CN106841113A - A kind of method and apparatus of Terahertz frequency range synchro measure material wave transparent reflection characteristic - Google Patents
A kind of method and apparatus of Terahertz frequency range synchro measure material wave transparent reflection characteristic Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/59—Transmissivity
Abstract
The invention discloses a kind of method and apparatus of Terahertz frequency range synchro measure material wave transparent reflection characteristic, including：Transmission detection light path and reflection detection light path are set；Placement refers to model so that terahertz pulse ripple is incided with 45 ° and refers to model, is referenced the second detector that the terahertz pulse ripple of model reflection is exported into reflection detection light path, obtains the second reference signal；Remove and refer to model, terahertz pulse ripple is directly output to the first detector in transmission detection light path, obtains the first reference signal；Place detected materials plate so that terahertz pulse ripple incides detected materials plate with 45 °, and first and second detector respectively obtains transmission signal and reflected signal；According to four signals for obtaining, transmission coefficient, reflectance factor and the required electromagnetic parameter of detected materials plate are calculated.Using methods and apparatus of the present invention, the reflectance factor of same sample, the synchro measure of transmission coefficient and data acquisition can be synchronously completed under same terahertz pulse.
Description
Technical field
The present invention relates to measuring for materials, more particularly to a kind of Terahertz frequency range synchro measure material wave transparent reflection characteristic
Method and apparatus.
Background technology
Terahertz frequency range target scattering characteristics basic research project is intended to set up typical target Terahertz electromagnetic property model,
Goal in research is calculated in the electromagnetic property of Terahertz frequency range, measurement, the method for analysis and feature extraction etc., grasp Terahertz frequency range
The scattering properties of target, forms typical target Terahertz frequency range Electromagnetic Scattering Characteristics database, be Terahertz active probe with into
The Military Application of picture provides technical support.
In Terahertz target property research, it is to be understood that the electromagnetic parameter of various materials, such that it is able to using these ginsengs
Number carries out the scattering modeling of target.And in the prior art, the electromagnetic parameter of material is obtained by the method tested mostly, lead to
It is often reflectance factor, the transmission coefficient for obtaining material respectively by two sets of Terahertzs reflections, transmitted light path system, then passes through again
Cross inverting and obtain electromagnetic parameter of the material in the Terahertz frequency range.Due to being to use two sets of different experiment test systems, therefore
Even if same material sample be placed, the parameter such as the position of electromagnetic wave incident on the material sample can all have larger
Test error, and testing efficiency is relatively low.
The content of the invention
In view of this, the present invention provides the method and dress of a kind of Terahertz frequency range synchro measure material wave transparent reflection characteristic
Put, such that it is able to synchronously completed under same terahertz pulse same detected materials sample reflectance factor and transmission coefficient it is same
Pacing amount and data acquisition, realize the synchronous acquisition of reflectance factor, transmission coefficient and the electromagnetic parameter of detected materials.
What technical scheme was specifically realized in：
A kind of method of Terahertz frequency range synchro measure material wave transparent reflection characteristic, the method includes：
One transmission detection light path for being used to measure transmission coefficient is set and a reflection for being used to measure reflectance factor is visited
Light-metering road；
Placed on material board mount and refer to model so that terahertz pulse ripple refers to model with 45 degree of oblique being mapped in angle,
And cause to be referenced the second detector that the terahertz pulse ripple of model reflection is exported into reflection detection light path；
Remove and refer to model so that terahertz pulse ripple is directly output to the first detector in transmission detection light path；
The terahertz pulse ripple that first detector will be received is converted to the first reference signal, and the second detector will be received
Terahertz pulse ripple be converted to the second reference signal；
Detected materials plate is placed on material board mount so that terahertz pulse ripple is mapped to detected materials so that 45 degree of angles are oblique
Plate, and the first detector that the terahertz pulse ripple that is transmitted by detected materials plate exported into transmission detection light path is caused, while
So that the terahertz pulse ripple reflected by detected materials plate exports the second detector into reflection detection light path；
The terahertz pulse ripple that first detector will be received is converted to transmission signal, and the second detector will be received too
Hertz impulse wave is converted to reflected signal；
According to the transmission signal, reflected signal, the first reference signal and the second reference signal, detected materials are calculated
The transmission coefficient of plate, reflectance factor and required electromagnetic parameter.
