CN110132886B - High-sensitivity terahertz spectrum detection device and method for liquid concentration - Google Patents
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- 239000007788 liquid Substances 0.000 title claims abstract description 52
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- 238000000034 method Methods 0.000 title abstract description 7
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Abstract
Description
技术领域Technical field
本发明属于太赫兹波技术应用领域，特别涉及一种液体浓度的高灵敏度太赫兹谱检测装置及方法。The invention belongs to the application field of terahertz wave technology, and particularly relates to a high-sensitivity terahertz spectrum detection device and method for liquid concentration.
背景技术Background technique
太赫兹波(terahertz wave)是指频率为0.1～10.0THz(1THz＝1012Hz)的电磁波，此波段下临微波波段上临红外波段，具有其二者的优点，空间分辨率比微波更好，穿透性也比红外线更强。太赫兹波有光子能量低的特点(1THz约为4.1meV)，不会产生电离效应破坏有机体和生物组织。物质本身的太赫兹谱具有丰富的信息，由于分子间或分子内部的氢键、范德华力以及偶极子转动等化学分子的振动和转动能级对应太赫兹频段，尤其是很多有机分子能级位于该波段，使得其分子在太赫兹波段具有独特透射谱，因此，物质的THz光谱(包括发射、反射和透射光谱)包含有丰富的物理质和化学信息，在物理学、化学、生物医学、天文学、材料科学和环境科学等方面具有重要的应用价值。Terahertz wave refers to electromagnetic waves with a frequency of 0.1~10.0THz (1THz=10 12 Hz). This band is adjacent to the microwave band and the infrared band. It has the advantages of both, and the spatial resolution is better than that of microwaves. , the penetrability is also stronger than infrared. Terahertz waves have the characteristics of low photon energy (1THz is about 4.1meV) and will not produce ionization effects that damage organisms and biological tissues. The terahertz spectrum of the substance itself is rich in information. Since the vibration and rotation energy levels of chemical molecules such as hydrogen bonds between molecules or within molecules, van der Waals forces, and dipole rotations correspond to the terahertz frequency band, especially many organic molecules have energy levels located in this range. band, so that its molecules have a unique transmission spectrum in the terahertz band. Therefore, the THz spectrum of a substance (including emission, reflection and transmission spectra) contains rich physical and chemical information, which is widely used in physics, chemistry, biomedicine, astronomy, Material science and environmental science have important application value.
铁电相钽酸锂晶体是功能材料领域的“万能”材料。它们具有良好的机械、物理性能和成本低等优点，并且作为非线性光学晶体、电光晶体、压电晶体、声光晶体和双折射晶体等在现今以光技术产业中得到了广泛的应用。以前的工作显示，晶体材料的结构与其光学性能息息相关。Ferroelectric phase lithium tantalate crystal is a "universal" material in the field of functional materials. They have the advantages of good mechanical and physical properties and low cost, and are widely used in today's optical technology industry as nonlinear optical crystals, electro-optical crystals, piezoelectric crystals, acousto-optical crystals and birefringent crystals. Previous work has shown that the structure of crystalline materials is closely related to their optical properties.
波谱分析主要是以光学理论为基础，以物质与光相互作用为条件，建立物质分子结构与电磁辐射之间的相互关系，从而进行物质分子几何异构、立体异构、构象异构和分子结构分析和鉴定的方法。波谱分析已成为现代进行物质分子结构分析和鉴定的主要方法之一。随着科技的发展，技术的革新和计算机应用，波谱分析也得到迅速发展。波谱分析法具有优点突出，广泛应用等特点，是诸多科研和生产领域不可或缺的工具。随着科技发展和分析要求的不断提高，使得科研工作者对波谱分析法也在不断创新。波谱分析法由于其快速、灵敏、准确、对环境条件要求不高、对材料折射率检测方面起着重要的作用，已成为材料分析和鉴定常用的分析工具和重要的分析方法。Spectral analysis is mainly based on optical theory and takes the interaction between matter and light as a condition to establish the relationship between the molecular structure of matter and electromagnetic radiation, thereby conducting geometric isomerism, stereoisomerism, conformational isomerism and molecular structure of matter molecules. Methods of analysis and identification. Spectral analysis has become one of the main methods for analyzing and identifying the molecular structure of substances in modern times. With the development of science and technology, technological innovation and computer applications, spectrum analysis has also developed rapidly. Spectral analysis method has outstanding advantages and wide application. It is an indispensable tool in many scientific research and production fields. With the development of science and technology and the continuous improvement of analysis requirements, scientific researchers are constantly innovating spectral analysis methods. Spectral analysis has become a commonly used analytical tool and important analytical method for material analysis and identification due to its rapid, sensitive, accurate, low requirements on environmental conditions, and its important role in detecting the refractive index of materials.
