CN102508241A - Millimeter wave imaging method and system - Google Patents

Abstract

The invention relates to a millimeter wave imaging method, which comprises the following steps of: generating millimeter wave signals by low-frequency signals, and transmitting the millimeter wave signals to an imaging plane; extracting reflected low-frequency signals from the millimeter wave signals reflected from the imaging plane; carrying out the holographic recording of the low-frequency signals and the reflected low-frequency signals to obtain a holofilm; restoring the holofilm according to the low-frequency signals to obtain a complex amplitude of a receiving plane wavefront; and imaging through the complex amplitude. According to the millimeter wave imaging method and a system, after the reflected millimeter wave signals are received, the reflected low-frequency signals are extracted from the millimeter wave signals, and the holographic recording is conducted through the low-frequency signals and the reflected low-frequency signals so as to record the complex amplitude of the receiving plane wavefront to obtain the imaging result. The energy of millimeter waves is much lower than the energy of X-ray, the millimeter waves do not cause harm to the human body, and can be widely used in the detection process of the human body; and the millimeter waves have very good penetration and spatial resolution, and can improve the accuracy of detection in the detection process of the human body.

Description

The mm-wave imaging method and system

[technical field]

The present invention relates to safety detection technology, particularly relate to a kind of mm-wave imaging method and system.

[background technology]

Along with development of times, the formation method that is used for the security detection has also obtained huge development, and applied occasion also increases gradually.For example,, analytical technique of mass spectrum, LR laser raman technology usually technological through radioscopy imaging technique, X ray back of the body astigmatic image technology, ion mobility spectrometry to the object to be checked of inorganic matters such as vehicle, goods, parcel and luggage, radioactive matter monitoring is technological and harmful organism/several different methods such as poison gas chemical probing technology are carried out security and detected.

Through in people's health, hiding dangerous material such as explosive safety is produced grave danger; Therefore the security that human body carried out being detected will be the weakest link; It is the detection that is different from inorganic matters such as article fully that the security of human body detects, and must assurance can not bring injury, damage etc. to human body.

Traditional security checkout equipment that can directly be used for human body mainly is divided into optical video detector and metal detector two big classes.The optical video detector is to use simple optical physics principle of reflection; Through the wide-angle camera imaging of high-resolution; Can not detect the dangerous device that is hidden under the clothing, have the not high defective of accuracy, only be fit to alert with or security department carry out security monitoring; Metal detector is a principle of utilizing electromagnetic induction; Produce vertiginous magnetic field by the coil that is connected with alternating current, this magnetic field vortex flow of can inducting in metal object inside, and vortex flow also can produce magnetic field; And then influence is caused detector and is sent song by the magnetic field of coil generation.

Metal detector is widely used in all kinds of needs and carries out the place that security detects, and still, has the phenomenon of flase drop, omission to take place frequently, can only be as complementary security detection equipment, and the accuracy of its detection depends critically upon safety check staff's experience.

[summary of the invention]

Based on this, be necessary to provide a kind of mm-wave imaging method that can in the human detection process, improve the accuracy that detects.

In addition, also be necessary to provide a kind of millimeter wave imaging system that can in the human detection process, improve the accuracy that detects.

A kind of mm-wave imaging method comprises the steps:

Generate millimeter-wave signal through low frequency signal, and said millimeter-wave signal is emitted to imaging plane;

From the millimeter-wave signal of said imaging plane reflection, extract the low frequency signal of reflection;

The low frequency signal of said low frequency signal and reflection is carried out holographic recording obtain holofilm;

According to low frequency signal holofilm is reduced the complex amplitude that obtains receiving plane wave front;

Carry out holographic imaging through said complex amplitude.

Preferably, saidly generate millimeter-wave signal, and be the step that said millimeter-wave signal is emitted to imaging plane through low frequency signal:

Working signal and low frequency signal are carried out the signal stack obtain millimeter-wave signal;

Said millimeter-wave signal is carried out the millimeter-wave signal that Frequency mixing processing obtains launching, and launch to imaging plane.

Preferably, saidly working signal and low frequency signal carried out the signal stack obtain also comprising before the step of millimeter-wave signal:

Said working signal is carried out processing and amplifying.

