阅读说明：本技术 基于太赫兹传播特性的绝缘材料厚度检测方法及系统 (insulating material thickness detection method and system based on terahertz propagation characteristics ) 是由 程志强 刘荣海 孔旭晖 郭新良 郑欣 杨迎春 许宏伟 虞鸿江 焦宗寒 周静波 陈 于 2019-10-15 设计创作，主要内容包括：本申请公开了基于太赫兹传播特性的绝缘材料厚度检测方法及系统,方法包括利用斩波器对脉冲太赫兹波源发出的脉冲太赫兹波降噪滤波,固定脉冲太赫兹波光源信号的照射频率和透射信号频率；利用反射式太赫兹波强度检测装置检测照射待测物体后的反射太赫兹脉冲,利用透射式太赫兹波强度检测装置检测照射待测物体后的透射太赫兹脉冲；利用太赫兹信息前端预处理设备提取透射太赫兹脉冲和反射太赫兹脉冲数据；利用数据处理终端计算材料的厚度。本申请在朗伯定律的基础上,将反射的太赫兹脉冲强度考虑到厚度检测误差影响因素里。通过检测待测物体的反射太赫兹脉冲和透射太赫兹脉冲,实现检测误差的修正,从而获得更高精度的检测结果。(The application discloses an insulating material thickness detection method and system based on terahertz propagation characteristics, wherein the method comprises the steps of utilizing a chopper to reduce noise and filter a pulse terahertz wave emitted by a pulse terahertz wave source, and fixing the irradiation frequency and the transmission signal frequency of a pulse terahertz wave light source signal; detecting a reflected terahertz pulse after irradiating the object to be detected by using a reflective terahertz wave intensity detection device, and detecting a transmitted terahertz pulse after irradiating the object to be detected by using a transmissive terahertz wave intensity detection device; extracting transmission terahertz pulse and reflection terahertz pulse data by utilizing terahertz information front-end preprocessing equipment; the thickness of the material is calculated using a data processing terminal. According to the terahertz pulse intensity measuring method and device, on the basis of the Lambert law, the reflected terahertz pulse intensity is considered in the influence factors of thickness detection errors. The correction of detection errors is realized by detecting the reflection terahertz pulse and the transmission terahertz pulse of the object to be detected, so that a detection result with higher precision is obtained.)

1. the insulating material thickness detection method based on the terahertz propagation characteristic is characterized by comprising the following steps of:

Utilizing a chopper to perform noise reduction and filtering on pulse terahertz waves emitted by a pulse terahertz wave source, and fixing the irradiation frequency and the transmission signal frequency of a pulse terahertz wave light source signal;

Detecting a reflected terahertz pulse after the noise-reduced pulse terahertz wave irradiates the object to be detected by using a reflective terahertz wave intensity detection device, and detecting a transmitted terahertz pulse after the noise-reduced pulse terahertz wave irradiates the object to be detected by using a transmissive terahertz wave intensity detection device;

Extracting transmission terahertz pulse and reflection terahertz pulse data by utilizing terahertz information front-end preprocessing equipment;

and calculating the thickness of the material according to the data of the transmission terahertz pulse and the reflection terahertz pulse by using a data processing terminal.

2. The method of claim 1, wherein the formula for calculating the thickness of the material from the transmitted terahertz pulse and the reflected terahertz pulse data is:

Wherein alpha represents the absorption coefficient of the material to the terahertz waves; IS represents the initial incident intensity of the terahertz wave; IF represents reflected terahertz wave pulse data; i represents transmitted terahertz wave pulse data; d represents the material thickness; theta represents an included angle between the surface of the sample to be measured and the normal line of the terahertz wave.

3. the method of claim 1, wherein the pulsed terahertz wave source has a pulse emission repetition frequency of 5-10 Hz.

