阅读说明：本技术 一种提高太赫兹波无损检测分辨率的系统及方法 (System and method for improving terahertz wave nondestructive testing resolution ) 是由 王金榜 年夫顺 王亚海 赵锐 常庆功 于 2020-08-03 设计创作，主要内容包括：本发明公开了一种提高太赫兹波无损检测分辨率的系统及方法,属于检测技术领域通过在太赫兹波聚焦元件后加入光学元件将准直高斯波束生成准零阶贝塞尔波束来实现太赫兹波成像中较长景深和较高的分辨率；并采用共聚焦技术来满足大的动态范围和较高的信噪比,系统包括太赫兹波发射端、太赫兹波接收端,以及用于测量太赫兹波发射端、太赫兹波接收端与探测区域距离的激光位移传感器,太赫兹波发射端和太赫兹波接收端中的太赫兹波的方向相异；太赫兹波发射端将太赫兹波投射到探测区域,太赫兹波接收端从探测区域接收太赫兹波；太赫兹波发射端和太赫兹波接收端均包括用于太赫兹波聚焦的聚焦元件以及用于生成准零阶贝塞尔波束的光学元件。(The invention discloses a system and a method for improving terahertz wave nondestructive testing resolution, which belong to the technical field of detection, and realize longer depth of field and higher resolution in terahertz wave imaging by adding an optical element behind a terahertz wave focusing element to generate a quasi-zero order Bessel beam from a collimated Gaussian beam; the system comprises a terahertz wave transmitting end, a terahertz wave receiving end and a laser displacement sensor for measuring the distance between the terahertz wave transmitting end, the terahertz wave receiving end and a detection area, wherein the terahertz wave transmitting end and the terahertz wave receiving end have different directions; the terahertz wave transmitting end projects terahertz waves to the detection area, and the terahertz wave receiving end receives the terahertz waves from the detection area; the terahertz wave transmitting end and the terahertz wave receiving end both comprise a focusing element for focusing the terahertz waves and an optical element for generating the quasi-zero order Bessel beam.)

1. A system for improving the resolution of nondestructive detection of terahertz waves is characterized by comprising a terahertz wave transmitting end, a terahertz wave receiving end and a laser displacement sensor for measuring the distance between the terahertz wave transmitting end, the terahertz wave receiving end and a detection area, wherein the terahertz waves in the terahertz wave transmitting end and the terahertz wave receiving end are different in direction; the terahertz wave transmitting end projects terahertz waves to the detection area, and the terahertz wave receiving end receives the terahertz waves from the detection area; the terahertz wave transmitting end and the terahertz wave receiving end both comprise a focusing element for focusing the terahertz waves and an optical element for generating the quasi-zero order Bessel beam.

2. The system for improving resolution of terahertz wave nondestructive testing according to claim 1, wherein the terahertz wave transmitting end further includes a terahertz wave transmitting module and a terahertz wave transmitting antenna, the optical element of the terahertz wave transmitting end is a first optical element, the terahertz wave focusing element of the terahertz wave transmitting end is a first terahertz wave focusing element, the terahertz wave transmitting module is connected to the terahertz wave transmitting antenna, the wave emitted by the terahertz wave transmitting antenna can pass through the first terahertz wave focusing element to reach the first optical element, and the collimated gaussian beam passing through the first optical element generates a quasi-zero order bessel beam to reach the testing surface.

3. The system for improving resolution of nondestructive testing of terahertz waves of claim 2 wherein said first terahertz wave focusing element is located between said first optical element and said terahertz wave transmitting antenna.

4. The system according to claim 1, wherein the terahertz wave receiving end further comprises a terahertz wave receiving module and a terahertz wave receiving antenna, the optical element of the terahertz wave receiving end is a second optical element, the terahertz wave focusing element of the terahertz wave receiving end is a second terahertz wave focusing element, a collimated gaussian beam generated by a quasi-zero-order bessel beam passing through the second optical element from the detection surface reaches the second terahertz wave focusing element, the gaussian beam passes through the second terahertz wave focusing element and the second optical element, the terahertz wave receiving antenna receives the gaussian beam passing through the second optical element, and the terahertz wave receiving module is connected to the terahertz wave receiving antenna.