Preferably, said low frequency signal to said low frequency signal and reflection carries out the step that holographic recording obtains holofilm and is:

The low frequency signal of said low frequency signal and reflection is carried out coherence stack obtain receiving plane wave front;

The field intensity information that writes down in the said reception plane wave front obtains holofilm.

Preferably, saidly according to low frequency signal holofilm is reduced the step of the complex amplitude that obtains receiving plane wave front and is:

Said holofilm is carried out the complex amplitude that quadrature demodulation obtains said reception plane wave front.

A kind of millimeter wave imaging system comprises:

The signal emission array is used for generating millimeter-wave signal through low frequency signal, and said millimeter-wave signal is emitted to imaging plane;

The reflected signal processing module is used for extracting the low frequency signal of reflection from the millimeter-wave signal of said imaging plane reflection;

The holographic recording module is used for low frequency signal to said low frequency signal and reflection and carries out holographic recording and obtain holofilm;

Recovery module is used for according to low frequency signal holofilm being reduced the complex amplitude that obtains receiving plane wave front;

Image-forming module is used for carrying out holographic imaging through said complex amplitude.

Preferably, said signal emission array comprises:

The signal superpositing unit is used for that working signal and low frequency signal are carried out the signal stack and obtains millimeter-wave signal;

The processing unit that transmits is used for said millimeter-wave signal is carried out the millimeter-wave signal that Frequency mixing processing obtains launching, and launches to imaging plane.

Preferably, said signal emission array also comprises:

Amplifying unit is used for said working signal is carried out processing and amplifying.

Preferably, said holographic recording module comprises:

The coherence stack unit is used for low frequency signal with said low frequency signal and reflection and carries out coherence stack and obtain receiving plane wave front;

Record cell, the field intensity signal that is used for writing down said reception plane wave front obtains holofilm.

Preferably, said recovery module also is used for said holofilm is carried out the complex amplitude that quadrature demodulation obtains said reception plane wave front.

In the above-mentioned mm-wave imaging method and system, after receiving the millimeter-wave signal of reflection, from millimeter-wave signal, extract the low frequency signal of reflection; And then carry out holographic recording through the low frequency signal of low frequency signal and reflection, with the complex amplitude of recorder plane wave front, and then obtain imaging results; The process of this mm-wave imaging belongs to active mm-wave imaging technology; Because the energy of millimeter wave can not damage human body well below the energy of X ray, can be widely used in the human detection process; And millimeter wave has good penetrability and very high spatial resolution, can in the human detection process, effectively improve the accuracy that detects.

[description of drawings]

Fig. 1 is the process flow diagram of mm-wave imaging method among the embodiment;

Fig. 2 generates millimeter-wave signal through low frequency signal among Fig. 1, and millimeter-wave signal is emitted to the method flow diagram of imaging plane;

Fig. 3 is the principle schematic of mm-wave imaging among the embodiment;

Fig. 4 carries out the method flow diagram that holographic recording obtains holofilm for the low frequency signal to low frequency signal and reflection among Fig. 1;

Fig. 5 is the structural representation of millimeter wave imaging system among the embodiment;

Fig. 6 is the structural representation of signal emission array among Fig. 5;

Fig. 7 is the structural representation of holographic recording module among Fig. 5.

[embodiment]

In one embodiment, as shown in Figure 1, a kind of mm-wave imaging method comprises the steps:

Step S110 generates millimeter-wave signal through low frequency signal, and millimeter-wave signal is emitted to imaging plane.

In the present embodiment; Because millimeter-wave signal typically refers to 30～300GHz frequency domain; Wavelength is the signal of 1～10mm, and such signal can't directly be handled, therefore by signal source emission working signal; And through working signal and low frequency signal generation millimeter-wave signal, this millimeter-wave signal is transmitted on the imaging plane after handling through appropriate signals; This low frequency signal is the signal that subsystem carries out AD sampling, digital signal computing of can supplying power, and for the processing power of electronic system, the signal that is lower than 1GHZ is low frequency signal.Particularly, signal source can be to adopt the electromagnetic wave of single-frequency, also can be the electromagnetic wave that adopts wideband, and launches through emission array, and the power of this emission array is identical everywhere.

