CN105866773B - High-power THz continuous wave two-dimensional imaging system - Google Patents
High-power THz continuous wave two-dimensional imaging system Download PDFInfo
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- CN105866773B CN105866773B CN201610322075.0A CN201610322075A CN105866773B CN 105866773 B CN105866773 B CN 105866773B CN 201610322075 A CN201610322075 A CN 201610322075A CN 105866773 B CN105866773 B CN 105866773B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
Abstract
The invention discloses a kind of high-power THz continuous wave two-dimensional imaging system, including duplexer, two-dimensional scanning platform, THz continuous wave transmitter module, THz continuous wave receiving module, TPX lens, data acquisition and processing (DAP) module, image processing module and image-display units.The present invention has frequency in terahertz wave band, and transmitter module transmission power is high, and system architecture is simple, the advantage such as small volume, resolution ratio height.
Description
Technical field
The present invention relates to Terahertz technical field of nondestructive testing, more particularly to a kind of high-power active THz continuous wave
The system and method for two-dimentional high-resolution imaging.
Background technology
The terahertz wave band of general appellation, its frequency range is 0.1THz to 10THz (wavelength is from 0.03mm to 3mm)；
Some occasions refer in particular to 0.3THz to 3THz, are also sometimes endowed a kind of definition of broad sense, and its frequency range can include up to
100THz ripple, this include it is whole in, far infrared band.In electromagnetic spectrum, THz wave be located at microwave and far infrared wave it
Between, the transition stage in macroelectronics to microcosmic photonic propulsion.In person in electronics, the electromagnetic wave of this wave band is claimed again
For millimeter wave or submillimeter wave；In field of spectroscopy, it is also referred to as far ir ray.
Possess substantial amounts of terahertz emission source in nature, for example, our most objects at one's side heat radiation all too
Hertz wave band.But due to the efficient emission source for lacking terahertz wave band and sensitive detector, the electricity of terahertz wave band
Magnetic radiation does not obtain as microwave the in-depth study as far infrared wave.Why THz wave causes our dense researchs
Interest, not merely it is widely present but electromagnetic radiation also not well known because it is one kind, more important reason is it
With many unique properties.Specifically, THz wave mainly has following feature：
1st, THz wave has good penetrability for many dielectric materials and nonpolar liquid.The one of terahertz emission
Individual very attractive application prospect is exactly the supplement as x-ray imaging and ultrasound imaging techniques, for safety inspection or
Person carries out nondestructive inspection in quality control.
2nd, Terahertz Technology has high security, compared to X ray have kiloelectron-volt photon energy, terahertz emission
Photon energy there was only the order of magnitude of milli electron volts.The photon energy of THz wave is less than the bond energy of various chemical bonds, therefore it
Harmful ionization reaction will not be caused.
3rd, terahertz wave band contains abundant spectral information.Substantial amounts of molecule, especially organic molecule, due to its rotation
With the transition of vibration (including collective's vibrations), strong absorption and dispersion characteristics are shown in this frequency range.
4th, for THz wave compared with microwave, frequency is higher, when as communications carrier, can be carried in the unit interval more
Information.
5th, because the wavelength of THz wave is shorter, his transmitting directivity is better than microwave.
6th, in imaging applications, THz wave has higher spatial resolution, or is keeping equal spatial resolution
When there is the longer depth of field.
At present in the world only have Rensselaer Polytech Inst of the U.S. (Rensselaer Polytechnic Institute,
RPI), the Terahertz POP of American National Air and Space Executive Agent (NASA) and department of physics of Capital Normal University of China and imaging are real
Room is tested to possess and THz continuous wave two-dimensional imaging system comes into operation.They realize that THz continuous wave two-dimensional imaging uses
Method cost it is higher, that complicated and imaging resolution is restricted condition is more.
The two of THz wave can be realized currently with vector network analyzer and terahertz time-domain spectroscopy analysis system
Dimension imaging, but the transmission power of the transmitter module of terahertz time-domain spectroscopy analysis system detection testee only has several milliwatts,
The transmission power of the transmitter module of vector network analyzer detection testee also only has tens milliwatts, and this will limit Terahertz
The resolution ratio of ripple two-dimensional imaging.
Therefore, it is necessary to the terahertz that a kind of transmitter module transmission power is higher, price is relatively low, simple in construction and higher resolution ratio
Hereby continuous wave two-dimensional imaging system.