近年来，随着太赫兹辐射产生和探测技术的发展，THz技术取得了许多令人瞩目的成果。超材料作为功能器件被越来越多地应用于太赫兹领域，如吸波器、滤波器、调制器、传感器和偏振器。特别是THz超材料在非电离的生物化学传感应用方面有着很大潜力，不仅因为许多物质在THz波段存在指纹谱。而且，相比常规的太赫兹时域光谱测量法，基于太赫兹超材料的传感测量法具有简便和灵敏度更高的优点。因此，基于超材料的太赫兹传感器研究成为了THz技术研究的热点。In recent years, with the development of terahertz radiation generation and detection technology, THz technology has achieved many remarkable results. Metamaterials are increasingly used in the terahertz field as functional devices, such as absorbers, filters, modulators, sensors and polarizers. In particular, THz metamaterials have great potential in non-ionizing biochemical sensing applications, not only because many substances have fingerprint spectra in the THz band. Moreover, compared with conventional terahertz time domain spectroscopy measurement methods, sensing measurement methods based on terahertz metamaterials have the advantages of simplicity and higher sensitivity. Therefore, research on terahertz sensors based on metamaterials has become a hot spot in THz technology research.
发明内容Contents of the invention
本发明为克服现有液体浓度检测方法的不足，利用太赫兹波对液体的透射特性进行液体浓度的分析检测，提出了一种液体浓度的高灵敏度太赫兹谱传感检测装置，满足安全性、高灵敏度、检测时间段、操作方便、可在室温下工作等要求。In order to overcome the shortcomings of existing liquid concentration detection methods, the present invention uses the transmission characteristics of terahertz waves to analyze and detect liquid concentration, and proposes a high-sensitivity terahertz spectrum sensing and detection device for liquid concentration, which meets the requirements of safety, High sensitivity, detection time period, easy operation, and can work at room temperature and other requirements.
本发明技术方案如下：The technical solution of the present invention is as follows:
一种液体浓度的高灵敏度太赫兹谱检测装置，包括飞秒激光器、斩波器、分束器、光电导天线、第一抛面镜、第一聚四氟乙烯透镜、第一硅透镜、太赫兹超材料阵列结构、第二硅透镜、第二聚四氟乙烯透镜、第二抛面镜、延时线、第一反射镜、第二反射镜、薄膜分束镜、ZnTe晶体、四分之一波片、沃拉斯顿棱镜、光电平衡探测器、锁相放大器和计算机；所述的太赫兹超材料阵列结构包括硅衬底、介质圆柱、聚乙烯盖板和聚乙烯封闭挡板；介质圆柱设置在聚乙烯盖板和硅衬底之间，介质圆柱的两个端面分别与聚乙烯盖板和硅衬底抵接，若干个介质圆柱呈周期性阵列结构；在聚乙烯盖板和硅衬底之间、介质圆柱周围设有存放待测液体的空腔，通过聚乙烯盖板和硅衬底之间的聚乙烯封闭挡板密封；电磁波在周期性阵列结构内耦合得到特定的太赫兹透射谱线，结构表面物质的细微变化都会引起太赫兹透射谱线产生明显的偏移，即可增强在太赫兹区域中对待测液体的感测效果，有效提高不同浓度液体的太赫兹透射谱的检测灵敏度。A high-sensitivity terahertz spectrum detection device for liquid concentration, including a femtosecond laser, a chopper, a beam splitter, a photoconductive antenna, a first parabolic mirror, a first polytetrafluoroethylene lens, a first silicon lens, a solar Hertz metamaterial array structure, second silicon lens, second PTFE lens, second parabolic mirror, delay line, first reflector, second reflector, thin film beam splitter, ZnTe crystal, quarter A wave plate, Wollaston prism, photoelectric balance detector, lock-in amplifier and computer; the terahertz metamaterial array structure includes a silicon substrate, a dielectric cylinder, a polyethylene cover plate and a polyethylene closing baffle; the medium The cylinder is arranged between the polyethylene cover plate and the silicon substrate. The two end surfaces of the dielectric cylinder