In one embodiment, as shown in Figure 2, the detailed process of above-mentioned steps S110 is:

Step S111 carries out the signal stack with working signal and low frequency signal and obtains millimeter-wave signal.

In the present embodiment, produce working signal and low frequency signal respectively, with working signal and the low frequency signal formation millimeter-wave signal that is superimposed.In a preferred embodiment, this working signal is 8.6GHz, and low frequency signal is 600MHz, and the millimeter-wave signal that stack obtains is 35GHz, to meet the atmospheric window of millimeter wave.

Step S113 carries out the millimeter-wave signal that Frequency mixing processing obtains launching to millimeter-wave signal, and launches to imaging plane.

In the present embodiment, imaging plane is the plane that imaging object receives the millimeter-wave signal place of emission, and the millimeter-wave signal that will pass through Frequency mixing processing is transmitted on the imaging object, and at this moment, millimeter-wave signal reflects away the object to be imaged.

In another embodiment, also comprise the step of working signal being carried out processing and amplifying before the above-mentioned steps S111.

In the present embodiment,,, working signal has been brought up to 34.4GHz carried out mixing to obtain the signal of 35GHz with low frequency signal more afterwards for the working signal of 8.6GHz for reaching the millimeter wave atmospheric window of 35GHz.

In another embodiment; The above-mentioned detailed process that working signal is carried out processing and amplifying is: through phase-locked loop circuit working signal is carried out process of frequency multiplication; Obtain the signal of 17.2GHz, carry out carrying out the second harmonic Frequency mixing processing with low frequency signal behind the bandpass filtering with the signal of base band sheet then 17.2GHz.

Step S130 extracts the low frequency signal of reflection from the millimeter-wave signal of imaging plane reflection.

In the present embodiment, receive millimeter-wave signal, through low frequency signal the millimeter-wave signal of reflection is handled, to extract the low frequency signal of reflection from imaging plane through receiving array.

Step S150 carries out holographic recording to the low frequency signal of low frequency signal and reflection and obtains holofilm.

In the present embodiment, as shown in Figure 3, transmitting and receiving in the process of millimeter-wave signal, (x, y) plane is for transmitting and receiving array, (X, Y) plane is an imaging plane, (x y) has the signal source of emission millimeter-wave signal on the plane, the time-domain signal of emission is:

According to optical principle, the complex amplitude of establishing signal source is 1, and whole for ease mm-wave imaging process emission array power is identical everywhere; Therefore, (x, y) complex amplitude on the plane is 1. theoretical according to Fourier optics; Millimeter-wave signal is equivalent to pass through a spatial filter h through the space between emission array and the imaging plane; Suppose to reach imaging plane a bit (X, the complex amplitude of Y) going up millimeter-wave signal be F (X, Y); The millimeter-wave signal of supposing emission is a spherical wave; And, can not cause amplitude to change apart from r, and only cause phase theta r to change owing to be the near field imaging; Therefore, can obtain:

If on launching site, set up receiving array; And (X Y) will produce desirable diffuse reflection, and reflectivity is scalar S (X to be set as the point that looks like on the plane; Y); (x, the y) space between plane and the imaging plane will be equivalent to and will have passed through a spatial filter h and will pass through once more from the millimeter wave of the reflection of imaging plane; At this moment, the complex amplitude of the millimeter-wave signal of received reflection is

R (x; Y) be point (X, the complex amplitude that reflect millimeter signal Y) causes, and in fact; At point (x; Y) actual reception of locating to millimeter-wave signal be the light intensity summation of the millimeter-wave signal of whole imaging plane reflection, therefore can obtain point (x, y) locate the receiver actual reception to the complex amplitude of millimeter-wave signal be:

$R(x,y)=\∫\∫r(x,y)\mathrm{dXdY}=\∫\∫e^{-{\mathrm{\θ}}_{r}i}\·S(X,Y)e^{-{\mathrm{\θ}}_{r}i}\mathrm{dXdY}$

$=\∫\∫S(X,Y)e^{-2{\mathrm{\θ}}_{r}i}\mathrm{dXdY}$ (2)