The content of the invention
It is an object of the invention to provide it is a kind of using high-power THz continuous wave transmitter module as the structure of core it is simple,
High resolution, lower-cost THz continuous wave two-dimensional imaging system.
The present invention includes：
Duplexer, for measurand measured surface send THz continuous wave transmission signal and receive from
The echo-signal that the measured surface of measurand returns；
Two-dimensional scanning platform, for fixed on two dimensional surface and mobile measurand；
THz continuous wave transmitter module, the THz continuous wave transmission signal of measurand is sent to for generating；
THz continuous wave receiving module, for receiving and handling the THz continuous wave echo from duplexer
Signal；
TPX lens, including TPX lens I and TPX lens II, for the terahertz for launching THz continuous wave transmitter module
Hereby continuous wave first passes through TPX lens I and becomes parallel, then the measured surface of measurand is converged to by TPX lens II；Or
Become parallel for the THz continuous wave of the measured surface reflection of measurand to be first passed through into TPX lens II, then by TPX
Lens I converge to the duplexer；
Data acquisition and processing (DAP) module, for gathering and handling the echo-signal from the output of THz continuous wave receiving module
To generate the two dimensional image of the measured surface of measurand；
Image processing module, for further processing data collection and processing module generation two dimensional image so that image more
It is clear to add；
Image-display units, for showing the two dimensional image generated by image processing module.
Duplexer launches the transmission signal from THz continuous wave transmitter module to TPX lens I, by terahertz
Hereby continuous wave becomes parallel；Further, THz continuous wave is converged to carry and split by THz wave by TPX lens II
The measured surface of the measurand of gap.
The distance between described TPX lens I and TPX lens II are less than the focal length of TPX lens.TPX lens I and TPX is saturating
Mirror II is identical, and TPX lens I and TPX lens II are staggered relatively.
THz continuous wave transmitter module includes the first signal source, the first power amplifier, the first varactor doubler, the two or two
Frequency multiplier, adjustable attenuator, isolator and directional coupler, THz continuous wave transmitter module are sent to tested pair for generation
The THz continuous wave transmission signal of elephant.
Specifically, the first signal source is the point-frequency signal source that working frequency is 27.5GHz, can be expressed as：
Wherein, A1It is expressed as initial magnitude, f1For frequency 27.5GHz, t is the time,For the initial phase of the first signal source
Value.
Second power amplifier is amplified to the power of the first signal source to reach the firm power of the first varactor doubler
Input range, the frequency of signal reaches 55GHz after the first varactor doubler, further across signal after the second varactor doubler
Frequency reaches 110GHz.First varactor doubler and the second varactor doubler are all active devices, and the high-power of transmission signal is mainly
By the high (high power from the first varactor doubler for VDI companies model D60 determined of the transformation efficiency of the two varactor doublers
Arrowband frequency multiplier, the conversion efficiency at 55GHz frequencies are more than 30%；Second varactor doubler is VDI companies model D110
High power arrowband frequency multiplier, 25%) conversion efficiency at 110GHz frequencies is.
Second varactor doubler is by the signal output after two frequencys multiplication to adjustable attenuator；Adjustable attenuator is by the second varactor doubler
Power output realize different degrees of reduction by adjusting the knob of adjustable attenuator, and by the output signal of adjustable attenuator
Export to isolator；The echo-signal that isolator returns to the straight-through end of directional coupler isolate with prevent echo-signal input to
The adjustable attenuator, the output end of adjustable attenuator are connected to the input of isolator, and the output end of isolator, which is connected to, determines
To the input of coupler；The straight-through end of adjustable attenuator is connected to the input of directional coupler by directional coupler, will be fixed
Duplexer is connected to the straight-through end of coupler；Finally sent through duplexer.Duplexer
Transmission signal is represented by：
Wherein, A1' be transmission signal amplitude.
THz continuous wave receiving module includes secondary signal source, the second power amplifier, attenuator, the three or two frequency multiplication
Device, th harmonic mixer, bandpass filter, low-noise amplifier and wave detector, THz continuous wave receiving module are used to receive
With THz continuous wave echo-signal of the processing from duplexer.
Specifically, secondary signal source is the point-frequency signal source that working frequency is 27.475GHz, can be expressed as：
Wherein, A2It is expressed as initial magnitude, f2For frequency 27.475GHz, t is the time,For the initial of secondary signal source
Phase value.
