17 results about "Doppler broadening" patented technology

The invention discloses a helium bubble size and density analysis method based on positron annihilation multiple parameters. The helium bubble size and density analysis method comprises the following steps: 1) calculating a low momentum annihilation ratio S and a high momentum annihilation ratio W according to Doppler broadening DBS of a sample to be detected; 2) obtaining the life value of each helium bubble in the sample to be detected according to the life spectrum PALS of the sample to be detected; (3) determining the helium bubbles in the sample to be detected and the types of the helium bubbles according to the service life values of the S, the W and the helium bubbles; 4) comparing the service life value of each helium bubble in the to-be-tested sample with the corresponding service life value calculated by the first principle to obtain the type of the helium bubble in the to-be-tested sample; the radiuses of the helium bubbles of different types are converted into sphere radiuses, and the helium bubble radiuses of the helium bubbles in the sample to be detected are obtained; 5, the matrix life, the helium bubble defect life and the average life of the sample to be measured are obtained according to the life spectrum PALS, and the helium bubble density is obtained through calculation according to the two-state capture model.The helium bubble evaluation robustness is improved.

This invention relates to a rotational Doppler correction method for lidar based on an elliptical vortex beam. Vortex beams with structural phase are highly sensitive to rotation and can be used for precise measurement of rotational speed. However, when the vortex beam emitted by the lidar does not coincide with the axis of rotation of the object, the rotational Doppler spectrum broadens, reducing the signal-to-noise ratio (SNR), which greatly limits the application scenarios of vortex lidar. To address this problem, a rotational Doppler correction method for lidar based on an elliptical vortex beam is proposed. First, an elliptical vortex beam is prepared by adjusting the intensity and phase distribution of the vortex beam using complex amplitude modulation. By using an elliptical vortex beam with appropriate ellipticity to detect a tilted rotating object, the rotational Doppler broadening effect can be almost completely offset, improving the SNR of the frequency domain signal. This method is simple to operate, flexible and controllable, has high redundancy, and can greatly increase the detection range, showing great promise for applications in telemetry.

The application discloses a kind of laser detection device and method, belong to laser detection technical field, the device includes beam output module, light splitting module, optical path multiplexing module, two coherent mixing modules and signal processing module;Beam output module outputs the positive and negative double-chirp laser of frequency-modulated time sequence synchronization of different wavelength, chirp rate absolute value equal, after light splitting, optical path multiplexing, get local light and echo light, two coherent mixing modules generate four-way quadrature beat frequency signal, signal processing module does product subtraction and addition operation to four-way beat frequency signal and constructs complex signal, offset Doppler broadening interference introduced by rotating polygon mirror, again Fourier transform, peak searching obtains intermediate frequency parameter and calculates target vector velocity, the application can completely eliminate the influence of Doppler broadening on speed measurement, significantly improve speed measurement precision.

The invention discloses a high-frequency oblique measurement characteristic signal Doppler spectrum identification method, which comprises the following steps of: 1, filtering various pattern noise information in an ionospheric oblique measurement Doppler spectrogram by utilizing a corrected median filtering method; 2, calculating a local area bottom noise median of the ionospheric oblique measurement Doppler spectrogram, and calculating a local area bottom noise median of the ionospheric oblique measurement Doppler spectrogram by taking a bottom noise parameter as a basis; judging the number of modes of the ionospheric oblique measurement Doppler spectrogram; 3, on the basis of the effective mode, calculating corresponding Doppler frequency shift, Doppler broadening and Doppler group distance; and step 4, fusing the processing result of the oblique measurement characteristic signal disturbance type identification algorithm, and comprehensively identifying the mode type of the oblique measurement Doppler spectrogram of the ionized layer. Simulation data and actual measurement data are used for verifying the method, it can be seen that whether the simulation data or the actual measurement data, all parameter information in the high-frequency oblique measurement Doppler spectrogram can be completely extracted through the recognition precision of the method, and it is indicated that the recognition effect of the method is good.

