184 results about "Terahertz time-domain spectroscopy" patented technology

The invention relates to a nondestructive testing analytical method for kerogen based on terahertz time-domain spectroscopy. The method comprises the following steps of: firstly, selecting a sample cell; secondly, preparing a kerogen standard sample and accommodating the kerogen standard sample in the sample cell; thirdly, detecting the kerogen standard sample and the empty sample cell by using the terahertz time-domain spectroscopy to obtain a terahertz pulse time-domain waveform of the kerogen standard sample and a terahertz pulse time-domain waveform of the empty sample cell; fourthly, carrying out data processing on the terahertz pulse time-domain waveform of the kerogen standard sample and the terahertz pulse time-domain waveform of the empty sample cell to construct a standard fingerprint spectrum library; and fifthly, analyzing the thermal evolution and hydrocarbon generating capabilities of the kerogen standard sample according to optical parameters of the standard fingerprint spectrum library. The nondestructive testing analytical method for the kerogen based on the terahertz time-domain spectroscopy which is disclosed by the invention has the advantages of quick and nondestructive detection for the kerogen, easiness in operation, simpleness in data processing, favorable repeatability and relatively accurate measuring result.

The invention provides an all-fiber transmission reflection integrated terahertz time-domain spectroscopy system. At present, most of the terahertz time-domain spectroscopy systems refer to free-space systems and have the defects of complex structure, low stability and the like. Aiming at the problem, femtosecond laser pulse is transmitted by virtue of optical fibers, so that the usage amount of optical devices in the light path is reduced, and the light path is simple and stable in structure. Meanwhile, because the femtosecond laser pulse comes into a terahertz emitter and a terahertz receiver by virtue of optical fibers, the light path structure of the system is not influenced by the movement and rotation of the positions of the terahertz emitter and the terahertz receiver, the terahertz receiver and the terahertz emitter can be respectively arranged on two rotatable optical guide rails, and flexible switch between terahertz transmission and reflection time-domain spectroscopy systems can be further realized. Therefore, the problem that the terahertz spectroscopy system is complex in structure and large in size in the prior art is solved.

The invention discloses a terahertz time domain spectroscopy-based textile fiber identification method. The method mainly comprises the following steps of: acquiring the absorption spectrum of a standard textile fiber at a terahertz wave band by using a terahertz time domain spectroscopy measuring device; extracting the principal component of the absorption spectrum of the textile fiber by using a principal component analysis method; establishing a textile fiber classification model by using a mode recognition method; and acquiring the terahertz absorption spectrum of the textile fiber to be identified by the method, extracting the principle component of the terahertz absorption spectrum, performing classification by calling the established model and determining the type of the textile fiber to be identified. The identification method is a spectroscopy-based identification method, does not need a complex pre-processing process and has short test time. The method belongs to the field of nondestructive testing, does not damage a tested sample, has high identification accuracy and is suitable for identifying textile fibers with similar components.

The invention relates to a method for measuring concentrations of sulfate, nitrate solutions by utilizing the terahertz time-domain spectroscopy. The method comprises the following steps: sample cells are selected, standard solution samples with different concentrations are prepared, terahertz time-domain spectra of the standard solution samples are measured, a terahertz time-domain spectra database of the standard solution samples is built, and the database comprises time-domain spectra, frequency-domain spectra, relation spectra of concentrations and absorption coefficients, relation spectra of concentrations and refractive indexes, relation spectra of concentrations and extinction coefficients of the standard solution samples. Terahertz time-domain spectra of the solutions to be measured are measured, the data is processed to obtain absorption coefficients of the solutions to be measured, and according to the terahertz time-domain spectra database of the standard solution samples, the concentrations of the solutions to be measured are analyzed and determined. The method utilizes the terahertz time-domain spectroscopy to measure solution concentrations, and is advantaged by simple operations, rapid measurement, simple data processing procedures, good repeatability, and high accuracy of results.