5. The system for improving resolution of nondestructive testing of terahertz waves of claim 4 wherein said second terahertz wave focusing element is located between said terahertz wave receiving element and said second optical element.

6. The system for improving resolution of nondestructive testing of terahertz waves of claim 1 wherein said optical element is a cone optical element or a diffraction mirror.

7. The system for improving resolution of nondestructive testing of terahertz waves according to claim 1, wherein said terahertz wave focusing element is a plano-convex lens, or a biconvex lens, or a diffractive element, or a metamaterial lens.

8. The system for improving resolution of nondestructive testing of terahertz waves according to claim 1, wherein a terahertz optical path in the terahertz wave transmitting end and an electromagnetic wave path in the terahertz wave receiving end are at right angles.

9. A method for improving the resolution of nondestructive detection of terahertz waves, characterized in that, with the system for improving the resolution of nondestructive detection of terahertz waves according to any one of claims 1 to 8, the terahertz wave transmitting end is used to transmit terahertz waves to a detection region of an object to be detected for measurement, and the terahertz waves reflected by the detection region are received by the terahertz wave receiving end.

10. The method for improving the resolution of nondestructive detection of terahertz waves according to claim 9, wherein the distances between the terahertz wave transmitting end, the terahertz wave receiving end and the object to be detected, i.e., the terahertz wave focusing position, are measured by using the laser displacement sensor while ensuring that the focusing positions of the terahertz wave transmitting end and the terahertz wave receiving end coincide.

Technical Field

The invention belongs to the technical field of detection, and particularly relates to a system and a method for improving terahertz wave nondestructive detection resolution.

Background

The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.

Terahertz waves refer to electromagnetic waves having a frequency in the range of 0.1THz to 10THz, corresponding to a wavelength between 3mm and 0.03 mm. Terahertz waves can also be used for object imaging, as well as visible light, X-rays, infrared, and ultrasound waves. Because terahertz waves can penetrate through non-metal and non-polar materials such as ceramics, graphite, polymer composite materials, plastics, foams and the like, clear imaging can be carried out on defects, holes, impurities, debonding, faults, dislocation, cracks and the like in sample pieces made of the materials, and nondestructive testing is realized. Compared with X-rays, the non-compact material has relatively high absorption of terahertz waves, the defects of the non-compact material can be distinguished by using a terahertz wave imaging technology, and the imaging resolution of the internal defects is higher. Compared with ultrasonic detection, the ultrasonic detection device has higher spatial resolution. Meanwhile, spectrum imaging can be realized based on terahertz (THz) waves, and the terahertz (THz) wave spectrum imaging method can be used for screening material components. As a new technology, the nondestructive testing technology has become a powerful supplement to the X-ray and ultrasonic nondestructive testing technologies. Terahertz wave can penetrate through nonmetal and nonpolar electrolyte materials, the absorption of the non-compact materials to the terahertz wave is relatively high, and the defects of the non-compact materials can be distinguished by using a terahertz wave imaging technology. In addition, the photon energy of the terahertz wave is lower than the energy threshold value for damaging biological tissues, so that the terahertz wave can be used for human body security inspection and biological detection. The terahertz wave imaging technology can be used as a supplement to the existing imaging technology, and has wide application prospects in the fields of nondestructive testing, human body security inspection and the like.

The inventor finds that most of the traditional terahertz wave imaging detection technologies are based on Gaussian beams and are difficult to combine long depth of field and high resolution, and even if the terahertz wave structured beams are generated, the terahertz wave structured beams are all in a single-channel mode, so that the terahertz wave imaging detection technologies have the problems of small dynamic range, low signal-to-noise ratio and the like.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a system and a method for improving the resolution of nondestructive detection of terahertz waves, wherein an optical element is added behind a terahertz wave focusing element to generate a quasi-zero order Bessel wave beam from a collimated Gaussian wave beam so as to realize longer depth of field and higher resolution in terahertz wave imaging; and the confocal technology is adopted to meet the requirements of large dynamic range and higher signal-to-noise ratio.

