245 results about "Terahertz pulse" patented technology

Systems for THz transmission using new types of THz waveguides with low loss, negligible group velocity dispersion and structural simplicity are described herein. The THz system incorporates the use of a waveguide with two or more substantially parallel conductive elements which may enable many new THz sensing applications. It is now possible to direct the THz pulse inside of containers or around corners, where line-of-sight optics are not practical. Moreover, the systems allow use of either radially polarized or linearly polarized THz antennas. The disclosed systems are compatible with existing terahertz generation and detection techniques.

A system for coupling teraherz (THz) radiation to a coaxial waveguide comprises an antenna that generates THz radiation having a mode that matches the mode of the waveguide. The antenna may comprise a pair of concentric electrodes, at least one of which may be affixed to or formed by one end of the waveguide. The radiation may have wavelengths between approximately 30 μm and 3 mm. The waveguide may comprise an inner core and an outer wall defining an annular region. A terahertz sensor system may comprise a terahertz antenna comprising first and second concentric electrodes, means for generating a field across the trodes and means for triggering the emission of terahertz radiation, a first waveguide having first and second ends, said first end being coupled to said antenna so as to receive at least a portion of said terahertz radiation, and a sensor for detecting said terahertz radiation.

The invention relates to a method and a system for measuring rock optical parameters based on Terahertz time-domain spectroscopy. The method comprises the steps of: detecting a rock substrate and a rock sample, and obtaining the Terahertz time-domain waveform of the rock substrate and the Terahertz time-domain waveform of the rock sample; processing the Terahertz time-domain waveform of the rock substrate and the Terahertz time-domain waveform of the rock sample, and obtaining the absorption spectrum and the refractive index spectrum data. The method and the system for measuring rock optical parameters based on the Terahertz time-domain spectroscopy provided by the invention have the advantages that the fast and nondestructive detection can be carried out on the rock, the operation of the detection method is easy, the data processing is simple, and the repeatability is good.

A multi-channeled measuring method for measuring a spectrum of a terahertz pulse includes the steps of a terahertz pulse generating step for generating a terahertz pulse by using an ultrashort pulsed pumping light, a white light generating step for generating a white light pulse by using an ultrashort pulsed probe light, a stretching step for stretching and chirping the white light pulse generated at the white light pulse generating step, an electro-optic modulating step for modulating the chirped white light pulse stretched and chirped at the stretching step in such a manner that the terahertz pulse and the chirped white light pulse irradiate into an electro-optic crystal synchronously, so that the chirped white light pulse is modulated by an electric field signal induced at the electro-optic crystal irradiated by the terahertz pulse, a multi-channeled spectral detecting step for detecting a spectrum of chirped white light pulse modulated at the electro-optic modulating step by a multi-channeled detector, an electric field signal analyzing step for analyzing an electric field of the terahertz pulse irradiated to the electro-optic crystal from the spectrum of the chirped white light pulse detected by the multi-channeled spectrum detecting step, and a Fourier transforming step for transforming the electric field signal analyzed by the electric field signal analyzing step into a frequency spectrum of the terahertz pulse.

The invention discloses a terahertz pulse measurement-based burning temperature sensing device and a terahertz pulse measurement-based burning temperature sensing method. Laser is emitted from a femtosecond laser device, and is divided into reference laser and detection laser through a beam splitter, the detection laser is focused on a photoconduction antenna type terahertz emitter, terahertz pulses emitted by the terahertz emitter are focused on a ZnTe crystal through an off-axis paraboloid lens group; and the reference layer is collimated and is coincident with terahertz waves focused on the ZnTe crystal after passing through a semi-transmission and self-reflection mirror, parallel grating groups and a polarizing film, the terahertz waves are modulated by using Pockels effect of the ZnTe crystal, and image signals corresponding to collected first reference layer carrying terahertz pulse strength information and second reference laser not carrying the terahertz pulse strength information are input into a computer by a CCD (Charge Coupling Device) detector for subsequence processing. According to the invention, the precision and speed of the non-contact combustion measurement method are increased, and the non-contact measurement of combustion object temperature and temperature distribution is realized.

