CN106442394B - A kind of Terahertz near field imaging system and method - Google Patents
A kind of Terahertz near field imaging system and method Download PDFInfo
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Abstract
It includes Terahertz coherent source module, external cavity optical path module and near field probe module that the present invention, which provides a kind of Terahertz near field imaging system and method, the Terahertz near field imaging system,.The present invention generates high power THz radiation using high power Terahertz quantum cascaded laser, using the near field terahertz signal of probe technique and laser self-mixing effect detection target, and then realizes high-resolution imaging function.Due to replacing near-field probe, light path system concision and compact using self-mixing effect；The near field terahertz signal and incoming signal of near field probe reflection are total to optical path, and precision is high and structure is simple, significantly improve the defect of typical near-field imaging technique, and the development and application to high-precision THz imaging technology have positive impetus.
Description
Technical field
The invention belongs to optical application technical field, it is related to a kind of Terahertz near field imaging system and method.
Background technique
Terahertz (Terahertz, THz) wave be often referred to frequency range be 100GHz~10THz, corresponding wavelength be 3mm~
The electromagnetic wave of 30um between millimeter wave and far ir ray, due to the effective source THz of shortage and is detecting in electromagnetic spectrum
Device, THz frequency range are that the last one in electromagnetic spectrum needs the frequency range (" Terahertz Gap ") furtherd investigate comprehensively.In recent years
Come, with the continuous development of photonics and nanotechnology, for THz the relevant technologies in public safety, communications are biomedical, produce
The fields such as quality control and atmosphere environment supervision show great application potential and value.In numerous THz research directions
In, THz imaging is considered as mostly important one of application technology, main reason is that: the imaging of THz wave can obtain moderate sky
Between resolution ratio, can penetrate a variety of non-polar materials (such as paper, plastics, ceramics etc.), realize to hiding target imaging；Especially
Ground, in the fields such as medical imaging and safety check imaging, compared to widely applied X-ray, THz wave has lower energy (1THz
~4meV), therefore it is safer, will not ionized biological molecule, compensate for X-ray and be easy to cause radiation injury to human body that this is lacked
It falls into, while THz wave can obtain better contrast to materials of low density imaging.
With the continuous development of THz imaging technique, the THz imaging system for meeting all kinds of functional needs is come into being.Terahertz
Hereby wavelength is in millimeter/submillimeter two-stage, and for general big target detection, THz image can obtain satisfactory effect.With
THz imaging technique is merged with the continuous of fields such as substance characterization and biomedical detection, and people are to THz imaging resolution and image
The requirement of fine degree is higher and higher, for the imaging system of the far field THz, according to Rayleigh criterion (Rayleigh
Criterion) it is found that the minimum resolution distance of image be not less than Aili spot (Airy disc) radius, image resolution ratio by
The limitation of diffraction limit.In order to break through the limitation, near-field imaging technique comes into being, and near field technique is anti-by acquisition measured target
The evanescent wave ingredient in signal is penetrated, to retain the reflection signal of " complete " to greatest extent, realizes high-definition picture reduction.
Generally, Near-Field Radar Imaging can provide the image resolution ratio of sub-wavelength dimensions, and aperture Near-Field Radar Imaging is often used in such as current field, surpass
The technologies such as lens near-field imaging or non-porous Near-Field Radar Imaging.Fig. 1 and Fig. 2 is that THz Near-Field Radar Imaging and common imaging effect compare,
Middle Fig. 1 is shown as THz Near-Field Radar Imaging effect, and Fig. 2 is shown as common imaging effect, it is therefore apparent that Near-Field Radar Imaging resolution ratio obtains
It significantly improves, image also shows more detailed information, so near-field imaging technique is for answering with high-precision requirement
It is very useful with scene.