Second power amplifier is amplified to the power in secondary signal source, and further attenuator is by the second power amplification
The power of the output signal of device is slightly decayed to reach the firm power input range of the 3rd varactor doubler；3rd varactor doubler will decline
The signal for subtracting device output carries out two frequencys multiplication to 54.95GHz, and by the signal output after two frequencys multiplication to th harmonic mixer local oscillator
End；The coupled end of directional coupler is connected to the radio-frequency head of th harmonic mixer by th harmonic mixer, now the letter at local oscillator end
Number frequency is 109.9GHz, and the signal frequency of radio-frequency head is 110GHz.The signal at th harmonic mixer local oscillator end is represented by
Wherein, A2' be local oscillator end signal amplitude.The signal at subharmonic mixed frequency RF end is represented by：
Wherein, A1" it is the amplitude of radio frequency end signal,It is the initial phase value of radio frequency end signal.Th harmonic mixer
IF output signal be represented by：
The medium frequency output end of th harmonic mixer is connected to the input of bandpass filter；The centre frequency of bandpass filter
For 100MHz, the clutter beyond 100MHz in the IF output signal of th harmonic mixer is filtered out, bandpass filter 314 it is defeated
Go out signal to be represented by：
The output end of bandpass filter is connected to low-noise amplifier；The noise of the output signal of bandpass filter is reduced
And power amplification, to improve the power output of 100MHz intermediate-freuqncy signals, the output signal of low-noise amplifier is represented by：
Wherein, K is the amplification coefficient of low-noise amplifier,It is the phase value of signal intensity.Low-noise amplifier can
Make to be amplified by the faint intermediate-freuqncy signal of down coversion twice, improve signal to noise ratio, the detectivity of output signal, then
The output signal of low-noise amplifier is changed into direct current signal from AC signal using wave detector, and outputs it signal and is admitted to
Data acquisition and processing (DAP) module.
Data acquisition and processing (DAP) module gathers echo-signal first, then echo-signal is carried out into data two dimension and reset, then
Carry out mean filter.Image processing module first realizes histogram equalization, then stretches contrast, then carry out rim detection and
Edge sharpening, finally give two dimensional image.
The first image is generated after data acquisition and processing (DAP) module, histogram equalization generates the second figure in image processing module
Picture, the 3rd image of generation is further stretched by contrast, the 4th image is further generated by rim detection, finally by side
Edge sharpens the 5th image of generation.
Following step is included to the imaging process of measurand using above-mentioned high-power THz continuous wave two-dimensional imaging system
Suddenly：
Two-dimensional scanning platform moves measurand；
THz continuous wave transmitter module and duplexer scanning measurand；
THz continuous wave transmitter module generates transmission signal；
Transmission signal is transmitted to measurand by duplexer；
Duplexer, which receives the echo-signal that measurand surface returns and echo-signal is sent into Terahertz, to be connected
Continuous ripple receiving module；
THz continuous wave receiving module is handled echo-signal and is sent to data acquisition and image processing module；
Data acquisition and processing (DAP) module is handled the signal from THz continuous wave receiving module tested to generate
The two-dimensional imaging of object；
Image processing module, for further processing data collection and processing module generation two dimensional image so that image more
It is clear to add；
Image-display units show the two dimensional image generated by image processing module.
Beneficial effects of the present invention：
(1) cost is relatively low：The present invention is using electronic device without using optical element (removing TPX lens), greatly reducing
The cost of system.
(2) it is simple in construction, it is easy of integration：The device volumes such as power amplifier, frequency multiplier and coupler that the present invention uses are small
It is low compared to the imaging system complexity of the devices such as chopper is utilized before and the circuit structure of system is simple.
(3) THz continuous wave transmitter module power is big：The performance number of THz continuous wave transmitter module is left in 200mW
It is right.
(4) imaging resolution is high：The present invention obtains 110GHz frequency using frequency multiplication mode, and the frequency multiplier used is conversion
The active device of efficiency high, which greatly enhances the transmission power of THz continuous wave transmitter module, so as to imaging resolution energy
Reach 2mm or so.
(5) image taking speed is fast：The present invention is imaged using THz continuous wave, it is not necessary to is examined as being imaged terahertz pulse
Consider depth and the information of frequency spectrum, also simpler in terms of imaging algorithm, which greatly enhances image taking speed.
