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41.
We propose a new approach for generating multiple focal hole segment of sub wavelength size, by tight focusing of phase modulated annular multi-Gaussian beam. The focusing properties are investigated theoretically by vector diffraction theory. We observed that focal segment with multiple focal rings structure separated with different axial distance can be generated by properly tuning the phase of the incident azimuthally polarized annular multi-Gaussian beam. Potential applications of this focal shaping technique are also discussed. 相似文献
42.
Daw Don Cheam Karl A. Walczak Manoranjan ArchayaCraig R. Friedrich Paul L. Bergstrom 《Microelectronic Engineering》2011,88(8):1906-1909
Focus ion beam (FIB) technology has been employed to fabricate quantum dot based devices such as the single electron transistor (SET) on a silicon substrate with Cr/Au/Al2O3 film stack. It was discovered that the dwell time of FIB gallium beam on an area impacted the dosage of gallium ions implanted into the insulating substrate, creating a highly doped region which could lead to device leakage current. This work focus on the potential electron transport possible when an over-dosed gallium rich Al2O3 layer will lead to leakage current between otherwise electrically isolated contact pads. Using the Keithley 4200 semiconductor parametric analyzer (SPA) and the energy dispersive X-ray spectrometer (EDS) analysis; we demonstrate the detrimental effect of leakage current in the range of pA, observed between drain/source electrodes due to the high dose of gallium implanted into the insulating Al2O3. The optimized FIB etching parameters to produce a high quality of device functionality with no leakage current is also demonstrated. 相似文献
43.
主题模型是用于识别博客、网络社区、微博等社交网络平台上用户关注点的重要手段。考虑到社交网络平台上短文本主题识别的特殊性,该文根据短文本内容在上下文上的相关性,提出一种基于混合权重合并策略的AW-LDA模型。该模型将符合上下文相关条件的短文本进行虚拟合并,并根据上下文相关程度对不同短文本赋予不同的权重,构建了一种新的短文本主题识别方法。通过网络BBS社区与微博社区两组数据的实验,该模型能够有效识别不同话题下社交网络用户关注点,为解决短文本主题识别问题提供了新的解决思路。 相似文献
44.
光学PICK UP技术概要 总被引:1,自引:1,他引:0
光学PICK UP是CD-ROM驱动器的关键部件,它能够把光盘上的信息凹坑和非凹坑的长度和跳变沿转换成电信号,并产生聚集误差信号和道跟踪误差信号。文中简单介绍了光学PICK UP的工作原理,结构和有关技术。 相似文献
45.
B. Iwan J. Andreasson A. Andrejczuk E. Abreu M. Bergh C. Caleman A.J. Nelson S. Bajt J. Chalupsky H.N. Chapman R.R. Fäustlin V. Hajkova P.A. Heimann B. Hjörvarsson L. Juha D. Klinger J. Krzywinski B. Nagler G.K. Pálsson W. Singer M.M. Seibert R. Sobierajski S. Toleikis T. Tschentscher S.M. Vinko R.W. Lee J. Hajdu N. Tîmneanu 《High Energy Density Physics》2011,7(4):336-342
Pulse intensities greater than 1017 Watt/cm2 were reached at the FLASH soft X-ray laser in Hamburg, Germany, using an off-axis parabolic mirror to focus 15 fs pulses of 5–70 μJ energy at 13.5 nm wavelength to a micron-sized spot. We describe the interaction of such pulses with niobium and vanadium targets and their deuterides. The beam produced craters in the solid targets, and we measured the kinetic energy of ions ejected from these craters. Ions with several keV kinetic energy were observed from craters approaching 5 μm in depth when the sample was at best focus. We also observed the onset of saturation in both ion acceleration and ablation with pulse intensities exceeding 1016 W/cm2, when the highest detected ion energies and the crater depths tend to saturate with increasing intensity.A general difficulty in working with micron and sub-micron focusing optics is finding the exact focus of the beam inside a vacuum chamber. Here we propose a direct method to measure the focal position to a resolution better than the Rayleigh length. The method is based on the correlation between the energies of ejected ions and the physical dimensions of the craters. We find that the focus position can be quickly determined from the ion time-of-flight (TOF) data as the target is scanned through the expected focal region. The method does not require external access to the sample or venting the vacuum chamber. Profile fitting employed to analyze the TOF data can extend resolution beyond the actual scanning step size. 相似文献
46.
Nicolae Vulpe 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(17):6553-6582
This article is about weak singularities of quadratic differential systems, that is, non-degenerate singular points with traces of the corresponding linearized systems at such points equal to zero. These could be foci, centers or saddles. Necessary and sufficient conditions for a real quadratic system to possess a fixed number of weak singularities of a specific order are given. The conditions are stated in terms of affine invariant polynomials in the 12-dimensional space of the coefficients. 相似文献
47.
上海永新彩色显像管股份有限公司技术开发中心基础设计研发QC小组 《电子质量》2004,(8):32-35,45
本文主要介绍了SFCE单聚焦电子枪设计开发的整个组织过程和实施. 相似文献
48.
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50.
Hai-Long Wang Qun Wu Hang Su Fan-Yi Meng Jian Wu 《International Journal of Infrared and Millimeter Waves》2008,29(2):157-166
The electric field properties of the horizontal dipole radiation in the presence of a lossless metamaterial sphere are investigated.
First, the solution of the electromagnetic field of the model could be obtained. Second, the near field properties are investigated
according to the electromagnetic and geometrical parameters. It could be seen that in the metamaterial sphere, the focusing
phenomenon is obviously observed. It is in consistent with the analysis. Throughout the article, the conventional sphere is
utilized as reference. No focus is observed in the conventional material sphere as it does not have the characteristic of
negative refraction. 相似文献