67 results about "Doppler broadening" patented technology

The invented Rayleigh windfinding laser radar calibration method uses acoustooptic frequency shift and laser spectrum Doppler broadening principle as basis, and utilizes two acoustooptic frequency shifters whose frequency can be regulated, and makes them be series-connected to implement laser frequency zero-crossed wideband continuous regulation, and utilizes Doppler stretcher to stretch spectrum so as to make accurate and quick calibration of Rayleigh windfinding radar.

The invention discloses a fusion reactor plasma density and temperature diagnosing method based on the Thomson scattering weak coherent technique. The method comprises the steps that a broadband low-coherency intense light source is set, a bandwidth modulator is set, a beam splitting system is set, a reference arm is used for generating an optical path difference and a frequency shift signal, the light returned from the reference arm and a detection arm interferes and passes through an optical grating to be divided into interference spectrum signals with different wavelengths to be received by an array CCD, the incident light direction, namely the axial scattering intensity distribution is obtained through the Fourier transform, and the plasma electron density axial distribution information is obtained through rayleigh scattering or raman scattering absolute calibration; the thermal motion rate information of electrons is obtained through the Doppler broadening of a spectral line, and then the plasma electron temperature distribution is obtained; the horizontal movement adjustment is carried out on the length of the reference arm to change the optical path difference changing so as to achieve measurement on the great depth plasma with the depth larger than 1 m. The electron temperature and density of the fusion reactor plasma are measured online through the Thomson back scattering optical coherent chromatographic technique.

The invention discloses a moving target detection method and an imaging method for a near space slow platform SAR (Synthetic Aperture Radar). In the detection method disclosed by the invention, the characteristics of low platform speed and smaller ground static clutter Doppler broadening of the near space slow platform SAR are utilized, and separation of a moving target from static clutter is realized by designing a Doppler filter in a Doppler domain, so that the problem of difficulty in separating dynamic and static clutters of the SAR in moving target imaging is solved. According to the imaging method disclosed by the invention, moving target echo is extracted after separation of dynamic and static clutters and moving target detection, one-order keystone conversion is combined with a variable-resolution Doppler frequency modulation estimation method, and range walk correction is completed under the condition that the speed of the moving target is unknown, so that the problem of difficulty in range walk correction of the moving target echo is solved. The methods have the advantages that rapid moving targes can be detected and imaged; and the methods are suitable for detecting and imaging slow moving targets.

The invention discloses a device for measuring gas temperature and concentration simultaneously through a single spectral line, and also discloses a method for measuring gas temperature and concentration simultaneously through the single spectral line. The method comprises the steps: firstly employing a peak normalization second harmonic signal line style which is only determined by temperature, and extracting the temperature of gas; extracting the concentration information through employing the directly proportional relation of the amplitude of the first-harmonic normalization second harmonic signal with concentration (background is removed), and obtaining the temperature and concentration of gas at the same time. The method can measure the temperature and concentration of gas at the same time, reduces the number of needed spectral lines, is high in sensitivity, is high in precision, and is quick in response. Compared with a conventional Doppler broadening temperature measurement method, the method can be used under the conditions of normal temperature and pressure. In addition, the method, compared with a conventional double-line temperature measurement method, does not need to consider the problems of frequency crosstalk and time resolution.

The present invention provides an atom sensor device based on hyperfine energy level frequency stabilization. The device comprises a pump light source, a detection light source, a first beam splitter, a second beam splitter, a quarter wave plate, a half wave plate, an atom air chamber, a first reflection mirror, a second reflection mirror, a photoelectric detector, a polarization analysis unit, first Helmholtz coils, second Helmholtz coils, a magnetic shielding layer and a signal processing unit. The atom sensor device based on hyperfine energy level frequency stabilization can eliminate the influence of the Doppler broadening on the pumping and detection process, improve the precision and stability of the atom sensor, enhance the anti-interference capability of the atom sensor to the optical element vibration noise and improve the shielding effect of the atom sensor to a stray field.