However, there are following several respects defects for common near-field imaging technique: 1. system complex, design difficulty are big.Near field
Imaging signal detection generallys use coherent detection technology, and coherent detection technology need to introduce synchronization signal, increase light path system and set
The complexity and operation difficulty of meter；2. light signal output power is low.The THz signal of Near-Field Radar Imaging, which generates, mainly uses two classes
Method, one kind are to emit THz signal by photoconduction by photomixing, and the second class is to generate THz signal using nonlinear crystal, this
The THz signal that two ways generates generally in microwatt magnitude, causes signal detection difficult；3. pair request detector height.On the one hand
Detector needs to have high sensitivity, is just able to achieve the detection to small-signal, on the other hand, because near field detection is distance
Evanescent wave signal within one wavelength of sample surfaces, so detector must be placed in the position very close to sensing point, this
Require detector that must have suitable volume and exquisite structure to meet spatial position demand.To close in terms of three above
The development and application of field imaging technique bring many restrictions, although the prioritization schemes phase such as non-porous technology, super lens switch technology
After appearance, but improvement is limited.
Therefore, a kind of novel Terahertz near field imaging system and method how are provided, to reduce the complexity of light path system
Degree, and imaging precision is improved, become those skilled in the art's important technological problems urgently to be resolved.
Summary of the invention
In view of the foregoing deficiencies of prior art, the purpose of the present invention is to provide a kind of Terahertz near field imaging systems
And method, for solving in the prior art, structure is complicated, THz output power is low and to request detector for THz near field imaging system
The problems such as harsh.
In order to achieve the above objects and other related objects, the present invention provides a kind of Terahertz near field imaging system, including too
Hertz coherent source module, external cavity optical path module and near field probe module；Wherein:
The Terahertz coherent source module includes Terahertz light source and the locking phase being connected with Terahertz light source amplification
Device；The Terahertz light source receives the reflection signal of sample near field terahertz signal for generating terahertz signal, in institute
It states and generates self-mixing effect in the resonant cavity of Terahertz light source；The lock-in amplifier is used to detect oneself of the Terahertz light source
Mixed frequency signal, to realize the signal extraction to imaging sampling location；
The external cavity optical path module is used to collect the terahertz signal that the Terahertz light source issues, and converges to sample table
Face；The external cavity optical path module is also used to collect the reflection signal of the near field terahertz signal of sample, and by the reflection signal edge
The optical path reverse transfer of the external cavity optical path module and is produced from resonant cavity mixed to the light output end of the Terahertz light source
Frequency effect；
The near field probe module includes near field probe；Near field Terahertz of the near field probe for reflected sample is believed
Number.
Optionally, the Terahertz coherent source module further includes and the Terahertz light source and the lock-in amplifier phase
Driving power even；The lock-in amplifier provides synchronous triggering signal to the driving power；The driving power drives institute
It states Terahertz light source and generates terahertz signal.
Optionally, the external cavity optical path module includes the first off axis paraboloidal mirror and the second off axis paraboloidal mirror；Described
One off axis paraboloidal mirror is used to collect the terahertz signal that the Terahertz coherent source module issues, and it is flat to convert thereof into first
Row light, second off axis paraboloidal mirror are used to first directional light converging to sample surfaces；The second off-axis parabolic
Face mirror is also used to collect the reflection signal of the near field terahertz signal of sample, which is converted to the second directional light, institute
The light output end that the first off axis paraboloidal mirror is also used to converge to second directional light Terahertz light source is stated, to generate
The self-mixing effect.
Optionally, the near field probe module further includes modulation signal generator and two-dimension translational platform；The two-dimension translational
Platform drives the sample to carry out step-scan in the plane perpendicular near field probe for carrying sample；The near field probe
For conductivity type probe；The modulation signal generator is connected with the near field probe, for modulating the near field probe along sample
The cycle movement of surface normal direction；The modulation signal generator is also connected with the lock-in amplifier, puts for the locking phase
Big device provides reference frequency；The reference frequency is equal to the modulation frequency that the modulation signal generator modulates the near field probe
Rate.
Optionally, scanning step s≤r of the step-scan, wherein r is near field probe tip radius；Near field probe pinpoint
Radius r≤λ/10, near field probe tip and sample surfaces distance D≤λ are held, wherein λ is Terahertz wavelength.