Be set as picture plane and (x; Y) distance between the plane is R; K is the wave vector of millimeter-wave signal; Fourier transform formula according to Fourier optics; If wave vector is carried out integration then can obtain the expression formula of complex amplitude, then the calculating of this complex amplitude

can calculate through following formula:

$e^{-2{\mathrm{\θ}}_{r}i}=e^{-2\mathrm{ik}}\sqrt{{(X-x)}^2+{(Y-y)}^2+R^2}=\∫\∫e^{{\mathrm{ik}}_x(X-x)+{\mathrm{ik}}_y(Y-y)+{\mathrm{ik}}_{z}R}{\mathrm{dk}}_x{\mathrm{dk}}_y$

$=e^{{\mathrm{ik}}_{z}R}{\∫\∫e}^{{\mathrm{ik}}_x(X-x)+{\mathrm{ik}}_y(Y-y)}{\mathrm{dk}}_x{\mathrm{dk}}_y$ (3)

Formula (3) substitution formula (2) can be obtained:

$R(x,y)=\∫\∫S(X,Y)e^{-2{\mathrm{\θ}}_{r}i}\mathrm{dXdY}$

$=\∫\∫S(X,Y)\{e^{{\mathrm{ik}}_{z}R}\∫\∫e^{{\mathrm{ik}}_x(X-x)+{\mathrm{ik}}_y(Y-y)}d{k}_x{\mathrm{dk}}_y\}\mathrm{dXdY}$

$=\∫\∫S(X,Y)\{e^{{\mathrm{ik}}_{z}R}\∫\∫e^{{\mathrm{ik}}_x(-x)+{\mathrm{ik}}_y(-y)}d{k}_x{\mathrm{dk}}_y{e}^{{\mathrm{ik}}_x\left(X\right)+{\mathrm{ik}}_y\left(Y\right)}\}\mathrm{dXdY}---\left(4\right)$

$={\∫\∫e}^{{\mathrm{ik}}_{z}R}\{\∫\∫S(X,Y)e^{{\mathrm{ik}}_x\left(X\right)+{\mathrm{ik}}_y\left(Y\right)}\mathrm{dXdY}\}{e}^{{\mathrm{ik}}_x(-x)+{\mathrm{ik}}_y(-y)}{\mathrm{dk}}_x{\mathrm{dk}}_y$

$=e^{{\mathrm{ik}}_{z}R}\∫\∫\{\∫\∫S(X,Y)e^{-i(k_{x}X+k_{y}Y)}\mathrm{dXdY}\}{e}^{i(k_{x}x+k_{y}y)}d{k}_{x}d{k}_y$

Obviously, formula (4) can be regarded as that (X Y) has done two-dimension fourier transform one time, and then the result of conversion is done two dimensional inverse fourier transform one time to complex amplitude R.

Formula (4) is carried out conversion obtains formula (5):

formula (5) be final holographic imaging formula; Wherein, R (X; Y) for receiving the complex amplitude of plane wave front; Representing (x, y) amplitude and the initial phase of every bit vibration on the plane, this initial phase are the phase place of the millimeter-wave signal phase place of hypothesis emission when being zero; Phase differential between the millimeter-wave signal of the imaging plane reflection that promptly receives and the millimeter-wave signal of emission, can know that according to the definition of complex amplitude the time-domain function with millimeter-wave signal emission millimeter-wave signal of the imaging plane reflection that receives is:

E(x，y) _real-time＝Ae ^-iwt (6)

R(x，y)) _real-time＝Ae ^-iwtR(x，y)

The two is carried out coherence stack obtain receiving plane wave front, that is:

E(x，y) _real-time+R(x，y)) _real-time＝Ae ^-iwt+Ae ^-iwtR(x，y) (7)

For obtaining receiving plane wave front, need the field intensity information that receive plane wave front in the formula (7) be noted and obtain holofilm.

In one embodiment, as shown in Figure 4, the detailed process of above-mentioned steps S150 is:

Step S151 carries out coherence stack with the low frequency signal of low frequency signal and reflection and obtains receiving plane wave front.

