CN203365318U - Acquisition device of substance at terahertz band absorption coefficient and refractive index - Google Patents

Abstract

The utility model relates to an acquisition device of a substance at a terahertz (THz) band absorption coefficient and a refractive index. The device comprises a femtosecond laser source, an optical splitter, a light delay unit, a THz emission source, a sample testing device, a THz detector and a computer. The acquisition device can utilize the same experiment testing device to rapidly and accurately measure and work out THz band absorption coefficients and refractive indexes of a solid sheet, solid powder and a liquid phase substance at the THz band absorption coefficient and the refractive index.

Description

Material is at the deriving means of terahertz wave band absorption coefficient and refractive index

Technical field

The utility model relates to the field of terahertz time-domain spectroscopic technology application, relates in particular to the deriving means of a kind of material in terahertz wave band absorption coefficient and refractive index.

Background technology

Terahertz (THz) ripple is between microwave and infrared radiation, and its spectral range is at 0.1-10THz.At the beginning of the nineties, due to the development of free electron laser and ultra-short pulse laser technology, greatly promoted the development of terahertz emission in the spectral technique field.In recent years, terahertz time-domain spectroscopic technology (Terahertz time-domain spectroscopy, THz-TDS) has been applied in the qualitative detection of amino acid, carbohydrate and nucleic acid pyrimidine etc., the aspects such as quantitative detection, medical treatment & health and dangerous material safety detection of pharmaceutical compositions more and more.This be collective vibration due to absolutely large number biomacromolecules all in terahertz wave band, make terahertz time-domain spectroscopic technology not only can judge qualitatively that material composition also can the quantitative test content of material.In addition, THz wave can penetrate plastics, paper, leather and wood, so terahertz time-domain spectroscopic technology can be applied in the safety detection of the airport person and parcel etc.; The energy of THz wave is very little, so terahertz time-domain spectroscopic technology can be applied to the lossless detection of precious biological sample, medicine and explosive.Yet, the application of terahertz time-domain spectroscopic technology relies on the test comparison analysis in terahertz wave band absorption coefficient and refractive index to material, by comparing absorption coefficient and the refractive index of material at terahertz wave band, not only can distinguish solid matter, and can distinguish different liquid phase substances.This is that extremely be short of in present stage medical treatment and safety inspection field, is also that other spectral technique is beyond one's reach.If terahertz time-domain spectroscopic technology can be applied to the aspects such as medicine production, therapeutic treatment and safety checking of people's life, this will be to safeguarding that human society is healthy and having safely very important realistic meaning.

In the practical application of terahertz time-domain spectroscopic technology, the problem at first run into is exactly fast and effeciently to obtain absorption coefficient and the refractive index of material at terahertz wave band.In brief, need exactly a set of method that effectively obtains fast material Terahertz absorption coefficient and refractive index.To solid matter Terahertz spectrum method of testing, relate to seldom at present, measurement to liquid phase substance is few especially, so the method terahertz time-domain spectroscopic technology that designs suitable Sample testing device and quick calculation sample absorption coefficient and refractive index is marched toward before practical application and is mentioned committed step.Usually, Sample testing device or for solid matter, or, for liquid phase substance, there is no to test the device of solid-liquid phase material simultaneously.But in actual applications, solid phase thin slice (as: tablet), solid phase powder (as: explosive and drugs etc.) and liquid phase substance (as: inflammability liquid) not only need to be tested fast in same device, and need to calculate fast afterwards the acquisition material in test and distinguish in order to carry out material in absorption coefficient and the refractive index of terahertz wave band.Therefore, suitable device for quick testing and simple parameter extracting method are that the terahertz time-domain spectroscopic technology practical application requisite two of marching toward is large crucial.

The utility model content

The utility model, in order to solve existing technical matters in background technology, has proposed the deriving means of a kind of material in terahertz wave band absorption coefficient and refractive index.