Optionally, using oblique incidence mode when terahertz signal converges to sample surfaces；The range of incident angle θ is 10 °-
60°。
Optionally, the voltage signal or current signal of self-mixing signal behavior Terahertz light source are detected, and chooses a tune
Response of the peak value as corresponding sensing point in period processed；High-order harmonics by detecting modulated signal completes self-mixing signal
Detection, high-order harmonics are selected as 2 ranks or 3 ranks.
Optionally, the Terahertz light source is Terahertz quantum cascaded laser；The Terahertz quantum cascaded laser
Using semi-insulating surface plasma waveguide, and use continuous wave operating mode.
The present invention also provides a kind of Terahertz Near-Field Radar Imaging methods, which comprises by sample near field terahertz signal
Reflection signal be transmitted to the light output end of Terahertz light source, self-mixing effect is generated in the resonant cavity of Terahertz light source, and
Self-mixing signal by detecting Terahertz light source realizes the signal extraction to imaging sampling location.
Optionally, the Terahertz light source is Terahertz quantum cascaded laser.
Optionally, the voltage signal or current signal of self-mixing signal behavior Terahertz light source are detected, and chooses a tune
Response of the peak value as corresponding sensing point in period processed.
Optionally, the near field terahertz signal of near field probe reflection sample is utilized；The near field probe is conductivity type probe.
As described above, Terahertz near field imaging system of the invention and method, have the advantages that proposition of the present invention
A kind of novel THz near-field imaging technique generates high power THz radiation using high power Terahertz quantum cascaded laser,
Using the near field terahertz signal of probe technique and laser self-mixing effect detection target, and then realize high-resolution imaging function
Energy.The present invention replaces near-field probe, light path system concision and compact using self-mixing effect；The near field terahertz of near field probe reflection
Hereby signal and incoming signal are total to optical path, and precision is high and structure is simple, the defect of typical near-field imaging technique are significantly improved, to height
The development and application of precision THz imaging technology have positive impetus.
Detailed description of the invention
Fig. 1 is shown as THz Near-Field Radar Imaging effect.
Fig. 2 is shown as common imaging effect.
Fig. 3 is shown as the structural schematic diagram of Terahertz near field imaging system of the invention.
Fig. 4 is shown as the relative position schematic diagram of thz beam, near field probe and sample.
Component label instructions
1 Terahertz coherent source module
101 Terahertz light sources
102 lock-in amplifiers
103 driving powers
2 external cavity optical path modules
201 first off axis paraboloidal mirrors
202 second off axis paraboloidal mirrors
3 near field probe modules
301 near field probes
302 modulation signal generators
303 two-dimension translational platforms
4 samples
Specific embodiment
Illustrate embodiments of the present invention below by way of specific specific example, those skilled in the art can be by this specification
Other advantages and efficacy of the present invention can be easily understood for disclosed content.The present invention can also pass through in addition different specific realities
The mode of applying is embodied or practiced, the various details in this specification can also based on different viewpoints and application, without departing from
Various modifications or alterations are carried out under spirit of the invention.
Please refer to Fig. 3 and Fig. 4.It should be noted that diagram provided in the present embodiment only illustrates this in a schematic way
The basic conception of invention, only shown in schema then with related component in the present invention rather than package count when according to actual implementation
Mesh, shape and size are drawn, when actual implementation kenel, quantity and the ratio of each component can arbitrarily change for one kind, and its
Assembly layout kenel may also be increasingly complex.
Embodiment one
The present invention provides a kind of Terahertz near field imaging system, referring to Fig. 3, being shown as the Terahertz near field imaging system
Structural schematic diagram, including Terahertz coherent source module 1, external cavity optical path module 2 and near field probe module 3；Wherein: it is described too
Hertz coherent source module 1 includes Terahertz light source 101 and the lock-in amplifier 102 being connected with the Terahertz light source 101；Institute
Stating external cavity optical path module 2 includes the first off axis paraboloidal mirror 201 and the second off axis paraboloidal mirror 202；The near field probe module 3
Including near field probe 301.