(6) long transmission distance：The THz continuous wave signal that the present invention is launched by THz continuous wave transmitter module is in sky
Transmission range in gas can reach nearly hundred meters.
(7) signal to noise ratio is high：System uses active terahertz imaging, by control the output power range of each device come
The transmission power of antenna is improved, certainly, transmission power is within safe radiation scope so that echo-signal signal to noise ratio is significantly larger than
The signal to noise ratio of passive type terahertz imaging system reception signal, and then obtain higher image quality.
(8) it is widely used：Utilize high-power THz continuous wave two-dimensional imaging technique high-resolution and simple in construction etc. excellent
Point, the detection of all kinds of large-scale instrument outer layer damages can be carried out, is also applied for the detection of contraband.
Brief description of the drawings
Fig. 1 is the composition frame chart of the present invention.
Fig. 2 is the structural representation of the present invention.
Fig. 3 is the transmitter module of the present invention and the circuit diagram of receiving module.
Fig. 4 is the data acquisition and processing (DAP) module and the stream of the two-dimensional imaging algorithm carried out in image processing module of the present invention
Cheng Tu.
Fig. 5 is comparison diagram of the data acquisition and processing (DAP) module with image processing module imaging effect of the present invention.
Fig. 6 is the flow chart of the imaging process of the present invention.
Embodiment
Terahertz imaging system is broadly divided into terahertz pulse imaging and THz continuous wave imaging.Terahertz pulse is imaged
General principle be：The space of the complex dielectric permittivity of sample is contained from the intensity and phase of the terahertz electromagnetic wave of sample reflection
Distributed intelligence.By reflected terahertz, hereby the intensity of electromagnetic wave and the two-dimensional signal of phase are recorded, and by appropriate processing and
Analysis obtains the Terahertz image of sample.THz continuous wave imaging general principle be：Continuous wave source provides than clock more
High radiation intensity, its essence is a kind of intensity imaging.When to image objects, according to the defects of interior of articles or damage side
Edge is to the scattering effect of terahertz light, and so as to influence the intensity distribution of THz wave electromagnetic field, the Terahertz of object is arrived in reflection
The light and shade i.e. difference of intensity is shown as on ripple image, the shape, defect or damage position of interior of articles can be released accordingly.Therefore,
In the case of without depth and spectrum information, using THz continuous wave imaging technique, THz wave imaging can be improved
Speed and the complexity for reducing imaging system.
As depicted in figs. 1 and 2, the present invention includes：
Duplexer 11, for sending THz continuous wave transmission signal to the measured surface of measurand 17 and connecing
Receive the echo-signal returned from the measured surface of measurand 17；
Two-dimensional scanning platform 18, for fixed on two dimensional surface and mobile measurand 17；
THz continuous wave transmitter module 10, the THz continuous wave that measurand 17 is sent to for generating launch letter
Number；
THz continuous wave receiving module 12, for receiving and handling the THz continuous wave from duplexer 11
Echo-signal；
TPX lens 16, including TPX lens I 25 and TPX lens II 26, for THz continuous wave transmitter module 10 to be sent out
The THz continuous wave penetrated first passes through TPX lens I 25 and becomes parallel, then converges to measurand 17 by TPX lens II 26
Measured surface；Or for the THz continuous wave of the measured surface reflection of measurand 17 to be first passed through into TPX lens II 26
Become parallel, then the duplexer 11 is converged to by TPX lens I 25；
Data acquisition and processing (DAP) module 13, for gathering and handling the echo letter from the output of THz continuous wave receiving module
Number to generate the two dimensional image of the measured surface 23 of measurand 17；
Image processing module 14, the two dimensional image generated for the collection of further processing data and processing module 13 is so that figure
As becoming apparent from；
Image-display units 15, for showing the two dimensional image generated by image processing module 14.
As shown in Fig. 2 duplexer 11 by the transmission signal from THz continuous wave transmitter module 10 launch to
TPX lens I 25, THz continuous wave is become parallel；Further, THz wave is by TPX lens II 26, by Terahertz
Continuous wave converges to the measured surface 23 of the measurand 17 with crack 24.
The distance between described TPX lens I 25 and TPX lens II 26 are less than the focal length of TPX lens 16.TPX lens I 25
Identical with TPX lens II 26, TPX lens I 25 and TPX lens II 26 are staggered relatively.