The invention discloses a paper sheet quantitative detection device which is based on a terahertz time-domain spectroscopy technology and a method thereof. The detection device includes: a femtosecond laser, a beam splitter, an optical delay device, a reflective mirror, a focusing lens, a photoconductive antenna type terahertz transmitter, a polyethylene lens, a polarizer, a zinc telluride electro-optical crystal, a phase-locking amplifier, a high-power amplifier and a data collection and processing system. The invention makes use of the polyethylene lens for aligning the terahertz waves to the parallel light beams, and the polyethylene lens is used for focusing the terahertz waves on a terahertz detector after penetrating the paper sheet. The paper sheet quantitative detection method which is disclosed by the invention firstly establishes a paper sheet quantitative detection mathematical model, then respectively measures the time-domain signals of the terahertz waves penetrating the air and penetrating the paper sheet, extracts the delay time and applies the established mathematical model to calculate the paper sheet quantitative value. The invention has high precision of the measurement, strong anti-interference capability, small influence of multiple reflections and safe usage, so the invention can be used in the precise paper sheet quantitative detection of the field of paper making.

The invention discloses a thermal barrier coating multi-layer thickness detection method based on a reflective terahertz time domain spectroscopy technology. The method includes the following steps: applying a terahertz time domain spectral detection device to measure signals reflected by the air and a detected thermal barrier coating when terahertz waves pass through the air and the detected thermal barrier coating, taking the measured signals as reference signals and sample signals in a time domain, conducting Fourier transform on the reference signals, and taking the transformed reference signals as terahertz incoming radio frequency domain spectral signals; establishing a terahertz multi-layer reflection theoretical model; and continuously changing thickness values of all layers in thethermal barrier coating, substituting the values into the multi-layer reflection theoretical model, conducting inverse Fourier transform after theoretical frequency domain spectral signals are obtained, obtaining theoretical values of the signals in the time domain, comparing the signals with sample signals measure by an experiment, and adopting an optimal algorithm for optimization till a theoretical calculation result is consistent with an experiment measuring result, wherein the thickness values of all layers are results of the detected thickness. The invention can provide a new method foraccurate, non-destructive and rapid detection of the thickness of the thermal barrier coating.

The invention relates to a method for detecting the content of a pesticide in cereal by utilizing a terahertz time-domain spectroscopy. The method comprises the following steps of grinding and then tabletting a to-be-detected cereal sample to obtain a to-be-detected cereal tablet sample, testing the to-be-detected cereal tablet sample by directly adopting a terahertz time-domain spectroscopy system, acquiring a terahertz area spectrum signal to be used as a sample signal, acquiring a terahertz time-domain spectrum signal under a nitrogen atmosphere as a reference signal, acquiring an absorptive coefficient spectrum of the to-be-detected cereal tablet sample, acquiring a characteristic wave band of a target pesticide, classifying the absorptive coefficient spectrum of the to-be-detected cereal tablet sample to a corrected set of sample absorptive coefficient spectrum and a verification set of sample absorptive coefficient spectrum, establishing a quantitative analysis model by utilizing a partial least-squares regression method, and acquiring a quantitative detection value of each to-be-detected cereal sample. The method can truly and effectively detect the pesticide residue in the cereal quantitatively, rapidly and accurately, and the prediction square correlation coefficient (R2) of the quantitative analysis model reaches up to 0.9903.

The invention discloses a method for detecting tetracycline hydrochloride by using terahertz time-domain spectroscopy, which comprises the following steps: preparing tetracycline hydrochloride tablet samples with different mass percents; acquiring terahertz time-domain spectra of the tetracycline hydrochloride tablet samples; performing Fourier transformation treatment on the terahertz time-domain spectra of the tablet samples, and obtaining absorption coefficients and refractive indices of the tablet samples through a formula; establishing a correction model according to the mass percent of each tablet sample and the corresponding absorption spectrum; and verifying and evaluating the correction model. According to the invention, the qualitative and quantitative detection of tetracycline hydrochloride can be realized; and the method has the advantages of simple sample pretreatment, easy operation, favorable repetitiveness, relatively accurate test result and the like. Thus, the method is of far reaching importance for detecting antibiotic residue in foods by using terahertz time-domain spectroscopy.