are in contact with the polyethylene cover plate and the silicon substrate respectively. Several dielectric cylinders form a periodic array structure; between the polyethylene cover plate and the silicon substrate There is a cavity between the substrates and around the dielectric cylinder to store the liquid to be measured, which is sealed by a polyethylene closed baffle between the polyethylene cover plate and the silicon substrate; the electromagnetic wave is coupled within the periodic array structure to obtain a specific terahertz frequency Subtle changes in the transmission spectrum line and structural surface material will cause a significant shift in the terahertz transmission spectrum line, which can enhance the sensing effect of the liquid to be measured in the terahertz region and effectively improve the terahertz transmission spectrum of liquids with different concentrations. Detection sensitivity.
进一步的，飞秒激光器产生的激光光路上顺次设有斩波器和分束器，分束器将飞秒激光器产生的激光分为较强的泵浦光和较弱的探测光；泵浦光光路上设有光电导天线，泵浦光经光电导天线激发太赫兹脉冲，太赫兹脉冲顺次通过第一抛面镜准直和第一聚四氟乙烯透镜聚焦后到达第一硅透镜的入射球面，经第一硅透镜耦合穿透聚乙烯盖板，进入存放待测液体的空腔，再经硅衬底进入第二硅透镜的入射平面，从第二硅透镜的出射球面耦合出射，出射的太赫兹脉冲顺次经过第二聚四氟乙烯透镜准直和第二抛面镜聚焦后，透过薄膜分束镜到达ZnTe晶体的入射面；探测光光路上顺次设有延时线、第一反射镜、第二反射镜和薄膜分束镜；探测光经薄膜分束镜反射后，在ZnTe晶体的入射面与太赫兹脉冲汇合，再顺次透过ZnTe晶体、四分之一波片、沃拉斯顿棱镜后被光电平衡探测器探测；光电平衡探测器通过锁相放大器与计算机连接。Further, the laser light path generated by the femtosecond laser is sequentially provided with a chopper and a beam splitter. The beam splitter divides the laser light generated by the femtosecond laser into stronger pump light and weaker detection light; pump light There is a photoconductive antenna on the optical path. The pump light excites terahertz pulses through the photoconductive antenna. The terahertz pulses are sequentially collimated by the first parabolic mirror and focused by the first polytetrafluoroethylene lens before reaching the first silicon lens. The incident sphere is coupled through the first silicon lens, penetrates the polyethylene cover, enters the cavity where the liquid to be measured is stored, then enters the incident plane of the second silicon lens through the silicon substrate, and is coupled and emitted from the exit spherical surface of the second silicon lens. The emitted terahertz pulse is sequentially collimated by the second polytetrafluoroethylene lens and focused by the second parabolic mirror, and then reaches the incident surface of the ZnTe crystal through the thin film beam splitter; a delay line is sequentially provided on the detection light path. , the first reflector, the second reflector and the thin-film beam splitter; after the detection light is reflected by the thin-film beam splitter, it merges with the terahertz pulse on the incident surface of the ZnTe crystal, and then passes through the ZnTe crystal, quarter The wave plate and Wollaston prism are then detected by the photoelectric balance detector; the photoelectric balance detector is connected to the computer through a lock-in amplifier.