Specifically, the Terahertz light source 101 is for generating terahertz signal and receiving 4 near field terahertz signal of sample
Signal is reflected, to generate self-mixing effect in the resonant cavity of the Terahertz light source 101.In the present embodiment, the Terahertz
Coherent source module 1 further includes the driving power 103 being connected with the Terahertz light source 101 and the lock-in amplifier 102；Institute
It states lock-in amplifier 102 and provides synchronous triggering signal to the driving power 103；The driving power 103 drives the terahertz
Hereby light source 101 generates terahertz signal.
As an example, the Terahertz light source 101 uses Terahertz quantum cascaded laser, high power terahertz can produce
It hereby radiates, is conducive to signal detection.In the present embodiment, the Terahertz quantum cascaded laser uses semi-insulating surface plasma
Bulk wave is led, and uses continuous wave operating mode.
Specifically, the off-axis degree of first off axis paraboloidal mirror 201 and the second off axis paraboloidal mirror 202 is 90, aperture
Diameter is 2 inches, and focal length is 4 inches (1 inch=25.4mm).The external cavity optical path module 2 utilizes the described first off-axis parabolic
Face mirror 201 collects the terahertz signal that the Terahertz light source 101 issues, and converts thereof into the first directional light, and further lead to
It crosses second off axis paraboloidal mirror 202 and first directional light is converged into 4 surface of sample, wherein converging to sample surfaces
Terahertz signal is reflected through sample, generates the near field terahertz signal of sample.
In the present invention, the near field terahertz signal of sample is collected using reflective-mode, and by thz laser device from
Mixing effect is detected.
Specifically, the near field probe 301 is used for the near field terahertz signal of reflected sample.Meanwhile the external cavity optical path
Module 2 collects the reflection signal of the near field terahertz signal of sample using second off axis paraboloidal mirror 202, which is believed
Number the second directional light is converted to, and is further converged to second directional light by first off axis paraboloidal mirror 201
The light output end of the Terahertz light source 101, to generate the self-mixing effect.In other words, sample near field terahertz signal
Reflection signal be along the external cavity optical path module 2 optical path reverse transfer to the Terahertz light source 101 light output end,
That is the near-field signals of near field probe reflection and incoming signal are total to optical path.
Referring to Fig. 4, being shown as thz beam, near field probe 301 and sample 4 in the y-z plane (x-z relative to Fig. 3
Plane angle) on relative position schematic diagram.In the present embodiment, using oblique incidence side when terahertz signal converges to sample surfaces
Formula；The range of incident angle θ is 10 ° -60 °.
As an example, the near field probe 301 is conductivity type probe, near field probe tip radius r≤λ/10, near field probe
Tip and sample surfaces distance D≤λ, wherein λ is Terahertz wavelength.In the present embodiment, the near field probe 301 is preferably table
Face platinum plating can increase the electric conductivity and flintiness of near field probe, play a protective role simultaneously.
In the present embodiment, the near field probe module 3 further includes and the near field probe 301 and the lock-in amplifier
102 connected modulation signal generators 302 and the two-dimension translational platform 303 for carrying sample 4.
Specifically, the two-dimension translational platform 303 for drive the sample 4 the plane perpendicular near field probe 301 into
Row step-scan, to realize the two-dimensional scanning function of sample.
As an example, scanning step s≤r of the step-scan, wherein r is near field probe tip radius, is divided with improving
Resolution.
Specifically, the modulation signal generator 302 amplifies for modulating the near field probe 301, and for the locking phase
Device provides reference frequency；The reference frequency is equal to the modulation that the modulation signal generator 302 modulates the near field probe 301
Frequency.
As an example, the modulation signal generator 302 is to modulate near field probe 301 by providing motion control signal
Along 4 surface normal direction cycle movement of sample, i.e., moved up and down relative to sample.
Specifically, lock-in amplifier is the amplifier that a kind of pair of alternating signal carries out phase sensitive detection.It is utilized and tested letter
Number there is the reference signal of identical frequency and phase relation as benchmark, only to measured signal itself and those and reference signal
There is response with frequency (or frequency multiplication), with the noise component(s) of phase.Therefore, it can significantly inhibit useless noise, improve detection signal-to-noise ratio.