4. the insulating material thickness detection system based on the terahertz propagation characteristic is characterized by comprising a chopper, a pulse terahertz wave source, a reflection type terahertz wave intensity detection device, a transmission type terahertz wave intensity detection device, terahertz information front-end preprocessing equipment and a data processing terminal;

the pulse terahertz wave source is used for emitting pulse terahertz waves;

the chopper is used for denoising and filtering the pulse terahertz wave emitted by the pulse terahertz wave source and fixing the irradiation frequency and the transmission signal frequency of the pulse terahertz wave light source signal;

the reflection type terahertz wave intensity detection device is used for detecting reflection terahertz pulses after the noise-reduced pulse terahertz waves irradiate the object to be detected;

the transmission type terahertz wave intensity detection device is used for detecting transmission terahertz pulses after the noise-reduced pulse terahertz waves irradiate the object to be detected;

The terahertz information front-end preprocessing device is used for extracting transmission terahertz pulse data and reflection terahertz pulse data;

And the data processing terminal is used for calculating the thickness of the material according to the data of the transmission terahertz pulse and the reflection terahertz pulse.

5. The system according to claim 4, wherein the distance from the reflective terahertz wave intensity detection device to the sample to be measured is equal to the distance from the transmissive terahertz wave intensity detection device to the sample to be measured.

Technical Field

The application relates to the technical field of terahertz spectroscopy, in particular to an insulating material thickness detection method and system based on terahertz propagation characteristics.

background

the insulating material is widely applied to the fields of machinery, construction, power transmission, aerospace and the like due to excellent mechanical property, electric insulating property, good corrosion resistance, aging resistance and the like. Taking the power industry as an example, the insulation materials widely applied in power transmission and transformation equipment mainly comprise ceramics, ethylene propylene diene monomer, epoxy resin, silicon rubber and the like. The insulating material has outstanding advantages in the aspects of cracking resistance, water repellency, antifouling property, tracking resistance, electric erosion resistance and the like, so the insulating material plays a very important role in the power industry. The insulating material has the function of isolating electrified parts with different electric potentials in the electrical equipment, so that electric power accidents such as short circuit, electric leakage, breakdown and the like are prevented. If the production quality of the insulating product can not be guaranteed, not only can huge property loss be caused, but also the personal safety of operators can be threatened in serious cases. Therefore, the production quality of the insulation material should be strictly controlled.

As one of the indexes for measuring the electrical properties of the insulating material, the dielectric strength plays a crucial role in testing whether the product meets the national standard. Numerous studies have shown that the dielectric strength of an insulating material is necessarily linked to the uniformity of the thickness of the material, and that the electrical properties of the insulating material are often dependent on the thickness of the thinnest point thereof. Therefore, how to realize accurate measurement of the thickness of the insulating material is a key problem for ensuring the production quality of products.

Non-destructive testing methods which have been used for the precise measurement of layer thicknesses at the present stage include ultrasonic methods, eddy current methods and X-ray methods. The ultrasonic method is mainly used for measuring the wall thickness of a compact material, cannot accurately measure the thickness of an insulating material layer with large attenuation, and has a measurement blind area and a measurement lower limit. The eddy current method is mainly used for measuring the layer thickness of a conductive material, and is not suitable for measuring the layer thickness of an insulating material. Although the X-ray detection method can detect the internal geometric size of a sample, the presence of ionizing radiation in the practical application process can affect the physical health of operators. Therefore, a non-contact, fast, safe and reliable method for detecting the thickness of the insulating material is lacked.

Disclosure of Invention

the application aims to provide an insulating material thickness detection method and system based on terahertz propagation characteristics, so as to solve the problem that the insulating material thickness detection method which is non-contact, rapid, safe and reliable is lacked.

in one aspect, according to an embodiment of the application, there is provided an insulating material thickness detection method based on terahertz propagation characteristics, including:

Utilizing a chopper to perform noise reduction and filtering on pulse terahertz waves emitted by a pulse terahertz wave source, and fixing the irradiation frequency and the transmission signal frequency of a pulse terahertz wave light source signal;

Detecting a reflected terahertz pulse after the noise-reduced pulse terahertz wave irradiates the object to be detected by using a reflective terahertz wave intensity detection device, and detecting a transmitted terahertz pulse after the noise-reduced pulse terahertz wave irradiates the object to be detected by using a transmissive terahertz wave intensity detection device;

extracting transmission terahertz pulse and reflection terahertz pulse data by utilizing terahertz information front-end preprocessing equipment;

And calculating the thickness of the material according to the data of the transmission terahertz pulse and the reflection terahertz pulse by using a data processing terminal.