本发明还公开了一种所述液体浓度的高灵敏度太赫兹谱检测装置的检测方法，步骤如下：The invention also discloses a detection method of a high-sensitivity terahertz spectrum detection device for liquid concentration. The steps are as follows:
1)向太赫兹超材料阵列结构中加入待测液体，直至存放待测液体的空腔全部填满；1) Add the liquid to be measured into the terahertz metamaterial array structure until the cavity storing the liquid to be measured is completely filled;
2)飞秒激光器产生的激光经过斩波器和分束器，分束器将飞秒激光器产生的激光分为泵浦光和探测光；泵浦光经光电导天线激发太赫兹脉冲，太赫兹脉冲顺次通过第一抛面镜准直和第一聚四氟乙烯透镜聚焦后到达第一硅透镜的入射球面，经第一硅透镜耦合穿透聚乙烯盖板，进入存放待测液体的空腔，再经硅衬底进入第二硅透镜的入射平面，从第二硅透镜的出射球面耦合出射，出射的太赫兹脉冲顺次经过第二聚四氟乙烯透镜准直和第二抛面镜聚焦后，透过薄膜分束镜到达ZnTe晶体的入射面；探测光顺次经过延时线、第一反射镜、第二反射镜和薄膜分束镜，在ZnTe晶体的入射面与太赫兹脉冲汇合，再顺次透过ZnTe晶体、四分之一波片、沃拉斯顿棱镜后被光电平衡探测器探测；所测电信号被锁相放大器放大后送入计算机，经计算机对太赫兹时域光谱系统所测的透过率数据信息进行拟合处理，得到待测液体的太赫兹透射谱；2) The laser generated by the femtosecond laser passes through a chopper and a beam splitter. The beam splitter divides the laser generated by the femtosecond laser into pump light and detection light; the pump light excites terahertz pulses through the photoconductive antenna. The terahertz pulse The pulses are sequentially collimated by the first parabolic mirror and focused by the first polytetrafluoroethylene lens, and then reach the incident spherical surface of the first silicon lens. They are coupled by the first silicon lens, penetrate the polyethylene cover, and enter the space where the liquid to be measured is stored. cavity, then enters the incident plane of the second silicon lens through the silicon substrate, and is coupled and emitted from the exit spherical surface of the second silicon lens. The emitted terahertz pulse is sequentially collimated by the second polytetrafluoroethylene lens and the second parabolic mirror. After focusing, it passes through the thin-film beam splitter and reaches the incident surface of the ZnTe crystal; the detection light sequentially passes through the delay line, the first reflector, the second reflector and the thin-film beam splitter, and collides with the terahertz pulse at the incident surface of the ZnTe crystal. merge, and then pass through the ZnTe crystal, quarter wave plate, and Wollaston prism in sequence, and then be detected by the photoelectric balance detector; the measured electrical signal is amplified by the lock-in amplifier and sent to the computer, and the computer analyzes the terahertz time The transmittance data information measured by the domain spectroscopy system is fitted and processed to obtain the terahertz transmission spectrum of the liquid to be measured;
3)将待测液体的太赫兹透射谱中透过率最低的点所对应的频率作为谐振频率点，待测液体的谐振频率点的位置跟待测液体浓度之间是一一对应关系；根据待测液体的谐振频率点与待测液体浓度之间的标定曲线，得到待测液体的浓度。3) The frequency corresponding to the point with the lowest transmittance in the terahertz transmission spectrum of the liquid to be measured is used as the resonant frequency point. There is a one-to-one correspondence between the position of the resonant frequency point of the liquid to be measured and the concentration of the liquid to be measured; according to The calibration curve between the resonant frequency point of the liquid to be measured and the concentration of the liquid to be measured is used to obtain the concentration of the liquid to be measured.