In addition, lock-in amplifier has very high detection sensitivity, signal processing is fairly simple, is that one kind of low light signals detection has efficacious prescriptions
Method.
In the present invention, the lock-in amplifier 102 is used to detect the self-mixing signal of the Terahertz light source 101, with reality
Now to the signal extraction of imaging sampling location.
It is visited as an example, the lock-in amplifier 102 completes self-mixing signal by the high-order harmonics of detection modulated signal
It surveys.Selection high-order harmonics detection is conducive to reduce ambient noise.In the present embodiment, modulated signal high-order harmonics is selected as 2 ranks or 3
Rank, i.e., described 102 response frequencies of lock-in amplifier are the self-mixing signal of 2 times or 3 times reference frequencies.
As an example, the voltage signal or current signal of detection self-mixing signal behavior Terahertz light source 101, and choose one
Response of the peak value as corresponding sensing point in a modulation period.In the present embodiment, the preferred Terahertz of self-mixing signal is detected
The voltage signal of light source 101.
Terahertz near field imaging system Terahertz coherent source module, external cavity optical path module and near field probe mould of the invention
Block is constituted, and generates high power THz signal using Terahertz coherent source, external cavity optical path guides THz signal attached near field probe
Close sample sensing point, the near field terahertz signal of sample reflect signal by external cavity optical path module feedback by near field probe reflection
It is produced from mixing effect to laser resonator is intracavitary, signal extraction is realized by the change in electric of detection laser.The present invention
Signal detection is completed using the near-field information and combination self-mixing effect of near field probe collection sample, breaks through the diffraction of imaging
Limitation, while retaining Near-Field Radar Imaging precision, the significant complexity for reducing system, so as to improve typical near-field imaging technique
Defect, to Terahertz high-precision imaging technique development with application have important impetus.
Embodiment two
The present invention also provides a kind of Terahertz Near-Field Radar Imaging methods, which comprises by sample near field terahertz signal
Reflection signal be transmitted to the light output end of Terahertz light source, self-mixing effect is generated in the resonant cavity of Terahertz light source, and
Self-mixing signal by detecting Terahertz light source realizes the signal extraction to imaging sampling location.
As an example, any THz wave generation device with resonant cavity may be selected in the Terahertz light source.The present embodiment
In, the Terahertz light source preferably uses Terahertz quantum cascaded laser, can produce high power terahertz emission, is conducive to
Signal detection.
As an example, the voltage signal or current signal of detection self-mixing signal behavior Terahertz light source, and choose one
Response of the peak value as corresponding sensing point in modulation period.Wherein, the voltage signal or electric current letter of Terahertz light source are detected
Number detector can be designed according to actual needs, should not excessively limit the scope of the invention herein.
As an example, completing self-mixing signal detection, such as 2 ranks or 3 ranks by the high-order harmonics of detection modulated signal, have
Conducive to reduction ambient noise.
As an example, the near field probe is conductivity type spy using the near field terahertz signal of near field probe reflection sample
Needle.
As an example, specific structure can root using the reflection signal of external cavity optical path transmission sample near field terahertz signal
It is designed according to actual needs.
As an example, the near-field signals of near field probe reflection and incoming signal are total to optical path.In the present embodiment, it is preferred to use one
Off axis paraboloidal mirror is organized to transmit the reflection of incoming signal and near field terahertz signal.
Light channel structure needed for Terahertz Near-Field Radar Imaging method of the invention is simple, and is believed using self-mixing effect instead of near field
Number detector, the position very close to sensing point must be placed in by avoiding detector in the prior art, it is desirable that detector is necessary
Have suitable volume and exquisite structure to meet the problem of spatial position requires.Terahertz Near-Field Radar Imaging method of the invention
The design difficulty that Terahertz near field imaging system can be reduced is conducive to push the development of Terahertz high-precision imaging technique and answer
With.
Embodiment three
The present embodiment provides a kind of construction methods of Terahertz near field imaging system, include the following steps:
Step 1: building Near-Field Radar Imaging light path system.
