共查询到18条相似文献,搜索用时 234 毫秒
1.
基于散射式近场探测原理,设计并搭建了散射式太赫兹扫描近场光学显微系统(THz s-SNOM),实现了纳米量级空间分辨率的太赫兹近场显微成像测量。该系统以输出频率范围为0.1~0.3THz的太赫兹倍频模块为发射源,通过纳米探针的针尖产生纳米光源与样品相互作用,并将样品表面的倏逝波转化为可在远场测量的辐射波。通过探针逐点扫描样品表面,同时获得了样品表面的形貌图和太赫兹近场显微图。该系统的显微分辨率取决于探针针尖的曲率半径,而与太赫兹波的波长无关。使用该系统测量了金薄膜/硅衬底样品和石墨烯样品的近场显微图,结果表明,近场显微的空间分辨率优于60nm,波长与空间分辨率之比高达λ/26000。 相似文献
2.
由于连续太赫兹波辐射具有非常窄的频宽,在需要精细光谱分辨力的测量中具有重要应用。文中基于光子混频原理,采用两个独立的半导体激光器作为蝶形光电导天线的辐照光源,搭建了一个室温工作且可调谐的连续太赫兹波系统。重点讨论了太赫兹信号采集软件的设计;并对诊断模式、抽样模式以及连续模式下获得的信号进行了简要分析。 相似文献
3.
4.
设计并搭建了太赫兹光致力显微成像系统(THz PiFM),首次在太赫兹波段实现了近场光力纳米显微成像测量。该系统基于原子力显微镜,利用探针对所受力的灵敏检测能力,通过探测探针与样品之间近场偶极相互作用产生的光场梯度力,实现无探测器的太赫兹近场显微成像。利用该系统,对可见光激发下的单层MoS2晶粒进行了近场纳米显微成像表征,并分析了晶粒边缘近场光力信号增强的机制。研究结果表明,THz PiFM对二维材料中的载流子具有高灵敏的探测能力。与传统的太赫兹近场显微成像技术相比,THz PiFM无需太赫兹探测器,而且可获得更加优越的空间分辨率和成像信噪比,是一种低成本、高性能的新型太赫兹近场显微成像技术。 相似文献
5.
太赫兹辐射具有低光子能量和较高的透射性,并对水分子等极性物质反应敏感,因此太赫兹数字全息成像法可以快速准确地获取生物组织信息。本文利用太赫兹数字全息成像系统对猪肉和羊肉组织切片进行测量,采用菲涅耳反衍射方法对实验结果进行优化,选取0.9THz分量的振幅图像进行分析。通过计算组织的吸光度获取0.9THz吸光度图像。实验结果显示,肌肉组织的吸光度均在8cm~(-1)以上,脂肪组织的吸光度不超过4cm~(-1)。采用主成分分析方法获得吸光度得分图并进行重建,从重建结果中可以清晰区分生物组织的不同区域。由此表明,太赫兹数字全息成像技术能够直接获取生物组织的二维信息,探测时间短、效率高,在生物检测领域具有广阔的应用前景。 相似文献
6.
7.
8.
近年来,太赫兹科学技术受到了世界各国政府、企业和科技部门的高度重视,得到了迅猛的发展,这不仅是因为太赫兹波本身具有独特的性质,更因为太赫兹科学技术给人们展示了广阔的应用前景。本文首先对太赫兹波及其有关特性进行介绍,说明太赫兹科学技术具有重要的学术价值和重大的应用前景。其次,重点说明太赫兹辐射源和探测技术的发展,进而介绍我们实验室在太赫兹波谱与成像方面所开展的一些工作。最后,结合太赫兹光电子学重点实验室的建设,介绍我们实验室正在开展的研究工作。 相似文献
9.
为研究气体密度对多色激光诱导空气等离子体拉丝辐射太赫兹波的调控作用,建立了由激光拉丝辐射太赫兹波的理论模型。该模型可描述太赫兹波的产生和随后的传输过程,基于该模型和仿真计算,研究了气体密度对太赫兹辐射的影响。结果表明,气体密度会影响激光拉丝的瞬时电流分布与太赫兹波的传播相位,进而影响激光拉丝的太赫兹辐射强度,使太赫兹辐射能量随气体密度的变化呈现非线性变化。该理论研究对激光拉丝物理过程的认知具有重要的参考意义。 相似文献
10.
<正>太赫兹是新一代产业的科学技术基础。太赫兹科学综合了电子学与光子学的特色,是典型的交叉前沿科学领域,蕴含着原创性重大机理和方法并亟待突破,具有重大的科学意义。太赫兹波具有较强的穿透能力。与可见光、X射线、电子束、中红外、近红外和超声波等广泛应用于医学诊断、材料分析以及工业生产领域中的成像信号源相比,太赫兹波因其在电磁波谱中所处的特殊位置,使其对很多介电材料和非极性的液体具有良好的穿透性,因此太赫兹波的一个很有吸引力的前景就是,作为X射线成像和超声波成像等技术的补充,用于生物医学成像、安全检查或者无损探伤。电磁波谱最后的"处女"地太赫兹应用面非常广泛,可以用于生命科学、材料科 相似文献
11.