Preferably, transmission coefficient and reflectance factor are calculated by formula below：
Wherein, τ and t represent reflectance factor and transmission coefficient, I respectivelyr(ω) and Is(ω) is respectively the anti-of detected materials plate
Penetrate the signal intensity that the transmission signal of signal and detected materials plate is obtained after Fourier transform, Ir0(ω) and Ii(ω) difference
For the signal intensity that the second reference signal and the first reference signal are obtained after Fourier transform.
Preferably, obtaining electromagnetic parameter according to following method：
When 45 ° of terahertz pulse ripples of incidence are transmitted by detected materials plate, the Propagation factor is：
Wherein, p (ω, L) is the Propagation factor, and ω is frequency, and L is the thickness of medium,It is complex refractivity index, c
It is the light velocity；
Being calculated affixture machine according to equation below is：
Wherein, H (ω) is affixture machine, Etotal(ω) is the electric-field intensity of the THz wave by detected materials plate,
Eref(ω) is the electric-field intensity of the first reference signal, incidence angleIt is refraction angle,It is the refractive index of air, for air dielectricIt is the birefringence of detected materials plate
Rate, L is the distance that THz wave is transmitted in detected materials plate, and b is that reference signal exists with the terahertz electromagnetic wave of directly transmission
The additional light path produced in detected materials plate, FP (ω) be due to the interference term that Fabry-Perot etalon effect causes,
Ignore and repeatedly shake in sample, can make：FP (ω)=1, then：
Wherein, n2It is complex refractivity index real part, k2It is complex refractivity index imaginary part extinction coefficient；
Multiple transmission function is write as the form of explement and mould：
The refractive index n of material is calculated by simultaneous equations (1) and (2), the measured value for substituting into ρ (ω), Φ (ω)2
(ω) and k2(ω)；
Real part and imaginary part according to complex refractivity index calculate complex dielectric permittivity：
εr=n2 2(ω)-k2 2(ω), εi=2n2(ω)k2(ω)；
Wherein, εrIt is real part of permittivity, εiIt is imaginary part of dielectric constant, n2(ω) and k2(ω) is respectively measured material
Refractive index and extinction coefficient.
A kind of device of Terahertz frequency range synchro measure material wave transparent reflection characteristic, the device bag are additionally provided in the present invention
Include：Light source, the first beam splitter, THz wave generator, material board mount, at least two reflectors, the first detector and second
Detector；
The light source, for exporting pulsed light；
First beam splitter, for the pulsed light of the light source output to be divided into two pulses light so that wherein a branch of
Pulsed light is exported to the THz wave generator as pump beam by delay line, and causes another beam pulse light as spy
After light-metering beam is by speculum and detection beam splitter, export respectively to the first detector and the second detector；
The THz wave generator, terahertz pulse ripple is exported for being excited by the pump beam；
The material board mount, for placing and fixed detected materials plate or refers to model；
At least two reflector, the terahertz pulse ripple for reflecting the THz wave generator output so that
The terahertz pulse ripple is with 45 degree of oblique detected materials plates being mapped on plate of material support in angle or with reference on model；
First detector, the detection light beam for receiving beam splitter output, and appoint when not placed on material board mount
During what object, the terahertz pulse ripple that reception is reflected by the reflector；When detected materials plate is placed on material board mount, connect
The terahertz pulse ripple that receipts are transmitted by detected materials plate；
Second detector, the detection light beam for receiving beam splitter output, and referred to when being placed on material board mount
When model or detected materials plate, reception is referenced the terahertz pulse ripple of model or the reflection of detected materials plate.