The application discloses an ISAR optimal imaging time period selection method and system based on D-S evidence theory, and the method comprises the following steps: obtaining the number of distance units occupied by a sub-aperture image according to the sub-aperture image; obtaining Doppler broadening according to the envelope summation result of the distance units; obtaining image contrast according to the sub-aperture image; calculating the information entropy of the sub-aperture image, and calculating the target-background ratio of the sub-aperture image; obtaining the probability distribution function after sub-aperture image fusion based on the D-S evidence theory; selecting the central moment corresponding to the maximum sub-aperture image in all the probability distribution functions after fusion as the optimal imaging moment; performing ISAR imaging according to a preset time length search range with the optimal imaging moment as the center, and obtaining the optimal imaging time period based on the imaging result. The application can not only screen out an arc data segment with high azimuth resolution, but also consider the focusing quality of the image.

The invention discloses a cold atom frequency stabilized laser and an implementation method thereof, and belongs to the technical field of laser. In order to solve the problems that cavity length thermal noise is large in laser frequency stabilization based on an optical resonant cavity and Doppler broadening and collision broadening exist in frequency stabilization based on an atom molecule air chamber, a closed-loop frequency stabilization system comprising an optical detection link and an electric feedback control link is constructed by using a cold atom recoil resonance spectral line as a frequency reference source; accurate modulation and stable control of the laser output frequency are realized. The influence of the Doppler effect and the collision effect on the frequency stabilization precision can be effectively suppressed, and the laser frequency stability and the long-term operation reliability are improved.

The invention discloses a pilot channel electron density diagnosis method and system. The method comprises the following steps: acquiring an image sequence of an emission spectrum in a time-continuous pilot channel development stage; extracting spectral data of an OI 777 nm triplet spectral line of each frame of image in the image sequence at a target height position h, wherein the central spectral line of the triplet spectral line is OI 777.41 nm; performing curve fitting on the spectral data of the triplet spectral line by adopting a triplet Lorentz function to obtain an FWHM parameter of a central spectral line; instrument broadening and Doppler broadening are removed from the FWHM parameters of the central spectral line, and effective Spark broadening of the central spectral line is obtained; calculating the electron density of a pilot channel based on the effective Spark broadening; the accuracy of the pilot channel electron density diagnosis result can be improved.

The invention discloses a Doppler spectrum identification method for a high-frequency vertical measurement characteristic signal. The method comprises the following steps: step 1, filtering various pattern noise information in an ionized layer vertical measurement Doppler spectrogram by using a modified mean filtering method; 2, calculating the average floor noise of the local area of the ionospheric vertical measurement Doppler spectrogram, and judging the number of modes of the ionospheric vertical measurement Doppler spectrogram on the basis of floor noise parameters; 3, on the basis of the effective mode, calculating corresponding Doppler frequency shift, Doppler broadening and Doppler virtual height; and step 4, fusing the processing result of the vertical measurement characteristic signal disturbance type identification algorithm, and comprehensively identifying the mode type of the ionospheric vertical measurement Doppler spectrogram. Simulation data and actual measurement data are used for verifying the method, it can be seen that whether the simulation data or the actual measurement data, all parameter information in the high-frequency vertical measurement Doppler spectrogram can be completely extracted through the recognition precision of the method, and it is indicated that the recognition effect of the method is good.

