21 results about "Thz time domain spectroscopy" patented technology

A system and methods for characterizing a semiconductor sample by terahertz (THz) time-domain spectroscopy (TDS), the system configured to implement methods including: directing an optical pump pulse, having one or more optical pump parameters, onto a region of the sample, thereby inducing a transient change within the region; directing a terahertz (THz) probe pulse to the region of the sample at a controlled time delay relative to the optical pump pulse; detecting the THz response signal from the transmission or reflection of the THz probe pulse from the region of the sample; and determining from the THz response signal at least one characteristic of the sample indicated by the transient change induced by the optical pump pulse..

This application discloses a conformal coating detection method, apparatus, electronic device, storage medium, and product, relating to the field of nondestructive testing technology. The disclosed conformal coating detection method includes: obtaining a terahertz reflection signal from a chip under test and generating a time-domain spectrum of the terahertz reflection signal; converting the time-domain spectrum into a frequency-domain spectrum, and constructing an initial transfer function based on the frequency-domain spectrum and a preset reference frequency-domain spectrum, wherein the initial transfer function is the ratio of the frequency-domain spectrum to the reference frequency-domain spectrum; performing a frequency-domain reconstruction operation on the transfer function using a preset autoregressive model to obtain an optimized transfer function; and calculating the characteristics of the conformal coating of the chip under test based on the optimized transfer function. This application can ensure high-precision measurement of conformal coatings.

The invention discloses a cable trench fireproof cover plate performance detection device and method based on multi-band electromagnetic waves. The device comprises a microwave detection module, a terahertz imaging module, a high-precision two-dimensional mechanical scanning platform, a synchronous control and data fusion unit and a comprehensive data analysis platform. The microwave module is used for transmitting and receiving 1-10GHz electromagnetic waves to realize deep structure detection; the terahertz module works at a frequency band of 0.1-3 THz and is used for acquiring near-surface time-domain spectral information. And the scanning platform drives the modules to perform two-dimensional rasterization scanning on the surface of the cover plate. And the synchronous control and data fusion unit coordinates the time sequence action of each module to ensure the time-space consistency of data acquisition. And the comprehensive data analysis platform performs fusion processing on the multi-source data through an inversion and imaging algorithm to generate a comprehensive evaluation report covering internal macroscopic defects, near-surface microdefects and coating thickness. According to the invention, through collaborative integration of microwave and terahertz technologies, multi-scale and integrated nondestructive testing and performance evaluation of the fireproof cover plate from a deep layer to a surface layer are realized.

The invention relates to a terahertz spectrum detection technology, in particular to a pericarpium citri reticulatae producing area identification method based on graph regularization sparse principal component analysis and a support vector machine algorithm, and belongs to the field of pericarpium citri reticulatae producing area quality detection. The method comprises the following steps: grinding and tabletting a dried orange peel sample to be detected, firstly detecting the dried orange peel sample in a nitrogen environment by adopting a terahertz time-domain spectroscopy system in a transmission mode to obtain a terahertz time-domain spectroscopy signal of the sample, and performing Fourier transform on the time-domain spectroscopy signal to obtain a frequency-domain spectrum of the sample; and obtaining a corresponding terahertz absorption spectrum according to the frequency domain spectrum. Savitzky-Golay smoothing preprocessing is carried out on the obtained terahertz absorption spectrum, the terahertz absorption spectrum is divided into a training set and a test set, and then feature extraction is carried out on data by utilizing sparse principal component analysis in combination with graph regularization. And taking the processed data as the input of a classification model. And finally, a combined parameter of an optimal regularization coefficient c and a kernel function parameter g of the support vector machine is obtained through a particle swarm optimization algorithm, so that an optimal pericarpium citri reticulatae producing area classification model is established. The method provided by the invention is convenient in sample preparation and simple in operation, can effectively realize rapid and accurate identification of dried orange peel from different producing areas, and provides a new method for identification of dried orange peel in high-value producing areas.

The invention discloses a terahertz time-domain spectroscopy-based wheat stripe rust uredospore optical parameter extraction method. The method comprises the following steps: mixing wheat stripe rust uredospore powder and polyethylene powder, and tabletting; a transmission module of the terahertz time-domain spectrometer is used for collecting time-domain spectral data of the mixed tablets in a nitrogen environment; carrying out filtering processing on the collected time-domain spectral data to eliminate high-frequency noise; main waves of the time domain signals are reserved, the echo position is estimated, sampling points are randomly generated through normal distribution to dynamically correct the echo signals, and time domain interference is reduced; and performing fast Fourier transform on the corrected time domain signal, and calculating the refractive index, the absorption coefficient and the dielectric constant of the wheat stripe rust uredospores through frequency domain amplitude and phase information on the basis of an improved Dorne-Duvillaret model. Through sample preparation optimization, echo correction and model improvement, the measurement precision can be remarkably improved.

