共查询到20条相似文献,搜索用时 15 毫秒
1.
Multislit entrance apertures and corresponding sequences of numbers, which are simpler and more efficient than available analogs, are proposed for application in static multislit dispersive optical spectroscopy. The use of reflective multislit entrance apertures based on the proposed sequences allows one to achieve a two-fold increase in the light flux in a spectrometer in comparison with nonreflective apertures. The proposed apertures are of interest for studying low-intensity radiations and time-dependent processes in solid-state spectroscopy. 相似文献
2.
Experimental study is performed of optical diffractions by two-dimensional, self-similar mass and surface fractal apertures as well as mass fractal apertures bounded by surface fractals. Self-similar intensity distributions are observed in the Fraunhofer diffraction fields from surface and mass fractal apertures. Power law decays in average intensities of the diffraction patterns are also investigated for the mass, surface and combined fractal apertures in connection with the fractal dimensions of the objects. 相似文献
3.
Q-Han Park 《Contemporary Physics》2013,54(2):407-423
Optical antenna is a nanoscale miniaturisation of radio or microwave antennas that is also governed by the rule of plasmonics. We introduce various types of optical antenna and make an overview of recent developments in optical antenna research. The role of local and surface plasmons in optical antenna is explained through antenna resonance and resonance conditions for specific metal structures are explicitly obtained. A strong electric field is shown to exist within a highly localised region of optical antennas such as antenna feed gap or apertures. We describe physical properties of field enhancement in apertures (circular and rectangular holes) and gaps (infinite slit and feed gap), as well as experimental techniques measuring enhanced electric vector field. We discuss the analogies and differences between conventional and optical antennas with a projection for future developments. 相似文献
4.
Confocal microscopy with serrated divided apertures is presented. Compared with using two smooth D-shaped apertures in confocal microscopy, the serrated divided apertures can suppress the out-of-focus central bright spot, thus increasing the efficiency of rejection of scattered light. Diffraction analysis shows that the serrated apertures maintain the optical sectioning strength while attenuating the background coming from far from the focal plane. In addition, the signal to background ratio (S/B) is also improved. 相似文献
5.
We propose a multi-aperture slow-light laser radar with two-dimensional scanning. We demonstrate experimentally that we can use two independent slow-light mechanisms, namely dispersive delay and stimulated Brillouin scattering, to dynamically compensate the group delay mismatch among different apertures, while we use optical phase locking to control the relative phases of the optical signals emitted from different apertures, as the system steers the beam in two dimensions. 相似文献
6.
A. M. Hamed 《Optics & Laser Technology》1984,16(2):93-96
A theoretical study is made of a simple method of obstructing an amplitude pupil which results in improved microscope resolution with only a little degradation of the image contrast. Using a confocal scanning optical microscope the resultant point spread function is calculated, from which the image of a point object is deduced. The calculations are made for two different apertures — the first has four-fold symmetry and the second has eight-fold symmetry — and are compared with full circular and annular apertures. 相似文献
7.
The development of simple to prepare, polarization‐sensitive plasmonic apertures with two plasmonic modes, is described. To achieve these results, monocrystalline nanosphere lithography masks of 438 nm polystyrene spheres are modified with reactive ion etching before silver is subsequently evaporated through the mask at varied angles. As the angle of evaporation increases, round apertures, elliptical apertures or lines with bow‐tie like features between two lines are produced. A primary plasmon mode is shown at 570 nm, while a tunable plasmon mode is demonstrated between 700 nm and 900 nm. Finite‐difference time‐domain calculations agree with the observed results and predict that this method of fabrication can produce tunable plasmonic features throughout the NIR optical telecommunication wavelength range. Lastly, the excitation polarization angle is compared with that of plasmonic nanorods and asymmetric nano‐apertures systems to describe why the excitation polarization of the low energy mode is orthogonal to the long axis of the apertures. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
8.
通过研究激光在湍流大气中的传输情况,旨在为光学高分辨率干涉成像提供理论依据。采用相位屏的近似处理方法对激光通过大气湍流传输进行模拟,研究激光通过湍流大气的干涉情况。试验结果表明:孔径间距越大,干涉条纹越密;在传输距离为2km,大气湍流折射率结构常数C2n为10-14,即接近强湍流的情况下,可以形成比较好的干涉条纹。孔径间距较小时,干涉的明暗条纹清晰可见。在实际干涉成像中,可以选择适当的孔径间距来获得较好的干涉条纹,从而获得目标的高分辨率像。 相似文献
9.
In this paper, the enhanced optical transmission through a special type of aperture of a bowtie shape is investigated through
near-field imaging and finite-difference numerical analysis. Under linear polarizations in two orthogonal directions, the
optical near fields of the bowtie aperture and comparable square and rectangular apertures made in gold and chromium thin
films are measured and compared. The bowtie aperture is able to provide a nanometer-sized optical spot when the incident light
is polarized across the bowtie gap and delivers a considerable amount of light. Localized surface plasmons are clearly observed
in the near-field images for both bowtie and rectangular apertures in gold, but invisible in chromium. Finite-difference time-domain
calculations reveal that, depending on the polarization of the incident light, the unique optical properties of the bowtie
aperture are a result of either the optical waveguide and the coupled surface plasmon polariton modes existing in the bowtie
gap or the coupling between the two open arms of the bowtie aperture.
PACS 81.07.-b; 07.79.Fc; 71.36.+c; 78.66.Bz; 42.79.Gn; 42.79.Vb 相似文献
10.