Preferably, the light source is femtosecond pulse light source.
Preferably, the THz wave generator is transmitting antenna.
Preferably, described device is still further comprised：Laser auxiliary positioning device；
The laser auxiliary positioning device is used for the accurate position for determining detected materials plate or reference model.
Preferably, being respectively arranged with an electro-optic crystal before the first detector and the second detector.
Preferably, the electro-optic crystal is ZnTe crystal.
Preferably, attenuator is provided with each light path, for adjusting the light intensity in light path.
As above it is visible, the method and apparatus of Terahertz frequency range synchro measure material wave transparent reflection characteristic in the present invention
In, terahertz time-domain spectroscopy measuring system (THz-TDS) of the prior art is carried out to improve upgrading, there is provided two-way is detected
Light path, wherein completing the measurement of reflectance factor all the way, another road completes the measurement of transmission coefficient, and the measurement for passing through light path simultaneously
With the design of light path, such that it is able to realize being synchronously completed under same terahertz pulse the reflectance factor of same detected materials sample
Synchro measure and data acquisition with transmission coefficient, realize the transmission coefficient of detected materials and the synchro measure of reflectance factor,
Such that it is able to quickly and accurately extract the electromagnetic parameter of material, reflectance factor, transmission coefficient and the electromagnetism ginseng of detected materials are realized
Several synchronous acquisitions.
In addition, further, due to the side of the Terahertz frequency range synchro measure material wave transparent reflection characteristic in the present invention
Method and device, are different from Terahertz frequency range material reflection coefficient of the prior art and transmission coefficient measuring method, will be measured and monitored the growth of standing timber
Material sample panel is placed with incident thz beam into 45 degree of angles, and in THz wave reflected energy of the measurement with reference to model,
Same 45 jiaos of placements are also required to reference to model, therefore material board mount are devised, and is devised laser auxiliary positioning device and give
It is accurate to determine detected materials plate and the position with reference to model, solve the problem of material model fast accurate positioning, reduce by
In detected materials plate and the measurement error introduced due to placed angle deviation with reference to model, for scattering modeling is provided reliably
Material characteristic data.
Brief description of the drawings
Fig. 1 is that the flow of the method for the Terahertz frequency range synchro measure material wave transparent reflection characteristic in the embodiment of the present invention is shown
It is intended to.
Fig. 2 is that the structure of the device of the Terahertz frequency range synchro measure material wave transparent reflection characteristic in the embodiment of the present invention is shown
It is intended to.
Fig. 3 is the schematic diagram after being totally reflected after 45 degree of angle incident reference models of terahertz pulse ripple.
Fig. 4 is 45 degree of Mathematical Modeling schematic diagrames of angle incidence detected materials plate of terahertz pulse ripple.
Fig. 5 is the terahertz time-domain spectroscopy schematic diagram of fiberglass.
Fig. 6 is the principle schematic of electromagnetic parameter derivation in the present invention.
Specific embodiment
To make the objects, technical solutions and advantages of the present invention become more apparent, develop simultaneously embodiment referring to the drawings, right
The present invention is further described.
A kind of method of Terahertz frequency range synchro measure material wave transparent reflection characteristic is provided in technical scheme
And device, such that it is able to.
Fig. 1 is that the flow of the method for the Terahertz frequency range synchro measure material wave transparent reflection characteristic in the embodiment of the present invention is shown
It is intended to.As shown in figure 1, the method for the Terahertz frequency range synchro measure material wave transparent reflection characteristic in the embodiment of the present invention is mainly wrapped
Include step as described below：
Step 11, setting a transmission detection light path for being used to measure transmission coefficient and one is used to measure reflectance factor
Reflection detection light path.
In this step, two detection light paths will be set simultaneously：Transmission detection light path and reflection detection light path, such as Fig. 2 institutes
Show.Wherein, a detector is provided with transmission detection light path, the first detector is properly termed as, is also set in reflection detection light path
A detector is equipped with, the second detector is properly termed as.
