CN109187418B - Terahertz imager - Google Patents
Terahertz imager Download PDFInfo
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- CN109187418B CN109187418B CN201811193566.5A CN201811193566A CN109187418B CN 109187418 B CN109187418 B CN 109187418B CN 201811193566 A CN201811193566 A CN 201811193566A CN 109187418 B CN109187418 B CN 109187418B
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- display screen
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- 239000004973 liquid crystal related substance Substances 0.000 claims abstract description 78
- 238000003384 imaging method Methods 0.000 claims abstract description 22
- 238000005315 distribution function Methods 0.000 claims abstract description 18
- 238000005314 correlation function Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 abstract 1
- 238000000034 method Methods 0.000 description 5
- 238000004364 calculation method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3581—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
Abstract
The invention discloses a THz imager, comprising: a THz source for generating a THz wave of a preset frequency; the liquid crystal display screen is arranged towards the THz wave emission direction and forms a preset angle with the THz source, and reflects the THz waves emitted by the THz source to an object to be detected; at least one THz power meter which is arranged in parallel with the object to be measured and is used for receiving the THz wave passing through the object to be measured; and the imaging device is respectively connected with the liquid crystal display screen and the THz power meter and is used for reconstructing the object to be measured according to the received THz waves and the orientation distribution function of liquid crystal molecules in the liquid crystal display screen or reconstructing the object to be measured according to the received THz waves and the distribution function of the THz waves reflected by the liquid crystal display screen. The imaging of the object to be measured can be realized only by using the THz power meter and without using a THz imaging array, mature liquid crystal panel growth manufacturing technology can be utilized, and the liquid crystal panel imaging device is simple in structure, small in size and low in cost.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a terahertz imager.
Background
THz (terahertz) radiation is electromagnetic radiation with the frequency of 0.1-10 THz. The THz wave length is far less than the microwave and millimeter wave length, which can be used to detect smaller target and more accurate position; in addition, the THz wave wavelength is far greater than the wavelength of visible light, can penetrate through a dense smoke and sand environment and can also penetrate through a wall to scan the interior of a house, so that the imaging technology is small in radiation damage to a human body, is an ideal imaging technology in a complex environment, and has application prospects in important fields such as physics, life sciences, national safety and anti-terrorism.
However, the THz wave detector is low in sensitivity, a low-temperature environment is usually required for reducing noise, and the THz wave detector is low in integration level, expensive, large in size and low in imaging quality, so that the application of THz imaging is seriously influenced.
Disclosure of Invention
The invention aims to provide a terahertz imager, which effectively solves the technical problems of low integration level, high price, large volume, low imaging quality and the like of the conventional terahertz imager.
The technical scheme provided by the invention is as follows:
a THz imager, comprising:
a THz source for generating a THz wave of a preset frequency;
the liquid crystal display screen is arranged towards the THz wave emission direction and forms a preset angle with the THz source, and reflects the THz waves emitted by the THz source to an object to be detected;
at least one THz power meter which is arranged in parallel with the object to be measured and is used for receiving the THz wave passing through the object to be measured;
and the imaging device is respectively connected with the liquid crystal display screen and the THz power meter and is used for reconstructing the object to be measured according to the received THz waves and the orientation distribution function of liquid crystal molecules in the liquid crystal display screen or reconstructing the object to be measured according to the received THz waves and the distribution function of the THz waves reflected by the liquid crystal display screen.
Further preferably, the liquid crystal display panel is an IPS (In-Plane Switching) liquid crystal panel.
Further preferably, the dot pitch of the liquid crystal display screen is greater than 0.3 mm.
Further preferably, the THz imager includes a polarizer disposed between the THz source and the liquid crystal display.
The THz imager provided by the invention has the beneficial effects that:
1. in the invention, the THz imager reflects THz waves by using the liquid crystal display screen to irradiate on an object to be detected, receives the THz waves passing through the object to be detected by using the THz power meter, and then performs correlation calculation on the THz waves received by the THz power meter and the orientation distribution of liquid crystal molecules in the liquid crystal display screen to obtain an image of the object to be detected, or performs correlation calculation on the THz waves received by the THz power meter and a THz wave distribution function reflected by the liquid crystal display screen to obtain an image of the object to be detected.