A system for emitting and detecting terahertz frequency electromagnetic pulses. The system comprises a single transceiver device, which may be an electro-optic crystal or photoconductive antenna, for both emitting and detecting the pulses. A related method comprises using a single transceiver device to both emit and detect electromagnetic terahertz frequency pulses. The transceiver device is excited by a pump pulse to emit a terahertz output pulse, which is modulated with a chopper. An object reflects the terahertz pulse and the reflected pulse is detected in the transceiver using a probe pulse. A lock-in amplifier set to the same frequency of the chopper is used to reduce noise in the signal detected by the transceiver. An image of the object may be created using the intensity or the timing of the peak amplitude of the terahertz pulses reflected from the object.

A system for coupling teraherz (THz) radiation to a coaxial waveguide comprises an antenna that generates THz radiation having a mode that matches the mode of the waveguide. The antenna may comprise a pair of concentric electrodes, at least one of which may be affixed to or formed by one end of the waveguide. The radiation may have wavelengths between approximately 30 μm and 3 mm. The waveguide may comprise an inner core and an outer wall defining an annular region. A terahertz sensor system may comprise a terahertz antenna comprising first and second concentric electrodes, means for generating a field across the trodes and means for triggering the emission of terahertz radiation, a first waveguide having first and second ends, said first end being coupled to said antenna so as to receive at least a portion of said terahertz radiation, and a sensor for detecting said terahertz radiation.

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.

Systems for THz transmission using new types of THz waveguides with low loss, negligible group velocity dispersion and structural simplicity are described herein. The THz system incorporates the use of a waveguide with two or more substantially parallel conductive elements which may enable many new THz sensing applications. It is now possible to direct the THz pulse inside of containers or around corners, where line-of-sight optics are not practical. Moreover, the systems allow use of either radially polarized or linearly polarized THz antennas. The disclosed systems are compatible with existing terahertz generation and detection techniques.

A device and method for non-invasively measuring analytes and physiological parameters by measuring terahertz radiation emitted though biological tissue. Terahertz pulses are emitted from a miniaturized quantum cascade laser to a fiber optic array into the wrist of the user. A corresponding sensor on the opposite side of the wrist receives the terahertz signals that have been modified by interacting with organic molecules. The data from the sensor is compiled and analyzed on a RAM chip and logic chip, where a program uses an algorithm to compare measurements to a library of existing measurements and topographic maps generated when the user first dons the device. Once the algorithm has parsed all the data points, a value, such as blood glucose level, appears on a display of the device. The device may be equipped with a gasket to reduce ambient light from contacting the sensor.

The invention relates to a paint film thickness measuring method based on terahertz pulse spectrum. The paint film thickness measuring method is characterized in that a paint film thickness measuring model can be established; a terahertz time domain spectrum device is used to measure terahertz pulse spectrum of a sample to be measured, the surface of which is covered by paint; a delay time difference of a reflection peak can be acquired according to the terahertz pulse spectrum; and the paint film thickness of the sample to be measured can be calculated according to the established paint film thickness measuring model. The paint film thickness measuring method based on the terahertz pulse spectrum is advantageous in that the new method can be provided for the paint film thickness measurement; and after the non-contact detection of different measuring points, the single-layer and multi-layer paint film thickness and the distribution uniformity can be detected.

The invention discloses a terahertz inverse synthetic aperture radar imaging method based on a frequency modulation step frequency to solve the problem that in the prior art, the range resolution and the direction resolution of inverse synthetic aperture radar imaging in the microwave band are not high. The method includes the steps of firstly, obtaining a terahertz pulse echo signal; secondly, conducting pulse compression; thirdly, synthesizing a broadband; fourthly, conducting windowing and correcting; fifthly, conducting distance Doppler imaging; sixthly, obtaining an imaged picture. According to the method, the characteristic that the terahertz wave has the high frequency and the broadband is combined with the frequency modulation step frequency system so that the high-resolution terahertz inverse synthetic aperture radar imaging can be achieved through the method of synthesizing the broadband.