The invention discloses a measurement method and a system of flow velocity vector of a three-dimensional flow field of a microfluidic chip. The spectral domain optical coherence tomography technology (SD-OCT) is combined with the Doppler Effect, and a narrow-band phase plate is applied on the basis. The spectral domain OCT realizes the extraction of deep information of the flow field of the microfluidic chip through the parallel detection of Interference spectrum; compared with the conventional time-domain OCT, the imaging speed is greatly improved. The Doppler frequency shift and the Doppler broadening are comprehensively utilized, the narrow-band phase plate is inserted between a collimating mirror and a focusing lens of an imaging probe, thereby implementing the spatial encoding of the Doppler information, realizing the imaging requirements on the spatial high-resolution three-dimensional speed vector, combining with the Doppler OCT method which is based on the phase resolution technology to meet the high-speed and high-sensitivity measurement requirements and finally realizing the speed vector imaging with high-resolution, high-speed, high-sensitivity and large-imaging range of the three-dimensional flow field of the microfluidic chip.

The invention relates to a laser frequency regulation technology and particularly discloses a thin-cell Doppler-broadening-free absorption spectrum frequency regulator. With the adoption of the thin-cell Doppler-broadening-free absorption spectrum frequency regulator provided by the invention, the problem that the conventional laser frequency regulation technology is influenced by Doppler broadening so that the improvement of the laser frequency stability is limited, can be solved. The thin-cell Doppler-broadening-free absorption spectrum frequency regulator comprises a semiconductor laser device, a polarization beam splitter prism, a light absorption sheet, a photoelectric detector, a white glass sheet, a phase-locked amplifier, a single-photon detector and an oscilloscope; a light path formed by connecting a laser isolator and a half-wave plate in series and in sequence is arranged between an emergent end of the semiconductor laser device and an incidence end of the polarization beam splitter prism; and a second total reflector is arranged between a reflection emergent end of the polarization beam splitter prism and an incidence end of the white glass sheet. The thin-cell Doppler-broadening-free absorption spectrum frequency regulator provided by the invention is applicable to fields such as researches of high-resolution molecule and atomic spectrum, laser interference measurement, atom cooling and trapping, optical fiber communication, frequency selection, optical data storage and the like.

The invention provides a fast neutron spectrum measurement system and method. The system mainly comprises a target material and a gamma spectrum instrument, wherein a to-be-measured neutron and nuclide in the target material react to generate characteristic gamma rays having the Doppler-broadening effect, and to-be-measured neutron spectrum can be acquired through measuring and analyzing the broadening gamma pulse amplitude spectrum. The system is advantaged in that the system is simple and simple, neutron spectrum measurement is converted into gamma spectrum measurement, and high measurement precision is realized.

The invention discloses a short wave channel model building method. The short wave channel model building method includes extracting M samples of a link from a database storing short wave channel parameter samples, and acquiring multipath broadening parameters and Doppler broadening parameters of the samples; utilizing the multipath broadening parameters and the Doppler broadening parameters in the samples as column vectors to establish a channel parameter matrix, and subjecting the vectors in the matrix to uniformization; detecting whether the number of array points covered in a neighborhood radius range of various cluster centers meets the cluster requirement or not; if yes, subjecting the cluster centers to de-uniformization and utilizing the multipath broadening parameters and the Doppler broadening parameters corresponding to the cluster centers subjected to de-uniformization as a short wave channel model. The short wave channel model building method solves the problem that a model obtained by existing channel building technology is large in error and cannot accurately describe the channel characteristics of the link.