Disclosed in the present invention is an Angelicae sinensis radix adulteration quantitative detection method based on terahertz spectroscopy and data fusion. The method comprises the following steps: (1) using Angelicae pubescentis radix powder as an adulterant, doping Angelicae pubescentis radix powder of different concentrations into Angelicae sinensis radix powder, and performing mixing to prepare samples having different adulteration levels; (2) putting each sample into a terahertz system, and measuring each sample to obtain terahertz absorption spectral information and time-domain spectral information of each sample; (3) performing feature extraction on the terahertz absorption spectral information of different samples; (4) using a Gramian angular difference field to convert terahertz time-domain spectra of different samples into images, and extracting image feature information; and (5) using a feature-level data fusion strategy to fuse feature information of terahertz absorption spectra with feature information of Gramian angular difference field images, so as to construct an Angelicae sinensis radix adulteration quantitative detection model. The present invention provides an efficient and reliable solution for Angelicae sinensis radix adulteration detection by using multi-modal feature information.

The application provides a kind of wood density detection method, system, computer equipment and storage medium, belong to wood detection and analysis field, this method includes: with fast-growing wood and Dalbergia wood as sample, prepare radial section wood chip and constant temperature and humidity treatment;Through terahertz time-domain spectroscopy system acquisition sample time-domain spectrum, obtains frequency domain spectrum by fast fourier transform conversion, extracts the refractive index of 0.2THz-1THz band from frequency domain spectrum as initial feature;73 terahertz refractive indexes are screened out by UVE, after comparing ENR, RF, XGBoost model, select the XGBoost optimized by PSO for training, the contribution of refractive index corresponding to terahertz refractive index to density prediction value is analyzed by combining SHAP value;Test shows that the density prediction R of cross-species reaches 0.9862, nondestructive, efficient detection can be realized, suitable for forestry processing and quality evaluation, and provides an innovative technical path for wood property analysis.

The present application relates to the terahertz field and specifically provides a method for detecting ferroelectric domains in ferroelectrics. The method comprises the following steps: S1, irradiating a ferroelectric to be tested with a laser, causing the ferroelectric to generate terahertz waves; S2, changing the polarization state of the laser to obtain corresponding terahertz wave time-domain spectra under different polarization states; and S3, obtaining ferroelectric domain information of the ferroelectric based on the terahertz wave time-domain spectra. The laser in step S1 is a femtosecond pulse laser, and the ferroelectric to be tested is a terahertz wave radiation source in a terahertz emission spectroscopy system in which the femtosecond pulse laser is used. The present application does not require external electrodes and wires to the ferroelectric, and can achieve all-optical detection of ferroelectric domains on a picosecond time scale or shorter. Furthermore, the present method does not require converting nonlinear current into ohmic current, which does not result in the loss of physical information contained in the nonlinear current. Therefore, the present method has a high accuracy in detecting ferroelectric domains.

The invention discloses a method for classifying and identifying three types of kaolin based on a terahertz time-domain spectroscopy technology, which comprises the following steps of: collecting time-domain spectrums of three types of kaolin samples, calculating absorption coefficients of different samples by utilizing corresponding formulas such as fast Fourier, and combining clustering analysis and principal component analysis methods to identify the three types of kaolin. The extraction of the Euclidean distance of spectral data and the dimension reduction processing of effective data are realized, and the Euclidean distance and the first principal component of a corresponding sample can be obtained. The result shows that the cumulative contribution rate of the first three principal components of the sample absorption coefficient screened by the PCA result can reach 97.26%, the samples are clustered into three classes according to the difference of the Euclidean distance by the CA result, and the cluster in the CA is consistent with the principal component result in the PCA. According to the method, three types of kaolin can be accurately identified and classified according to similarity and difference among different samples in combination with a CA-PCA model, and the identification rate can reach 99.99%. The method has the advantages of no damage to the detected kaolin sample, simple experiment operation, efficient spectrum acquisition and short detection period.

The invention discloses an insulating oil breakdown voltage field detection method, equipment, equipment, a medium and a product, and relates to the field of power equipment detection.The method comprises the steps that a portable terahertz insulating oil breakdown voltage detection platform is built; acquiring time-domain spectral signals of insulating oil samples with different masses by using a portable terahertz insulating oil breakdown voltage detection platform; determining corresponding spectral characteristics according to the time-domain spectral signals of the insulating oil samples with different masses; respectively extracting terahertz characteristic values according to the spectral characteristics of the insulating oil samples with different masses; constructing a sample data set according to the breakdown voltage values of the corresponding insulating oil samples; establishing a breakdown voltage quantitative evaluation model according to the sample data set in combination with a support vector machine regression algorithm; and carrying out breakdown voltage field detection on the to-be-detected insulating oil by using the breakdown voltage quantitative evaluation model. According to the invention, on-site rapid, lossless and accurate detection of the breakdown voltage of the insulating oil can be realized.

