CN113514417A - Suppression method and device for self interference of detector in terahertz imaging system - Google Patents
Suppression method and device for self interference of detector in terahertz imaging system Download PDFInfo
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- CN113514417A CN113514417A CN202111002826.8A CN202111002826A CN113514417A CN 113514417 A CN113514417 A CN 113514417A CN 202111002826 A CN202111002826 A CN 202111002826A CN 113514417 A CN113514417 A CN 113514417A
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- 238000003384 imaging method Methods 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 10
- 230000001629 suppression Effects 0.000 title claims description 8
- 230000005855 radiation Effects 0.000 claims abstract description 53
- 230000003287 optical effect Effects 0.000 claims abstract description 14
- 238000007689 inspection Methods 0.000 claims description 26
- 230000000903 blocking effect Effects 0.000 claims description 3
- 230000002441 reversible effect Effects 0.000 claims description 3
- 230000002401 inhibitory effect Effects 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 7
- 238000002834 transmittance Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000002310 reflectometry Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
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- 230000021615 conjugation Effects 0.000 description 1
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- 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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Abstract
The invention provides a method for inhibiting self interference of a detector in a terahertz imaging system, which reflects terahertz radiation emitted by the detector to other places, prevents the terahertz radiation from being finally received by the detector or other terahertz imaging systems, and does not influence the receiving and imaging of the detector on external terahertz radiation, thereby improving the signal-to-noise ratio of terahertz images and improving the quality of the images. The terahertz isolator is obliquely arranged between the optical system of the terahertz imaging system and the detector, so that terahertz radiation emitted by the detector can be reflected to other places, the terahertz radiation is not finally received by the detector or other terahertz imaging systems, and the receiving and imaging of the detector on external terahertz radiation are not influenced.
Description
Technical Field
The invention relates to the technical field of terahertz imaging, in particular to a method for inhibiting self-interference of a detector in a terahertz imaging system, and further provides a device for inhibiting self-interference of the detector in the terahertz imaging system.
Background
A terahertz imaging system acquires a terahertz signal emitted by an object through a terahertz optical system and focuses the terahertz signal on a terahertz detector array (hereinafter referred to as a "detector") to image the object, the principle of which is shown in fig. 1, terahertz radiation emitted by the object 1 passes through a terahertz optical system 2 and is focused on a focal plane of a detector 3 to form a terahertz image 4. Limited by the performance of the current terahertz device, the detector can also emit a certain amount of terahertz radiation. According to the light path conjugation principle, after terahertz radiation emitted by the detector is focused by the terahertz optical system, a real image of the detector is formed at the object plane position, and the principle is shown in fig. 2.
In fig. 2, terahertz radiation emitted by a detector 3 itself passes through a terahertz optical system 2 and is focused on an object plane to form a real image 4 of the detector. Because the terahertz radiation emitted by the detector 3 is opposite to the terahertz radiation emitted by the object 1 in the direction opposite to the detector 3, the detector 3 does not receive the radiation emitted by itself. Namely, the single terahertz imaging system cannot interfere the terahertz imaging effect thereof due to radiation emitted by the detector thereof.
In practical use, however, terahertz imaging systems often encounter two use occasions. Firstly, need be to the positive and negative two-sided simultaneous imaging of the not high object of certain reflectivity, for example when carrying out real-time contraband security check to the passenger, need place two terahertz security check equipment face to face, the interval is the object distance of twice. The person or object to be detected is located in the middle of two devices, and the two devices form images respectively, as shown in fig. 3.
In the application scenario of fig. 3, when a person or an object is not at the detection position, if the detector does not radiate itself, the two devices receive the terahertz waves that should be the environmental background, and at this time, the devices can perform zero adjustment correction on the detector inside the devices, and the terahertz radiation intensity of the environmental background is used as a zero point.
Because the detector itself actually emits a certain amount of terahertz radiation, when the person or object to be detected is not at the position to be detected in fig. 3, the detector of the terahertz security inspection device on one side (assumed to be the left side) forms a real image of the detector at the position to be detected (i.e., the object distance), and the real image, although not received by the terahertz security inspection device on the left side, can be just received and imaged by the terahertz security inspection device on the other side (the right side), as shown in fig. 4.
In fig. 4, when the object or person to be detected is not at the position to be detected, the terahertz radiation emitted by the detector of the left terahertz security inspection apparatus forms a real image 5 at the position to be detected, and the real image 5 is exactly located on the object plane of the right terahertz security inspection apparatus, so that the real image 5 can form a real image 6 on the focal plane of the right terahertz security inspection apparatus through the optical system of the right terahertz security inspection apparatus. Namely, when the rape people or the rape objects are not at the position to be detected, the right terahertz security inspection instrument can detect the image of the detector of the left terahertz security inspection equipment, and vice versa. Such interference can obviously increase the background noise of terahertz security inspection equipment, reduces the imaging effect.