The invention presents a high-speed missile-borne radar waveform designing method. One embodiment of the method comprises: limiting the synthetic bandwidth and determining its value by the distance resolution and the signal-to-noise threshold; giving the number of intra-frame pulses; determining the frequency step amount; determining the lower limit of the pulse repetition frequency and the upper limit of the pulse width; setting the initial value for the pulse width according to the limitation of the value range of the pulse repetition frequency; determining the value range and the value of the pulse repetition frequency; if the value range is an empty set, indicating that the initial value of the preset pulse width is unreasonable and re-setting an initial value for the pulse width; and determining the number of pulse accumulation points; determining the ultimately appropriate distance range by the non-fuzzy distance and blind distance. This embodiment, with the technologies of millimeter waves, large bandwidth, step frequency and duplex frequency, solves the problem that that a target passes off and deviates from a distance unit caused by the reduced signal-to-noise ratio, the main lobe clutter Doppler broadening and the high speed movement between the bombs, therefore, achieving the purpose of precision strikes.

The invention discloses a method for detecting the ageing of a composite insulator umbrella skirt. The method comprises the following steps: selecting a composite insulator high-pressure side umbrella skirt as a sample; performing slow positron beam measurement on the sample, so as to obtain a Doppler broadening spectrum distributed along with positron incident energy; collecting an S parameter of the Doppler broadening spectrum; judging whether the S parameter is in a preset parameter range or not; if so, judging that the composite insulator umbrella skirt is aged. The detection method disclosed by the invention is small in sampling amount, and simple and convenient in test method, and information of substances can be very sensitive to defect; the detection method can serve as a scanning probe of a silicon rubber surface structure and can be applied to preliminary identification and evaluation of the ageing of the composite insulator umbrella skirt.

The invention provides a method for choosing time for ISAR optimal imaging. According to the method, length apriori information in the target distance direction is used, the pitching rule of a ship target is combined, and the intrinsic pitching period of a ship is estimated; the intrinsic pitching period is used for insulating the interference of a micro-Doppler effect on a Doppler broadening curve, and a reliable basis is provided for selecting the cut-off frequency of a low-pass filter of the Doppler broadening curve; a variance concept in a probability statistics theory is used, and the average Doppler broadening of all primary images of the target is estimated. The method for choosing the time for ISAR optimal imaging obtains good estimation accuracy and robustness, the computation amount is low, and the method is suitable for real-time application.

The invention discloses a vacuum degree detection method and system based on an infrared laser spectrum. By use of the high-resolution absorption line broadening characteristic of adsorption steam released by the headspace of a sealing container, through double-optical-path detection, by use of synchronization interference fringe signals, the time domain of a detection spectrum is converted to a frequency domain, the absolute value of spectral line broadening is obtained, and absolute measurement of a gas pressure intensity is realized; light intensity information is obtained by use of a background fitting algorithm, and the influence of the change of the transmittance of the container on detection is eliminated through normalization processing; rapid fitting is performed on a steam absorption line by use of a composite linear model, and Doppler-broadening and pressure broadening of the spectral line broadening are separated from each other; and through synchronous measurement of steam pressure dividing, the precision of vacuum air pressure measurement is improved. The method and system provided by the invention can be applied to vacuum degree detection of a vacuum sealing container in foodstuff and medical industries and realize rapid leak detection.

The invention discloses a multidimensional positron annihilation lifetime spectrum and doppler broadening spectrum measurement systems. Each of the multidimensional positron annihilation lifetime spectrum measurement system and the doppler broadening spectrum measurement system comprises an anticoincidence system and a three-dimensional moving system. Each anticoincidence system comprises a positron detector, a first preamplifier, a first spectrum amplifier, a first single-channel analyzer and a coincidence device, which are sequentially connected; each positron detector consists of a flicker flake and a photomultiplier tube, which are coupled through silicone oil, and a radioactive source is an isotope radioactive source, and is directly dropped on the flicker flake; the three-dimensional moving systems are used for loading a sample and moving the sample in a three-dimensional direction. According to the system, annihilation information not belonging to the sample is eliminated by adopting the anticoincidence systems, so that the detection reliability and the detection accuracy can be improved; the distances and the directions between the sample and the positron detectors are regulated by adopting three-dimensional moving platforms, so that multidimensional, accurate and nondestructive defect detection of a single irregular sample can be realized.