The invention provides a nuclear reactor high-entropy alloy defect detection method, system, equipment and medium, and belongs to the technical field of material detection.The nuclear reactor high-entropy alloy defect detection method comprises the steps that a high-entropy alloy treated by simulating reactor service working conditions of different temperatures and irradiation conditions is obtained; the method comprises the following steps: respectively carrying out positron life spectrum test and Doppler broadening test on the high-entropy alloy to obtain life spectrum and Doppler broadening spectrum data of the high-entropy alloy, and obtaining a life component related to defects and an intensity factor corresponding to the life component through the life spectrum; analyzing a low-momentum component S parameter and a high-momentum component W parameter of the high-entropy alloy through Doppler broadening spectrum data, and constructing an S-W parameter diagram representing a data offset trajectory; and fitting the life component and the strength factor related to the defect, performing cross analysis on the fitting result and the S-W parameter diagram, and judging the defect size distribution, the defect concentration and the defect type of the high-entropy alloy according to the analysis result. According to the invention, high sensitivity and high resolution of nanoscale vacancy and vacancy cluster detection can be ensured.

The application discloses an ultranarrow-bandwidth atomic filter based on cold atoms and an implementation method thereof. The application combines cold atoms with an atomic filter, slows down atoms through laser cooling technology, reduces the influence of Doppler effect, and further realizes an ultranarrow-bandwidth atomic filter with a transmission bandwidth close to the natural line width of atomic transition. The implementation of the application can solve the problem that the influence of thermal atomic Doppler broadening causes the transmission bandwidth to be unable to be further narrowed in the existing transmission bandwidth narrowing technology of a Faraday atomic filter, and can expand the research of a traditional thermal atomic Faraday filter to the field of cold atoms in modern science, provide new possibilities for substantial and significant progress and construction of a filter based on cold atoms, and bring extremely potential development to many fields. The application overcomes the limitation of thermal atomic Doppler broadening on the further narrowing of the transmission bandwidth of a Faraday atomic filter, and brings a significant bandwidth narrowing effect.

The invention discloses a helium bubble size and density analysis method based on slow positron beam chromatography, which comprises the following steps of: 1) measuring Doppler broadening (DBS) of a material to be measured by using a slow positron beam, and calculating a low momentum annihilation ratio S and a high momentum annihilation ratio W of each energy point in the DBS; 2) for the energy points with the helium bubbles, according to the life spectrum PALS of the corresponding energy points of the to-be-tested material, obtaining the life values of the helium bubbles in the to-be-tested material; 3) analyzing the depth distribution of each helium bubble in the to-be-tested material to obtain the average injection depth of each helium bubble; 4) calculating the type of helium bubbles in the material to be measured, and converting the radius of each helium bubble into a spherical radius to obtain the helium bubble size of the helium bubbles in the material to be measured, and 5) calculating the density of the helium bubbles to be solved at the corresponding injection depth through the two-state capture model according to the helium bubble size in the material to be measured, the matrix life of the material to be measured, the life value of the helium bubbles and the average life of the helium bubbles.

The invention relates to the field of nuclear reaction, and discloses a Kernel Broadening coupled Gaussian integral-based high-efficiency Doppler broadening method at ultrahigh temperature, electronic equipment and a computer readable storage medium. The method comprises the following steps: S1, calculating parameters required by Doppler broadening of a nuclear reaction cross section; s2, Doppler broadening calculation is carried out on the section under the initial energy point; s3, determining a next energy point conforming to a Doppler broadening condition, and performing broadening calculation; s4, performing linearization processing on the Doppler broadening cross section by adopting an inverted stack algorithm; and S5, based on the determined Doppler broadening energy range, repeating the steps S3 to S4 until Doppler broadening calculation of the nuclear reaction cross section under all energy points is completed. Through the adaptive strategy, intelligent optimization matching of Doppler broadening calculation of all energy sections and different nuclide types is realized, and the efficiency bottleneck in ultra-high temperature calculation is overcome.

