

The application discloses a chip active optical clock based on grating magneto-optical trap cooling and an implementation method thereof. Three saturated absorption spectrum frequency stabilization DBR lasers are used to generate cooling laser, re-pumping laser and pumping laser respectively, wherein the cooling laser and the re-pumping laser cooperate with the grating magneto-optical trap, are used for cooling and confining atoms, and form a cold atom group in an atom chamber; the pumping laser excites the cold atoms, and the generated stimulated radiation signal is directly used as an optical frequency standard signal output, and after frequency beating with a microcavity optical comb, a chip active optical clock is realized. Compared with a traditional cold atom optical clock, the application greatly reduces the volume of the system, can be integrated on a chip, and is suitable for a compact and portable device application scene; compared with a current chip microwave atomic clock, the stability index of the application is higher. The application has important application value, and can provide a long-time and high-precision frequency reference for a movable device.

The technology described herein is directed towards a capacitor with a modified design (relative to standard capacitors), in which a first conductor is coupled to a second conductor via a distributed array of conducting interconnects through a dielectric that separates the conductors. The array of interconnects facilitates electrical surface current flow between the first conductor and the second conductor, and determines the self-resonant frequency of the capacitor. The array (or enlarged area) of conducting interconnects, not present in standard capacitors, results in capacitors with larger self-resonant frequency, e.g., having a substantially stable capacitance over a range of high radio frequencies, including millimeter wave frequencies. This further provides an improved quality factor. The improvements resulting from the technology described herein facilitate more optimal surface current density. The modified capacitor provides benefits in various circuits, e.g., in an impedance or a millimeter wave frequency phase shifter for antenna elements.

The invention provides a scheduling method, device and equipment for energy storage equipment in a micro-grid system, the micro-grid system at least comprises new energy power generation equipment and the energy storage equipment, and the method comprises the following steps: obtaining an output scene of the new energy power generation equipment in the micro-grid system; acquiring a first relationship between frequency deviation and power disturbance of the micro-grid system, and a second relationship between frequency modulation capacity demand of the micro-grid system and frequency deviation standard deviation of the micro-grid system; based on the output scene, the first relationship and the second relationship, obtaining a target frequency modulation capacity demand when the system frequency standard deviation meets a preset condition, establishing a target function by taking benefit maximization as an optimization target, and solving the target function in combination with the target frequency modulation capacity demand to obtain a predicted frequency modulation capacity and a predicted frequency modulation mileage; and scheduling the energy storage equipment based on the predicted frequency modulation capacity and the predicted frequency modulation mileage. According to the scheme of the invention, the frequency stability of the power grid can be enhanced, and the operation economy and flexibility of the micro-grid system are improved.

The invention discloses an ultrasonic blood flow imaging method, device and equipment, and relates to the field of blood flow imaging.The method comprises the steps that a plane wave radio frequency echo signal time sequence is preprocessed, then extraction is conducted through an initial sampling window, and an initial blood Doppler signal is obtained; calculating an instantaneous frequency standard deviation and a mean value according to the initial blood Doppler signal; updating the length of the initial sampling window according to the instantaneous frequency standard deviation and the mean value; extracting a radio frequency echo signal time sequence only containing blood components by using the updated sampling window to obtain an adjusted blood Doppler signal; calculating the composite number of plane waves according to the average frequency of the adjusted blood Doppler signals; coherent compounding is carried out according to the compounding number of the plane waves and the adjusted blood Doppler signals, and compounded blood flow Doppler signals are generated; and determining the blood flow velocity according to the compounded blood flow Doppler signal. The imaging quality can be improved.

The application discloses a method for time service by using Beidou II satellite, and time reference is obtained by using the clock of Beidou II navigation satellite, and standard time is kept, so that the time service function is realized. Since the relative frequency stability of the clock loaded on each Beidou II navigation satellite of the Beidou II satellite navigation system is very high, the clock is used to generate high-precision frequency standard, and the time service is performed by using the Beidou II navigation satellite in the sky, and an atomic clock is not needed to generate and keep the standard time. However, the atomic clock is needed to be used as the time reference to generate and keep the standard time in other traditional time service modes. Therefore, the time service mode realized by using the Beidou II navigation satellite is lower in cost and saves hardware resources compared with other traditional time service modes.