1) by external cavity optical path the first off axis paraboloidal mirror (hereinafter referred to as PM1) and the second off axis paraboloidal mirror it is (following
Abbreviation PM2) it is placed on parallel optical track, it is adjusted convenient for subsequent external cavity length；
2) it will be seen that radiant, which is placed in PM1 focal point, carries out light path calibration and sample position calibration, is identified according to visible light,
The pitch angle for adjusting PM1 and PM2 makes the convergence hot spot of PM2 and visible light source be in sustained height, facula position and PM2
Focal position is overlapped, and uniform round scaling is presented along optical axis direction variation in hot spot；
It 3), will be in Terahertz coherent source according to visible light Calibrating source and sensing point (the convergence hot spot of PM2) position
THz light source light output end is placed at the light source position of calibration, nearly the sensing point that is placed in calibration of the sample in field probe module
At position, sample direction is adjusted, makes its surface normal and 45 ° of optical axis included angle, sample is fixed on two-dimension translational platform, passes through step
Sample two-dimensional scanning function is realized into mobile.
Step 2: near field probe is adjusted.
1) laser is lighted by driving power, lock-in amplifier monitors the voltage signal variation of laser in real time；
2) signal generator provides reference frequency to lock-in amplifier, and modulates near field probe；
3) nearly field probe is disposed adjacent to sensing point and any position apart from one wavelength distance of sample surfaces, and near field is visited
Needle direction is perpendicular to sample surfaces, the sensing point position that slowly mobile near field probe approach identifies, according to Terahertz coherent source
Lock-in amplifier signal intensity situation in module chooses the peak position of signal as sensing point, and fixes near field probe.
Step 3: Sample Scan.
1) setting scan path covers sample surfaces；
2) scanning step, step-length range≤r are set (r is near field probe tip radius)；
3) image reconstruction is carried out to sample according to detectable signal.
In conclusion Terahertz near field imaging system of the invention and method use the Terahertz quantum cascaded laser of high power
Device generates high power THz radiation, and the near field terahertz signal of target is detected using probe technique and laser self-mixing effect, into
And realize high-resolution imaging function.The present invention replaces near-field probe, light path system concision and compact using self-mixing effect；Closely
The near field terahertz signal and incoming signal of field probe reflection are total to optical path, and precision is high and structure is simple, significantly improve traditional close
The defect of field imaging technique, development and application to high-precision THz imaging technology have positive impetus.So this
Invention effectively overcomes various shortcoming in the prior art and has high industrial utilization value.
The above-described embodiments merely illustrate the principles and effects of the present invention, and is not intended to limit the present invention.It is any ripe
The personage for knowing this technology all without departing from the spirit and scope of the present invention, carries out modifications and changes to above-described embodiment.Cause
This, institute is complete without departing from the spirit and technical ideas disclosed in the present invention by those of ordinary skill in the art such as
At all equivalent modifications or change, should be covered by the claims of the present invention.
Claims (12)
1. a kind of Terahertz near field imaging system, including Terahertz coherent source module, external cavity optical path module and near field probe mould
Block；It is characterized by:
The Terahertz coherent source module includes Terahertz light source and the lock-in amplifier that is connected with the Terahertz light source；Institute
Terahertz light source is stated for generating terahertz signal, and receives the reflection signal of sample near field terahertz signal, with it is described too
Self-mixing effect is generated in the resonant cavity of hertz light source；The lock-in amplifier is used to detect the self-mixing of the Terahertz light source
Signal, to realize the signal extraction to imaging sampling location；
The external cavity optical path module is used to collect the terahertz signal that the Terahertz light source issues, and converges to sample surfaces,
The terahertz signal for wherein converging to sample surfaces is reflected through sample, generates the near field terahertz signal of sample；The exocoel light
Road module is also used to collect the reflection signal of the near field terahertz signal of sample, and by the reflection signal along the external cavity optical path mould
The optical path reverse transfer of block to the Terahertz light source light output end, and in resonant cavity generate self-mixing effect；
The near field probe module includes near field probe；The near field probe is used for the near field terahertz signal of reflected sample,
Described near field probe reflection near field terahertz signal and incoming signal be total to optical path.