The invention relates to a terahertz time-domain spectroscopy system. In the terahertz time-domain spectroscopy system, femtosecond laser radiated by a femtosecond laser is collimated by a first diaphragm, and then, the femtosecond laser is split into pump light and probe light through a beam splitter; the pump light generates terahertz pulses through a first light path assembly; the probe light generates linear polarization probe light aplanatic with the pump light through a second light path assembly; and the linear polarization probe light and the terahertz pulses are combined through a beam combiner to obtain a light beam to be detected and carrying terahertz pulse information. Meanwhile, a detection device is provided with two equal-thickness electro-optical crystals; and by adjusting the included angle between crystal axes of the two pieces of electro-optical crystals, corresponding phase compensation is realized on phase delay of two components, o light and e light, of the probe light passing through the first electro-optical crystal, thereby realizing linear probing of strong terahertz pulses and improving measurement precision.

The invention provides an erosion morphology test method of a thermal barrier coating based on a terahertz technology. The method comprises the following steps of vertically emitting terahertz pulsesby using a reflective terahertz time-domain spectroscopy system to the thermal barrier coating; obtaining a time domain spectrogram; extracting the moment value of the front three times of reflectionpeaks in the spectrogram; obtaining the time delay of the two adjacent peaks; performing Fourier transform on the front three times of reflection peaks to obtain a frequency domain spectrogram; calculating the refractive index and the thickness of the ceramic layer of the thermal barrier coating; performing erosion on the thermal barrier coating; performing scanning; using the time-domain spectroscopy system for measurement so as to obtain a plurality of time-domain spectrograms; extracting the moment value of the first time reflection peak in the spectrogram; calculating the difference from the moment value of the first time reflection peak; calculating the thinning thickness value of the thermal barrier coating according to the difference value; obtaining the erosion morphology of the thermal barrier coating. The test method has the advantages that the step of measuring the refractive index of the thermal barrier coating is omitted; the thinning thickness of the thermal barrier coating after the erosion is calculated, so that the calculation by using the refractive index of the thermal barrier coating is not needed; therefore the error is reduced.

The invention discloses a method for accurately measuring optical parameters of edible oil by using Terahertz time-domain spectroscopy. By using a transmission-type Terahertz time-domain spectroscopy (THz-TDS) device, the THz time domain spectroscopy of dry paper is measured as a reference signal and the THz time domain spectroscopy of the paper immersed in the edible oil is measured as a sample signal, Flourier transform values of the sample signal and the reference signal are calculated, and refractive index and absorption coefficient of the edible oil in Terahertz waveband is obtained by means of the formula. The invention is low in experimental cost and is simple and convenient in operation as well as reduces multiple reflections and FP effect of the THz wave transmitted in a far-infrared quartz cuvette and efficiently improves measurement accuracy of the optical parameters of the edible oil. The method is fast, convenient and accurate and can measure the optical parameters of the edible oil fast and simply, and the invention can provide a detection method for quality assessment and ingredient analysis of the edible oil.

The invention discloses an all-fiber terahertz quasi-time-domain real-time spectrograph which comprises a multi-mode laser system, a multi-mode laser optical fiber transmission system, a terahertz transmitting module and a terahertz receiving module. The multi-mode laser system outputs multi-mode laser light surrounding a center frequency, and the adjacent longitudinal mode frequency difference is a constant value equal interval. The multi-mode laser light is divided into two paths of light signals through the multi-mode laser optical fiber transmission system, wherein one path of light signals are input into a photoconduction transmitting antenna, and the other path of light signals are input into a photoconduction receiving antenna. The all-fiber terahertz quasi-time-domain real-time spectrograph is low in cost, achieves all-fiber integration, is portable and rapid, has real-time capability, and can be widely and actually applied in the industrial field. The quasi-time-domain system has the advantages of replacing expensive femtosecond laser and a fixed free space terahertz spectrum system, low-cost multi-mode laser is adopted, all-fiber integration is achieved, the signal to noise ratio is high, and the spectrograph is portable and can be used in the typical field of partial substitution terahertz time-domain spectroscopy and frequency domain continuous wave spectrographs.