The technical solution of the utility model is: a kind of material is at the deriving means of terahertz wave band absorption coefficient and refractive index, and its special character is: comprise femtosecond laser source, optical splitter, light delay unit, THz emissive source, Sample testing device, THz detector, computing machine; Also comprise for covering the top cover of depression test circle spot;

Above-mentioned optical splitter is arranged on rear, femtosecond laser source, and its road light separated enters the THz detector, and its another road light separated enters the THz emissive source behind the light delay unit;

Above-mentioned Sample testing device is placed on the light path of advancing of THz ripple;

Above-mentioned Sample testing device comprises disk and translation stage;

Above-mentioned disk is arranged on translation stage;

Be evenly distributed in a plurality of blind holes on above-mentioned disk;

Above-mentioned THz detector is for receiving the THz ripple through Sample testing device;

The output signal of above-mentioned THz detector is sent into computing machine;

The material of above-mentioned disk and top cover is teflon;

Above-mentioned optical delay unit comprises that two acutangulate or one-way mirror that obtuse angle is placed;

Above-mentioned disc thickness is 4mm; Described top cover thickness is 1mm; The described depression test circle spot degree of depth is 3mm.

The beneficial effects of the utility model are:

Utilize the utility model, can obtain fast and effectively absorption coefficient and the refractive index of solid-liquid phase material at terahertz wave band, for terahertz time-domain spectroscopic technology has been created feasibility in the popularization of practical application.The utility model has mainly comprised the substance testing device and has relied on the computing method of proving installation model.Be different from common substance testing device as solid draw-in groove and liquid cuvette etc., need to change different proving installations to different samples, the proving installation of this utility model is all applicable to general solid thin-sheet, pressed powder and liquid phase substance; Proving installation is made by teflon, and test result reliability is high and with low cost.On the experiment test basis, according to test model, can calculate fast absorption coefficient and the refractive index of material at terahertz wave band.

The accompanying drawing explanation

Fig. 1 is the schematic diagram of proving installation in light path;

Fig. 2 is the structural representation of Sample testing device;

Fig. 3 is the cut-open view of sample apparatus for placing;

Fig. 4 is the propagation schematic diagram of THz wave in proving installation.

Embodiment

Referring to Fig. 1-4, a kind of material, at the deriving means of terahertz wave band absorption coefficient and refractive index, comprises femtosecond laser source, optical splitter, light delay unit, THz emissive source, Sample testing device, THz detector, computing machine; Optical splitter is arranged on rear, femtosecond laser source, and its road light separated is for the generation of THz pulse behind the light delay unit, and its another road light separated is for the detection of THz signal; The THz detectable signal is the sequential sampling scanning realized under the light delay unit whole signal; Sample testing device is placed on the light path of advancing of THz ripple; Sample testing device comprises disk and translation stage; Disk is arranged on translation stage; Be evenly distributed in a plurality of blind holes on disk; The THz detector is for receiving the THz ripple through Sample testing device; The output signal of THz detector is sent into computing machine; The material of disk and top cover is teflon.The basic structure of optical delay unit can be reduced to two one-way mirror.When a road light passes through the catoptron of light beam incident direction, the position that changes catoptron (with the difference of original position is

), the relative time that just can change sampled light and measured signal in light path postpone (

), realize the sequential sampling scanning to whole measured signal with this.

The utility model proposes and a kind ofly be intended to effectively to obtain fast the method for material in terahertz wave band absorption coefficient and refractive index.The method realizes by two large key factors: the one, and the design of Sample testing device; The 2nd, use special formula substance for calculation of deriving in terahertz wave band absorption coefficient and refractive index.

Fig. 1 is the schematic diagram of proving installation (sample spot) in light path.Wherein, the size of Sample testing device determines (disk of the design's diameter 60mm, thickness 4mm) with the concrete size of experiment light path.

Fig. 2 is the structural representation of Sample testing device.It is the disk of being made by polytetrafluoroethylmaterial material, on the A-A surface level, along circle designs the individual circle of position Zhou Junbu of N (N=12) round spot (blind hole of diameter 8mm) as sample test point, i.e. sample lay down location.Disc centre has the M6 threaded hole, and this is the translation in order to facilitate Sample testing device and fixes, and in this design, selects translation stage fixing and mobile.In cross section A-A figure, each sample set-point is depression circle spot (each sample test point all has the wall thickness of 1mm for disc thickness 4mm, sample set-point degree of depth 3mm), and design is mainly for easy solid powder and liquid phase substance test like this.In addition, during powder method, specimen may be due to its not stationarity or the unequal reason of grain size, and surface produces uneven phenomenon, and this can have a strong impact on the authenticity of test result; And liquid phase substance, due to its mobility, exists and may leak when test; For this reason, our specialized designs the top cover of sample test point (right cylinder of top end diameter 10mm, thickness 1mm, rear end diameter 8mm, the thickness of top cover rear end is determined by tested object).While carrying out the liquid phase substance test, adopt the top cover of bottom diameter 8mm, thickness 1mm to be sealed; While carrying out the solid phase powder test, adopt the top cover of diameter 8mm, thickness 3mm to press even pressed powder surface; During the test solid thin-sheet, generally do not need top cover, if worry the sample landing, can utilize the top cover fixed sample of test liquid phase substance yet, concrete, when test substances is solid thin-sheet, with tweezers, sample directly is placed in depression circle spot and gets final product; When test substances is pressed powder, get appropriate sample with spoon and place in the circle spot, and with top cover, press gently even, until sample surfaces smoothly gets final product; When test substances is liquid, extract sample with dropper, the polarity size is put for appropriate in depression circle spot per sample, for preventing leak of liquid and volatilization, with top seal, gets final product.