Hard-edge apertures are common devices in optical systems. The light beam would be diffracted while transmitting through an aperture. The diffraction characteristics of terahertz (THz) beam passing through two hard-edge apertures have been simulated based on the Fresnel diffraction integral function, and an approximate parallel beam has been obtained. The effect on the diffraction spot has been compared and analyzed by changing the aperture diameter and distance between the two apertures and the diffraction plane. Then the experimental results were presented, which basically accorded with the numerical results. It can be inferred that the diameter of THz beam diminishes and the divergence angle can be neglected after the restriction of two apertures. The method is preferably available in some experiments which require small beam diameter and divergence angle. 相似文献
11.
12.
Xiaolei Wen Luis M. Traverso Pornsak Srisungsitthisunti Xianfan Xu Euclid E. Moon 《Applied Physics A: Materials Science & Processing》2014,117(1):307-311
We report optical parallel nanolithography using bowtie apertures with the help of the interferometric-spatial-phase-imaging (ISPI) technique. The ISPI system can detect and control the distance between the bowtie aperture, and photoresist with a resolution of sub-nanometer level. It overcomes the difficulties brought by the light divergence of bowtie apertures. Parallel nanolithography with feature size of 22 ± 5 nm is achieved. This technique combines high resolution, parallel throughput, and low cost, which is promising for practical applications. 相似文献
13.
The intensity point spread functions and the optical transfer functions for focussed and defocussed optical systems with slit shaped rectangular apertures are given. Focussed and defocussed systems with point spread functions of similar size are compared. An application to the incoherent processing of geological data is described. 相似文献
14.
Arpad Barna 《Optics Communications》1978,26(3):284-288
The far-field diffraction pattern of apodized semicircular apertures is described. The exact amplitude is given using incomplete cylinder functions. The paper also presents a simple approximation for the intensity that is suitable for further computations when the aperture is part of an optical system. 相似文献
15.
Nicholas Murphy-DuBay Liang Wang X. Xu 《Applied Physics A: Materials Science & Processing》2008,93(4):881-884
Nanoscale ridge apertures provide a highly confined radiation spot with a high transmission efficiency when used in the near
field approach. The radiation confinement and enhancement is due to the electric–magnetic field concentrated in the gap between
the ridges. This paper reports the experimental demonstration of radiation enhancement using such antenna apertures and lithography
of nanometer size structures. The process utilizes a NSOM (near field scanning optical microscopy) probe with a ridge aperture
at the tip, and it combines the nonlinear two photon effect from femtosecond laser irradiation to achieve sub-diffraction
limit lithography resolution. 相似文献
16.
Numerical simulations have been carried out in the framework of waveguide theory to model collection mode scanning near-field
optical microscopy (SNOM). The theoretical model includes the optical fiber end and describes the metal coated aperture on
the probe tip. The developed formalism goes beyond the existing Bethe-Bouwkamp theories for electromagnetic transmission of
subwavelength apertures. The finite coating and optical fiber end are now taken into account. The new features enable us to
simulate the near-field probes that are widely used in the collection mode SNOM. The emphases of the numerical analyses have
been mainly on the resolution mechanism of the microscopy. Influence on the resolution from important parameters of the probe
tips, such as the size of the apertures and the probe-sample distance, is extensively studied. The resolution dependence has
been analyzed in the light of the near-field coupling efficiency of the probe tip. An optimum tip size has been found which
is balanced between the significant signal transmission and the resolution of the device. 相似文献
17.
A multiple image cryptosystem based on different apertures in an optical set-up under a holographic arrangement is proposed. The system is a security architecture that uses different pupil aperture mask in the encoding lens to encrypt different images. Based on this approach multiple encryption is achieved by changing the pupil aperture arrangement of the optical system among exposures. In addition to the classical speckle phase mask, the geometrical parameters characterizing the apertures are introduced to increase the system security. Even when an illegal user steals the speckle phase mask, the system cannot be broken into without the correct pupil geometrical parameters. The experimental set-up is based on a volume photorefractive BSO crystal as storing device. Information retrieval is done via a phase conjugation operation. We also have to stress that the multiple storage under this scheme, is only possible with the help of the aperture mask. Simulation and experimental results are further introduced to verify the proposed method. 相似文献
18.
小孔阵列衍射特性与应用 总被引:5,自引:4,他引:1
以单色标量波衍射理论为基础,研究了均匀平面波从不同角度入射小孔阵列的衍射特性。运用单孔衍射理论,同时考虑相邻小孔间衍射光强的相互影响,建立了小孔阵列衍射的理论模型和光强分布的数值积分式,小孔为硬边小孔。利用Matlab对500 nm波长的平面波入射微小方孔阵列衍射图样进行了计算机仿真,得到了不同几何参量下平面波从不同角度入射时的衍射图样的一维和二维光强分布图,并将仿真结果用于微型数字式太阳敏感器的光学系统中的结构参量设计和图像处理中的参量确定。太阳敏感器的成像实验结果表明,小孔阵列衍射光强分布图的仿真结果正确、太阳敏感器光学系统参量设计合理。小孔阵列衍射理论为太阳敏感器的光学系统设计和图像处理提供了可靠的理论基础。 相似文献
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20.
N. N. Salashchenko A. S. Skryl’ M. N. Toropko N. I. Chkhalo 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2011,5(3):512-516
The design of an aspheric Schwarzschild lens applicable to a nanolithographic test bench with an operating wavelength of 13.5
nm is discussed. Lenses with numerical apertures of 0.3 and 0.4 are examined. The influence of lens aberrations and deviations
of optical scheme parameters from rated values on the image quality is analyzed. 相似文献