2. Terahertz near field imaging system according to claim 1, it is characterised in that: the Terahertz coherent source module
It further include the driving power being connected with the Terahertz light source and the lock-in amplifier；The lock-in amplifier provides synchronous touching
Signal to the driving power；The driving power drives the Terahertz light source to generate terahertz signal.
3. Terahertz near field imaging system according to claim 1, it is characterised in that: the external cavity optical path module includes the
One off axis paraboloidal mirror and the second off axis paraboloidal mirror；First off axis paraboloidal mirror is for collecting the Terahertz coherent light
The terahertz signal that source module issues, converts thereof into the first directional light, and second off axis paraboloidal mirror is used for described the
One directional light converges to sample surfaces；Second off axis paraboloidal mirror is also used to collect the anti-of the near field terahertz signal of sample
Signal is penetrated, which is converted into the second directional light, first off axis paraboloidal mirror is also used to parallel by described second
Light converges to the light output end of the Terahertz light source, to generate the self-mixing effect.
4. Terahertz near field imaging system according to claim 1, it is characterised in that: the near field probe module further includes
Modulation signal generator and two-dimension translational platform；The two-dimension translational platform for carrying sample, and drive the sample perpendicular to
The plane of probe carries out step-scan；The near field probe is conductivity type probe；The modulation signal generator and the near field
Probe is connected, for modulating the near field probe along sample surfaces normal direction cycle movement；The modulation signal generator
Also it is connected with the lock-in amplifier, provides reference frequency for the lock-in amplifier；The reference frequency is equal to the modulation
Signal generator modulates the modulating frequency of the near field probe.
5. Terahertz near field imaging system according to claim 4, it is characterised in that: the scanning step of the step-scan
S≤r, wherein r is near field probe tip radius；Near field probe tip radius r≤λ/10, near field probe tip and sample surfaces
Distance D≤λ, wherein λ is Terahertz wavelength.
6. Terahertz near field imaging system according to claim 1, it is characterised in that: terahertz signal converges to sample table
Oblique incidence mode is used when face；The range of incident angle θ is 10 ° -60 °.
7. Terahertz near field imaging system according to claim 1, it is characterised in that: the lock-in amplifier detection is certainly mixed
The voltage signal or current signal of frequency signal behavior Terahertz light source, and choose the peak value in a modulation period and visited as corresponding
The response of measuring point；By detect modulated signal high-order harmonics complete self-mixing signal detection, high-order harmonics be selected as 2 ranks or
3 ranks.
8. Terahertz near field imaging system according to claim 1, it is characterised in that: the Terahertz light source is Terahertz
Quantum cascade laser；The Terahertz quantum cascaded laser uses semi-insulating surface plasma waveguide, and using continuous
Wave operating mode.
9. a kind of Terahertz Near-Field Radar Imaging method, the Terahertz Near-Field Radar Imaging method uses such as claim 1-8 any one
The Terahertz near field imaging system carries out, it is characterised in that: is transmitted to the reflection signal of sample near field terahertz signal
The light output end of Terahertz light source generates self-mixing effect in the resonant cavity of Terahertz light source, and passes through detection terahertz light
The self-mixing signal in source realizes the signal extraction to imaging sampling location.
10. Terahertz Near-Field Radar Imaging method according to claim 9, it is characterised in that: the Terahertz light source is terahertz
Hereby quantum cascade laser.
11. Terahertz Near-Field Radar Imaging method according to claim 9, it is characterised in that: detection self-mixing signal behavior is too
The voltage signal or current signal of hertz light source, and choose response of the peak value in a modulation period as corresponding sensing point
Value.
