共查询到20条相似文献,搜索用时 15 毫秒
1.
B. Grześkiewicz A. Sierakowski J. Marczewski N. Pałka E. Wolarz 《Opto-Electronics Review》2018,26(4):329-337
We report on the absorption properties of polarization-insensitive transmissive and reflective metamaterial absorbers based on two planar aluminium periodic structures and SU-8 epoxy resist. These absorbers were investigated using numerical simulation and experimental methods in the terahertz range (below 2 THz). SU-8 is a very promising organic material for dielectric layers in planar metamaterials, because its application simplifies the process of fabricating these structures and significantly reduces the fabrication time. The experimental absorption of the metamaterial absorbers has narrowband characteristics that were consistent with the numerical simulations. Power flow analysis in the transmissive metamaterial unit cell shows that the absorption in the terahertz range occurs primarily in the SU-8 layer of the absorber. 相似文献
2.
为满足红外热像仪MRTD野外在线全自动检测要求,设计了一种新型MRTD检测方法。硬件采用单黑体温差控制技术,在减小检测设备体积质量的同时保证了黑体目标与环境背景的温差控制精度,采用串口通信控制与CCD图像采集处理等技术有机结合实现温差控制及图像采集处理的协调统一;在软件上采用优化的处理算法精确地提取目标及背景区域,并利用不同温差下目标与背景区域的灰度差计算出被测热像仪MRTD参数值。经实验检验,该结果与人眼观测所得结果误差在002℃以内,研制出的检测设备具有结构简单、体积及质量小、操作简便等优点。 相似文献
3.
为满足红外热像仪MRTD野外在线全自动检测要求,设计了一种新型MRTD检测方法。硬件采用单黑体温差控制技术,在减小检测设备体积质量的同时保证了黑体目标与环境背景的温差控制精度,采用串口通信控制与CCD图像采集处理等技术有机结合实现温差控制及图像采集处理的协调统一;在软件上采用优化的处理算法精确地提取目标及背景区域,并利用不同温差下目标与背景区域的灰度差计算出被测热像仪MRTD参数值。经实验检验,该结果与人眼观测所得结果误差在002℃以内,研制出的检测设备具有结构简单、体积及质量小、操作简便等优点。 相似文献
4.
C. Rockstuhl T. Zentgraf H. Guo N. Liu C. Etrich I. Loa K. Syassen J. Kuhl F. Lederer H. Giessen 《Applied physics. B, Lasers and optics》2006,84(1-2):219-227
We study the spectral response of optical metamaterials consisting of gold split-ring resonators. We utilize reflection spectroscopy
in the near infrared region at normal incidence in the experiments. Our theoretical modeling is based on rigorous diffraction
theory. We perform a comprehensive analysis of the dependence of the features of both the electric and the oscillating-circuit
resonance on the geometry of the metamaterial. We show that theory and experiment are in good agreement.
PACS 73.20.Mf; 78.67.-n; 78.66.Sq; 78.67.Bf 相似文献
5.
6.
The emission spectra of thermally stimulated surface plasmon polaritons (thermally stimulated surface plasmon polaritons) and a blackbody have been analyzed and compared, and the temperature dependence of these spectra has been studied. It has been found that the total energy of the entire ensemble of surface plasmons is proportional to the cube of temperature and their spectrum is red-shifted from the blackbody spectrum. It has been shown that the spectrum of thermally stimulated surface plasmon polaritons obeys the Wien’s displacement law, yet with another constant. The fraction of the photon energy of the conducting layer transferred to the surface plasmons has been estimated. It has been demonstrated numerically by the example of a gold layer that this fraction can exceed 10% for a layer thickness of less than 1 mm. 相似文献
7.
8.
高精度非致冷长波红外热像仪的辐射标定 总被引:2,自引:0,他引:2
为使非致冷长波红外热像仪在不同温度下保持较高的测温精度,建立了考虑探测器工作温度效应的非致冷长波红外热像仪的辐射标定模型。对非致冷长波红外热像仪进行辐射标定实验,在不同黑体温度和不同亮度增益值条件下,获得了16组图像灰度与探测器工作温度之间的函数关系,建立了目标温度的数学计算模型,并对定标结果进行了实验验证。结果表明:在25~40℃,探测器的工作温度效应可做线性化处理,且与目标温度无关。通过设定合适的亮度增益值可使红外热像仪的测温误差〈0.5℃,极大地提高了非致冷长波红外热像仪在不同温度环境下的测温精度。 相似文献
9.
10.
11.