2. In the invention, the liquid crystal display screen is an IPS liquid crystal panel, compared with the traditional liquid crystal panel, the IPS liquid crystal panel has the advantages that the electrode is in the plane, and the upper layer does not have an ITO (indium tin oxide) transparent electrode, so that THz is not absorbed; in addition, the electrodes and the bottom plate in the IPS liquid crystal panel have a strong reflection effect on THz, an optical cavity structure is formed, the regulation and control effect of polarized liquid crystal molecules on THz waves is greatly enhanced, and the defect that the liquid crystal molecules have small birefringence in the THz frequency range is overcome. And moreover, the polaroid between the THz source and the liquid crystal display screen enhances the regulation and control of the liquid crystal display screen on the THz wave and improves the imaging quality.
3. In the invention, the liquid crystal display screen with low resolution and high dot pitch is selected, which is beneficial to avoiding the diffraction of THz wave and improving the imaging quality.
Drawings
The foregoing features, technical features, advantages and implementations will be further described in the following detailed description of the preferred embodiments, which is to be read in connection with the accompanying drawings.
FIG. 1 is a schematic diagram of an embodiment of a THz imager of the present invention.
Description of reference numerals:
the device comprises a 1-THz source, a 2-liquid crystal display screen, a 3-object to be measured, a 4-THz power meter and a 5-imaging device.
Detailed Description
The essence of the invention is further illustrated below with reference to the figures and examples, but the invention is not limited thereto.
Fig. 1 is a schematic diagram of an embodiment of the THz imager provided in the present invention, and as can be seen from the diagram, the THz imager includes: the THz power meter comprises a THz source 1, a liquid crystal display screen 2, at least one THz power meter 4 and an imaging device 5, wherein the liquid crystal display screen 2 is arranged towards the transmitting direction of THz waves and forms a preset angle with the THz source 1; the THz power meter 4 and the object 3 to be measured are arranged in parallel, and the imaging device 5 is respectively connected with the liquid crystal display screen and the THz power meter.
In the working process, firstly, the THz source 1 generates THz waves with preset frequency according to requirements, and the THz waves are emitted towards the direction of the liquid crystal display screen 2; then, adjusting the position and the angle of the liquid crystal display screen 2, reflecting the THz wave emitted by the THz source 1 to the surface 3 of the object to be measured, and carrying out spatial modulation on the THz wave by controlling the display image of the liquid crystal display screen 2; after passing through the object to be measured, the THz wave is absorbed by the THz power meter 4 disposed parallel thereto. The imaging device 5 obtains the THz wave signal n absorbed by the THz power meter1P (x, y) as an alignment distribution function of liquid crystal molecules in the liquid crystal display panel and e (x, y) as a distribution of the THz wave reflected by the liquid crystal display panel, and further calculating a correlation Δ G1(x, y) between the THz wave and the alignment distribution function p (x, y) of liquid crystal molecules in the liquid crystal display panel<(n1-<n1>)[(p(x,y)-<p(x,y)>]>Reconstructing the object to be detected by using a compressed sensing algorithm through the second-order correlation function delta G1(x, y) to obtain an image of the object to be detected; or by calculating the correlation Δ G2(x, y) between the THz wave and the THz wave distribution function e (x, y) reflected by the liquid crystal display panel<(n1-<n1>)[(e(x,y)-<e(x,y)>]>And the image of the object to be measured is obtained by utilizing a compressed sensing algorithm to reconstruct through the second-order correlation function delta G2(x, y). In the two methods, the liquid crystal molecular orientation distribution function p (x, y) is utilized to carry out correlation calculation, so that the method is simpler, has higher processing speed and is suitable for quick imaging; and secondly, the THz wave distribution function e (x, y) is utilized to carry out correlation calculation more accurately, the speed is relatively low, and the method is suitable for high-precision imaging.
In the embodiment, the reflectance of the THz waves by the liquid crystal molecules with different orientations is different, the orientation of the liquid crystal molecules in the liquid crystal display screen of the terahertz imager can be regulated and controlled by an external electric field according to requirements, and when the THz waves are reflected by the liquid crystal display screen, the reflected THz waves have certain spatial distribution. In an example, the liquid crystal display panel is an IPS liquid crystal panel, and the dot pitch is greater than 0.3mm (millimeters). As for the preset angle between the THz source and the liquid crystal display screen, it can be set according to the actual situation, such as 30 °, 45 °, 60 °, etc.