Further, a formula for calculating the thickness of the material according to the data of the transmission terahertz pulse and the reflection terahertz pulse is as follows:

Wherein alpha represents the absorption coefficient of the material to the terahertz waves; IS represents the initial incident intensity of the terahertz wave; IF represents reflected terahertz wave pulse data; i represents transmitted terahertz wave pulse data; d represents the material thickness; theta represents an included angle between the surface of the sample to be measured and the normal line of the terahertz wave.

Further, the pulse emission repetition frequency of the pulse terahertz wave source is 5Hz-10 Hz.

on the other hand, according to an embodiment of the present application, there is provided an insulating material thickness detection system based on terahertz propagation characteristics, including a chopper, a pulsed terahertz wave source, a reflective terahertz wave intensity detection device, a transmissive terahertz wave intensity detection device, a terahertz information front-end preprocessing apparatus, and a data processing terminal;

The pulse terahertz wave source is used for emitting pulse terahertz waves;

the chopper is used for denoising and filtering the pulse terahertz wave emitted by the pulse terahertz wave source and fixing the irradiation frequency and the transmission signal frequency of the pulse terahertz wave light source signal;

the reflection type terahertz wave intensity detection device is used for detecting reflection terahertz pulses after the noise-reduced pulse terahertz waves irradiate the object to be detected;

the transmission type terahertz wave intensity detection device is used for detecting transmission terahertz pulses after the noise-reduced pulse terahertz waves irradiate the object to be detected;

The terahertz information front-end preprocessing device is used for extracting transmission terahertz pulse data and reflection terahertz pulse data;

And the data processing terminal is used for calculating the thickness of the material according to the data of the transmission terahertz pulse and the reflection terahertz pulse.

Further, the distance between the reflection-type terahertz wave intensity detection device and the sample to be detected is equal to the distance between the transmission-type terahertz wave intensity detection device and the sample to be detected.

according to the technical scheme, the embodiment of the application provides the insulating material thickness detection method and system based on the terahertz propagation characteristic, the method comprises the steps of utilizing a chopper to reduce noise and filter the pulse terahertz wave emitted by a pulse terahertz wave source, and fixing the irradiation frequency and the transmission signal frequency of the pulse terahertz wave source signal; detecting a reflected terahertz pulse after the noise-reduced pulse terahertz wave irradiates the object to be detected by using a reflective terahertz wave intensity detection device, and detecting a transmitted terahertz pulse after the noise-reduced pulse terahertz wave irradiates the object to be detected by using a transmissive terahertz wave intensity detection device; extracting transmission terahertz pulse and reflection terahertz pulse data by utilizing terahertz information front-end preprocessing equipment; and calculating the thickness of the material according to the data of the transmission terahertz pulse and the reflection terahertz pulse by using a data processing terminal. According to the terahertz pulse intensity measuring method and device, on the basis of the Lambert law, the reflected terahertz pulse intensity is considered in the influence factors of thickness detection errors. The correction of detection errors is realized by detecting the reflection terahertz pulse and the transmission terahertz pulse of the object to be detected, so that a detection result with higher precision is obtained.

drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

fig. 1 is a flowchart illustrating an insulating material thickness detection method based on terahertz propagation characteristics according to an embodiment of the present application;

FIG. 2 is a Lambert's law diagram;

fig. 3 is a schematic structural diagram illustrating an insulating material thickness detection system based on terahertz propagation characteristics according to an embodiment of the present application.