As shown in figure 3, THz continuous wave transmitter module 10 include the first signal source 301, the first power amplifier 302,
First varactor doubler 303, the second varactor doubler 304, adjustable attenuator 305, isolator 306 and directional coupler 307, Terahertz
Continuous wave transmitter module 10 is used to generate the THz continuous wave transmission signal for being sent to measurand.
Specifically, the first signal source 301 is the point-frequency signal source that working frequency is 27.5GHz, can be expressed as：
Wherein, A1It is expressed as initial magnitude, f1For frequency 27.5GHz, t is the time,For the initial of the first signal source 301
Phase value.
Second power amplifier 302 is amplified to the power of the first signal source 301 to reach the first varactor doubler 303
Firm power input range, the frequency of signal reaches 55GHz after the first varactor doubler 303, further across the two or two times
The frequency of signal reaches 110GHz after frequency device 304.First varactor doubler 303 and the second varactor doubler 304 are all active devices, hair
Penetrate the high-power of signal mainly (is from the first varactor doubler 303 by what the transformation efficiency height of the two varactor doublers determined
VDI companies model D60 high power arrowband frequency multiplier, the conversion efficiency at 55GHz frequencies are more than 30%；Two or two times
Frequency device 304 is VDI companies model D110 high power arrowband frequency multiplier, 25%) conversion efficiency at 110GHz frequencies is.
Second varactor doubler 304 is by the signal output after two frequencys multiplication to adjustable attenuator 305；Adjustable attenuator 305 is by
The power output of two varactor doublers 304 realizes different degrees of reduction by adjusting the knob of adjustable attenuator 305, and will be adjustable
The output signal of attenuator 305 is exported to isolator 306；The echo that isolator 306 returns to the straight-through end of directional coupler 307
Signal isolation is to prevent echo-signal from inputting to the adjustable attenuator 305, the output end of adjustable attenuator 305 to be connected to isolation
The input of device 306, the output end of isolator 306 are connected to the input of directional coupler 307；Directional coupler 307 can
The straight-through end of controlled attenuator 305 is connected to the input of directional coupler 307, and the straight-through end of directional coupler 307 is connected to
Duplexer 11；Finally sent through duplexer 11.The transmission signal of duplexer 11 is represented by：
The straight-through end of directional coupler 307 is connected to the duplexer；Finally sent through duplexer
Go out.The transmission signal of duplexer is represented by：
Wherein, A1' be transmission signal amplitude.
Further as shown in figure 3, THz continuous wave receiving module 12 includes secondary signal source 309, the second power is put
Big device 310, attenuator 311, the 3rd varactor doubler 312, th harmonic mixer 313, bandpass filter 314, low-noise amplifier
315 and wave detector 316, THz continuous wave receiving module 12, which is used to receiving and handle the Terahertz from duplexer, to be connected
Continuous ripple echo-signal.
Specifically, secondary signal source 309 is the point-frequency signal source that working frequency is 27.475GHz, can be expressed as：
Wherein, A2It is expressed as initial magnitude, f2For frequency 27.475GHz, t is the time,For the first of secondary signal source 309
Beginning phase value.
Second power amplifier 310 is amplified to the power in secondary signal source 309, and further attenuator 311 is by
The power of the output signal of two power amplifiers 310 is slightly decayed to reach the firm power input range of the 3rd varactor doubler 312；
The signal that 3rd varactor doubler 312 exports attenuator 311 carries out two frequencys multiplication to 54.95GHz, and the signal after two frequencys multiplication is defeated
Go out to the local oscillator end of th harmonic mixer 313；The coupled end of directional coupler 307 is connected to subharmonic by th harmonic mixer 313
The radio-frequency head of frequency mixer 313, now the signal frequency at local oscillator end is 109.9GHz, and the signal frequency of radio-frequency head is 110GHz.It is secondary
The signal at the local oscillator end of harmonic mixer 313 is represented by
Wherein, A2' be local oscillator end signal amplitude.The signal that subharmonic is mixed 313 radio-frequency heads is represented by：
Wherein, A1" it is the amplitude of radio frequency end signal,It is the initial phase value of radio frequency end signal.It is secondary humorous
The IF output signal of wave mixing device 313 is represented by：
The medium frequency output end of th harmonic mixer 313 is connected to the input of bandpass filter 314；Bandpass filter 314
Centre frequency be 100MHz, the clutter beyond 100MHz in the IF output signal of th harmonic mixer 313 is filtered out, band logical
The output signal of wave filter 314 is represented by：
The output end of bandpass filter 314 is connected to low-noise amplifier 315；By the output signal of bandpass filter 314
Noise reduce and power amplification is to improve the power output of 100MHz intermediate-freuqncy signals, the output signal of low-noise amplifier 315
It is represented by：
Wherein, K is the amplification coefficient of low-noise amplifier,It is the phase value of signal intensity.Low-noise amplifier 315
It can make to be amplified by the faint intermediate-freuqncy signal of down coversion twice, improve signal to noise ratio, the detectivity of output signal,
Then the output signal of low-noise amplifier 315 is changed into direct current signal from AC signal using wave detector 316, and output it
Signal is admitted to data acquisition and processing (DAP) module.