In the present embodiment, the low frequency signal of reflection is to note after receiving the millimeter-wave signal that reflects, and according to the method for holography stack, the low frequency signal that signal source is launched carries out the holographic information that coherence stack can obtain receiving the plane with the reflection low frequency signal.

Step S153, the field intensity information in the recorder plane wave front obtains holofilm.

In the present embodiment, the field intensity information in the plane wave front has comprised the time-domain function of signal and the complex amplitude of plane wave front.

Step S170 reduces the complex amplitude that obtains receiving plane wave front according to low frequency signal to holofilm.

In the present embodiment, the holofilm that has write down the field intensity information in the plane wave front is reduced, to obtain information recorded in the holofilm.

In a preferred embodiment, for guaranteeing the real-time of imaging, the detailed process of above-mentioned steps S170 is: holofilm is carried out the complex amplitude that quadrature demodulation obtains receiving plane wave front.Particularly, holofilm can obtain corresponding complex amplitude and phase angle information through quadrature demodulation, has realized the real-time reduction of complex amplitude in the mm-wave imaging process, can improve the efficient of imaging effectively.

Step S190 is carried out to picture through complex amplitude.

In the present embodiment, the complex amplitude input holographic imaging formula that reduction is obtained can obtain the pairing picture of imaging object.Particularly, complex amplitude and the phase angle information that obtains of will from holofilm, reducing carried out the digital-to-analog conversion sampling processing, and carries out computing through the holographic imaging formula in the complex amplitude after will handling and the phase angle information input computing machine and obtain imaging results.

In one embodiment, as shown in Figure 5, a kind of millimeter wave imaging system comprises signal emission array 10, reflected signal processing module 30, holographic recording module 50, recovery module 70 and image-forming module 90.

Signal emission array 10 is used for generating millimeter-wave signal through low frequency signal, and millimeter-wave signal is emitted to imaging plane.

In the present embodiment; Because millimeter-wave signal typically refers to 30～300GHz frequency domain; Wavelength is the signal of 1～10mm, and such signal can't directly be handled, and therefore signal emission array 10 is launched working signal as signal source; And through working signal and low frequency signal generation millimeter-wave signal, this millimeter-wave signal is transmitted on the imaging plane after handling through appropriate signals; This low frequency signal is the signal that subsystem carries out AD sampling, digital signal computing of can supplying power, and for the processing power of electronic system, the signal that is lower than 1GHZ is low frequency signal.Particularly, signal emission array 10 can be launched the electromagnetic wave of single-frequency, also can launch the electromagnetic wave of wideband, and the power in the signal emission array is identical everywhere.

In one embodiment, as shown in Figure 6, above-mentioned signal emission array 10 comprises signal superpositing unit 110 and the processing unit 130 that transmits.

Signal superpositing unit 110 is used for that working signal and low frequency signal are carried out the signal stack and obtains millimeter-wave signal.

In the present embodiment, signal superpositing unit 110 produces working signal and low frequency signal respectively, with working signal and the low frequency signal formation millimeter-wave signal that is superimposed.In a preferred embodiment, the working signal in the signal superpositing unit 110 is 8.6GHz, and low frequency signal is 600MHz, and the millimeter-wave signal that stack obtains is 35GHz, to meet the atmospheric window of millimeter wave.

The processing unit 130 that transmits is used for millimeter-wave signal is carried out the millimeter-wave signal that Frequency mixing processing obtains launching, and launches to imaging plane.

In the present embodiment, imaging plane is the plane that imaging object receives the millimeter-wave signal place of emission, and the millimeter-wave signal that will pass through Frequency mixing processing is transmitted on the imaging object, and at this moment, millimeter-wave signal reflects away the object to be imaged.

In another embodiment, above-mentioned signal emission array 10 has also comprised amplifying unit, and this amplifying unit is used for working signal is carried out processing and amplifying.

In the present embodiment, for reaching the millimeter wave atmospheric window of 35GHz, for the working signal of 8.6GHz, amplifying unit carries out mixing to obtain the signal of 35GHz with low frequency signal after working signal has been brought up to 34.4GHz again.