Illustration of the drawings:

wherein, 1-a pulse terahertz wave source; 2-a chopper; 3-a first terahertz wave mirror surface; 4-a sample to be tested; 5-a second terahertz wave reflecting mirror surface; 6-a reflective terahertz intensity detection device; 7-a data processing terminal; 8-terahertz information front-end preprocessing equipment; 9-a transmissive terahertz intensity detection device; 10-third terahertz wave mirror surface.

Detailed Description

from lambert's law, when terahertz waves vertically irradiate on a transmissive sample, the transmitted light intensity I and the material thickness d have a simpler functional relationship:

I＝Iexp(-αd)；

wherein alpha represents the absorption coefficient of the material to the terahertz waves; i0 represents the initial intensity of incident terahertz waves; d represents the thickness of the material to be transmitted. The absorption coefficient alpha of the material to the terahertz waves can be measured through experiments, and when the absorption coefficient alpha is known, the thickness of the material can be calculated according to the functional relation.

However, the calculation method does not consider the situation that the terahertz waves are reflected on the material interface, and a certain error exists between the obtained result and the actual thickness of the object. In order to reduce the influence of errors on results, the technical scheme of the application is provided.

Referring to fig. 1, an embodiment of the present application provides a method for detecting a thickness of an insulating material based on a terahertz propagation characteristic, including:

S1, denoising and filtering the pulse terahertz wave emitted by the pulse terahertz wave source by using a chopper, and fixing the irradiation frequency and the transmission signal frequency of the pulse terahertz wave light source signal;

And a signal of chopper frequency is searched at a detection end, so that the interference of other terahertz waves in the surrounding environment is eliminated.

step S2, detecting a reflection terahertz pulse after the noise-reduced pulse terahertz wave irradiates the object to be detected by using a reflection terahertz wave intensity detection device, and detecting a transmission terahertz pulse after the noise-reduced pulse terahertz wave irradiates the object to be detected by using a transmission terahertz wave intensity detection device;

step S3, extracting transmission terahertz pulse and reflection terahertz pulse data by utilizing terahertz information front-end preprocessing equipment;

and step S4, calculating the thickness of the material according to the transmission terahertz pulse and the reflection terahertz pulse data by using the data processing terminal.

terahertz waves are electromagnetic waves located between microwaves and infrared rays, and occupy a specific position in the electromagnetic spectrum. On one hand, when the terahertz waves are used for detecting objects, harmful photoionization cannot be generated, the terahertz wave detector is an effective nondestructive detection means, and has the characteristics of high signal-to-noise ratio, high detection speed and the like. And the terahertz wave pulse width is picoseconds magnitude, and the terahertz wave pulse width can be effectively used for researching time resolution. On the other hand, some non-polar, non-metallic substances are transparent to terahertz electromagnetic radiation, and more importantly: the terahertz wave is sensitive to thickness and can be used for measuring the thickness of an object.

Further, a formula for calculating the thickness of the material according to the data of the transmission terahertz pulse and the reflection terahertz pulse is as follows:

wherein alpha represents the absorption coefficient of the material to the terahertz waves; IS represents the initial incident intensity of the terahertz wave; IF represents reflected terahertz wave pulse data; i represents transmitted terahertz wave pulse data; d represents the material thickness; theta represents an included angle between the surface of the sample to be measured and the normal line of the terahertz wave.

The derivation process is as follows:

referring to fig. 2, when the terahertz wave is incident on the surface of the sample to be measured at an angle θ, and the reflected terahertz pulse intensity is considered, the following functional relationship is established on the basis of the original functional relationship:

I＝(I-I)exp(-αd′)；

d＝d′*cosθ；

wherein IS represents an initial incident intensity of the terahertz wave; i represents the intensity of the transmitted terahertz wave; IF represents the reflected terahertz intensity; theta is an included angle between the terahertz wave and the normal of the surface of the sample to be detected.

The above two formulas are arranged to obtain

Since the initial incident intensity IS of the terahertz wave IS known, the absorption coefficient α of the material to the terahertz wave can be measured in a laboratory, and the thickness d of the material can be calculated according to the above formula by detecting the reflection intensity IF and the transmission intensity I of the terahertz wave.

optionally, θ is 45 °.

