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Conventional phase diffraction gratings can be used to localize the incoming optical radiation in the near‐field region. A new design of the binary phase diffraction grating is proposed with embedded pupil opaque mask inside each stripe. By means of numerical simulations, it is shown that with this masked phase grating the spatial resolution of the near‐field localization can be substantially improved and brought even beyond the solid immersion limit (λ/2n). Moreover, due to anomalous apodization effect, the subdiffraction field localization is accompanied by intensity enhancement as compared to the non‐masked design. The pupil mask rearranges the optical fluxes within the stripes and promotes the Fano resonances excitation in the periodic step lattice. This can be important for advancing the phase grating‐based super‐resolution technologies, including subdiffraction imaging, interferometry, and surface fabrication. 相似文献
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Focusing properties of the radially polarized axisymmetric Bessel-modulated Gaussian beam with quadratic radial dependence (QBG beam) and annular aperture are investigated theoretically by vector diffraction theory. Simulation results show that the intensity distribution in the focal region of the radially polarized axisymmetric QBG beam can be adjusted considerably by small beam parameter (μ) and annular aperture (δ). When μ increases, the focal spot may change to focal hole and changes focal pattern remarkably. On introducing annular aperture, focus can split or extends along the optical axis for different μ. In this paper, we have shown the generation of the focal spot, dark focal spot, focal split and increase in focal depth in the axial direction of the incident beam propagating through the aligned optical system. 相似文献
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Abstract This article presents a theoretical study of the dispersion properties of the asymmetrically apodized fiber Bragg gratings. It is shown that the dispersive behavior of these gratings may be changed from normal to anomalous, depending on the apodization function and the grating strength. The asymmetrical Bessel functions were chosen in order to demonstrate these properties of the gratings. The application of this effect in a dispersion-less Fabry-Pérot fiber cavity formed by two asymmetrically apodized fiber Bragg gratings is discussed. 相似文献
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为实时获取战场激光、大气污染物气体、毒气等待测物光谱信息的光谱复原,设计了基于现场可编程门阵列(FPGA) 的实时光谱采集分析系统。该系统选用迈克尔逊干涉具和碲镉汞探测器获取待测光谱信息,将采集到的数据传入FPGA。利用硬件描述语言VerilogHDL在Xilinx FPGA芯片上依据傅里叶变换(FFT)实现干涉条纹到光谱数据的实时处理。实验结果表明,FPGA实际计算1 024点基2-FFT频谱分布信息与Matlab理论计算结果相同,可满足实时光谱探测的要求。 相似文献
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Numerical investigation of slow solitons in Bragg gratings with a hyperbolic tangent apodization 下载免费PDF全文
This paper numerically and analytically investigates the formation and propagation motion of optical soliton in the Bragg grating.We choose the fibre Bragg grating with hyperbolic tangent apodization in the middle section in order to obtain slower solitons.Optical fibre soliton but not Bragg grating soliton is used as input pulse in the discussion,which is much more approximate to the light source for the practical purpose.We discuss in detail the effects of the soliton’s velocity with some parameters in the process of transmission.The results show that by choosing special parameters,one can make the soliton slow-down with a little distortion and energy decay and obtain tunable time-delay on a small scale. 相似文献
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Tatsuro Otaki 《Optical Review》2001,8(4):284-286
A new phase contrast microscopy technique has been developed which achieves halo reduction by applying an apodization to the Zernike phase contrast method. In this technique, a new apodized phase plate is placed at the back focal plane of the objective. This plate consists of a quarter wave phase shift ring conjugated of the illuminating aperture, which has a 25#x0025; transmittance, and a pair of adjacent rings having 50#x0025; transmittance. The developed technique yields the highest resolution images without a bluish hue effect ever achieved in phase contrast microscopy.This paper was originally presented at the 2nd International Conference on Optical Design and Fabrication, ODF2000 which was held on November 15-17, 2000 at the International Conference Center, Tokyo, Waseda University, Japan. 相似文献
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利用共焦扫描显微术和变迹术相结合实现光学超分辨 总被引:2,自引:0,他引:2
运用适当形式匠光瞳滤波器民成像系统点振响应的分布,歙 具心于冲击函数的形式,这样就有可能实现光学超分辨,但变迹术的运用往往会因其强烈的旁瓣效应而导致成像系统对比度的急剧下降。本文提出的共焦型超分辨方案则能有效地抑制上述旁瓣。此外,本文学进一瞠提出了实现三维光学超分辨手理论框轲。 相似文献
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