Fig. 3 is the stereographic map of proving installation.The design's proving installation is the teflon disk, and periphery has the individual equally spaced depression circle spot sample test point of N (N=12), and the test point top is top pressure closure, the threaded hole that center is M6.

Fig. 4 is the propagation schematic diagram of THz wave at the sample test vessel.This schematic diagram be take the proving installation of this design and is basis, and R means the test model of reference signal, test model when S means to place sample.Wherein, a means air dielectric, and p means teflon, d _p1and d _p2mean respectively top cover and base thickness, r means reference, and s means sample.

In general experiment, reference time-domain signal and sample time-domain signal that test obtains, pass through fast Fourier transform, obtains their electric field signal E at frequency domain _ref(ω) and E _s(ω).Sample with reference to electric field, at the ratio formula of terahertz wave band, be:

Wherein, the amplitude ratio that ρ is sample and reference,

for the phase place ratio of sample with reference signal.

Take Fig. 4 as test model, and when THz wave process reference and sample, the ratio of its electric field strength is:

$E_s\left(\mathrm{\ω}\right)/E_{\mathrm{ref}}\left(\mathrm{\ω}\right)=\frac{t_{\mathrm{ap}}\exp \left(\frac{-{\mathrm{jn}}_p\mathrm{\ω}{d}_{p1}}{c}\right)t_{\mathrm{ps}}\exp \left(\frac{-{\mathrm{jn}}_s\mathrm{\ω}{l}_s}{c}\right)t_{\mathrm{sp}}\exp \left(\frac{-j{n}_p\mathrm{\ω}{d}_{p2}}{c}\right)t_{\mathrm{pa}}}{t_{\mathrm{ap}}\exp \left(\frac{-j{n}_p\mathrm{\ω}{d}_{p1}}{c}\right)t_{\mathrm{pr}}\exp \left(\frac{-j{n}_r\mathrm{\ω}{l}_r}{c}\right)t_{\mathrm{rp}}\exp \left(\frac{-j{n}_p\mathrm{\ω}{d}_{p2}}{c}\right)t_{\mathrm{pa}}}$

Wherein, n _pthe refractive index that means teflon, n _rthe refractive index that the refractive index that means reference is air, n _sthe refractive index that means sample, d _p1and d _p2be respectively the thickness of top cover and depression circle spot base, l _sand l _rlight path while meaning THz wave through reference and sample, t _abthe expression THz wave is the transmission coefficient to medium b by medium a.

When a, test substances are solid thin-sheet, there is no top cover (d _p1=0), have:

$E_s\left(\mathrm{\ω}\right)/E_{\mathrm{ref}}\left(\mathrm{\ω}\right)=\frac{t_{\mathrm{as}}\exp \left(\frac{-j{n}_s\mathrm{\ω}{l}_s}{c}\right)t_{\mathrm{sp}}\exp \left(\frac{-j{n}_p\mathrm{\ω}{d}_{p2}}{c}\right)t_{\mathrm{pa}}}{t_{\mathrm{ar}}\exp \left(\frac{-{\mathrm{jn}}_r\mathrm{\ω}{l}_r}{c}\right)t_{\mathrm{rp}}\exp \left(\frac{-j{n}_p\mathrm{\ω}{d}_{p2}}{c}\right)t_{\mathrm{pa}}}$

$=\frac{t_{\mathrm{as}}\exp \left(\frac{-j{n}_s\mathrm{\ω}{l}_s}{c}\right)t_{\mathrm{sp}}}{t_{\mathrm{ar}}\exp \left(\frac{-{\mathrm{jn}}_r\mathrm{\ω}{l}_r}{c}\right)t_{\mathrm{rp}}}$