The invention relates to an optical fiber coupling terahertz time-domain spectroscopy testing system. Lasers emitted by a laser device are reflected by a reflector set to enter a main optical fiber coupling system, the lasers are divided into two paths of light signals through the optical fiber coupling system, one path of light signals is input into an independent optical fiber coupling terahertz emitter through emitter transmission optical fibers for generating terahertz signals, and the other path of light signals is input into an independent optical fiber coupling terahertz receiver through receiver transmission optical fibers for detecting the terahertz signals. The independent optical fiber coupling terahertz emitter and the independent optical fiber coupling terahertz receiver are installed on a two-dimensional imaging movable platform, terahertz emitted by the independent optical fiber coupling terahertz emitter penetrates through a sample or is reflected by the sample to enter the independent optical fiber coupling terahertz receiver, and the sample is tested or imaged. The system can be freely switched between multiple modes according to sample characteristics. The system has the advantages of being rarely limited by space, supporting measuring and imaging of large-size and irregular-size samples, and being good in imaging effect.

The invention relates to an accessory combined type terahertz time-domain spectroscopy system. A femtosecond pulse laser device radiates linearly polarized ultra-short pulse laser, the ultra-short pulse laser passes a laser plane mirror and then passes a half-wave plate and a polarization beam splitter, and pumping light and detection light which are perpendicular to each other are obtained; the pumping light enters a terahertz emission module, and parallel terahertz waves are radiated and enter a terahertz detection module through a testing device with a sample; the detection light passes a quarter-wave plate and reaches a time delay module, the detection light is returned along the original path after being reflected by a laser retroreflection mirror, then the detection light passes the time delay module and the quarter-wave plate again, the polarization state of the detection light is converted to be consistent with that of the pumping light, the detection light is reflected by the polarization beam splitter to a foldable mirror, and then the detection light is reflected by the laser plane mirror to enter the terahertz detection module. The testing device with the sample is designed for multifunctional accessories, so functions of transmission and reflection, parallel and focusing, attenuated total reflection, reflection measurement at any angle, imaging and the like can be easily switched and used.

The invention provides a method for utilizing a terahertz time-domain spectroscopy technology to detect amino acid content in grain. The method comprises the following steps: grinding and then performing tableting on a grain sample to be detected, directly utilizing a terahertz time-domain spectroscopy system to detect the sample subject to tableting in a transmission measurement mode and under the nitrogen condition to obtain terahertz time-domain spectroscopy signals as sample signals, under the same conditions, acquiring the terahertz time-domain spectroscopy signals under the nitrogen condition as reference signals, then obtaining an absorptivity spectrum of the grain tableting sample to be detected, at last dividing the absorptivity spectrum of the grain tableting sample to be detected into a calibration set sample absorptivity spectrum and a verification set sample absorptivity spectrum, utilizing a partial least squares regression method to establish a quantitative analysis mode, and obtaining the quantitative detection value of the grain sample to be detected. The method disclosed by the invention is simple in preparation of the sample, is not required to process any pretreatment, and can practically and effectively realize fast and accurate quantitative detection on the amino acid in the grain or food.

A photoconductive antenna that generates and detects a terahertz wave has a substrate, a buffer layer, a first semiconductor layer, a second semiconductor layer, and an electrode in this order. The substrate is made of Si, the buffer layer contains Ge, and the first and second semiconductor layers both contain Ga and As. The element ratio Ga/As of the second semiconductor layer is smaller than the element ratio Ga/As of the first semiconductor layer.

The invention discloses a terahertz time-domain spectroscopy complete polarization electromagnetic scattering measurement system and acquisition method. According to the method, HH transceiving polarization, HV transceiving polarization, VH transceiving polarization and VV transceiving polarization are achieved by the aid of a terahertz time-domain spectroscopy complete polarization target electromagnetic scattering measurement system. The system mainly comprises a femtosecond laser source, a terahertz transmitting source, a terahertz wave beam collimation system, a target turntable system, aterahertz wave polarization control system, a terahertz wave detection system and a data acquisition and control system, a transceiving polarization mode is determined by adjusting rotating directionsof a hertz polarizer and a femtosecond laser half-wave plate, so that a turntable and a time delay line are controlled, and target polarization terahertz time-domain spectroscopy scattering signals under different postures are acquired in a scanned manner. According to the system, scattering characteristic measurement of target complete polarization RCS and 3D (three-dimensional) ISAR and the like within a terahertz high-frequency point and large-spectrum width range can be achieved, and the mechanical stability of the system is further ensured.