The invention discloses a shaping method of a difference frequency terahertz pulse and a shaping system thereof. In the shaping method, a laser pulse shaping device is used for realizing the programmable shaping of a laser pulse; two arrays of laser pulses passing through the converting and shaping device are regulated to be mutually vertical in polarization directions and then are overlaid in a non-linear crystal and subjected to difference frequency to generate a terahertz wave; and through controlling the wave forms and the phases of the two arrays of the laser pulses with mutually vertical polarization directions, the wave form and the electric field polarization direction of the generated terahertz pulse can be controlled and the wave form and the polarization direction of generated terahertz radiation can be detected. The invention not only can control the wave form and the pulse interval of the terahertz pulse, but also can control the electric field polarization direction of the terahertz pulse. Compared with a scheme for shaping the terahertz pulse by using a photoconductive antenna or through an optical rectification process, the invention has obvious advantages.

The invention discloses a terahertz polarization real-time imaging method, which comprises the following steps of: (1) putting samples to be tested in a terahertz polarization real-time imaging device; (2) continuously changing the optical path difference between pump light and detection light, and measuring a polarized component Ex of a terahertz pulse passing through the samples; (3) changing the polarization state of the detection light, continuously changing the optical path difference between the pump light and the detection light again, and measuring another polarized component Ey of the terahertz pulse; and (4) processing two groups of terahertz polarized components of the samples, and forming relative-intensity images. The terahertz polarization real-time imaging method can rapidly and accurately measure different polarized components of terahertz light waves, highly precisely identifies target objects, and has wide application range.

The invention relates to a terahertz-spectrum-based quick nondestructive detection method for coal. The terahertz-spectrum-based quick nondestructive detection method comprises the following steps of: selecting a sample cell; preparing a standard coal material sample and an ordinary coal sample; detecting the standard coal material sample and an empty sample cell by utilizing a terahertz time-domain spectrometer to obtain a terahertz pulse time-domain waveform of the standard coal material sample and a terahertz pulse time-domain waveform of the empty sample cell; performing data processing on the terahertz pulse time-domain waveforms of the standard coal material sample and the empty sample cell to construct a standard fingerprint database; and detecting and analyzing the ordinary coal sample, and obtaining the sort, ash content and carbon content data of the ordinary coal sample according to the standard fingerprint database. According to the method provided by the invention, the coal can be quickly and nondestructively detected; the method is easy to operate, simple in data processing, high in repeatability and accurate in test result; and a coal property can be quickly and accurately analyzed.

The invention belongs to the technical field of electrooptics, in particular to a method for measuring pumping electrooptics of Terahertz impulse energy. The method is characterized by comprising the following steps: firstly, acquiring Terahertz absolute electric field strength; then, collecting Terahertz light spot, and obtaining energy of Terahertz impulse through integral of the Terahertz light spot on certain area and impulse duration. The method solves the problem of energy measurement of Terahertz impulse to overcome the defect that the existing method can not directly measure the energy because of shortage of a direct Terahertz wave response element, provides an effectively technical proposal for Terahertz energy meter designing, and provides a reference calibrating method for high-power Terahertz radiation source study.

The invention relates to terahertz pulse imaging, and provides a high-performance terahertz time-domain spectral imaging device. The terahertz time-domain spectral imaging device has the advantages of simplicity, easiness in adjustment, high stability, high signal to noise ratio, wide broadband, high speed, flexibility, convenience, rapidness and high space resolution ratio. The multifunctional terahertz time-domain spectral imaging device based on femtosecond laser comprises an optical fiber femtosecond laser device, an optical fiber, an optical fiber beam splitter, an optical fiber delay line, an optical fiber integrated terahertz transmitting antenna, a COC terahertz lens, an optical fiber collimator, a frequency multiplication module, a lens, a reflector, a terahertz probe, a two-directional electric detection translation stage, a three-dimensional electric sample frame, a square-wave voltage source, a current amplifier, a phase-locked amplifier, a data collection card and a computer. The terahertz time-domain spectral imaging device is mainly applied to terahertz pulse imaging.

An information acquiring apparatus includes a light source portion for generating pulse-shaped pump light, and first and second probe light in synchronization with each other. A generating portion generates terahertz pulses when irradiated with the pump light. A detecting portion detects pulses of terahertz radiation from the object. A first delay portion adjusts an optical path difference between optical paths of the pump light and the first probe light reaching the detecting portion, so that the detecting portion detects a field intensity of a fixed point on the time domain waveform of the terahertz pulse from the object, following the fixed point. A second delay portion adjusts an optical path difference between the optical path of the pump light and the second probe light reaching the detecting portion by a sum of an additional optical path adjustment amount and the optical path difference, so that the detecting portion obtains the time domain waveform. A correction processing portion compensates for influence of a change in condition of the object on the time domain waveform, using the field intensity of the fixed point, or the adjustment amount adjusted by the first delay portion.