The first purpose of the invention is to provide a system for improving the resolution of terahertz wave nondestructive testing.

The second purpose of the invention is to provide a method for improving the resolution of terahertz wave nondestructive testing.

In order to achieve the purpose, the invention is realized by the following technical scheme:

in a first aspect, the technical scheme of the invention provides a system for improving terahertz wave nondestructive testing resolution, which comprises a terahertz wave transmitting end, a terahertz wave receiving end and a laser displacement sensor for measuring the distance between the terahertz wave transmitting end, the terahertz wave receiving end and a detection area, wherein the terahertz wave directions in the terahertz wave transmitting end and the terahertz wave receiving end are different; the terahertz wave transmitting end irradiates terahertz waves to the detection area, and the terahertz wave receiving end receives the terahertz waves from the detection area; the terahertz wave transmitting end and the terahertz wave receiving end both comprise a focusing element for focusing the terahertz waves and an optical element for generating the quasi-zero order Bessel beam.

In a second aspect, the technical solution of the present invention further provides a system and a method for improving the resolution of the nondestructive detection of terahertz waves, where the system for improving the resolution of the nondestructive detection of terahertz waves is used, a terahertz wave emitting end is used to emit terahertz waves to a detection region of an object to be detected for irradiation, and a terahertz wave receiving end is used to receive terahertz waves to the detection region of the object to be detected.

The terahertz wave transmitting device has the working principle that terahertz waves generated by a terahertz wave transmitting module are transmitted to a free space by a terahertz wave antenna and are converged by a focusing element, a converged Gaussian beam passes through an optical element to generate a terahertz wave quasi-zero order Bessel beam, the beam irradiates an object to be measured, the object to be measured reflects the beam, a terahertz wave detecting end is placed on a transmission route of the reflected terahertz waves, so that the detecting end can maximally detect the reflected terahertz waves, and the terahertz waves received by a second optical element are finally received by a terahertz wave receiving module after passing through the terahertz wave focusing element.

The technical scheme of the invention has the following beneficial effects:

1) according to the terahertz wave imaging device, an optical element is added behind a terahertz wave focusing element to enable a collimated Gaussian beam to generate a quasi-zero-order Bessel beam, so that long depth of field and high resolution in terahertz wave imaging are achieved; and the confocal technology is adopted to meet the requirements of large dynamic range and higher signal-to-noise ratio.

2) According to the invention, the functions of the traditional terahertz wave detection device are separated, and a confocal detection mode can be formed by using two sets of terahertz wave devices, so that the signal dynamic range of the system is improved, and the detection resolution is improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a schematic diagram of the general architecture of the present invention according to one or more embodiments.

In the figure: 1. a terahertz wave emitting module; 2. a terahertz wave transmitting antenna; 3. a first terahertz wave focusing element; 4. a first optical element; 5. a laser displacement sensor; 6. a terahertz wave receiving module; 7. a terahertz wave receiving antenna; 8. a second terahertz wave focusing element; 9. a second optical element; 10. and (5) a tested piece.

The spacing or dimensions between each other are exaggerated to show the location of the various parts, and the illustration is for illustrative purposes only.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an", and/or "the" are intended to include the plural forms as well, unless the invention expressly state otherwise, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;

term interpretation section: the terms "mounted," "connected," "fixed," and the like in the present invention are to be understood in a broad sense, and for example, the terms "mounted," "connected," and "fixed" may be fixed, detachable, or integrated; the two components can be connected mechanically or electrically, directly or indirectly through an intermediate medium, or connected internally or in an interaction relationship, and the terms used in the present invention should be understood as having specific meanings to those skilled in the art.

As introduced by the background art, aiming at the defects in the prior art, the invention aims to provide a system and a method for improving the terahertz wave nondestructive testing resolution, wherein an optical element is added behind a terahertz wave focusing element to generate a quasi-zero order Bessel beam from a collimated Gaussian beam so as to realize longer depth of field and higher resolution in terahertz wave imaging; and the confocal technology is adopted to meet the requirements of large dynamic range and higher signal-to-noise ratio.