Step 12, places on material board mount and refers to model so that terahertz pulse ripple is mapped to ginseng so that 45 degree of angles are oblique
Model is examined, and causes to be referenced the second detector that the terahertz pulse ripple of model reflection is exported into reflection detection light path.
In this step, will be set on the material board mount in two above-mentioned detection light paths and refer to model so that by
The terahertz pulse ripple of THz wave generator output is referred on model with 45 degree of oblique being mapped in angle, so that being referenced model
The terahertz pulse ripple of reflection exports the second detector into reflection detection light path.
Step 13, removes and refers to model so that terahertz pulse ripple is directly output to the first spy in transmission detection light path
Survey device.
In this step, will remove and refer to model, now, the terahertz pulse ripple exported by THz wave generator will be straight
Output is connect to the first detector in transmission detection light path,
Step 14, the terahertz pulse ripple that the first detector will be received is converted to the first reference signal, the second detector
The terahertz pulse ripple that will be received is converted to the second reference signal.
Step 15, places detected materials plate on material board mount so that terahertz pulse ripple is mapped to so that 45 degree of angles are oblique
Detected materials plate, and cause that the terahertz pulse ripple transmitted by detected materials plate exports the first detection into transmission detection light path
Device, while so that the terahertz pulse ripple reflected by detected materials plate exports the second detector into reflection detection light path.
In this step, detected materials plate will be placed on material board mount, will detected materials plate be placed on and refer to sample
The same location of plate so that the terahertz pulse ripple exported by THz wave generator is mapped to detected materials plate so that 45 degree of angles are oblique
On, so that a part of terahertz pulse ripple is transmitted through the first detection that detected materials plate is exported into transmission detection light path
Device, and another part terahertz pulse ripple then reflexes to the second detector in reflection detection light path by detected materials plate.
Step 16, the terahertz pulse ripple that the first detector will be received is converted to transmission signal, and the second detector will connect
The terahertz pulse ripple for receiving is converted to reflected signal.
Step 17, according to the transmission signal, reflected signal, the first reference signal and the second reference signal, is calculated
The transmission coefficient of detected materials plate, reflectance factor and required electromagnetic parameter.
By above-mentioned step 11~17, you can while measurement obtains the transmission coefficient of sample (i.e. detected materials plate), anti-
Penetrate coefficient and required electromagnetic parameter.
A kind of device of Terahertz frequency range synchro measure material wave transparent reflection characteristic is additionally provided in the present invention.Fig. 2 is this
The structural representation of the device of the Terahertz frequency range synchro measure material wave transparent reflection characteristic in inventive embodiments.As shown in Fig. 2
The device of the Terahertz frequency range synchro measure material wave transparent reflection characteristic in the embodiment of the present invention mainly includes：Light source 11, first
Beam splitter 12, THz wave generator 13, material board mount 14, at least two reflectors 15, the first detector 16 and second are visited
Survey device 17；
The light source, for exporting pulsed light；
First beam splitter, for the pulsed light of the light source output to be divided into two pulses light so that wherein a branch of
Pulsed light is exported to the THz wave generator 13 as pump beam by delay line 18, and causes that another beam pulse light is made
After passing through speculum 23 and detection beam splitter 24 for detection light beam, export respectively to the first detector and the second detector；
The THz wave generator, terahertz pulse ripple is exported for being excited by the pump beam；
The material board mount, for placing and fixed detected materials plate 21 or refers to model (not shown)；
At least two reflector, the terahertz pulse ripple for reflecting the THz wave generator output so that
The terahertz pulse ripple is with 45 degree of oblique detected materials plates being mapped on plate of material support in angle or with reference on model；
First detector, the detection light beam for receiving beam splitter output, and appoint when not placed on material board mount
During what object, the terahertz pulse ripple that reception is reflected by the reflector；When detected materials plate is placed on material board mount, connect
The terahertz pulse ripple that receipts are transmitted by detected materials plate；
Second detector, the detection light beam for receiving beam splitter output, and referred to when being placed on material board mount
When model or detected materials plate, reception is referenced the terahertz pulse ripple of model or the reflection of detected materials plate.