12. Terahertz Near-Field Radar Imaging method according to claim 9, it is characterised in that: utilize near field probe reflection sample
Near field terahertz signal；The near field probe is conductivity type probe.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106996918B (en) * | 2017-03-24 | 2023-03-28 | 中国科学院上海微系统与信息技术研究所 | Terahertz imaging system based on photonics technology |
| CN107144950A (en) * | 2017-05-12 | 2017-09-08 | 深圳市太赫兹科技创新研究院 | Terahertz Near-Field Radar Imaging is popped one's head in and Terahertz near field imaging system |
| CN107171166B (en) * | 2017-07-03 | 2019-07-09 | 中国科学院上海微系统与信息技术研究所 | Terahertz quantum cascaded laser phase-locked system and method |
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| CN112730315B (en) * | 2020-12-25 | 2022-06-24 | 中国科学院上海微系统与信息技术研究所 | High-resolution terahertz near-field spectrum test system |
| CN113267465B (en) * | 2021-05-13 | 2023-04-18 | 重庆邮电大学 | Terahertz dual-mode imaging system and method based on time domain spectroscopy technology |
| CN116008217B (en) * | 2022-10-31 | 2024-01-30 | 合肥综合性国家科学中心能源研究院(安徽省能源实验室) | Measurement method for terahertz imaging of sperm tail |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050185188A1 (en) * | 2001-11-06 | 2005-08-25 | Mcgrew Stephen P. | Quantum resonance analytical instrument |
| US20080137093A1 (en) * | 2006-12-07 | 2008-06-12 | Electronic And Telecommunications Research Institute | APPARATUS AND METHOD FOR GENERATING THz WAVE BY HETERODYNING OPTICAL AND ELECTRICAL WAVES |
| WO2011134593A1 (en) * | 2010-04-29 | 2011-11-03 | Rheinisch-Westfälische Technische Hochschule Aachen | Photoconducting measuring tip, measurement arrangement, and method for producing and/or detecting electromagnetic field signals |
| CN102323040A (en) * | 2011-05-30 | 2012-01-18 | 中国科学院上海微系统与信息技术研究所 | Power measuring device and method for pulse ejection tera-hertz quantum cascade laser |
| CN102749341A (en) * | 2012-07-11 | 2012-10-24 | 中国科学院上海微系统与信息技术研究所 | Tomography imaging system and method based on terahertz quantum device |
| CN103954802A (en) * | 2014-05-13 | 2014-07-30 | 中国科学技术大学 | Long-wavelength scanning near-field microscopic analysis system |
| CN105628641A (en) * | 2015-12-28 | 2016-06-01 | 中国科学院重庆绿色智能技术研究院 | Real-time scattering type terahertz quasi-time-domain near field polarization spectrograph |
| CN105829844A (en) * | 2013-08-22 | 2016-08-03 | 昆士兰大学 | A laser system for imaging and materials analysis |
-
2016
- 2016-09-28 CN CN201610859262.2A patent/CN106442394B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050185188A1 (en) * | 2001-11-06 | 2005-08-25 | Mcgrew Stephen P. | Quantum resonance analytical instrument |
| US20080137093A1 (en) * | 2006-12-07 | 2008-06-12 | Electronic And Telecommunications Research Institute | APPARATUS AND METHOD FOR GENERATING THz WAVE BY HETERODYNING OPTICAL AND ELECTRICAL WAVES |
| WO2011134593A1 (en) * | 2010-04-29 | 2011-11-03 | Rheinisch-Westfälische Technische Hochschule Aachen | Photoconducting measuring tip, measurement arrangement, and method for producing and/or detecting electromagnetic field signals |
| CN102323040A (en) * | 2011-05-30 | 2012-01-18 | 中国科学院上海微系统与信息技术研究所 | Power measuring device and method for pulse ejection tera-hertz quantum cascade laser |
| CN102749341A (en) * | 2012-07-11 | 2012-10-24 | 中国科学院上海微系统与信息技术研究所 | Tomography imaging system and method based on terahertz quantum device |
| CN105829844A (en) * | 2013-08-22 | 2016-08-03 | 昆士兰大学 | A laser system for imaging and materials analysis |
| CN103954802A (en) * | 2014-05-13 | 2014-07-30 | 中国科学技术大学 | Long-wavelength scanning near-field microscopic analysis system |
| CN105628641A (en) * | 2015-12-28 | 2016-06-01 | 中国科学院重庆绿色智能技术研究院 | Real-time scattering type terahertz quasi-time-domain near field polarization spectrograph |
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