The invention is directed to a defect imaging device that has an energy beam that is directed at a device under test. The energy beam creates positrons deep within the material of the device under test. When the positrons combine with electrons in the material they produce a pair of annihilation photons. The annihilation photons are detected. The Doppler broadening of the annihilation photons is used to determine if a defect is present in the material. Three dimensional images of the device under test are created by directing the energy beam at different portions of the device under test.

The invention relates to a nondestructive test method for microhardness of a metal surface layer subjected to laser shock processing. The method comprises aiming at a metal pipe subjected to laser shock processing, firstly measuring the parameter value S of a Doppler broadening spectrum of the surface of the metal piece, then using a hardness instrument to measure the microhardness of the corresponding position, and finally performing linear fitting on the measured hardness value and the parameter value S by employing least squares, so as to obtain the linear relation curve of the measured hardness value and the parameter value S. According to the method, for the metal piece which is subjected to laser shock processing and needs hardness measurement, the parameter value S of the surface Doppler broadening spectrum of a to-be measured position of the metal piece is firstly measured, and then the microhardness of the position can be estimated according to the relation curve of the parameter value and the hardness value. The method realizes nondestructive test of the microhardness of the metal surface layer subjected to laser shock processing, the disadvantage that the metal surface layer possesses impressions because of hardness instrument measurement is effectively avoided, and the metal surface integrity is guaranteed.

A method of signal processing for a receiver for OFDM encoded digital signals, for counteracting inter-carrier interference (ICI) caused by Doppler broadening. The OFDM encoded digital signals are transmitted as sub-carriers in several channels, which form OFDM blocks. The method comprises estimation of a channel transfer function (H1) by a channel estimation scheme in each sub-carrier and estimation of data (a1) by a data estimation scheme from said channel transfer function (H1) and a received signal (y0). Then, a derivative (Hj') of said channel transfer function in each sub-carrier is estimated by a temporal filtering; and the inter-carrier interference (ICI) is removed from said received signal by using the estimated data (a1) and the estimated derivative (Hj' ) of the channel transfer function in order to obtain a cleaned received signal (y1).

The invention provides an atomic Doppler broadening peak laser frequency locking device and a frequency locking laser comprising the same. The atomic Doppler broadening peak laser frequency locking device comprises: a beam splitting device used for splitting a laser emitted by a tunable laser to a first laser; an atomic gas chamber located on the optical path of the first laser; a photodetector used for converting the first laser transmitted from the atomic gas chamber to electric signals; a phase-locked amplifier used for receiving the electric signals output by the photodetector and outputting error signals; and a negative feedback controller used for locking the frequency of the laser emitted by the tunable laser according to the error signals output by the phase-locked amplifier. The frequency locking device has the advantages that the optical path is relatively simple, no large power consumption equipment is used, and the stability and the operability are greatly improved, the construction of the optical path is simpler, the cost is reduced, and favorable conditions are provided for industrialization.

The invention discloses an anticoincidence-based positron annihilation doppler broadening spectra method and system. The method comprises the following steps: generating positron through a radioactive source, wherein the positron comprises a first positron which enters a sample, and a second positron which enters a flicker flake; acquiring gamma photon energy information generated by positron annihilation, wherein the gamma photon energy information comprises first gamma photon energy information generated by first positron annihilation, and second gamma photon energy information generated by second positron annihilation; acquiring a fluorescence signal generated by the second positron through the flicker flake; removing the second gamma photon energy information from the gamma photon energy information according to the fluorescence signal. With the adoption of the method and the system, invalid gamma photon energy information can be removed.

The broadening of the lines in NRF from an isotope that is part of a material may be due to several causes: the temperature of the material, the molecular structure of the material and the crystalline structure of the material. By measuring the broadening caused by the molecular structure and the crystalline structure the material itself can be identified. The exact energy of the lines in NRF may also depend on the nature of the crystalline and molecular structure of the material. By measuring the changes in the energy of the NRF lines caused by the structure of the material the material itself may be identified. These techniques provide a “fingerprint” of the molecule or crystal that is involved. The fingerprint information may be used to determine a potential threat.