By using above-mentioned device, transmission coefficient, the reflection system for obtaining sample (i.e. detected materials plate) can be simultaneously measured
Number and required electromagnetic parameter.
In addition, preferably, in a particular embodiment of the present invention, the light source can be femtosecond (femtosecond) arteries and veins
Impulse radiant.The femtosecond pulse light source can export pulsed light with certain repetition period.
In addition, preferably, in a particular embodiment of the present invention, the THz wave generator can be transmitting antenna.
In addition, preferably, in a particular embodiment of the present invention, the Terahertz frequency range synchro measure material wave transparent reflects
The device of characteristic can further include：Laser auxiliary positioning device；The laser auxiliary positioning device is used for accurate determination
Detected materials plate or the position with reference to model.
Additionally, preferably, in a particular embodiment of the present invention, can also be before the first detector and the second detector
It is respectively arranged with an electro-optic crystal 25.For example, the electro-optic crystal can be zinc telluridse (ZnTe) crystal.
When THz wave reaches the electro-optic crystal together with detection light beam, the electric field of THz wave can change the electric light
The index ellipsoid of crystal, so as to change the o light e light states of detection light beam.By detecting the intensity difference of the two, can survey indirectly
Measure the electric-field intensity of THz wave.
Additionally, preferably, in a particular embodiment of the present invention, can also be according to practical situations the need for, each
Attenuator 26 is set in individual light path, for adjusting the light intensity in light path.For example, pumping can be reduced in Terahertz by attenuator
Light intensity on transmitting antenna, in case light intensity is too strong.
Fig. 3 is the schematic diagram after being totally reflected after 45 degree of angle incident reference models of terahertz pulse ripple, and Fig. 4 is Terahertz arteries and veins
45 degree of Mathematical Modeling schematic diagrames of angle incidence detected materials plate of ripple are rushed, Fig. 5 is the terahertz time-domain spectroscopy schematic diagram of fiberglass.Such as
Shown in Fig. 3,4 and 5, in a preferred embodiment of the invention, experiment test can select glass epoxy (FRP) material conduct
Detected materials plate.In actual experiment, the thickness d of glass epoxy used is 1.1mm, test environment：23.4 DEG C of temperature, humidity
2.7%.Detected using compound THz-TDS systems (for example, the device shown in Fig. 2), terahertz pulse ripple is with 45 degree of angles
Oblique being mapped to is test on the sample that thickness is d.
Terahertz pulse ripple mutually there occurs change with position through its amplitude after sample.E shown in Fig. 3iFor incidence too
The electric-field intensity of hertz impulse wave, Er0To be referenced the electric-field intensity of the terahertz pulse ripple after model is totally reflected, shown in Fig. 4
ErIt is the electric-field intensity of the terahertz pulse ripple after being reflected by detected materials plate, EsIt is through the Terahertz after detected materials plate
The electric-field intensity of impulse wave, d is thickness of sample, n1It is the refractive index of air, n2It is the refractive index of detected materials plate.
In the inventive solutions, as a example by testing used detected materials plate for glass epoxy, it is possible to use
Above-mentioned method carries out the detection of material transmission and reflectance spectrum to glass epoxy.
Oblique being mapped in 45 degree of angles of terahertz pulse ripple is test for when on the sample (i.e. detected materials plate) that thickness is d, its
Amplitude and position mutually there occurs change.Terahertz signal during without sample is measured by the use of transmitted light path to believe as the first reference
Number, terahertz signal when placing total reflection with reference to model by the use of reflected light path measurement is used as the second reference signal；It is being put into sample
It is (i.e. anti-through the energy that the terahertz signal (i.e. transmission signal) and sample of sample reflect using two light path synchro measures after product
Penetrate signal), such that it is able to according to the transmission signal, reflected signal, the first reference signal and the second reference signal, be calculated
The transmission coefficient of detected materials plate, reflectance factor and required electromagnetic parameter.