本发明具有如下优点：The invention has the following advantages:
1)由于太赫兹本身光子能量低，不会产生电离效应，所以使用安全，不会对人体造成伤害；1) Since terahertz photons have low energy and will not produce ionization effects, they are safe to use and will not cause harm to the human body;
2)太赫兹超材料阵列结构采用全介质材料构成，不存在欧姆损耗，其结果更为精确；2) The terahertz metamaterial array structure is composed of all dielectric materials, there is no ohmic loss, and the results are more accurate;
3)电磁波传播速度为光速，系统检测等待时间大部分为计算机对信号的处理时间，具有检测时间短的优点；3) The propagation speed of electromagnetic waves is the speed of light, and most of the system detection waiting time is the computer's signal processing time, which has the advantage of short detection time;
4)液体浓度高灵敏度太赫兹谱传感检测装置可在室温下产生电磁波对样品进行检测，具有设备简单可常温检测的优点；4) The liquid concentration high-sensitivity terahertz spectrum sensing detection device can generate electromagnetic waves at room temperature to detect samples, and has the advantage of simple equipment and normal temperature detection;
本发明可以广泛应用于液体浓度的精确测定，可以高效地对液体进行浓度传感，为未知浓度液体的测量提供了一种方便、快捷、精确的检测装置。The invention can be widely used for accurate measurement of liquid concentration, can efficiently conduct concentration sensing of liquids, and provides a convenient, fast and accurate detection device for measuring liquids of unknown concentration.
附图说明Description of the drawings
图1为本发明液体浓度的高灵敏度太赫兹谱检测装置结构图；Figure 1 is a structural diagram of a high-sensitivity terahertz spectrum detection device for liquid concentration according to the present invention;
图2为本发明太赫兹超材料阵列结构的结构图；Figure 2 is a structural diagram of the terahertz metamaterial array structure of the present invention;
图3为本发明太赫兹超材料阵列结构正视方向的三层结构示意图；Figure 3 is a schematic diagram of the three-layer structure of the terahertz metamaterial array structure of the present invention in the front direction;
图4为本发明对酒精溶液的浓度从0％到100％检测的太赫兹透射谱；Figure 4 is the terahertz transmission spectrum detected by the present invention when the concentration of alcohol solution is from 0% to 100%;
图5为本发明酒精的谐振频率点与酒精浓度之间的标定曲线；Figure 5 is a calibration curve between the resonant frequency point of the alcohol of the present invention and the alcohol concentration;
图中：飞秒激光器1、斩波器2、分束器3、光电导天线4、第一抛面镜5、第一聚四氟乙烯透镜6、第一硅透镜7、太赫兹超材料阵列结构8、第二硅透镜9、第二聚四氟乙烯透镜10、第二抛面镜11、延时线12、第一反射镜13、第二反射镜14、薄膜分束镜15、ZnTe晶体16、四分之一波片17、沃拉斯顿棱镜18、光电平衡探测器19、锁相放大器20、计算机21、聚乙烯盖板22、硅衬底23、整个周期性阵列结构中的单个周期24、介质圆柱25、存放待测液体的空腔26、聚乙烯封闭挡板27。In the picture: femtosecond laser 1, chopper 2, beam splitter 3, photoconductive antenna 4, first parabolic mirror 5, first PTFE lens 6, first silicon lens 7, terahertz metamaterial array Structure 8, second silicon lens 9, second PTFE lens 10, second parabolic mirror 11, delay line 12, first reflector 13, second reflector 14, thin film beam splitter 15, ZnTe crystal 16. Quarter wave plate 17, Wollaston prism 18, photoelectric balance detector 19, lock-in amplifier 20, computer 21, polyethylene cover plate 22, silicon substrate 23, a single element in the entire periodic array structure Period 24, medium cylinder 25, cavity 26 for storing liquid to be measured, polyethylene closing baffle 27.