In another embodiment, amplifying unit also is used for through phase-locked loop circuit working signal being carried out process of frequency multiplication, obtains the signal of 17.2GHz, carries out carrying out the second harmonic Frequency mixing processing with low frequency signal behind the bandpass filtering with the signal of base band sheet to 17.2GHz then.

Reflected signal processing module 30 is used for extracting the low frequency signal of reflection from the millimeter-wave signal of imaging plane reflection.

In the present embodiment, reflected signal processing module 30 receives the millimeter-wave signal from imaging plane through receiving array, through low frequency signal the millimeter-wave signal of reflection is handled, to extract the low frequency signal of reflection.

Holographic recording module 50 is used for low frequency signal to low frequency signal and reflection and carries out holographic recording and obtain holofilm.

In the present embodiment, the low frequency signal of low frequency signal and reflection is carried out holographic recording to obtain receiving the field intensity information of plane wave front, the field intensity information of the reception plane wave front that just obtains is noted and is obtained holofilm.

In one embodiment, as shown in Figure 7, above-mentioned holographic recording module 50 comprises coherence stack unit 510 and record cell 530.

Coherence stack unit 510 is used for low frequency signal with low frequency signal and reflection and carries out coherence stack and obtain receiving plane wave front.

In the present embodiment; The low frequency signal of reflection is to receive behind the millimeter-wave signal of reflection the signal that obtains after handling with working signal; Coherence stack unit 510 carries out coherence stack with the low frequency signal of launching with the reflection low frequency signal and can obtain receiving plane wave front according to the method for holography stack.

Record cell 530, the field intensity signal that is used for the recorder plane wave front obtains holofilm.

In the present embodiment, the field intensity information in the plane wave front has comprised the time-domain function of signal and the complex amplitude of plane wave front.

Recovery module 70 is used for according to low frequency signal holofilm being reduced the complex amplitude that obtains receiving plane wave front.

In the present embodiment, the holofilm that recovery module 70 will write down the field intensity information in the plane wave front reduces, to obtain information recorded in the holofilm.

In a preferred embodiment, for guaranteeing the real-time of imaging, recovery module 70 also is used for holofilm is carried out the complex amplitude that quadrature demodulation obtains receiving plane wave front.70 pairs of holofilms of recovery module carry out quadrature demodulation can obtain corresponding complex amplitude and phase angle information, has realized the real-time reduction of complex amplitude in the mm-wave imaging process, can improve the efficient of imaging effectively.

Image-forming module 90 is used for being carried out to picture through complex amplitude.

In the present embodiment, image-forming module 90 can obtain the pairing picture of imaging object with the complex amplitude input holographic imaging formula

that reduction obtains.Particularly; Image-forming module 90 will reduce the complex amplitude and the phase angle information that obtain and carry out the digital-to-analog conversion sampling processing from holofilm, and will carry out computing through the holographic imaging formula in complex amplitude after will handling and the phase angle information input computing machine and obtain imaging results.

Come to set forth in detail above-mentioned mm-wave imaging method and system below in conjunction with concrete embodiment.This embodiment is first atmospheric window that utilizes millimeter-wave signal, and promptly the millimeter-wave signal of 35GHz is carried out to picture.

In the above-mentioned millimeter wave imaging system; Signal emission array 10 can be made up of the oscillator of 8.6GHz and the oscillator of 600MHz; To produce millimeter-wave signal, promptly the working signal of 8.6GHz and the low frequency signal of 600MHz are carried out the millimeter-wave signal that Frequency mixing processing generates 35GHz through frequency mixer as the millimeter-wave signal source.This frequency mixer is 64 tunnel designs; And 64 way switch arrays have been equipped with; The millimeter-wave signal of the 35GHz of process mixing is sent in the array antenna to be launched, and wherein, array antenna is 64 bell-mouthed one-dimensional array antennas; If need to accomplish the imaging of two dimensional image, then need the one-dimensional array antenna be accomplished the Machine Movement Process of one dimension.

