CAJ | 학술논문

太赫兹波成像技术一个最显著的制约因素是其有限的空间分辨率。提出通过在样品前加小孔的方法来提高传统太赫兹时域光谱装置成像的空间分辨率。采用在样品前约2mm处加直径为0.5mm小孔的方法使成像的空间分辨率从1.276mm提高到0.774mm，提高0.502mm，约39％。通过这个简单的方法在传统的太赫兹时域光谱成像装置上实现了空间分辨率从毫米量级到亚毫米量级的提高。聚乙烯板上直径为1mm的小孔被作为成像的研究对象，分别采用传统的太赫兹时域光谱装置对样品进行直接成像和在样品前约2mm处加直径为0.5mm的小孔后对样品成像两种方式，并采用损失成像中信噪比较好的能量损失成像，对比两种方式得到的样品的太赫兹像，结果显示聚乙烯板上小孔的边界加小孔后成像比不加小孔直接成像明显清晰。证实了在样品前加小孔可以有效的提高太赫兹成像系统的空间分辨率。从理论上对通过在样品前加小孔提高系统空间分辨率的方法进行了分析，指出小孔尺寸越小，系统的空间相干长度越大，空间分辨率越高，但同时太赫兹信号的强度会相应减小。该方法可以简单有效的提高太赫兹时域光谱装置成像的空间分辨率，从而进一步拓展太赫兹谱成像技术的应用领域。
태혁자파성상기술일개최현저적제약인소시기유한적공간분변솔。제출통과재양품전가소공적방법래제고전통태혁자시역광보장치성상적공간분변솔。채용재양품전약2mm처가직경위0.5mm소공적방법사성상적공간분변솔종1.276mm제고도0.774mm，제고0.502mm，약39％。통과저개간단적방법재전통적태혁자시역광보성상장치상실현료공간분변솔종호미량급도아호미량급적제고。취을희판상직경위1mm적소공피작위성상적연구대상，분별채용전통적태혁자시역광보장치대양품진행직접성상화재양품전약2mm처가직경위0.5mm적소공후대양품성상량충방식，병채용손실성상중신조비교호적능량손실성상，대비량충방식득도적양품적태혁자상，결과현시취을희판상소공적변계가소공후성상비불가소공직접성상명현청석。증실료재양품전가소공가이유효적제고태혁자성상계통적공간분변솔。종이론상대통과재양품전가소공제고계통공간분변솔적방법진행료분석，지출소공척촌월소，계통적공간상간장도월대，공간분변솔월고，단동시태혁자신호적강도회상응감소。해방법가이간단유효적제고태혁자시역광보장치성상적공간분변솔，종이진일보탁전태혁자보성상기술적응용영역。
Terahertz radiation is an electromagnetic radiation in the range between millimeter waves and far infrared .Due to its low energy and non-ionizing characters ,T Hz pulse imaging emerges as a novel tool in many fields ,such as material ,chemical , biological medicine ,and food safety .Limited spatial resolution is a significant restricting factor of terahertz imaging technology . Near field imaging method was proposed to improve the spatial resolution of terahertz system .Submillimeter scale’s spauial res-olution can be achieved if the income source size is smaller than the wawelength of the incoming source and the source is very close to the sample .But many changes were needed to the traditional terahertz time domain spectroscopy system ,and it’s very complex to analyze sample’s physical parameters through the terahertz signal .A method of inserting a pinhole upstream to the sample was first proposed in this article to improve the spatial resolution of traditional terahertz time domain spectroscopy sys-tem .The measured spatial resolution of terahertz time domain spectroscopy system by knife edge method can achieve spatial res-olution curves .The moving stage distance between 10% and 90% of the maximum signals respectively was defined as the spatial resolution of the system .Imaging spatial resolution of traditional terahertz time domain spectroscopy system was improved dra-matically after inserted a pinhole with diameter 0.5 mm ,2 mm upstream to the sample .Experimental results show that the spa-tial resolution has been improved from 1.276 mm to 0.774 mm ,with the increment about 39% .Though this simple method ,the spatial resolution of traditional terahertz time domain spectroscopy system was increased from millimeter scale to submillimeter scale .A pinhole with diameter 1 mm on a polyethylene plate was taken as sample to terahertz imaging study .The traditional ter-ahertz time domain spectroscopy system and pinhole inserted terahertz time domain spectroscopy system were applied in the ima-ging experiment respectively .The relative THz-power loss imaging of samples were use in this article .This method generally delivers the best signal to noise ratio in loss images ,dispersion effects are cancelled .Terahertz imaging results show that the sample’s boundary was more distinct after inserting the pinhole in front of sample .The results also conform that inserting pin-hole in front of sample can improve the imaging spatial resolution effectively .The theoretical analyses of the method which im-prove the spatial resolution by inserting a pinhole in front of sample were given in this article .The analyses also indicate that the smaller the pinhole size ,the longer spatial coherence length of the system ,the better spatial resolution of the system .At the same time the terahertz signal will be reduced accordingly .All the experimental results and theoretical analyses indicate that the method of inserting a pinhole in front of sample can improve the spatial resolution of traditional terahertz time domain spectrosco-py system effectively ,and it will further expand the application of terahertz imaging technology .