Utility model content
For solving the technical matters of existing existence, the utility model embodiment is expected to provide a kind of terahertz imaging device, can accelerate speed and the performance of terahertz imaging.
The technical scheme of the utility model embodiment is achieved in that
The utility model embodiment provides a kind of terahertz imaging device, and this device comprises: collimating module, mask module and transmitted wave acquisition module; Wherein,
Collimating module, collimates rear irradiation to mask module and article to be imaged for being carried out by the terahertz signal of incidence;
Mask module, before covering article to be imaged, controls the irradiation area that terahertz signal irradiates described article;
Transmission signal acquisition module, for gathering the transmission terahertz signal after described article transmission, and is converted to electric signal by described transmission terahertz signal and is sent to signal processing module;
Signal processing module, for controlling the movement of mask module, and carries out article imaging according to the electric signal of correspondence.
In such scheme, described mask module comprises:
Adama mask unit, before covering article to be imaged, according to Hadamard transform rule, controls the irradiation area of the described article to be imaged of irradiation of terahertz signal;
Mask control module, moves according to preset path for controlling Adama mask unit.
In such scheme, described device also comprises:
Frequency division module, after being positioned at article to be imaged, for focusing on the different position of optical axis respectively by the transmission terahertz signal of each frequency transmitted through described article.
In such scheme, described transmission signal acquisition module comprises:
N number of transmission signal fixes collecting unit, is respectively used to the transmission terahertz signal gathering N number of different frequency, is positioned at the different focal positions of described optical axis.
In such scheme, described transmission signal acquisition module comprises:
Transmission signal mobile collection unit, for moving on optical axis, gathers the transmission terahertz signal of different frequency.
In such scheme, described collimating module comprises:
Convex lens or off axis paraboloidal mirror.
In such scheme, described Adama mask unit comprises:
The Adama mask plate be made of metal.
In such scheme, described frequency division module comprises:
Fresnel Lenses or Fresnel zone plate.
The terahertz imaging device that the utility model embodiment provides, utilize and place Adama mask before article to be imaged, the signal to noise ratio (S/N ratio) of sampled signal is improve while achieving the batch sampling to article pixel, simultaneously, article to be imaged are not moved by mobile Adama mask, realize the comprehensive sampling to described each pixel of article, thus the aberration avoided mobile article and bring; In addition, utilize Fresnel Lenses or Fresnel zone plate that the THz wave transmitted through article is focused on positions different on optical axis, thus realize the image of the THz wave gathering each different frequency, improve the speed of terahertz imaging further.
Embodiment
In order to be illustrated more clearly in the utility model embodiment and technical scheme, below in conjunction with drawings and Examples, the technical solution of the utility model is described in detail, obviously, described embodiment is a part of embodiment of the present utility model, instead of whole embodiment.Based on embodiment of the present utility model, the every other embodiment that those of ordinary skill in the art obtain under the prerequisite not paying creative work, all belongs to the scope of the utility model protection.
The composition schematic diagram of the terahertz imaging device that Fig. 1 provides for the utility model embodiment, as shown in Figure 1, this device comprises: collimating module 101, mask module 102, transmitted wave acquisition module 103 and signal processing module 104; Wherein,
Collimating module 101, collimates rear irradiation to mask module and article to be imaged for being carried out by the terahertz signal of incidence;
Mask module 102, before covering article to be imaged, controls the irradiation area that terahertz signal irradiates described article;
Transmission signal acquisition module 103, for gathering the transmission terahertz signal after described article transmission, and is converted to electric signal and is sent to signal processing module;
Signal processing module 104, for controlling the movement of mask module, and carries out article imaging according to the electric signal of correspondence.
Concrete, collimating module 101 can comprise convex lens or off axis paraboloidal mirror etc. and have device THz wave being carried out straight standard.
Preferably, mask module 102 comprises:
Adama mask unit, before covering article to be imaged, according to Hadamard transform rule, controls the irradiation area of the described article to be imaged of irradiation of terahertz signal;
Mask control module, moves according to preset path for controlling Adama mask unit.