Designing nonlinear thermal devices and metamaterials under the Fourier law: A route to nonlinear thermotics 总被引:1,自引:0,他引:1
Gao-Le Dai 《Frontiers of Physics》2021,16(5):53301
Nonlinear heat transfer can be exploited to reveal novel transport phenomena and thus enhance people’s ability to manipulate heat flux at will. However, there has not been a mature discipline called nonlinear thermotics like its counterpart in optics or acoustics to make a systematic summary of relevant researches. In the current review, we focus on recent progress in an important part of nonlinear heat transfer, i.e., tailoring nonlinear thermal devices and metamaterials under the Fourier law, especially with temperature-dependent thermal conductivities. We will present the basic designing techniques including solving the equation directly and the transformation theory. Tuning nonlinearity coming from multi-physical effects, and how to calculate effective properties of nonlinear conductive composites using the effective medium theory are also included. Based on these theories, researchers have successfully designed various functional materials and devices such as the thermal diodes, thermal transistors, thermal memory elements, energy-free thermostats, and intelligent thermal materials, and some of them have also been realized in experiments. Further, these phenomenological works can provide a feasible route for the development of nonlinear thermotics. 相似文献
12.
A blackbody cavity is used as a temperature sensor for measuring the average temperature of the molten liquid. Due to the deviation of fabrication and installation, the detector usually receives the radiation from the different regions of the measuring cavity, so the local effective emissivity distribution is an important parameter to evaluate the measuring temperature discrepancy of a blackbody cavity sensor. We introduced the net-radiation method into the finite element method and extended it to calculate the local effective emissivity of blackbody cavities. It was applied to three typical cavities, and the calculated results are in very well agreement with those in references. This method is simple, easy to use, replicable, and very suitable to evaluate and design a novel cavity. 相似文献
13.
14.
The spectral thermal emission of LiF slabs on metallic substrate is measured for different polarizations in the wavelength region between 30 μm and 130 μm at a temperature of 523 K. The thickness of the slabs varies from 0.26 μm to 26 μm. We observe various resonances, whose number and positions depend on the thickness and the angle of the emitted radiation. The experimental results are compared with the theory of Kliewer and Fuchs. 相似文献
15.
Inhibitory coupled bursting Hindmarsh-Rose neurons are considered as constitutive units of the Macaque cortical network. In the absence of information transmission delay the bursting activity is desynchronized,giving rise to spatiotemporally disordered dynamics. This paper shows that the introduction of finite delays can lead to the synchronization of bursting and thus to the emergence of coherent propagating fronts of excitation in the space-time domain. Moreover,it shows that the type of synchronous bursting is uniquely determined by the delay length,with the transitions from one type to the other occurring in a step-like manner depending on the delay. Interestingly,as the delay is tuned close to the transition points,the synchronization deteriorates,which implies the coexistence of different bursting attractors. These phenomena can be observed by different but fixed coupling strengths,thus indicating a new role for information transmission delays in realistic neuronal networks. 相似文献
16.
17.
The thermal infrared imaging system is of greatest importance in modern optics and the image quality closely relies on the accuracy of the optical system. Heat-induced mirror deformation influences the transmission performance of the optical antenna system significantly, which further degrades the accuracy of the whole system. In this work, the simulation on lens deformation circumstances under the thermal environment is carried out using the finite-element analysis software ANSYS. The focus shift property caused by the thermal effect is studied in the cases of reflective and refractive Cassegrain optical antennas, and the athermalizing performance of Cassegrain optical antenna system is also concluded. This work presents a direction to accurate designing of the thermal infrared optical system. 相似文献
18.
W. Eckhardt 《Zeitschrift für Physik B Condensed Matter》1977,26(3):291-297
Electromagnetic equilibrium fluctuations in cavities with non ideal metallic walls are considered. On the boundary the electric and magnetic fields are connected by Leontovich's boundary condition. With the aid of Maxwell's equations and Leontovich's relation the response of the EM-field to a polarization field is calculated. The correlation functions of the EM-field are then given by the fluctuation dissipation theorem. For cube shaped cavities explicit considerations are made. Expressing the surface impedance by a frequency independent conductivity the volume averaged autocorrelation functions of the EM-field and the total energy density are calculated. Besides the contributions due to the normal modes an additional term is found which characterizes the contributions due to the evanescent waves existing near the internal surface of the cavity. As a consequence of the frequency dependence of the impedance this term shows aT
7/2 dependence. 相似文献
19.
Gunnar Myhre Frode Stordal Ingvil Gausemel Emanuel Mahieu 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,97(3):317-331
We estimate a current direct radiative forcing due to CFC-12 of 0.18 Wm-2, which is likely to be the peak radiative forcing for CFC-12. Global measurements of CFC-12 show at present an almost negligible trend for CFC-12 and measurement in an industrialized region show evidence that the peak concentration is reached. It is expected that concentration of CFC-12 in industrialized regions begins to decline 1-3 years before the global concentration.Our radiative forcing calculations are based on a line-by-line model appropriate for simulation of global mean radiative forcing, including clouds and stratospheric temperature adjustment. The radiative forcing of 0.33 Wm-2/ppbv is close to earlier published results for this compound. New spectroscopic measurements for CFC-12 are performed and compared to previously published results. 相似文献