The invention provides a dynamic multipoint grass variety identification and authentication method based on terahertz time domain spectroscopy. The method comprises the following steps: preparing a standard grass seed sample; respectively detecting the standard grass seed sample and dry nitrogen by using a terahertz time domain spectroscopy device to respectively obtain a terahertz pulse time domain waveform sum of the standard grass seed sample and the dry nitrogen, taking the terahertz pulse time domain waveform of the dry nitrogen as a reference signal, and taking the terahertz pulse time domain waveform of the standard grass seed sample as a sample signal; carrying out data processing on the terahertz pulse time domain waveform of the standard grass seed sample and the terahertz pulse time domain waveform of the dry nitrogen to construct a standard fingerprint spectrum library; and analyzing, calculating and establishing an identification database of unknown grass varieties according to optical parameters of the standard fingerprint spectrum library in combination with a mathematical statistical method, thereby carrying out qualitative analysis and recognition on unknown grass samples. By adoption of the method, the grass varieties can be effectively recognized and detected, the database can also be established for the unknown grass samples, and the unknown grass samples can be quickly distinguished and identified in batches.

The invention discloses a terahertz time-domain spectroscopy method for quantitatively detecting tetracycline hydrochloride solutions. The method comprises the following steps: preparing polyvinylidene fluoride film samples of the tetracycline hydrochloride solutions with different concentrations; collecting terahertz time-domain spectroscopies of the polyvinylidene fluoride film samples of the tetracycline hydrochloride solutions; performing fourier transform processing on the terahertz time-domain spectroscopies of the polyvinylidene fluoride film samples, and using a formula to obtain absorption spectrums of the polyvinylidene fluoride film samples; establishing a correction model for predicting tetracycline hydrochloride concentrations; performing verification and evaluation on the correction model. The method can realize quantitative detection of the tetracycline hydrochloride solutions, and has the advantages of simplicity in pretreatment of the samples, easiness in operation, good repeatability, simplicity in data processing, relative accuracy in testing results and the like. Therefore, an important significance is provided by using the terahertz time-domain spectroscopy technology to detect antibiotic residues in liquid food.

The invention discloses a metal surface roughness detection device based on the reflection-type terahertz time-domain spectroscopy. The device comprises a femtosecond laser (1), a beam splitter (2), an optical delay line (3), a reflecting mirror (4), a first optical fiber coupler (5), a first optical fiber (6-1), a second optical fiber (6-2), a terahertz transmitter (7), a sample table (8), a terahertz detector (9), a second optical fiber coupler (10) and a computer (11). The invention further discloses a detection method utilizing the device. The method comprises the steps of firstly, utilizing the device for obtaining the terahertz reflection spectrum of a standard test piece of a certain material, building a roughness detection model, then measuring the terahertz reflection spectrum of the piece to be tested, and applying the built roughness detection model for obtaining the roughness. On the basis of the terahertz wave principle, the surface roughness difference, corrosion, surface damage of metal with a cladding layer can be accurately detected, and the device and method have the advantages of being free of damage, contactless, rapid in analysis speed and the like.

The invention discloses a renminbi selectable multiple-characteristic-point transmission authenticity-identifying method based on terahertz time-domain spectroscopy, comprising the following steps of: firstly transmitting total or selected characteristic points of hundred-yuan authorized renminbi by utilizing terahertz waves of discrete pulses to establish a dactylogram database of the terahertz absorption coefficients of the hundred-yuan authorized renminbi; then selecting only 3-5 transmission points to be detected on suspected renminbi to be identified by utilizing a random method according to the classified data of the dactylogram database, and enabling the terahertz waves of the discrete pulses to respectively transmit through each selected transmission point to obtain the terahertz absorption coefficient spectrums of the transmission points; and then comparing and analyzing the spectrums and the dactylogram database to judge the ascription on the authenticity of each transmission point and then judge the authenticity of the suspected renminbi to be identified. The accuracy of an identifying result is ensured through the fingerprint characteristics of the terahertz waves, thetransmission of paper sheets and the randomness of the selected transmission points to be detected; and in addition, by means of the renminbi selectable multiple-characteristic-point transmission authenticity-identifying method, overall scanning is omitted and a small quantity of characteristic points only need to be scanned, therefore the identifying time is greatly shortened.