For example, preferably, in a particular embodiment of the present invention, transmission coefficient and reflectance factor can be by following public affairs
Formula is calculated：
Wherein, τ and t represent reflectance factor and transmission coefficient, I respectivelyr(ω) and Is(ω) is respectively the anti-of detected materials plate
Penetrate the signal intensity that the transmission signal of signal and detected materials plate is obtained after Fourier transform, Ir0(ω) and Ii(ω) difference
(i.e. first with reference to letter for the signal freely passed through when being the signal (i.e. the second reference signal) and n.s with reference to model total reflection
Number) signal intensity that is obtained after Fourier transform, respectively by reflected light path and first detector and second of transmitted light path
Detector measurement is obtained.
To ensure the accuracy of measurement, it is necessary to be accurately measured to two detection light paths, ensureing that the two is equal same
When, it is also desirable to ensure itself and two path aplanatisms of exploring laser light pulse propagation, so that it is guaranteed that synchro measure transmission and reflection
Terahertz pulse be same pulse signal, and detected using same twin exploring laser light pulse.
In addition, in the inventive solutions, can also be according to the transmission signal, reflected signal, the first reference signal
With the second reference signal, the electromagnetic parameter of detected materials plate is calculated.
For example, preferably, in a particular embodiment of the present invention, needed for can also being derived by by such a way
Electromagnetic parameter.
Fig. 6 is the principle schematic of electromagnetic parameter derivation in the present invention.As shown in fig. 6, because detected materials plate is into 45
(i.e. incidence angle is 45 degree) is placed at angle, normal incidence (incidence angle is 0 degree) under normal circumstances is different from, from fresnel formula
Derive as follows：
When 45 ° of terahertz pulse ripples of incidence are transmitted by detected materials plate, the Propagation factor is：
Wherein, p (ω, L) is the Propagation factor, and ω is frequency, and L is the thickness of medium,It is complex refractivity index, c
It is the light velocity.
Model and Fresnel formula according to Fig. 6 can calculate affixture machine：
Wherein, H (ω) is affixture machine, Etotal(ω) is the electric-field intensity of the THz wave by detected materials plate,
Eref(ω) is the electric-field intensity with reference to terahertz pulse (i.e. the first reference signal), incidence angleIt is refraction
Angle,It is the refractive index of air, for air dielectricIt is medium (i.e. detected materials
Plate) complex refractivity index, L is distance transmit in detected materials plate of THz wave, and b is reference signal and the terahertz for directly transmiting
The additional light path that hereby electromagnetic wave is produced in detected materials plate, FP (ω) is caused due to Fabry-Perot etalon effect
Interference term.
Ignore and repeatedly shake in sample, can make：FP (ω)=1, then：
Wherein, n2It is complex refractivity index real part, k2It is complex refractivity index imaginary part extinction coefficient.
Multiple transmission function is write as the form of explement and mould：
The refractive index n of material is calculated by equation (1) and (2) simultaneous, the measured value for substituting into ρ (ω), Φ (ω)2
(ω) and k2(ω)。
Real part and imaginary part according to complex refractivity index calculate complex dielectric permittivity：
εr=n2 2(ω)-k2 2(ω), εi=2n2(ω)k2(ω)；
Wherein, εrIt is real part of permittivity, εiIt is imaginary part of dielectric constant, n2(ω) and k2(ω) is respectively measured material
Refractive index and extinction coefficient.