The invention discloses an explicit indistinguishable resonance region continuous energy section construction method, which comprises: sampling average resonance energy level spacing to obtain formant positions of an indistinguishable resonance region, and sampling resonance widths to obtain resonance widths of different reaction channels at each formant; during the period, performing interpolation on resonance parameters in the evaluation kernel database to obtain resonance parameters at all formant positions not in energy points given by the evaluation kernel database; and then, through a multi-energy-level Blade-Wigner formula and a Psi-Chi Doppler broadening formula, obtaining continuous energy point sections at different temperatures. According to the method, the continuous energy cross section of the indistinguishable resonance region can be explicitly constructed, so that the high-precision self-shielding cross section calculation requirement of the indistinguishable resonance region of a modern reactor can be met.

The invention relates to the nuclear electronics technology, in particular to an all-digital two-dimensional coincident Doppler broadening system, comprising a first detector, a second detector , a host computer, a first acquisition channel, a second acquisition channel, an FPGA digital processing platform and a gigabit Ethernet port. The first acquisition channel and the second acquisition channel have the same structures. The first detector and the second detector are connected with the first acquisition channel and the second acquisition channel respectively. The FPGA digital processing platform is respectively connected with the first and second acquisition channels and the gigabit Ethernet port; and the gigabit Ethernet port is connected to the host computer. According to the system, the system design is simplified by using the dual-channel all-digital acquisition circuit; and the pulse extraction, time calibration, and time coincident analysis are realized in the FPGA. The ADC is used directly to carry out pulse sampling and then pulse shaping, baseline recovery, stack identification, amplitude extraction, and time calibration are performed by entering the FPGA digital processing platform, so that the peak-to-background ratio of the Doppler broadening spectrum is increased by 2 to 3 magnitude order.

The invention relates to the technical field of a positron beam measurement, and particularly relates to a novel multifunctional positron beam measuring system. The measuring system comprises a multifunctional measuring target room, a magnetic field focusing system, a positron annihilation service life measuring system, a Doppler broadening measuring system, and a compliance Doppler broadening measuring system. The measuring system can realize the multi-parameter measurement of the positron annihilation service life, the Doppler broadening and the compliance Doppler broadening, reduce the backscattering positron effect, decrease diameter of positron beam spot, and improve the instrument measuring efficiency.

The invention discloses a method for detecting the arrangement of ordered nano-tubular pores of a porous film. The method comprises measuring a sample-beam current geometric Doppler broadening spectrum of a nanoporous film to be tested based on the Doppler broadening spectrum of a slow positron beam through rotating the nanoporous film to be tested around a beam axis by 90 degrees, acquiring Doppler broadening spectrums of the nanoporous film before and after rotation, respectively calculating linear S parameters or linear W parameters of the Doppler broadening spectrums acquired by the two processes and determining the order of the nanoporous film according to the change of the linear S parameters and linear W parameters acquired by the two processes. The method can detect surface information of the detected material and accurately detect the pore structure information of the film and the change of defects along with depth distribution. The substrate does not affect the detection of the porosity of the film, thereby eliminating the need for the film to be removed from the substrate. The method does not damage the nanopore structure of the film and guarantees the accuracy of the measurement results and the reusability of the sample.

The invention discloses a method for measuring atmospheric temperature based on Doppler broadening, and the method emits laser, receives an atmospheric scattered echo signal, images by FP interferometer stripe, measures spectral broadening, and calculates the atmosphere temperature at different heights by using the spectral broadening. The method for measuring atmospheric temperature based on Doppler broadening provided by the invention is simple in operation and small in calculation amount, can realize the temperature measurement from low altitude to high altitude, and is stable in echo signals and accurate in measurement results.