In another use occasion, the reflectivity of the detected object is high, so that the terahertz radiation emitted by the detector is reflected on the surface of the detected object and is received by the detector together with the terahertz radiation emitted by the detected object. The detector therefore receives an image with a low signal-to-noise ratio after interference from its own radiation, as shown in figure 5.
In fig. 5, the terahertz radiation emitted by the object 7 is imaged at the position of the detector 3, and the real image 5 formed on the object plane by the radiation emitted by the detector 3 itself is reflected by the object 7 with high reflectivity and then imaged at the position of the detector 3, thereby interfering with the image of the object 7, and the image actually received by the detector 3 is substantially a superimposed image 8 of the two.
Therefore, in the terahertz imaging system in the prior art, the detector per se has interference on the image, and the self interference needs to be restrained urgently.
Disclosure of Invention
In order to solve the problems, the invention provides a method for suppressing self-interference of a detector in a terahertz imaging system, which reflects terahertz radiation emitted by the detector to other places, prevents the terahertz radiation from being finally received by the detector or other terahertz imaging systems, and does not influence the receiving and imaging of the detector on external terahertz radiation, so that the signal-to-noise ratio of a terahertz image is improved, and the quality of the image is improved.
A method for suppressing self interference of a detector in a terahertz imaging system is characterized by comprising the following steps: the terahertz isolator is obliquely arranged between the optical system of the terahertz imaging system and the detector, so that terahertz radiation emitted by the detector can be reflected to other places, the terahertz radiation is not finally received by the detector or other terahertz imaging systems, and the receiving and imaging of the detector on external terahertz radiation are not influenced.
A suppression device of self-interference of a detector in a terahertz imaging system is characterized by comprising:
the terahertz security check instrument comprises a detector and a scanning mechanism;
a terahertz isolator;
a terahertz isolator is arranged between the detector and the scanning mechanism, the terahertz isolator is obliquely arranged relative to the detector, and the reverse blocking end face of the terahertz isolator faces the detector.
It is further characterized in that:
the system comprises two terahertz security check instruments which are respectively arranged at two sides of a security check area, wherein a scanning mechanism of each terahertz security check instrument is obliquely arranged towards the security check area, and an obliquely arranged terahertz isolator is arranged in each terahertz security check instrument;
the security inspection area is located in the middle of the two terahertz security inspection instruments;
the terahertz isolator is obliquely arranged at an angle of 45 degrees relative to the surface of the detector, and the upper part or the lower part of the terahertz isolator is obliquely arranged towards an image entrance port of the terahertz security inspection instrument.
By adopting the technical scheme, the terahertz isolator is a terahertz optical device and has the functions that when terahertz radiation irradiates the isolator in the forward direction, the transmittance is high, the loss is low, and the isolator is used for allowing the terahertz radiation to pass; when terahertz radiation reversely irradiates the isolator, the transmittance is low, the reflection is high, the isolator is used for preventing terahertz radiation from passing through and reflecting most of terahertz radiation back, so that the terahertz isolator is used for realizing unidirectional transmission of terahertz radiation, the terahertz isolator is obliquely placed between an optical system of a terahertz imaging system and the detector, the terahertz radiation emitted by the detector can be reflected to other places, the terahertz radiation is not finally received by the detector or other terahertz imaging systems, and the receiving and imaging of the detector on the external terahertz radiation are not influenced, so that the signal-to-noise ratio of a terahertz image is improved, and the quality of the image is improved.
Drawings
FIG. 1 is a schematic diagram of the terahertz imaging system;
FIG. 2 is a schematic diagram of a single terahertz imaging system not interfering with its terahertz imaging effect due to radiation emitted by its detector itself;
FIG. 3 is a schematic view of a conventional security arrangement;
FIG. 4 is a schematic diagram of a conventional terahertz imaging system subjected to self-interference;
FIG. 5 is another schematic diagram of the terahertz imaging system subjected to self-interference;
FIG. 6 is a working schematic diagram of a terahertz isolator;
FIG. 7 is a schematic diagram of the method of the present invention;
FIG. 8 is a schematic diagram of the structure of the apparatus of the present invention;
the names corresponding to the sequence numbers in the figure are as follows:
the terahertz detection device comprises an object 1, an optical system 2, a detector 3, a terahertz image 4, a real image 5, a real image 6, an object to be detected 7, a superposed image 8, a terahertz isolator 9, a scanning mechanism 11, a security inspection area 12, an image entrance port 13 and a display screen 14.