The invention relates and belongs to the field of terahertz time-domain spectroscopy diagnostic technique, in particular to a terahertz spectrograph and a terahertz transceiver probe (b). ( / b) The technical problems to be solved are as follows: the existing terahertz time-domain spectroscopy systems mostly adopt an off-axis parabolic mirror to implement the space transmission for terahertz pulses, and have complex structures, long optical paths and weak stability, so that the energy utilization rate of terahertz waves is low. Against the existing problems, the invention provides the terahertz spectrograph and the terahertz transceiver probe; laser emitted by a laser is converted to detection light and pump light through a terahertz converter; then, the detection light and the pump light output by the terahertz converter are received through the terahertz transceiver probe so as to implement the sample reflection type detection and transmission type detection to obtain sample spectral information. The problems of complex structure and large volume of the existing terahertz spectrographs in the prior art are solved. Further, the defects of large volume and low utilization efficiency of terahertz energy of the existing terahertz transceiver probes are solved. The terahertz spectrograph comprises the laser, the terahertz converter, the terahertz transceiver probe and the like. The terahertz spectrograph and the terahertz transceiver probe are applied to the terahertz spectral imaging and diagnose application fields.

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 provides a terahertz scanning system and method. The scanning system comprises a repeat frequency locking and adjustable femtosecond laser device, a repeat frequency tuning part, a beam splitting part, a terahertz pulse generating part, a terahertz pulse collecting part, a pulse space shifting part, a reference laser pulse transmitting direction changing part, a beam combining part, a focusing part, a photoelectric detection part and a processing part. The repeat frequency tuning part comprises a signal generating unit, a triggering unit and a tuning unit, wherein the signal generating unit outputs an inherent-frequency electrical signal, the triggering unit uses the inherent-frequency electrical signal as a triggering signal and transmits the triggering signal to the femtosecond laser device, and the tuning unit continuously changes cavity length according to a feedback signal of the femtosecond laser device to tune repeat frequency. Then, the repeat frequency locking and adjustable femtosecond laser device locks the tuned repeat frequency.

The invention provides a high-speed multi-width terahertz time-domain spectral imager, aiming at problems in the prior art. Femtosecond laser pulse is divided, and certain time delay exists among pulses; then the sequence is divided into two ways, one way is used for generating a terahertz pulse sequence, and the other way is used for generating probe light pulse with an oblique leading edge through an oblique leading edge pulse light generating device, so that the one-time transient measurement of the terahertz pulse is realized; a signal acquiring and processing module is combined for imaging each probe pulse, so that the wave form information of each sub pulse of a plurality of terahertz pulse sequences can be obtained. According to the invention, the wave form information of a plurality of sub pulses of the terahertz pulse sequence is measured by a femtosecond pulsed laser device, a negative chirp pulse light generating device, a light splitting delay device, a terahertz generating device, an oblique leading edge pulse light generating device, an electrooptical effect crystal and the signal acquiring and processing module.

A holder (30) that holds a specimen (100) is disposed outside a vacuum chamber (50) with a light transmission window (52a). A light detection unit and a light radiation unit having a terahertz light generator (6) are fixed on a base (53) disposed inside the vacuum chamber. The light radiation unit irradiates terahertz pulse light onto the specimen (100) placed outside the vacuum chamber via the light transmission window (52a) and the resulting specimen light from the specimen (100) is received at the light detection unit via the light transmission window (52a). The base (53) in the vacuum chamber and the holder (30) disposed outside the vacuum chamber are connected via a connecting member (54a) passing displaceably through a barrier wall of a vacuum chamber (50) with airtight sealing so as to fix the relative position of the holder to the base.