In summary, the method and apparatus of Terahertz frequency range synchro measure material wave transparent reflection characteristic in the present invention
In, terahertz time-domain spectroscopy measuring system (THz-TDS) of the prior art is carried out to improve upgrading, there is provided two-way is detected
Light path, wherein completing the measurement of reflectance factor all the way, another road completes the measurement of transmission coefficient, and the measurement for passing through light path simultaneously
With the design of light path, such that it is able to realize being synchronously completed under same terahertz pulse the reflectance factor of same detected materials sample
Synchro measure and data acquisition with transmission coefficient, realize the transmission coefficient of detected materials and the synchro measure of reflectance factor,
Such that it is able to quickly and accurately extract the electromagnetic parameter of material, reflectance factor, transmission coefficient and the electromagnetism ginseng of detected materials are realized
Several synchronous acquisitions.
In addition, further, due to the side of the Terahertz frequency range synchro measure material wave transparent reflection characteristic in the present invention
Method and device, are different from Terahertz frequency range material reflection coefficient of the prior art and transmission coefficient measuring method, will be measured and monitored the growth of standing timber
Material sample panel is placed with incident thz beam into 45 degree of angles, and in THz wave reflected energy of the measurement with reference to model,
Same 45 jiaos of placements are also required to reference to model, therefore material board mount are devised, and is devised laser auxiliary positioning device and give
It is accurate to determine detected materials plate and the position with reference to model, solve the problem of material model fast accurate positioning, reduce by
In detected materials plate and the measurement error introduced due to placed angle deviation with reference to model, for scattering modeling is provided reliably
Material characteristic data.
Presently preferred embodiments of the present invention is the foregoing is only, is not intended to limit the invention, it is all in essence of the invention
Within god and principle, any modification, equivalent substitution and improvements done etc. should be included within the scope of protection of the invention.
Claims (10)
1. a kind of method of Terahertz frequency range synchro measure material wave transparent reflection characteristic, it is characterised in that the method includes：
One transmission detection light path for being used to measure transmission coefficient and the reflection detection light for being used to measure reflectance factor are set
Road；
Placed on material board mount and refer to model so that terahertz pulse ripple refers to model with 45 degree of oblique being mapped in angle, and makes
The second detector that the terahertz pulse ripple of model reflection is exported into reflection detection light path must be referenced；
Remove and refer to model so that terahertz pulse ripple is directly output to the first detector in transmission detection light path；
The terahertz pulse ripple that first detector will be received is converted to the first reference signal, and the second detector will be received too
Hertz impulse wave is converted to the second reference signal；
Detected materials plate is placed on material board mount so that terahertz pulse ripple is mapped to detected materials plate so that 45 degree of angles are oblique,
And cause the first detector that the terahertz pulse ripple that is transmitted by detected materials plate exported into transmission detection light path, while so that
The terahertz pulse ripple reflected by detected materials plate exports the second detector into reflection detection light path；
The terahertz pulse ripple that first detector will be received is converted to transmission signal, the Terahertz that the second detector will be received
Impulse wave is converted to reflected signal；
According to the transmission signal, reflected signal, the first reference signal and the second reference signal, detected materials plate is calculated
Transmission coefficient, reflectance factor and required electromagnetic parameter.
2. method according to claim 1, it is characterised in that transmission coefficient and reflectance factor are calculated by formula below
Obtain：
Wherein, τ and t represent reflectance factor and transmission coefficient, I respectivelyr(ω) and Is(ω) is respectively the reflection letter of detected materials plate
Number and detected materials plate the signal intensity that is obtained after Fourier transform of transmission signal, Ir0(ω) and Ii(ω) is respectively
The signal intensity that two reference signals and the first reference signal are obtained after Fourier transform.