具体实施方式Detailed ways
下面结合附图和实例对本发明做进一步说明：The present invention will be further described below in conjunction with the accompanying drawings and examples:
如图1所示，一种液体浓度的高灵敏度太赫兹谱传感检测装置，飞秒激光器1、斩波器2、分束器3、光电导天线4、第一抛面镜5、第一聚四氟乙烯透镜6、第一硅透镜7、太赫兹超材料阵列结构8、第二硅透镜9、第二聚四氟乙烯透镜10、第二抛面镜11、延时线12、第一反射镜13、第二反射镜14、薄膜分束镜15、ZnTe晶体16、四分之一波片17、沃拉斯顿棱镜18、光电平衡探测器19、锁相放大器20和计算机21。As shown in Figure 1, a high-sensitivity terahertz spectrum sensing and detection device for liquid concentration, femtosecond laser 1, chopper 2, beam splitter 3, photoconductive antenna 4, first parabolic mirror 5, first PTFE lens 6, first silicon lens 7, terahertz metamaterial array structure 8, second silicon lens 9, second PTFE lens 10, second parabolic mirror 11, delay line 12, first Reflector 13, second reflector 14, thin film beam splitter 15, ZnTe crystal 16, quarter wave plate 17, Wollaston prism 18, photoelectric balance detector 19, lock-in amplifier 20 and computer 21.
如图2所示，所述的太赫兹超材料阵列结构8包括硅衬底23、介质圆柱25、聚乙烯盖板22和聚乙烯封闭挡板27；介质圆柱25设置在聚乙烯盖板22和硅衬底23之间，介质圆柱25的两个端面分别与聚乙烯盖板22和硅衬底23抵接，若干个介质圆柱呈周期性阵列结构，单个周期中包括四个尺寸相等的介质圆柱；在聚乙烯盖板22和硅衬底23之间、介质圆柱25周围设有存放待测液体的空腔26，通过聚乙烯盖板22和硅衬底23之间的聚乙烯封闭挡板27密封。As shown in Figure 2, the terahertz metamaterial array structure 8 includes a silicon substrate 23, a dielectric cylinder 25, a polyethylene cover plate 22 and a polyethylene closing baffle 27; the dielectric cylinder 25 is arranged between the polyethylene cover plate 22 and the polyethylene closing baffle 27. Between the silicon substrates 23, the two end surfaces of the dielectric cylinder 25 are respectively in contact with the polyethylene cover 22 and the silicon substrate 23. Several dielectric cylinders form a periodic array structure, and a single period includes four dielectric cylinders of equal size. ; Between the polyethylene cover plate 22 and the silicon substrate 23, and around the dielectric cylinder 25, there is a cavity 26 for storing the liquid to be measured, and a polyethylene closed baffle 27 is provided between the polyethylene cover plate 22 and the silicon substrate 23. seal.
电磁波在周期性阵列结构内耦合得到特定的太赫兹透射谱线，结构表面物质的细微变化都会引起太赫兹透射谱线产生明显的偏移，即可增强在太赫兹区域中对待测液体的感测效果，有效提高不同浓度液体的太赫兹透射谱的检测灵敏度。Electromagnetic waves are coupled within the periodic array structure to obtain specific terahertz transmission spectral lines. Subtle changes in the surface material of the structure will cause obvious shifts in the terahertz transmission spectral lines, which can enhance the sensing of the liquid to be measured in the terahertz region. The effect is to effectively improve the detection sensitivity of terahertz transmission spectra of liquids with different concentrations.