Further, the pulse emission repetition frequency of the pulse terahertz wave source is 5Hz-10 Hz. The pulse emission repetition frequency is 5Hz-10Hz, so that the terahertz waves of every two pulses cannot interfere with each other, and the data processing speed of the detection end can be kept synchronous.

Referring to fig. 3, the embodiment of the application provides an insulating material thickness detection system based on terahertz propagation characteristics, which includes a chopper 2, a pulse terahertz wave source 1, a reflective terahertz wave intensity detection device 6, a transmissive terahertz wave intensity detection device 9, a terahertz information front-end preprocessing device 8 and a data processing terminal 7;

The reflection-type terahertz wave intensity detection device 6 and the transmission-type terahertz wave intensity detection device 9 are respectively connected with the terahertz information front-end preprocessing device 8, and the terahertz information front-end preprocessing device 8 is connected with the data processing terminal 7.

the pulse terahertz wave source 1 is used for emitting pulse terahertz waves;

the chopper 2 is used for denoising and filtering the pulse terahertz wave emitted by the pulse terahertz wave source 1 and fixing the irradiation frequency and the transmission signal frequency of the pulse terahertz wave light source signal;

The reflection type terahertz wave intensity detection device 6 is used for detecting reflection terahertz pulses after the noise-reduced pulse terahertz waves irradiate the object to be detected 4;

The transmission-type terahertz wave intensity detection device 9 is used for detecting transmission terahertz pulses after the noise-reduced pulse terahertz waves irradiate the object to be detected 4;

The terahertz information front-end preprocessing device 8 is used for extracting transmission terahertz pulse data and reflection terahertz pulse data;

and the data processing terminal 7 is used for calculating the thickness of the material according to the data of the transmission terahertz pulse and the reflection terahertz pulse.

In order to better guide the transmission direction of the pulse terahertz, the detection system provided by the application further comprises a first terahertz wave reflecting mirror surface 3, a second terahertz wave reflecting mirror surface 5 and a third terahertz wave reflecting mirror surface 10. The first terahertz wave reflecting mirror surface 3 is used for irradiating the pulse terahertz waves subjected to noise reduction to the object to be detected 4; the second terahertz wave reflecting mirror surface 5 is used for transmitting the terahertz pulses reflected by the object to be detected to the reflective terahertz wave intensity detection device 6; the third terahertz wave reflecting mirror surface 10 is used for transmitting the terahertz pulses transmitted by the object to be detected to the transmission-type terahertz wave intensity detection device 9.

Further, the distance between the reflection-type terahertz wave intensity detection device and the sample to be detected is equal to the distance between the transmission-type terahertz wave intensity detection device and the sample to be detected. The influence of terahertz attenuation generated by different paths and transmission distances on detection precision is avoided.

according to the technical scheme, the embodiment of the application provides the insulating material thickness detection method and system based on the terahertz propagation characteristic, the method comprises the steps of utilizing a chopper to reduce noise and filter the pulse terahertz wave emitted by a pulse terahertz wave source, and fixing the irradiation frequency and the transmission signal frequency of the pulse terahertz wave source signal; detecting a reflected terahertz pulse after the noise-reduced pulse terahertz wave irradiates the object to be detected by using a reflective terahertz wave intensity detection device, and detecting a transmitted terahertz pulse after the noise-reduced pulse terahertz wave irradiates the object to be detected by using a transmissive terahertz wave intensity detection device; extracting transmission terahertz pulse and reflection terahertz pulse data by utilizing terahertz information front-end preprocessing equipment; and calculating the thickness of the material according to the data of the transmission terahertz pulse and the reflection terahertz pulse by using a data processing terminal. According to the terahertz pulse intensity measuring method and device, on the basis of the Lambert law, the reflected terahertz pulse intensity is considered in the influence factors of thickness detection errors. The correction of detection errors is realized by detecting the reflection terahertz pulse and the transmission terahertz pulse of the object to be detected, so that a detection result with higher precision is obtained.

Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.

It will be understood that the present application is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.