The invention relates to the technical field of terahertz spectrum detection, and discloses a Liupao tea year grade identification method based on terahertz spectrum. According to the method, time-domain spectrums of Liupao tea of different years and grades are obtained through a terahertz time-domain spectroscopy system, and a multi-task learning model is constructed to realize identification. Aiming at the problem that a traditional algorithm is easy to fall into local optimum, three optimization strategies are provided: an exponential decay formula is adopted to dynamically adjust a boundary range, and a search space is prevented from being reduced too early; a mirror reflection mechanism is introduced to process boundary-crossing individuals, exploration information is reserved, and search coverage is expanded; and a dynamic mixing strategy of probability selection is adopted to balance global exploration and local development capabilities. According to the improved algorithm, the convergence and the optimization capacity are remarkably improved, and the year and grade identification accuracy reaches 100% finally by combining an attention layer and a customized gating model. The method disclosed by the invention is simple to operate, can effectively realize rapid and accurate identification of Liupao tea of different years and grades, and provides a new method for tea quality grading.

The present disclosure discloses a method for quantitative detection of adulteration in Angelica sinensis based on terahertz spectroscopy and data fusion, including: (1): taking Angelica pubescens powder as an adulterant; mixing different concentrations of the Angelica pubescens powder into Angelica sinensis powder to prepare samples with varying adulteration levels; (2): placing each sample into a terahertz system, and measuring each sample to obtain terahertz absorption spectrum and time-domain spectral information for the sample; (3): performing feature extraction on the terahertz absorption spectral information of each sample; (4): Utilizing Gramian Angular Difference Field (GADF) to achieve conversion of terahertz time-domain spectra to images, and extracting image feature information; and (5): adopting a feature-level data fusion strategy to integrate feature information from the terahertz absorption spectra and GADF images, and constructing a quantitative adulteration detection model for Angelica sinensis.

The invention discloses a terahertz-based insulation operating rod internal humidity detection method and system, and belongs to the technical field of power equipment detection, and the method comprises the steps: enabling terahertz pulses to enter a to-be-detected region of an insulation operating rod, and receiving terahertz echo signals transmitted and reflected by the to-be-detected region, thereby obtaining time-domain spectral data; fourier transform is carried out on the time-domain spectral data to obtain a frequency-domain spectrum, a target spectral component in the frequency-domain spectrum is screened out based on the frequency absorption characteristic of water molecules, and an internal humidity detection parameter is obtained by using the target spectral component; and obtaining the internal humidity according to the detection parameters and a correlation model obtained based on the historical internal humidity of the historical insulation operating rod. The technical problem that the integrity of the insulating operating rod and the detection precision of the internal humidity are difficult to consider in the prior art is solved.

Various embodiments of the present disclosure provide systems and methods for classifying and evaluating an electronic object based at least in part on terahertz (THz) data. THz data may comprise time-domain THz data collected via THz time domain spectroscopy of the electronic object. THz data may further comprise frequency-domain THz data, which may be generated based at least in part on the time-domain THz data. A unique THz fingerprint may be generated for the electronic object based at least in part on the THz data. This unique THz fingerprint may be compared to an earlier generated THz fingerprint of the same electronic object to evaluate reliability and consistency. The unique THz fingerprint may also be compared to THz fingerprints or THz data of other electronic objects of the same object type, class, design, and / or the like, to validate the electronic object (e.g., determine if the electronic object is counterfeit).

This application provides a terahertz wave testing device and a method for correcting CO2 diffusion and solubility parameters, relating to the field of oil and gas field development technology. The device includes: a CO2 storage tank, a reference cylinder, a sample cylinder, a pulsed laser emitter, a beam splitter, a signal delayer, a reflector, a signal generator, a signal receiver, a first reflector, and a second reflector. The CO2 storage tank is connected to the reference cylinder, and the reference cylinder is connected to the sample cylinder. A controllable valve is also installed on the connecting pipeline between the reference cylinder and the sample cylinder to control the on / off state of the connecting pipeline. The beam splitter, signal delayer, and reflector are sequentially arranged in the laser emission direction of the pulsed laser emitter. The terahertz pulse wave generated by the signal generator is incident on the sample cylinder through the first reflector and then reflected to the signal receiver by the second reflector. The terahertz wave testing device of this application can monitor the bulk water content in real time based on terahertz wave time-domain spectroscopy, thereby correcting the diffusion coefficient and solubility of CO2 in heavy oil.