As shown in figure 4, data acquisition and processing (DAP) module 13 gathers echo-signal 401 first, then echo-signal is entered into line number
402 are reset according to two dimension, then carries out mean filter 403.Image processing module 14 first realizes histogram equalization 404, then makes pair
Than degree stretching, extension 405, rim detection 406 and edge sharpening 407 are then carried out, finally gives two dimensional image 408.
As shown in figure 5, the first image 501 is generated after data acquisition and processing (DAP) module 13, Nogata in image processing module 14
Figure equalization the second image 502 of generation, further stretches the 3rd image 503 of generation by contrast, is further examined by edge
The 4th image 504 of generation is surveyed, the 5th image 505 is generated finally by edge sharpening.
As shown in fig. 6, using above-mentioned high-power THz continuous wave two-dimensional imaging system to the imaging process of measurand
Comprise the following steps：
Two-dimensional scanning platform 18 moves measurand 17；
THz continuous wave transmitter module 12 and duplexer 11 scan measurand；
THz continuous wave transmitter module 12 generates transmission signal；
Transmission signal is transmitted to measurand 17 by duplexer 11；
Duplexer 11 receives the echo-signal that the surface of measurand 17 returns and echo-signal is sent into terahertz
Hereby continuous wave receiving module 12；
THz continuous wave receiving module 12 is handled echo-signal and is sent to data acquisition and image procossing mould
Block 13；
Data acquisition and processing (DAP) module 13 is handled the signal from THz continuous wave receiving module to generate quilt
Survey the two-dimensional imaging of object 17；
Image processing module 14, the two dimensional image generated for the collection of further processing data and processing module 13 is so that figure
As becoming apparent from；
Image-display units 15 show the two dimensional image generated by image processing module 14.
Claims (8)
- A kind of 1. high-power THz continuous wave two-dimensional imaging system, it is characterised in that：Include：Duplexer (11), for sending THz continuous wave transmission signal to the measured surface of measurand (17) and connecing Receive the echo-signal returned from the measured surface of measurand (17)；Two-dimensional scanning platform (18), for the fixed and mobile measurand (17) on two dimensional surface；THz continuous wave transmitter module (10), the THz continuous wave that measurand (17) is sent to for generating launch letter Number；THz continuous wave receiving module (12), for receiving and handling the THz continuous wave from duplexer (11) Echo-signal；TPX lens (16), including TPX lens I (25) and TPX lens II (26), for by THz continuous wave transmitter module (10) THz continuous wave of transmitting first passes through TPX lens I (25) and becomes parallel, then is converged to by TPX lens II (26) The measured surface of measurand (17)；Or for the THz continuous wave of the measured surface reflection of measurand (17) first to be passed through Cross TPX lens II (26) and become parallel, then the duplexer (11) is converged to by TPX lens I (25)；Data acquisition and processing (DAP) module (13), for gathering and handling the echo-signal from the output of THz continuous wave receiving module To generate the two dimensional image of the measured surface of measurand (17) (23)；Image processing module (14), for the two dimensional image of the collection of further processing data and processing module (13) generation so that figure As becoming apparent from；Image-display units (15), for showing the two dimensional image generated by image processing module (14)；THz continuous wave receiving module (12) includes secondary signal source (309), the second power amplifier (310), attenuator (311), the 3rd varactor doubler (312), th harmonic mixer (313), bandpass filter (314), low-noise amplifier (315) and Wave detector (316), THz continuous wave receiving module (12) are used to receive and handle the Terahertz company from duplexer Continuous ripple echo-signal；The secondary signal source (309) is the point-frequency signal source that working frequency is 27.475GHz, can be expressed as：Wherein, A2It is expressed as initial magnitude, f2For frequency 27.475GHz, t is the time,For the initial of secondary signal source (309) Phase value；Second power amplifier (310) is amplified to the power of secondary signal source (309), and further attenuator (311) will The power of the output signal of second power amplifier (310) is slightly decayed defeated to reach the firm power of the 3rd varactor doubler (312) Enter scope；The signal that 3rd varactor doubler (312) exports attenuator (311) carries out two frequencys multiplication to 54.95GHz, and by two times Signal output after frequency is to th harmonic mixer (313) local oscillator end；Th harmonic mixer (313) is by directional coupler (307) Coupled end is connected to the radio-frequency head of th harmonic mixer (313), and now the signal frequency at local oscillator end is 109.9GHz, radio-frequency head Signal frequency is 110GHz；The signal at th harmonic mixer (313) local oscillator end is represented byWherein, A2' be local oscillator end signal amplitude；The signal of th harmonic mixer (313) radio-frequency head is represented by：Wherein, A1" it is the amplitude of radio frequency end signal,It is the initial phase value of radio frequency end signal；It is secondary humorousThe IF output signal of wave mixing device (313) is represented by：The medium frequency output end of th harmonic mixer (313) is connected to the input of bandpass filter (314)；Bandpass filter (314) centre frequency is 100MHz, and the clutter beyond 100MHz in the IF output signal of th harmonic mixer (313) is filtered Remove, the output signal of bandpass filter (314) is represented by：The output end of bandpass filter (314) is connected to low-noise amplifier (315)；The output of bandpass filter (314) is believed Number noise reduce and power amplification is to improve the power output of 100MHz intermediate-freuqncy signals, the output of low-noise amplifier (315) Signal is represented by：Wherein, K is the amplification coefficient of low-noise amplifier,It is the phase value of signal intensity；Low-noise amplifier (315) energy Enough make to be amplified by the faint intermediate-freuqncy signal of down coversion twice, improve signal to noise ratio, the detectivity of output signal, so The output signal of low-noise amplifier (315) is changed into direct current signal from AC signal using wave detector (316) afterwards, and its is defeated Go out signal and be admitted to data acquisition and processing (DAP) module.
- A kind of 2. high-power THz continuous wave two-dimensional imaging system according to claim 1, it is characterised in that：The receipts Hair common antenna (11) launches the transmission signal from THz continuous wave transmitter module (10) to TPX lens I (25), will too Hertz continuous wave becomes parallel；THz wave is converged to THz continuous wave with crack by TPX lens II (26) (24) measured surface (23) of measurand (17).
- A kind of 3. high-power THz continuous wave two-dimensional imaging system according to claim 1, it is characterised in that：Described The distance between TPX lens I (25) and TPX lens II (26) are less than the focal length of TPX lens (16)；The TPX lens I (25) with TPX lens II (26) are staggered relatively.
- A kind of 4. high-power THz continuous wave two-dimensional imaging system according to claim 1, it is characterised in that：Described THz continuous wave transmitter module (10) includes the first signal source (301), the first power amplifier (302), the first varactor doubler (303), the second varactor doubler (304), adjustable attenuator (305), isolator (306) and directional coupler (307).
- A kind of 5. high-power THz continuous wave two-dimensional imaging system according to claim 4, it is characterised in that：First letter Number source (301) is the point-frequency signal source that working frequency is 27.5GHz, can be expressed as：Wherein, A1It is expressed as initial magnitude, f1For frequency 27.5GHz, t is the time,For the initial phase of the first signal source (301) Place value；Second power amplifier (302) is amplified to the power of the first signal source (301) to reach the first varactor doubler (303) Firm power input range, the frequency of signal reaches 55GHz after the first varactor doubler (303), further across second The frequency of varactor doubler (304) signal afterwards reaches 110GHz；First varactor doubler (303) and the second varactor doubler (304) are all Active device, the high-power of transmission signal is mainly to be determined by the transformation efficiency height of the two varactor doublers；Second varactor doubler (304) is by the signal output after two frequencys multiplication to adjustable attenuator (305)；Adjustable attenuator (305) will The power output of second varactor doubler (304) realizes different degrees of reduction by adjusting the knob of adjustable attenuator (305), and The output signal of adjustable attenuator (305) is exported to isolator (306)；Isolator (306) is straight by directional coupler (307) The echo-signal that go side returns is isolated to prevent echo-signal from inputting to the adjustable attenuator (305), adjustable attenuator (305) Output end be connected to the inputs of isolator (306), the output end of isolator (306) is connected to directional coupler (307) Input；The straight-through end of adjustable attenuator (305) is connected to the input of directional coupler (307) by directional coupler (307), The straight-through end of directional coupler (307) is connected to duplexer (11)；Finally sent out through duplexer (11) Go；The transmission signal of duplexer (11) is represented by：Wherein, A1' be transmission signal amplitude.