Simultaneously; Also be equipped with receiving antenna in the array antenna; Receive the millimeter-wave signal of reflection at receiving antenna after, reflected signal processing module 30 will be handled the low frequency signal to obtain reflecting to the millimeter-wave signal of reflection, so by the mode of holographic recording module 50 through coherence stack to the processing that is concerned with of the low frequency signal of reflection and low frequency signal; Recovery module 70 obtains receiving the complex amplitude of plane wave front through quadrature demodulation then, and carries out holographic imaging by image-forming module 90.

In addition, in another embodiment, above-mentioned mm-wave imaging method and system for reaching the millimeter wave atmospheric window of 35GHz, also need be carried out processing and amplifying to working signal in the signal emission array 10.

Particularly; Signal emission array 10 has carried out process of frequency multiplication through phase-locked loop circuit to the working signal of 8.6GHz; To obtain the signal of 17.2GHz; Carry out carrying out the second harmonic Frequency mixing processing with low frequency signal behind the bandpass filtering with the signal of base band sheet then, obtain the millimeter-wave signal of 35GHz, and launch to imaging object to 17.2GHz.

Reflection through imaging object; Receiving antenna in the signal emission array 10 has received the millimeter signal of reflection; At this moment; Reflected signal processing module 30 is carried out secondary with the millimeter-wave signal amplification back of reflection with low frequency signal and is called on the low frequency signal that wave mixing is handled the reflection that comprises in the millimeter-wave signal that obtains reflecting, and then writes down the corresponding time-domain function and the complex amplitude equifield intensity information of plane wave front by holographic recording module 50.

The time-domain function of supposing working signal is cos (w _LOT+ θ), the time-domain function of low frequency signal does Call on the principle of wave mixing according to secondary and can know that the time-domain function of the millimeter-wave signal of emission does

Through the received millimeter-wave signal in imaging plane reflection back complex amplitude and phase change have taken place, pairing time-domain function does

The pairing time-domain function of low frequency signal that can obtain reflecting through the processing to the millimeter-wave signal of this reflection does

And then the complex amplitude that obtains receiving plane wave front is Be ^{-i σ}, therefore, need obtain the complex amplitude that receives every bit on the plane.

Can know by foregoing description, do the pairing time-domain function of low frequency signal that reflects

Handling resulting complex amplitude is Be ^{-i σ}, the time-domain function of working signal is cos (w _LOT+ θ), the two being carried out coherence stack obtains the time domain field intensity and does As interference signal, the pairing light intensity of E is I=EE ^*∝ B ²+ 1+2Bcos σ makes the phase shifts of pi/2 to working signal, becomes

And accomplish an interventional procedures, the record light intensity can obtain $I^{\′}=E\·E^{*}\∝B^2+1+2B\mathrm{Cos}(\mathrm{\σ}+\frac{\mathrm{\π}}{2}).$

Obviously, through simultaneous formula I=EE ^*∝ B ²+ 1+2Bcos σ and formula

Can obtain the pairing numerical value of σ and B, and then obtain receiving the complex amplitude Be of every bit in the plane ^{-i σ}, input holographic imaging formula can obtain imaging results.

In the above-mentioned mm-wave imaging method and system, after receiving the millimeter-wave signal of reflection, from millimeter-wave signal, extract the low frequency signal of reflection; And then carry out holographic recording through the low frequency signal of low frequency signal and reflection, with the complex amplitude of recorder plane wave front, and then obtain imaging results; The process of this mm-wave imaging belongs to active mm-wave imaging technology; Because the energy of millimeter wave can not damage human body well below the energy of X ray, can be widely used in the human detection process; And millimeter wave has good penetrability and very high spatial resolution, can in the human detection process, effectively improve the accuracy that detects.

In above-mentioned mm-wave imaging method and system; Because millimeter-wave signal has good penetrability and very high spatial resolution; Can penetrate cigarette, cloud, mist, dirt etc. detects in the environment of subsideing, carrying out real-time imaging; Also can carry out Real-time Imaging to the article in the non-metal kind packing case; This will make above-mentioned mm-wave imaging method and system can be widely used in various public places; Comprise various public places such as airport, customs, subway, stadiums, public place of entertainment, exhibition center, museum, also can be applicable to the detection of all kinds of connection with wrapping of piece such as mail, express delivery, parcel, and can not produce ionization damage the material in the connection with wrapping of piece.