Concrete, Adama mask unit can be one piece of mask as shown in Figure 2, and this mask is made up of the impervious material of the THz wave such as metal, and in Fig. 2, the part of grey represents solid, and THz wave can not be through; The part of white represents hollow out, and THz wave can be through.Move before this mask is placed on article to be imaged, be equal to and carry out variable space encoding on light path cross section, each coding unit corresponds to a pixel on image, and each unit all can be placed in 0 or 1 state, does not namely cross state through state or full impregnated.Such as, corresponding with mask shown in Fig. 2 space encoding as shown in Figure 3.This Adama mask unit moves according to the path of presetting by mask control module, can complete the Hadamard transform to the terahertz signal irradiating article to be imaged, and then realizes the Hadamard transform to the terahertz signal transmitted through article to be imaged.
Fig. 2 merely illustrates the Adama mask of a kind of 3*5 (namely 15) imaging pixel, and the specification of Adama mask in practical application and kind a variety of in addition, specifically how to select the specification of Adama mask and kind to be mainly considered to the pixel count of picture.And once selected specific Adama mask, then namely the mobile route that this mask is corresponding has been determined, and this is determined by Hadamard transform algorithm.Directly can make Adama mask with reference to the rule of existing Adama spectrometer.Concrete, Adama mask shown in Fig. 2, then it is positioned at the upper left corner in region to be imaged when initial, then first to line down, at the row that move right under the control of mask control module, circulate successively, until this Adama mask moves to the lower right corner in region to be imaged.Before row/column moves each time, all first carry out the collection of transmission terahertz signal.
Further, in order to accelerate the speed of signals collecting, before transmission signal acquisition module 103, described terahertz imaging device also comprises:
Frequency division module, after being positioned at article to be imaged, for focusing on the different position of optical axis respectively by the transmission terahertz signal of each frequency transmitted through described article.
Concrete, frequency division module can comprise Fresnel Lenses or Fresnel zone plate etc., its terahertz signal frequency division on optical axis that can will modulate through mask plate, therefore, in described transmission signal acquisition module 103, can comprise:
N number of transmission signal fixes collecting unit, is respectively used to the transmission terahertz signal gathering N number of different frequency, is positioned at the different focal positions of described optical axis.
N is larger, then the efficiency of parallel acquisition transmission signal is higher, but also will cause the increase of the manufacturing cost of imaging device.
Therefore, transmission signal acquisition module 103 can also comprise:
Transmission signal mobile collection unit, for moving on optical axis, gathers the transmission terahertz signal of different frequency.
Certainly, in order to balanced transmission signals collecting efficiency and imaging device manufacturing cost, also can arrange multiple transmission signal mobile collection unit, each transmission signal mobile collection unit is responsible for the transmission terahertz signal of the different frequency gathered in optical axis the preceding paragraph distance simultaneously.Like this, the transmission terahertz signal of parallel acquisition different frequency can be realized, the quantity of collecting unit can be reduced again.
In practical application, above-mentioned transmission signal fixes collecting unit and transmission signal mobile collection unit all can be realized by terahertz detector, and terahertz signal can be converted to electric signal and be sent to signal processing module 104 by terahertz detector.
Concrete, signal processing module 104 for controlling the movement of mask module, and carries out article imaging according to the electric signal of correspondence.Its image-forming principle used is as follows:
In the signal detection system of encoding optical imaging, suppose the image information that will obtain a width two dimensional image, its object is exactly obtain the space distribution of image intensity signal and the size of semaphore.We can consider the coding form of piece image in a two-dimensional space.If (x, y) is the volume coordinate of a width two dimensional image, the function that φ (x, y) is x, y, its size corresponds to the intensity of this coordinate place pixel, and the object of imaging measurement determines the distribution of φ (x, y) exactly.In actual measurement, be φ (x, y) discretize is processed determine that it distributes.For this reason, sliding-model control is carried out to target image,
For 3*5 image, 3 and 5 line number and the columns being respectively division, then the information of a width two dimensional image can be expressed as:
At this time have 15 unknown numbers to need to carry out 15 times to measure:
Suppose i-th measure in, coding be configured as W
i1, W
i2, W
i3w
i15, accordingly result is Y
i
Wherein
coordinate x
jy
sthe intensity of place's pixel, e
iit is noise when measuring specifically.