Detailed Description
A method for suppressing self-interference of a detector in a terahertz imaging system is disclosed, and the method is shown in FIG. 7: the terahertz isolator 9 is obliquely arranged between the optical system 2 of the terahertz imaging system and the detector 3, terahertz radiation emitted by the detector 3 can be reflected to other places, the terahertz radiation is not finally received by the terahertz isolator or other terahertz imaging systems, and the receiving and imaging of the detector 3 to external terahertz radiation are not influenced, so that the signal-to-noise ratio of a terahertz image is improved, and the quality of the image is improved.
A self-interference suppression device for a detector in a terahertz imaging system is shown in figure 8 and comprises a terahertz security check instrument 10 and a terahertz isolator 9
The terahertz security check instrument 10 comprises a detector 3 and a scanning mechanism 11;
a terahertz isolator 9 is arranged between the detector 3 and the scanning mechanism 11, the terahertz isolator 9 is obliquely arranged relative to the detector 3, and the reverse blocking end face of the terahertz isolator 9 is arranged towards the detector 3.
In the specific implementation: the system comprises two terahertz security check instruments 10 which are respectively arranged at two sides of a security check area, wherein a scanning mechanism 11 of each terahertz security check instrument 10 is obliquely arranged towards the security check area 12, and a terahertz isolator 9 which is obliquely arranged is arranged in each terahertz security check instrument 10;
the security inspection area 10 is located in the middle of the two terahertz security inspection instruments 10;
the terahertz isolator 9 is obliquely arranged at an angle of 45 degrees relative to the surface of the detector 3, and the upper part or the lower part of the terahertz isolator 9 is obliquely arranged towards the image entrance port 13 of the terahertz security inspection instrument 10;
the terahertz isolator 9 is specifically a sheet grating type terahertz isolator;
in specific implementation, each terahertz security check instrument 10 is further provided with a display screen 14.
The working principle is as follows: the terahertz isolator is a terahertz optical device and has the functions (see fig. 6) that when terahertz radiation irradiates the isolator in the forward direction, the transmittance is high, the loss is low, and the isolator allows the terahertz radiation to pass through; when terahertz radiation reversely irradiates the isolator, the transmittance is low, the reflection is high, the isolator is used for preventing terahertz radiation from passing through and reflecting most of terahertz radiation back, so that the terahertz isolator is used for realizing unidirectional transmission of terahertz radiation, the terahertz isolator is obliquely placed between an optical system of a terahertz imaging system and the detector, the terahertz radiation emitted by the detector can be reflected to other places, the terahertz radiation is not finally received by the detector or other terahertz imaging systems, and the receiving and imaging of the detector on the external terahertz radiation are not influenced, so that the signal-to-noise ratio of a terahertz image is improved, and the quality of the image is improved.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (5)
1. A method for suppressing self interference of a detector in a terahertz imaging system is characterized by comprising the following steps: the terahertz isolator is obliquely arranged between the optical system of the terahertz imaging system and the detector, so that terahertz radiation emitted by the detector can be reflected to other places, the terahertz radiation is not finally received by the detector or other terahertz imaging systems, and the receiving and imaging of the detector on external terahertz radiation are not influenced.
2. A suppression device of self-interference of a detector in a terahertz imaging system is characterized by comprising:
the terahertz security check instrument comprises a detector and a scanning mechanism;
a terahertz isolator;
a terahertz isolator is arranged between the detector and the scanning mechanism, the terahertz isolator is obliquely arranged relative to the detector, and the reverse blocking end face of the terahertz isolator faces the detector.
3. The self-interference suppression device for the detector in the terahertz imaging system as claimed in claim 2, wherein: the terahertz security inspection device comprises two terahertz security inspection instruments which are respectively arranged on two sides of a security inspection area, a scanning mechanism of each terahertz security inspection instrument is obliquely arranged towards the security inspection area, and a terahertz isolator which is obliquely arranged is arranged in each terahertz security inspection instrument.
4. The self-interference suppression device for the detector in the terahertz imaging system as claimed in claim 3, wherein: the security inspection area is located in the middle of the two terahertz security inspection instruments.
5. The self-interference suppression device for the detector in the terahertz imaging system as claimed in claim 3, wherein: the terahertz isolator is obliquely arranged at an angle of 45 degrees relative to the surface of the detector, and the upper part or the lower part of the terahertz isolator is obliquely arranged towards an image entrance port of the terahertz security inspection instrument.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111002826.8A CN113514417A (en) | 2021-08-30 | 2021-08-30 | Suppression method and device for self interference of detector in terahertz imaging system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111002826.8A CN113514417A (en) | 2021-08-30 | 2021-08-30 | Suppression method and device for self interference of detector in terahertz imaging system |
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| Publication Number | Publication Date |
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| CN113514417A true CN113514417A (en) | 2021-10-19 |
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| CN202111002826.8A Pending CN113514417A (en) | 2021-08-30 | 2021-08-30 | Suppression method and device for self interference of detector in terahertz imaging system |
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