Above-mentioned mm-wave imaging method and system belong to active mm-wave imaging technology; Imaging mode with respect to mechanical scannings such as traditional single channel scanning imagery, array scanning imaging, raster-scan-imagings; And imaging mode such as focal plane imaging, phased array imaging, synthetic aperture imaging; The algorithm difficulty is lower, and corresponding system architecture is also comparatively simple, helps its practicability; Possessed and be simple and easy to be widely used in fields such as safety inspection and medical imaging with, advantage such as cost is lower, image taking speed is fast.

The above embodiment has only expressed several kinds of embodiments of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to claim of the present invention.Should be pointed out that for the person of ordinary skill of the art under the prerequisite that does not break away from the present invention's design, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with accompanying claims.

Claims (10)

1. a mm-wave imaging method comprises the steps:

Generate millimeter-wave signal through low frequency signal, and said millimeter-wave signal is emitted to imaging plane;

From the millimeter-wave signal of said imaging plane reflection, extract the low frequency signal of reflection;

The low frequency signal of said low frequency signal and reflection is carried out holographic recording obtain holofilm;

According to low frequency signal holofilm is reduced the complex amplitude that obtains receiving plane wave front;

Carry out holographic imaging through said complex amplitude.

2. mm-wave imaging method according to claim 1 is characterized in that, saidly generates millimeter-wave signal through low frequency signal, and with the step that said millimeter-wave signal is emitted to imaging plane is:

Working signal and low frequency signal are carried out the signal stack obtain millimeter-wave signal;

Said millimeter-wave signal is carried out the millimeter-wave signal that Frequency mixing processing obtains launching, and launch to imaging plane.

3. mm-wave imaging method according to claim 2 is characterized in that, saidly working signal and low frequency signal are carried out the signal stack obtains also comprising before the step of millimeter-wave signal:

Said working signal is carried out processing and amplifying.

4. mm-wave imaging method according to claim 1 is characterized in that, said low frequency signal to said low frequency signal and reflection carries out the step that holographic recording obtains holofilm and is:

The low frequency signal of said low frequency signal and reflection is carried out coherence stack obtain receiving plane wave front;

The field intensity information that writes down in the said reception plane wave front obtains holofilm.

5. mm-wave imaging method according to claim 1 is characterized in that, saidly according to low frequency signal holofilm is reduced the step of the complex amplitude that obtains receiving plane wave front and is:

Said holofilm is carried out the complex amplitude that quadrature demodulation obtains said reception plane wave front.

6. a millimeter wave imaging system is characterized in that, comprising:

The signal emission array is used for generating millimeter-wave signal through low frequency signal, and said millimeter-wave signal is emitted to imaging plane;

The reflected signal processing module is used for extracting the low frequency signal of reflection from the millimeter-wave signal of said imaging plane reflection;

The holographic recording module is used for low frequency signal to said low frequency signal and reflection and carries out holographic recording and obtain holofilm;

Recovery module is used for according to low frequency signal holofilm being reduced the complex amplitude that obtains receiving plane wave front;

Image-forming module is used for carrying out holographic imaging through said complex amplitude.

7. millimeter wave imaging system according to claim 6 is characterized in that, said signal emission array comprises:

The signal superpositing unit is used for that working signal and low frequency signal are carried out the signal stack and obtains millimeter-wave signal;

The processing unit that transmits is used for said millimeter-wave signal is carried out the millimeter-wave signal that Frequency mixing processing obtains launching, and launches to imaging plane.

8. millimeter wave imaging system according to claim 7 is characterized in that, said signal emission array also comprises:

Amplifying unit is used for said working signal is carried out processing and amplifying.

9. millimeter wave imaging system according to claim 6 is characterized in that, said holographic recording module comprises:

The coherence stack unit is used for low frequency signal with said low frequency signal and reflection and carries out coherence stack and obtain receiving plane wave front;

Record cell, the field intensity signal that is used for writing down said reception plane wave front obtains holofilm.

10. mm-wave imaging method according to claim 6 is characterized in that, said recovery module also is used for said holofilm is carried out the complex amplitude that quadrature demodulation obtains said reception plane wave front.

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