The application provides a laser frequency stabilization system and method based on optical multi-frequency point cooperative locking, and relates to the technical fields of laser frequency stabilization and precision measurement. The system comprises a tunable laser unit, a multi-sideband modulation unit, an error signal generation unit and a feedback control unit. The multi-sideband modulation unit uses a controllable first radio frequency signal to modulate the phase of the laser to generate multiple sidebands; the error signal generation unit obtains a time domain electrical signal through frequency discrimination modulation. The feedback control unit calculates a total frequency discrimination error signal after the coherent superposition of multiple error signals, generates a feedback control signal according to the total frequency discrimination error signal and outputs the feedback control signal to the tunable laser unit to realize the locking of the center frequency of the laser. The application significantly improves the signal-to-noise ratio of the frequency discrimination signal through the cooperative action of multiple frequency points, can output an electrical absolute frequency signal anchored to the optical frequency reference interval while outputting high-stability frequency laser, and realizes the direct transfer of the optical domain frequency standard to the electrical domain.

The application discloses a kind of based on diffuse reflection laser cooling atom's optical frequency standard frequency governing device and method, belong to laser cooling and quantum frequency standard technical field.The application is to solve the technical problem that existing diffuse reflection cold atom optical frequency standard is affected by the optical frequency shift introduced by cooling and repumping laser, resulting in limited long-term frequency stability, by periodically turning on or off cooling and repumping light source through time sequence control module, sampling and counting the error signal of probe light after passing through the cold atom group prepared by diffuse reflection by data acquisition and processing module during laser-off stage, calculating the deviation of local laser relative to cold atom transition frequency, and then realizing closed-loop calibration by frequency control unit driving frequency tuning unit.The application can effectively suppress the limitation of optical frequency shift on frequency stability, continuously improve the stability according to the law, while not interfering with the continuous output of the system, meet the needs of miniaturization, portability and long-time high-performance operation of optical frequency standard.

The invention relates to the technical field of atomic frequency standards, in particular to a two-photon optical frequency standard based on an alkali metal atomic beam, which comprises a laser system, an atomic beam system, a detection system and a control system, wherein the laser system comprises a laser, an electro-optical modulator, a frequency multiplier, a power amplifier, an adjustable power attenuator, a polarization splitting prism, a collimating lens group, a reflector and a photoelectric detector. According to the invention, hot atoms are adopted as working atoms, a two-photon transition principle is adopted, a complex laser cooling system is avoided, and the overall miniaturization of the system is ensured; by combining the advantage of no collision frequency shift of moving atoms in an atomic beam, the defect of insufficient long-term performance caused by collision frequency shift of a traditional small-sized optical frequency scale is eliminated; the Doppler effect can be further eliminated by utilizing the characteristic that the movement rate of the atoms in the vertical direction of the center line of the atomic beam is close to zero, the narrower spectral line width is obtained, and meanwhile the characteristics of excellent long and short term stability and environmental adaptability are achieved.

This invention belongs to the field of optical sensing technology and relates to an in-situ calibration device for a temperature sensor based on laser frequency sweeping technology. The main structure includes a laser, an optical attenuator, an optical beam splitter, a first circulator, a second circulator, a gas molecule absorption cell, a sensing probe, a calibration probe, a photodetector, a data acquisition box, an industrial computer, a voltage output module, an analog-to-digital converter, a current controller, and a temperature controller. It uses a laser frequency sweeping system as the sensor demodulation system and a π-PSFBG as the temperature sensing probe. A gas molecule line, unaffected by ambient temperature, is introduced as a frequency standard to compensate for frequency drift caused by environmental noise in real time. A gallium dot bottle is introduced as an absolute temperature reference to provide an absolutely stable temperature environment for the calibration probe, thus calibrating the system frequency drift caused by the π-PSFBG. In-situ calibration technology achieves long-term stability of the temperature sensor. Its structure is simple and can achieve high-resolution and long-term stable measurement.