飞秒激光器产生的激光光路上顺次设有斩波器和分束器，分束器将飞秒激光器产生的激光分为较强的泵浦光和较弱的探测光；泵浦光光路上设有光电导天线，泵浦光经光电导天线激发太赫兹脉冲，太赫兹脉冲顺次通过第一抛面镜准直和第一聚四氟乙烯透镜聚焦后到达第一硅透镜的入射球面，经第一硅透镜耦合穿透聚乙烯盖板，进入存放待测液体的空腔，再经硅衬底进入第二硅透镜的入射平面，从第二硅透镜的出射球面耦合出射，出射的太赫兹脉冲顺次经过第二聚四氟乙烯透镜准直和第二抛面镜聚焦后，透过薄膜分束镜到达ZnTe晶体的入射面；探测光光路上顺次设有延时线、第一反射镜、第二反射镜和薄膜分束镜；探测光经薄膜分束镜反射后，在ZnTe晶体的入射面与太赫兹脉冲汇合，再顺次透过ZnTe晶体、四分之一波片、沃拉斯顿棱镜后被光电平衡探测器探测；光电平衡探测器通过锁相放大器与计算机连接。The laser light path generated by the femtosecond laser is sequentially equipped with a chopper and a beam splitter. The beam splitter divides the laser light generated by the femtosecond laser into a stronger pump light and a weaker detection light; the pump light path is A photoconductive antenna is provided. The pump light excites terahertz pulses through the photoconductive antenna. The terahertz pulses are sequentially collimated by the first parabolic mirror and focused by the first polytetrafluoroethylene lens and then reach the incident spherical surface of the first silicon lens. It penetrates the polyethylene cover plate through coupling through the first silicon lens, enters the cavity where the liquid to be measured is stored, and then enters the incident plane of the second silicon lens through the silicon substrate. It is coupled from the exit spherical surface of the second silicon lens and emitted. After the Hertzian pulse is collimated by the second PTFE lens and focused by the second parabolic mirror, it reaches the incident surface of the ZnTe crystal through the thin film beam splitter; the detection light path is sequentially provided with a delay line, a first Reflector, second reflector and thin film beam splitter; after the detection light is reflected by the thin film beam splitter, it merges with the terahertz pulse at the incident surface of the ZnTe crystal, and then passes through the ZnTe crystal, quarter wave plate, The Wollaston prism is then detected by a photoelectric balance detector; the photoelectric balance detector is connected to the computer through a lock-in amplifier.
在本发明的一个优选实施例中，选用4×4阵列的完全相同的介质圆柱，且相邻介质圆柱之间的距离相等，具体的，选用介质圆柱的半径为5微米，高度为1微米，相邻介质圆柱之间的距离为5微米。In a preferred embodiment of the present invention, a 4×4 array of identical dielectric cylinders is used, and the distance between adjacent dielectric cylinders is equal. Specifically, the radius of the dielectric cylinder is 5 microns and the height is 1 micron. The distance between adjacent dielectric cylinders is 5 microns.
在本发明的一个优选实施例中，介质圆柱25的介质材料选用高介电常数的钽酸锂。In a preferred embodiment of the present invention, the dielectric material of the dielectric cylinder 25 is lithium tantalate with high dielectric constant.
在本发明的一个优选实施例中，所述的衬底材料为介质硅。In a preferred embodiment of the present invention, the substrate material is dielectric silicon.