- A kind of 6. high-power THz continuous wave two-dimensional imaging system according to claim 1, it is characterised in that：The number Echo-signal (401) is gathered first according to collection and processing module (13), then echo-signal is subjected to data two dimension and resets (402), Then mean filter (403) is carried out；Image processing module (14) first realizes histogram equalization (404), then stretches contrast (405) rim detection (406) and edge sharpening (407), are then carried out, finally gives two dimensional image (408).
- A kind of 7. high-power THz continuous wave two-dimensional imaging system according to claim 1, it is characterised in that：The number The first image (501) is generated afterwards according to collection and processing module (13), histogram equalization generation the in image processing module (14) Two images (502), the 3rd image (503) of generation is further stretched by contrast, further generates the 4th by rim detection Image (504), the 5th image (505) is generated finally by edge sharpening.
- 8. a kind of imaging process of high-power THz continuous wave two-dimensional imaging system includes following step according to claim 1 Suddenly：The mobile measurand (17) of two-dimensional scanning platform (18)；THz continuous wave transmitter module (12) and duplexer (11) scanning measurand；THz continuous wave transmitter module (12) generates transmission signal；Transmission signal is transmitted to measurand (17) by duplexer (11)；Duplexer (11) receives the echo-signal that measurand (17) surface returns and echo-signal is sent into terahertz Hereby continuous wave receiving module (12)；THz continuous wave receiving module (12) is handled echo-signal and is sent to data acquisition and image processing module (13)；Data acquisition and processing (DAP) module (13) is handled the signal from THz continuous wave receiving module tested to generate The two-dimensional imaging of object (17)；Image processing module (14), for the two dimensional image of the collection of further processing data and processing module (13) generation so that figure As becoming apparent from；The two dimensional image that image-display units (15) display is generated by image processing module (14).
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| CN106990413B (en) * | 2017-06-02 | 2023-04-18 | 吉林大学 | System and method for heterodyne type full-coherent terahertz three-dimensional high-resolution imaging |
| CN107607944B (en) * | 2017-08-29 | 2020-01-17 | 中国人民解放军国防科技大学 | Forward-looking imaging device based on terahertz frequency band transmission type aperture coding |
| CN109060713A (en) * | 2018-06-08 | 2018-12-21 | 深圳市华讯方舟太赫兹科技有限公司 | A kind of three-dimensional chromatographic imaging system and method |
| CN109307868B (en) * | 2018-09-20 | 2022-09-27 | 北京遥感设备研究所 | Single-pulse imaging system and method suitable for terahertz waveband |
| CN109031255A (en) * | 2018-09-30 | 2018-12-18 | 清华大学 | The experimental provision of Terahertz radar scattering imaging |
| CN109781655A (en) * | 2018-12-25 | 2019-05-21 | 华中科技大学 | A kind of Terahertz CW with frequency modulation fast imaging system and method |
| CN109959938A (en) * | 2019-04-10 | 2019-07-02 | 中国计量大学 | Polythene material terahertz time-domain spectroscopy imaging method based on synthetic aperture focusing |
| CN110736987A (en) * | 2019-10-25 | 2020-01-31 | 合肥中科离子医学技术装备有限公司 | terahertz active imaging scanning system |
| CN113823888B (en) * | 2021-05-06 | 2022-05-17 | 北京理工大学 | Double-frequency matching and second harmonic terahertz frequency mixer based on high-temperature superconducting technology |
| CN115913148A (en) * | 2022-12-28 | 2023-04-04 | 北京无线电测量研究所 | Terahertz power amplification chain device |
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