In another embodiment, the THz imager further comprises: the THz power meter comprises a THz source, a liquid crystal display screen, at least one THz power meter and an imaging device, and also comprises a polaroid arranged between the THz source and the liquid crystal display screen.
In the working process, firstly, the THz source generates THz waves with preset frequency according to requirements, and the THz waves are emitted towards the direction of the liquid crystal display screen; the transmitted THz wave irradiates the surface of the liquid crystal display screen through a polaroid; then, the liquid crystal display screen reflects the THz wave emitted by the THz source to the surface of the object to be measured, and the liquid crystal display screen is controlled to display an image to perform spatial modulation on the THz wave; after the THz wave passes through the object to be measured, the THz wave is absorbed by a THz power meter arranged in parallel with the THz wave. An imaging device acquires THz wave signal n absorbed by a THz power meter1The distribution function of the orientation of the liquid crystal molecules in the liquid crystal display screen is p (x, y) and the distribution of the THz wave after the reflection of the liquid crystal display screen is e (x, y), and then the incidence relation delta G1(x, y) between the THz wave and the distribution function p (x, y) of the orientation of the liquid crystal molecules in the liquid crystal display screen is calculated]Reconstructing the object to be measured through the second order correlation function delta G1(x, y) to obtain the image of the object to be measured; or by calculating the correlation Δ G2(x, y) between the THz wave and the THz wave distribution function e (x, y) reflected by the liquid crystal display panel]And reconstructing the object to be measured through the second order correlation function delta G2(x, y) to obtain the image of the object to be measured.
It should be noted that the above embodiments can be freely combined as necessary. The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (4)
1. A terahertz imager is characterized in that the terahertz imager comprises:
the terahertz source is used for generating terahertz waves with preset frequency;
the liquid crystal display screen is arranged towards the terahertz wave emission direction and forms a preset angle with the terahertz source, and reflects the terahertz waves emitted by the terahertz source to the object to be detected;
at least one terahertz power meter arranged in parallel with the object to be measured and used for receiving terahertz waves passing through the object to be measured;
the imaging device is respectively connected with the liquid crystal display screen and the terahertz power meter and is used for reconstructing an object to be measured according to the received terahertz waves and the liquid crystal molecule orientation distribution function in the liquid crystal display screen or reconstructing the object to be measured according to the received terahertz waves and the terahertz wave distribution function reflected by the liquid crystal display screen;
an imaging device acquires THz wave signal n absorbed by a THz power meter1P (x, y) as an alignment distribution function of liquid crystal molecules in the liquid crystal display panel and e (x, y) as a distribution of the THz wave reflected by the liquid crystal display panel, and further calculating a correlation Δ G1(x, y) between the THz wave and the alignment distribution function p (x, y) of liquid crystal molecules in the liquid crystal display panel<(n1-<n1>)[(p(x,y)-<p(x,y)>]>Reconstructing the object to be detected by using a compressed sensing algorithm through the second-order correlation function delta G1(x, y) to obtain an image of the object to be detected; or by calculating the correlation Δ G2(x, y) between the THz wave and the THz wave distribution function e (x, y) reflected by the liquid crystal display panel<(n1-<n1>)[(e(x,y)-<e(x,y)>]>And the image of the object to be measured is obtained by utilizing a compressed sensing algorithm to reconstruct through the second-order correlation function delta G2(x, y).
2. The terahertz imager of claim 1, wherein the liquid crystal display is an IPS liquid crystal panel.
3. The terahertz imager of claim 2, wherein the liquid crystal display screen has a dot pitch greater than 0.3 mm.
4. The terahertz imager as claimed in any one of claims 1 to 3, wherein the terahertz imager comprises a polaroid arranged between the terahertz source and the liquid crystal display.
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| CN201811193566.5A CN109187418B (en) | 2018-10-12 | 2018-10-12 | Terahertz imager |
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| CN201811193566.5A CN109187418B (en) | 2018-10-12 | 2018-10-12 | Terahertz imager |
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| CN109187418A CN109187418A (en) | 2019-01-11 |
| CN109187418B true CN109187418B (en) | 2021-10-26 |
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2018
- 2018-10-12 CN CN201811193566.5A patent/CN109187418B/en active Active
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|---|---|---|---|---|
| CN105158887A (en) * | 2015-09-29 | 2015-12-16 | 南京理工大学 | Multi-mode microimaging method based on programmable LED array illumination |
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Non-Patent Citations (1)
| Title |
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