The invention relates to the field of textile materials, and aims at providing a method for identifying a bamboo hemp fiber by using a terahertz time-domain spectroscopy technique. The method comprises the following steps of: respectively mixing and pressing a fiber with polyethylene powder to prepare a disc sheet after preparing the powder from the fiber as a guide sample; testing by adopting a transmission-type terahertz time-domain spectroscopy test device, thus respectively obtaining terahertz pulse time-domain waveforms through each guide sample; calculating the absorption coefficient and the refractive index of each guide sample, so as to respectively draw out an absorption spectrum and a refraction spectrum of the fiber; obtaining an absorption coefficient and a refractive index of the fiber to be identified; and confirming the type of the fiber to be identified according to the corresponding relation with the absorption spectrum and the refraction spectrum of each guide sample. According to the method, required sample quantity is simple, samples are simple and convenient to prepare, test time is short, and chemical pollutants are not caused in a test process; the absorption spectrum and the refraction spectrum of the sample at a terahertz waveband can be obtained at the same time when the sample is tested; the feature information of the samples is increased; the reliability of a test result is also improved.

A fast optical (with or without a photonic crystal) switch is fabricated / constructed, utilizing a phase change material, activated by either an electrical pulse (a voltage pulse or a current pulse) and / or a light pulse and / or pulses in terahertz (THz) frequency of a suitable field strength. The applications of such a fast optical switch for an on-demand optical add-drop subsystem, integrating with (a) a light slowing / light stopping component (based on metamaterials and / or nanoplasmonic structures) and (b) with or without a wavelength converter are also described.

The invention belongs to the technical field of terahertz time-domain spectrums and provides a pulse terahertz time-domain spectral system with single photoconductive antenna and a detection method thereof. A terahertz emitter and a detector in an existing terahertz time-domain spectral system are spatially separated, thus system size is large, the cost is high, the structure is complex and carrying is inconvenient. Femtosecond laser is divided into pumped light and detecting light; the detecting light combines with the pumped light after passing by an optical delay line and then enters the photoconductive antenna; pumped light pulses and detecting light pulses arrive at the photoconductive antenna at different time; the pumped light pulses have bias voltage when arriving at the photoconductive antenna, and meanwhile, the photoconductive antenna is used as the terahertz emitter, emitting terahertz pulses; the detecting light pulses have no bias voltage when arriving at the photoconductive antenna, and meanwhile, the photoconductive antenna serves as a terahertz detector, detecting terahertz pulses. Therefore, emission and detection of the terahertz can be finished with only the photoconductive antenna, and the terahertz emitter and the terahertz detector are spatially integrated.

The invention relates to a device for improving the test accuracy of spectrum absorbance on the basis of terahertz optical combs. The device is characterized in that one of two ultrafast laser pulse beams with set repeat frequency difference is transmitted through a terahertz wave generating system to generate terahertz waves, terahertz wave signals and the other ultrafast laser pulse beam are respectively focused and are jointly transmitted into a photoconductive detection antenna, the terahertz waves can be quickly scanned by the aid of tiny repeat frequency difference between pump beams and probe beams, a digital converter is controlled by the aid of a cross-correlation instrument and a rubidium atom frequency standard, the signal acquisition time is prolonged to obtain time-domain spectra of continuous terahertz pulse chains, terahertz comb-shaped spectra are obtained by means of Fourier transformation, accurate change of the optical combs is compared before and after sample placement, and accordingly terahertz absorption spectrum lines of samples can be obtained. The device has the advantages that the shortcoming of excessive scanning time consumption of mechanical delay devices can be overcome, the problem of inaccuracy of existing terahertz super-continuous spectra due to laser pulse time jitter can be solved, and the test accuracy of the terahertz spectrum absorbance can be improved.

The invention relates to a method and device to measure hertzhz pulse sequence by using chatter pulse-frequency spectrum. It includes ultrashort pulse light, first beam splitting sheet and grating pair. The ultrashort pulse light is a linear clatter pulse-frequency light. The polarizer and the second beam splitting sheet are on the reflecting direction of the first beam splitting sheet. A tested high speed light pulse frequency transmitting from the other direction of the second beam splitting sheet and the front direction is the second beam splitting sheet, non-linear crystal, the third beam-splitting sheet, analyzer and the first CCD spectroscope, the reflecting direction of the third beam splitting sheet would enter into the second CCD spectroscope. The invention is simple structure and is convenience to adjust.

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.