The application discloses a kind of based on saturated absorption cavity ring-down spectroscopy of middle infrared laser frequency up-conversion 14 The application discloses a CO2 detection method and device. In view of the existing middle infrared direct detection heat noise, low signal-to-noise ratio of tail section of ring-down signal and other bottlenecks, the application adopts double QCL light sources, absolute frequency locking, saturated absorption cavity ring-down light cavity, frequency up-conversion detection and data processing module. By saturated absorption, Doppler broadening is eliminated, and by using sum frequency effect, 4.5 μm middle infrared ring-down signal is converted into 861 nm near infrared sum frequency light, which is received by a low-noise silicon-based detector, so that the signal-to-noise ratio of weak ring-down signal is significantly improved. In combination with double optical beat frequency technology, laser frequency absolute locking is realized. The device can obtain MHz-level narrow linewidth absorption, effectively suppresses isotope cross interference, and has a limit detection sensitivity of ppq order of magnitude, and has the advantages of small size, low cost and on-site detection.

The application discloses a cold atom frequency stabilization laser and an implementation method thereof, and belongs to the technical field of lasers. In order to solve the problems of large cavity length thermal noise in laser frequency stabilization based on an optical resonant cavity and Doppler broadening and collision broadening in frequency stabilization based on an atomic and molecular gas chamber, the application uses a cold atom recoil resonance spectrum as a frequency reference source, constructs a closed-loop frequency stabilization system including an optical detection link and an electrical feedback control link, and realizes accurate modulation and stable control of laser output frequency. The application can effectively inhibit the influence of Doppler effect and collision effect on frequency stabilization accuracy, and improve laser frequency stability and long-term operation reliability.

The invention provides a high-temperature gas thermodynamic temperature calibration device and method for an ultraviolet broadband absorption spectrum, and relates to the field of thermal metering testing and the field of absorption spectrum temperature measurement. The graphite plate is electrically heated to generate a high-temperature gas environment, and a high-resolution spectrometer is combined to measure Doppler broadening to realize the primary thermodynamic temperature standard, so that the traceable calibration capability within the high-temperature range of 2000K-3500K is provided for an ultraviolet broadband absorption spectrum temperature measurement system, and four technical advantages of high temperature, steady state, non-contact and traceability are realized; the temperature meter is suitable for temperature metering requirements in high-temperature and high-pressure environments such as aerospace and energy power.

The invention relates to the technical field of atomic frequency standards, in particular to a device for evaluating transition time broadening of an air chamber type optical frequency standard. Comprising a seed laser, a variable magnification laser beam expanding system, laser beam splitters, a laser intensity adjusting and stabilizing system, an atomic gas chamber assembly, a laser reflector, a light spot quality analyzer and a signal acquisition and analysis system, wherein the laser beam splitters comprise a first beam splitter and a second beam splitter; and the signal acquisition and analysis system is used for acquiring a voltage signal after fluorescence conversion and a measurement result of the light spot quality analyzer. According to the method, the size of atomic transition spectral line broadening introduced by the transit time effect can be obtained, the influence of effects such as residual Doppler broadening caused by replacement of laser collimators with different light spot diameters is avoided, the operation steps are simplified, the efficiency of transit time broadening evaluation is improved, and the method is suitable for popularization and application. And acquisition of a narrow-linewidth transition spectral line based on the hot atom air chamber type optical frequency standard and realization of a high-performance optical frequency standard are facilitated.

The invention discloses a lithium atom scattering cross section calculation method, device and system, and a storage medium. The method comprises the following steps: calculating the relative transition intensity of each transition line of a lithium atom D2 line; the lithium atom D2 comprises a D2 line of 7Li and a D2 line of 6Li; according to the D2 line hyperfine structure of the lithium atoms, the deviation frequency of each transition line relative to the center line is calculated; doppler broadening is calculated according to each line frequency; according to Doppler broadening, an absorption cross section at a peak value is obtained through calculation; according to the absorption cross section at the peak value, obtaining a relation graph between the scattering cross section of 7Li and the frequency and a relation graph between the scattering cross section of 6Li and the frequency; and multiplying the relation graph of the scattering cross section of 7Li and the frequency and the relation graph of the scattering cross section of 6Li and the frequency by respective isotope abundance, and adding to obtain a total scattering cross section. By adopting the technical scheme of the invention, the backscattering cross section of the lithium atom can be accurately calculated.