提出了一种适用于太赫兹频段、长距离传输的阶梯式宽带传输线.将2个基片集成波导(substrate integrated waveguide,SIW)分别置于一个矩形波导两端并分别呈直角转接,整个结构组成一级阶梯形状以实现波导口的空间位置平移.通过在矩形波导两端使用耦合窗的方法完成空气与基片介质之间无模式转换的转接.所提... 相似文献
12.
为满足"神光Ⅱ"升级激光装置实验的激光等离子体高空间分辨和窄带宽的精密成像诊断需求,本文研究球面弯晶单色成像技术,并对其进行优化设计及实验验证。首先,使用光线追迹方法分析了成像像距、布拉格角、背光源尺寸等成像系统参数对球面弯晶成像性能的影响,分析了设计参数的变化对成像空间分辨能力的影响,并在X射线管上开展了测试验证实验。研究结果表明:二维成像时,在等分辨成像像距处可以获得较好的成像结果,增大布拉格角可以抑制像差进而提高成像质量,更小的背光源尺寸也有助于提高成像的空间分辨率。测试实验获得了清晰的网格背光成像,成像结果与预期相符,空间分辨率优于14μm。这一工作有助于球面弯晶成像系统的优化设计及其在激光等离子体精密诊断中的应用。 相似文献
13.
Backscattered electron imaging and scanning transmission electron microscopy imaging of multi-layers
Experimental and theoretical results on image contrast of semiconductor multi-layers in scanning electron microscopy investigation are reported. Two imaging modes have been considered: backscattered electron imaging of bulk specimen and scanning transmission imaging of thinned specimens. The following main results have been reached. The image resolution of the multi-layers is, in both cases, defined by the probe size. The contrast, governed by density and atomic number differences, is affected by the size of the interaction volume in backscattered electron imaging and by the beam broadening in scanning transmission. Operating in the scanning transmission mode, the contrast of bright field images can be easily related to local variation in atomic number and density of the specimen while the dark field image contrast is strongly affected by electron beam energy, detector collection angles and specimen thickness. All these factors are able to produce contrast reversals that are difficult to explain without the support of a suitable simulation code. 相似文献
14.
A. A. Mamrashev O. I. Potaturkin 《Optoelectronics, Instrumentation and Data Processing》2011,47(4):332-337
Characteristics of a system of polarization-optical detection of a pulsed terahertz spectrometer in nonlinear crystals of
zinc telluride (ZnTe) are considered. The influence of the ZnTe crystal thickness (0.5, 1, and 2 mm) on the detection system
sensitivity is studied experimentally; a comparison with model calculations is performed. The effect of the time step and
the interval of scanning of the terahertz pulse on the spectral resolution and range of the spectrometer is demonstrated experimentally
and theoretically. Terahertz transmission spectra of typical container materials are measured. 相似文献
15.
16.
Scanning luminescence X-ray microscopy is based on the use of the very small focused probe of a scanning X-ray microscope to stimulate visible light emission from phosphors and dyes. Using an undulator X-ray source and a Fresnel zone plate to produce a focused X-ray probe, images of P31 phosphor grains with a resolution of 50–75 nm have been obtained, and luminescence from polystyrene spheres loaded with 50–100 μmol/g of fluorescent dye has been imaged. The resolution was not limited by the focused X-ray probe (the microscope has imaged features at 36-nm spacing in transmission mode) but by dark noise and the low net efficiency of the luminescence detection system used for this investigation. This technique may make it possible to image dye-tagged sites of biochemical activity at the resolution of the X-ray microscope in wet, unsectioned, and unfixed cells, especially with soft X-ray optimized dyes. Because the image is formed from the detection of signal against a dark background, calculations suggest that the radiation dose for luminescence imaging of dye-tagged features should be 2–22 times lower than it is in transmission X-ray microscopy. A possible extension of the technique for three-dimensional imaging at the transverse resolution of the X-ray microscope is described, where visible light collection optics might be used to obtain submicrometre axial resolution. 相似文献
17.
18.
Deninger AJ Göbel T Schönherr D Kinder T Roggenbuck A Köberle M Lison F Müller-Wirts T Meissner P 《The Review of scientific instruments》2008,79(4):044702
We realized a tunable continuous-wave terahertz source with megahertz frequency resolution. The system is based on optical heterodyning of two near-infrared distributed feedback diode lasers, each laser being stabilized by electronic feedback from a low-finesse quadrature interferometer. The control loop permits precisely linear laser frequency scans over >1200 GHz, and a beat signal linewidth of 1 MHz at 80 ms time scale. Using GaAs photomixers and log-periodic antennae, we achieve a signal-to-noise ratio of the terahertz power of >70 dB at 100 GHz and 100 ms integration time, and still approximately 30 dB at 1 THz. As an example for high-resolution terahertz spectroscopy, we characterize the transmission properties of a subwavelength metal grating. 相似文献