The invention relates to a method and a device for time-domain spectroscopy with a reduced number of sampling points compared to the WKS sampling theorem. The aim is to enable the approximation of a time signal using a limited number of periodic and / or periodically attenuated fundamental signals. In particular, the invention relates to the selection of suitable sampling points for measuring a time signal and the measurement itself, in order to approximate the time signal using the limited number of fundamental signals. The sampling points are determined according to a deterministic method.

The invention provides a wood density detection method and system, computer equipment and a storage medium, and belongs to the field of wood detection and analys.The method comprises the steps that fast-growing wood and pterocarpus wood serve as samples, and radial section wood chips are prepared and subjected to constant-temperature and constant-humidity treatment; the method comprises the following steps: collecting a sample time-domain spectrum through a terahertz time-domain spectroscopy system, obtaining a frequency-domain spectrum through fast Fourier transform, and extracting a refractive index of a 0.2 THz-1 THz frequency band from the frequency-domain spectrum as an initial feature; 73 terahertz refractive indexes are screened out through UVE, after an ENR model, an RF model and an XGBoost model are compared, the XGBoost optimized through PSO is selected for training, and contribution of the refractive indexes corresponding to the terahertz refractive indexes to a density prediction value is analyzed in combination with an SHAP value; the test shows that the cross-tree density prediction Rreaches 0.9862, nondestructive and efficient detection can be realized, the method is suitable for forestry processing and quality evaluation, and an innovative technical path is provided for wood characteristic analysis.

The invention discloses a graphene terahertz metasurface sensor and application thereof in pesticide residue detection, and relates to the technical field of sensors and detection. The graphene terahertz metasurface sensor comprises a substrate, a metasurface layer, a graphene film and an aptamer layer. The invention further provides application of the graphene terahertz metasurface sensor in pesticide residue detection. The metasurface layer is composed of the asymmetric metal wire array, the metasurface layer is placed in a light path of a transmission-type THz time-domain spectroscopy system, under the condition that the polarization direction of incident waves is along the x axis, the structure can generate extremely strong local electric field enhancement, and when the metasurface layer is used for detecting pesticide molecules, the detection sensitivity is greatly improved. The interaction between THz waves and pesticide molecules to be detected is obviously enhanced, so that the purpose of trace sensing of a target object is achieved. In addition, graphene is utilized and the metasurface of the aptamer layer is modified, so that the detection sensitivity and specificity are improved.

The application discloses a time-domain spectrum system capable of generating and detecting ultra-wideband terahertz pulses. The system comprises a laser light source, a light splitting module, an optical path adjustment coupling module, a terahertz emission module, a sample detection module and an electro-optic sampling module. After the laser pulses output by the laser light source are split, the pump light is chopped, modulated, expanded and irradiated to a spin terahertz emitter to generate ultra-wideband terahertz pulses of 0.1-10 THz. After the terahertz pulses interact with the sample through a confocal off-axis parabolic mirror, the terahertz pulses are collimated and output again. The detection light formed by light splitting is adjusted in optical path and coincides with the terahertz pulses in time and space, and is focused on an ultra-thin ZnTe crystal in the <110> crystal direction. Finally, the terahertz time-domain signal is obtained through electro-optic sampling. The system has the functions of emitting and detecting ultra-wideband terahertz pulses, and can be used not only in the fields of material detection and physicochemical analysis, but also in the precise verification of the characteristics of other terahertz sources and detection crystals.

A system is presented for use in photoreflectance (PR) measurements of a sample. The system comprises a light source system comprising a pump source assembly and a non-linear medium. The pump source assembly produces: an ultra-short seed pulse exciting the non-linear medium presenting a supercontinuum laser generating a broadband probe pulse propagating along a first path towards the sample to create a broadband focal spot on the sample; and an exciting pump pulse propagating along a second path, inclined with respect to the first path, to create an excitation focal spot on the sample. The light source system defines a delay line to controllably vary a time of arrival of the exciting pump pulse to the sample, thereby inducing a controllably variable pump-probe time delay in real time during a PR measurement session, thereby enabling successive time-domain spectroscopic PR measurements of the sample.

This invention discloses a graphene terahertz metasurface sensor and its application in pesticide residue detection, relating to the fields of sensor and detection technology. The graphene terahertz metasurface sensor comprises a substrate, a metasurface layer, a graphene film, and an aptamer layer. This invention also provides the application of the graphene terahertz metasurface sensor in pesticide residue detection. The metasurface layer of this invention is composed of an asymmetric metal wire array. When placed in the optical path of a transmission THz time-domain spectroscopy system, with the incident wave polarization direction along the x-axis, the structure itself can generate a very strong local electric field enhancement. When used to detect pesticide molecules, the interaction between the THz wave and the pesticide molecules to be measured is significantly enhanced, thereby achieving trace sensing of the target analyte. Furthermore, this invention utilizes graphene and modifies the aptamer layer metasurface to improve the sensitivity and specificity of detection.