使用本实施例中所述的液体浓度的高灵敏度太赫兹谱传感检测装置检测酒精浓度，步骤如下：Use the high-sensitivity terahertz spectrum sensing detection device for liquid concentration described in this embodiment to detect alcohol concentration. The steps are as follows:
1)向太赫兹超材料阵列结构中加入待测酒精溶液，直至存放待测液体的空腔全部填满；1) Add the alcohol solution to be tested into the terahertz metamaterial array structure until the cavity storing the liquid to be tested is completely filled;
2)飞秒激光器产生的激光经过斩波器和分束器，分束器将飞秒激光器产生的激光分为泵浦光和探测光；泵浦光经光电导天线激发太赫兹脉冲，太赫兹脉冲顺次通过第一抛面镜准直和第一聚四氟乙烯透镜聚焦后到达第一硅透镜的入射球面，经第一硅透镜耦合穿透聚乙烯盖板，进入存放待测液体的空腔，再经硅衬底进入第二硅透镜的入射平面，从第二硅透镜的出射球面耦合出射，出射的太赫兹脉冲顺次经过第二聚四氟乙烯透镜准直和第二抛面镜聚焦后，透过薄膜分束镜到达ZnTe晶体的入射面；探测光顺次经过延时线、第一反射镜、第二反射镜和薄膜分束镜，在ZnTe晶体的入射面与太赫兹脉冲汇合，再顺次透过ZnTe晶体、四分之一波片、沃拉斯顿棱镜后被光电平衡探测器探测；所测电信号被锁相放大器放大后送入计算机，经计算机对太赫兹时域光谱系统所测的的透过率数据信息进行拟合处理，最终得到被检测酒精溶液的太赫兹透射谱；2) The laser generated by the femtosecond laser passes through a chopper and a beam splitter. The beam splitter divides the laser generated by the femtosecond laser into pump light and detection light; the pump light excites terahertz pulses through the photoconductive antenna. The terahertz pulse The pulses are sequentially collimated by the first parabolic mirror and focused by the first polytetrafluoroethylene lens, and then reach the incident spherical surface of the first silicon lens. They are coupled by the first silicon lens, penetrate the polyethylene cover, and enter the space where the liquid to be measured is stored. cavity, then enters the incident plane of the second silicon lens through the silicon substrate, and is coupled and emitted from the exit spherical surface of the second silicon lens. The emitted terahertz pulse is sequentially collimated by the second polytetrafluoroethylene lens and the second parabolic mirror. After focusing, it passes through the thin-film beam splitter and reaches the incident surface of the ZnTe crystal; the detection light sequentially passes through the delay line, the first reflector, the second reflector and the thin-film beam splitter, and collides with the terahertz pulse at the incident surface of the ZnTe crystal. merge, and then pass through the ZnTe crystal, quarter wave plate, and Wollaston prism in sequence, and then be detected by the photoelectric balance detector; the measured electrical signal is amplified by the lock-in amplifier and sent to the computer, and the computer analyzes the terahertz time The transmittance data information measured by the domain spectroscopy system is fitted and processed, and the terahertz transmission spectrum of the detected alcohol solution is finally obtained;
3)将酒精溶液的太赫兹透射谱中透过率最低的点所对应的频率作为酒精的谐振频率点，酒精的谐振频率点的位置跟酒精溶液浓度之间是一一对应关系，如图4所示为酒精浓度标定中的酒精溶液浓度从0％到100％的太赫兹透射谱，同一浓度的酒精溶液在不同频率下的太赫兹透射率不同，且不同浓度酒精溶液的太赫兹透射谱存在明显差异，根据图4所述曲线可以得到如图5所示的酒精溶液的谐振频率点与酒精浓度之间的标定曲线，然后根据谐振频率点与酒精浓度的标定曲线进一步得到待测酒精溶液的浓度。3) The frequency corresponding to the point with the lowest transmittance in the terahertz transmission spectrum of the alcohol solution is used as the resonant frequency point of alcohol. There is a one-to-one correspondence between the position of the resonant frequency point of alcohol and the concentration of the alcohol solution, as shown in Figure 4 Shown is the terahertz transmission spectrum of the alcohol solution concentration from 0% to 100% in the alcohol concentration calibration. The terahertz transmission spectrum of the same concentration of alcohol solution at different frequencies is different, and the terahertz transmission spectrum of the alcohol solution of different concentrations exists. There is an obvious difference. According to the curve shown in Figure 4, the calibration curve between the resonant frequency point and the alcohol concentration of the alcohol solution can be obtained as shown in Figure 5. Then based on the calibration curve between the resonant frequency point and the alcohol concentration, the calibration curve of the alcohol solution to be tested can be further obtained. concentration.
以上仅为本发明优选实例，并不用于限制本发明。对本领域的技术人员来说，凡在本发明的思想、原理之内做的任何改进、替换等，均视为在本发明的保护范围内。The above are only preferred examples of the present invention and are not intended to limit the present invention. For those skilled in the art, any improvements, substitutions, etc. made within the ideas and principles of the present invention will be deemed to be within the protection scope of the present invention.
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