When b, test substances are liquid phase substance, need top seal (d _p1≠ 0).Wherein, when liquid phase substance polarity is larger, l _sbe controlled at below 1mm; Polarity hour, l _sbe controlled at the 1mm left and right; Nonpolar liquid phase material l _ssubstantially more than 1mm.Concrete, liquid phase substance is as follows in the computing formula of terahertz wave band absorption coefficient and refractive index:

$E_s\left(\mathrm{\ω}\right)/E_{\mathrm{ref}}\left(\mathrm{\ω}\right)=\frac{t_{\mathrm{ap}}\exp \left(\frac{-{\mathrm{jn}}_p\mathrm{\ω}{d}_{p1}}{c}\right)t_{\mathrm{ps}}\exp \left(\frac{-{\mathrm{jn}}_s\mathrm{\ω}{l}_s}{c}\right)t_{\mathrm{sp}}\exp \left(\frac{-j{n}_p\mathrm{\ω}{d}_{p2}}{c}\right)t_{\mathrm{pa}}}{t_{\mathrm{ap}}\exp \left(\frac{-j{n}_p\mathrm{\ω}{d}_{p1}}{c}\right)t_{\mathrm{pr}}\exp \left(\frac{-j{n}_r\mathrm{\ω}{l}_r}{c}\right)t_{\mathrm{rp}}\exp \left(\frac{-j{n}_p\mathrm{\ω}{d}_{p2}}{c}\right)t_{\mathrm{pa}}}$

$=\frac{t_{\mathrm{ps}}\exp \left(\frac{-j{n}_s\mathrm{\ω}{l}_s}{c}\right)t_{\mathrm{sp}}}{t_{\mathrm{pr}}\exp \left(\frac{-{\mathrm{jn}}_r\mathrm{\ω}{l}_r}{c}\right)t_{\mathrm{ap}}}$

C, from a and b, whether add top cover, sample with reference at the electric field of terahertz wave band than constant.From model, l _s=l _r=l, n _rfor real number (being referenced as air), it is n that specimen is surveyed refractive index _s=n _s+ jk _s.By test gained electric field, than calculating with model, can be obtained:

N wherein _r=1, sample is at refractive index and the absorption coefficient of terahertz wave band:

Sample is at the absorption coefficient of terahertz wave band:

$\mathrm{\α}\left[{\mathrm{cm}}^{-1}\right]=\frac{2{\mathrm{\ωk}}_s}{c}=\frac{20}{l}\ln \left[\frac{n_s{(1+n_p)}^2}{\mathrm{\ρ}\left(\mathrm{\ω}\right){(n_p+n_s)}^2}\right]$

When sample is solid, l _sfor thickness of sample;

When sample is liquid, l _sfor the test light path;

A is air dielectric;

P is teflon;

D _p1and d _p2be respectively the thickness of top cover and base;

Subscript r is reference material, and s is sample.

Claims (5)

1. a material, at the deriving means of terahertz wave band absorption coefficient and refractive index, is characterized in that: comprise femtosecond laser source, optical splitter, light delay unit, THz emissive source, Sample testing device, THz detector, computing machine;

Described optical splitter is arranged on rear, femtosecond laser source, and its road light separated enters the THz detector, and its another road light separated enters the THz emissive source behind the light delay unit;

Described Sample testing device is placed on the light path of advancing of THz ripple; Described Sample testing device comprises disk and translation stage; Described disk is arranged on translation stage; Be evenly distributed in a plurality of blind holes on described disk;

Described THz detector is for receiving the THz ripple through Sample testing device;

The output signal of described THz detector is sent into computing machine.

2. material according to claim 1, at the deriving means of terahertz wave band absorption coefficient and refractive index, is characterized in that: also comprise for covering the top cover of depression test circle spot.

3. material according to claim 1 and 2, at the deriving means of terahertz wave band absorption coefficient and refractive index, is characterized in that: the material of described disk and top cover is teflon.

4. material according to claim 3, at the deriving means of terahertz wave band absorption coefficient and refractive index, is characterized in that: described optical delay unit comprises that two acutangulate or one-way mirror that obtuse angle is placed.

5. material according to claim 4, at the deriving means of terahertz wave band absorption coefficient and refractive index, is characterized in that: described disc thickness is 4mm; Described top cover thickness is 1mm; The described depression test circle spot degree of depth is 3mm.

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