3. method according to claim 2, it is characterised in that electromagnetic parameter is obtained according to following method：
When 45 ° of terahertz pulse ripples of incidence are transmitted by detected materials plate, the Propagation factor is：
Wherein, p (ω, L) is the Propagation factor, and ω is frequency, and L is the thickness of medium,It is complex refractivity index, c is light
Speed；
Being calculated affixture machine according to equation below is：
Wherein, H (ω) is affixture machine, Etotal(ω) is the electric-field intensity of the THz wave by detected materials plate, Eref
(ω) is the electric-field intensity of the first reference signal, incidence angle It is refraction angle, It is sky
The refractive index of gas, for air dielectric It is the complex refractivity index of detected materials plate, L is THz wave in detected materials
The distance transmitted in plate, b is the additional optical that reference signal is produced with the terahertz electromagnetic wave of directly transmission in detected materials plate
Path difference, FP (ω) be due to the interference term that Fabry-Perot etalon effect causes,
Ignore and repeatedly shake in sample, can make：FP (ω)=1, then：
Wherein, n2It is complex refractivity index real part, k2It is complex refractivity index imaginary part extinction coefficient；
Multiple transmission function is write as the form of explement and mould：
The refractive index n of material is calculated by simultaneous equations (1) and (2), the measured value for substituting into ρ (ω), Φ (ω)2(ω) and
k2(ω)；
Real part and imaginary part according to complex refractivity index calculate complex dielectric permittivity：：
εr=n2 2(ω)-k2 2(ω), εi=2n2(ω)k2(ω)；
Wherein, εrIt is real part of permittivity, εiIt is imaginary part of dielectric constant, n2(ω) and k2(ω) is respectively the refractive index of measured material
And extinction coefficient.
4. a kind of device of Terahertz frequency range synchro measure material wave transparent reflection characteristic, it is characterised in that the device includes：Light
Source, the first beam splitter, THz wave generator, material board mount, at least two reflectors, the first detector and the second detection
Device；
The light source, for exporting pulsed light；
First beam splitter, for the pulsed light of the light source output to be divided into two pulses light so that a wherein beam pulse
Light is exported to the THz wave generator as pump beam by delay line, and causes another beam pulse light as detection light
After beam is by speculum and detection beam splitter, export respectively to the first detector and the second detector；
The THz wave generator, terahertz pulse ripple is exported for being excited by the pump beam；
The material board mount, for placing and fixed detected materials plate or refers to model；
At least two reflector, the terahertz pulse ripple for reflecting the THz wave generator output so that described
Terahertz pulse ripple is with 45 degree of oblique detected materials plates being mapped on plate of material support in angle or with reference on model；
First detector, the detection light beam for receiving beam splitter output, and when not placing any thing on material board mount
During body, the terahertz pulse ripple that reception is reflected by the reflector；When detected materials plate is placed on material board mount, quilt is received
The terahertz pulse ripple of detected materials plate transmission；
Second detector, the detection light beam for receiving beam splitter output, and refer to model when being placed on material board mount
Or during detected materials plate, reception is referenced the terahertz pulse ripple of model or the reflection of detected materials plate.
5. device according to claim 4, it is characterised in that：
The light source is femtosecond pulse light source.
6. device according to claim 4, it is characterised in that：
The THz wave generator is transmitting antenna.
7. device according to claim 4, it is characterised in that described device is still further comprised：Laser assisted positioning dress
Put；
The laser auxiliary positioning device is used for the accurate position for determining detected materials plate or reference model.
8. device according to claim 4, it is characterised in that：
An electro-optic crystal was respectively arranged with before the first detector and the second detector.
9. device according to claim 8, it is characterised in that：
The electro-optic crystal is ZnTe crystal.
10. device according to claim 4, it is characterised in that：
Attenuator is provided with each light path, for adjusting the light intensity in light path.
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| CN109188105A (en) * | 2018-10-19 | 2019-01-11 | 北京环境特性研究所 | Suitable for Terahertz frequency range high reflection dielectric material parameter measuring apparatus and method |
| CN109211842A (en) * | 2018-10-19 | 2019-01-15 | 北京环境特性研究所 | A kind of Terahertz frequency range material reflection coefficient calibration measuring device and method |
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