Matrix is adopted to be simplified shown as;
Ignore noise then can obtain
its value can be programmed on computers and be solved, and can be realized the reproduction of image by this unbiased estimator.
In actual applications, signal processing module 104 can be realized by the central processing unit of described terahertz imaging device (CPU), microprocessor (MPU), digital signal processor (DSP) or field programmable gate array (FPGA).
In order to be embodied as picture, in described terahertz imaging device, also comprise collector, storage medium and display screen; Wherein, collector the data of terahertz wave detector are carried out amplify, analog to digital conversion; Storage medium is used for poke template sequence, reconfiguration program, raw data, view data, and display screen is for showing reconstructed image.
The composition structural drawing of one specific embodiment of the terahertz imaging device that Fig. 4 provides for the utility model, wherein, straight arrows indicates THz wave travel path in the apparatus.If shown in 4, through Fresnel Lenses, the transmission THz wave of different frequency converges at difference place on optical axis respectively, and such as, A, B, C point place in figure, terahertz detector can gather the THz wave at these some places respectively.
The utility model embodiment also provides a kind of terahertz imaging method, and the method comprises:
The terahertz signal of incidence is carried out collimate rear irradiation to mask module and article to be imaged;
Before mask module is covered article to be imaged, to control the irradiation area that terahertz signal irradiates described article;
Gather the transmission terahertz signal after described article transmission, and described transmission terahertz signal is converted to electric signal;
Control the movement of mask module, and carry out article imaging according to the electric signal of correspondence.
In such scheme, described mask module is covered article to be imaged before, the irradiation area irradiating described article to control terahertz signal comprises:
Before Adama mask is covered described article, and move this Adama mask according to the path of presetting, realize Hadamard transform.
In such scheme, before gathering the transmission terahertz signal after described article transmission, described method also comprises:
The transmission terahertz signal of each frequency transmitted through described article is focused on the different position of optical axis respectively.
In such scheme, gather the transmission terahertz signal after described article transmission and comprise:
Use N number of transmission signal being fixed on N number of position of the different focal position of optical axis to fix collecting unit, gather the transmission terahertz signal of N number of different frequency respectively; Or
Use a transmission signal mobile collection unit, optical axis moves, gather the transmission terahertz signal of different frequency.
Those skilled in the art should understand, embodiment of the present utility model can be provided as method, system or computer program.Therefore, the utility model can adopt the form of hardware embodiment, software implementation or the embodiment in conjunction with software and hardware aspect.And the utility model can adopt in one or more form wherein including the upper computer program implemented of computer-usable storage medium (including but not limited to magnetic disk memory and optical memory etc.) of computer usable program code.
The utility model describes with reference to according to the process flow diagram of the method for the utility model embodiment, equipment (system) and computer program and/or block scheme.Should understand can by the combination of the flow process in each flow process in computer program instructions realization flow figure and/or block scheme and/or square frame and process flow diagram and/or block scheme and/or square frame.These computer program instructions can being provided to the processor of multi-purpose computer, special purpose computer, Embedded Processor or other programmable data processing device to produce a machine, making the instruction performed by the processor of computing machine or other programmable data processing device produce device for realizing the function of specifying in process flow diagram flow process or multiple flow process and/or block scheme square frame or multiple square frame.
These computer program instructions also can be stored in can in the computer-readable memory that works in a specific way of vectoring computer or other programmable data processing device, the instruction making to be stored in this computer-readable memory produces the manufacture comprising command device, and this command device realizes the function of specifying in process flow diagram flow process or multiple flow process and/or block scheme square frame or multiple square frame.
These computer program instructions also can be loaded in computing machine or other programmable data processing device, make on computing machine or other programmable devices, to perform sequence of operations step to produce computer implemented process, thus the instruction performed on computing machine or other programmable devices is provided for the step realizing the function of specifying in process flow diagram flow process or multiple flow process and/or block scheme square frame or multiple square frame.
The above, be only preferred embodiment of the present utility model, is not intended to limit protection domain of the present utility model.