共查询到19条相似文献,搜索用时 109 毫秒
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提出了一种基于谱域相位分辨光学相干层析的纳米级表面形貌成像方法,由干涉光谱计算样品相邻两点的相位差,得到样品表面相位差分图,经过积分,重建样品表面形貌的定量分布.当相邻两点相位差的绝对值小于π,不产生相位包裹,避免了目前的干涉法相位解包裹存在的问题,将干涉法相邻两点相位差绝对值的限制条件由目前的π扩大到2π,提高了干涉法表面形貌成像的适用范围.参考面和样品置于同一平台之上,消除环境干扰及系统振动的影响,噪声幅度小于0.3 nm.通过对光学分辨率片及表面粗糙度标准样板的表面形貌成像,对本方法进行了验证,系统的轴向分辨率优于1 nm. 相似文献
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发展了一种新型相位共轭干涉法可用于简单方面地测定介质三次非线性极化率的相位。文中用这种方法研究了二种染料掺杂高分子膜X^(3)的相位,发现由饱和吸收效应产生的X^(3)的相位,当波长远离吸收峰时,由-π/2趋于-π,而由光到漂白效应产生的X^(3)的相位都落在-17/18π附近。 相似文献
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提高声全息成像分辨率的有限频谱重建法 总被引:2,自引:0,他引:2
本文提出用脉冲波声全息提高成像分辨率(特别是纵向分辨率)的新方法。理论分析及模拟计算表明,利用脉冲信号的有限谱分析及成像系统对有限谱的响应,脉冲波的全息重建比连续波具有较高的分辨率。在此基础上,利用重建波相位识别及解卷技术,能进一步提高其分辨率。 相似文献
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对时间成像理论进行简要研究. 利用电光相位调制器进行光脉冲压缩实验,并分别对基于电光相位调制和交叉相位调制的时间透镜组成的时间成像系统进行了仿真和讨论. 实验结果表明,基于电光相位调制的时间透镜组成的时间成像系统可以有效压缩光脉冲,但是该系统受到了孔径限制,压缩系数较小,分辨率较低. 进一步的仿真分析结果表明,基于交叉相位调制的时间透镜组成的时间成像系统不受孔径限制,能够获得更大的压缩系数和更高的分辨率,但是该系统的实现难度较大.
关键词:
光脉冲压缩
时间透镜
电光相位调制
交叉相位调制 相似文献
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Humberto Garcilazo 《Nuclear Physics A》1983,408(3):559-572
Bound-state solutions for the system composed of a pion and two nucleons are studied, and it is shown that their existence is essentially determined by the range of the πN interaction in momentum space. The relativistic Faddeev equations are solved to search for bound-state solutions of a negative pion and two neutrons, using the newly constructed πN separable potentials that reproduce the phase shift of the P33 channel from 0 to 350 MeV, and realistic NN interactions such as the Reid soft-core, Paris, and Malfliet-Tjon potentials. It is found that bound-state solutions are possible for some of the πN interactions that have very long range in momentum space. 相似文献
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π相移光纤光栅用于水中超声传感时,超声波沿光纤轴向入射和垂直光纤入射时的传感波形及幅度显著不同。针对这一现象,本文建立了基于光学传递矩阵的光纤光栅声传感理论模型,计算了超声波分别沿轴向和沿垂直方向入射时π相移光纤光栅中的非均匀应变场分布,进而分析了光谱偏移,揭示了两种入射角度下π相移光纤光栅的传感特性与声传播导致的应变场分布相关,并通过实验进行了验证。结果表明,两种入射角度产生的不同的非均匀应变场分布对π相移光纤光栅的传感特性影响明显。超声波垂直入射时的传感波形和幅度均优于轴向入射,且π相移处对传感有显著作用。当入射位置远离π相移处时,垂直入射的响应也明显降低。本研究可为π相移光纤光栅超声传感的机理分析提供参考。 相似文献
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提出了外腔延时反馈半导体激光器法拉第效应控制下的新激光系统, 构造出两种类型结构光路, 建立了法拉第效应控制下的延时负反馈、延时正反馈激光动力学物理模型, 研究了激光混沌控制与反控制等. 利用法拉第效应原理及磁致旋光性和系统特点, 调节控制光路中的光旋转角度和光延时间可实现双参数控制激光器, 控制激光到双周期、三周期及多周期, 使激光产生拍动等现象, 反控制激光周期到混沌等. 发现了以磁致旋光角分布的激光混沌控制与反控制区域. 并研究了激光混沌控制与周期控制的动态情况, 演示讨论了激光态的转化演变过程等. 相似文献
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In the limit where the pion is assumed to be emitted only by the nucleon which first absorbed it, we show that the equations we developed in order to describe the coupled πNN(πd)-NN system do reduce to three-body equations of conventional (Faddeev or Alt-Grassberger-Sandhas) type. Specifically, it is found in this limit that the input πNp11t-matrix which, when put on-shell, is related to the experimental phase shift, in contrast to the original equations where the direct (dressed) nucleon pole contribution and the remainder (the non-pole contribution) of this partial wave enter separately. The present study serves to clarify the limitation of the three-body approach to the coupled πNN-NN problem as well as to suggest a rare opportunity of observing a possible resonance-like behavior of the non-pole part of the πN P11 amplitude through the πd scattering. 相似文献
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K. V. Nerkararyan T. S. Yezekyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2018,53(4):332-337
The relaxation dynamics of a quantum dipole emitter coupled to a metal nanostructure in the presence of an external resonant pump field is studied. It was found that in the mode of weak pumping, the phase of the response from a metallic nanostructure plays a key role in the dynamics of the quantum dipole emitter and allows one to control the fluorescence process. It is shown that when the phase shift is set close to π/2, the quantum emitter makes a quick transition into the ground state, then slowly passes into a superposition state with a small probability to remain in an excited state. Meanwhile, in the case of phase shift values close to 3π/2, the system relaxes into a stationary superposition state where the probability to be in the excited state is close to unity. It was established that the dynamics of the system also depends on the intensity of the external field and with the amplification of the latter, the system enters into the mode of the asymmetric Rabi oscillations. 相似文献
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Y.H. Huang S.Y. HungFarrokh Janabi-Sharifi W. WangY.S. Liu 《Optics and Lasers in Engineering》2012,50(4):534-539
The rapid progress of modern manufacturing and inspection technologies has posed stringent requirements on optical techniques for vibration characterization and dynamic testing. Due to its simplicity, accuracy and whole-field characters, laser speckle interferometry has served as one of the major techniques for dynamic measurement. In this paper, a two-step phase shifting method is developed for quantitative speckle phase measurement, which helps to eliminate the specklegrams needed for phase evaluation and facilitate dynamic measurement. Unlike previously reported two-step methods using fringe patterns with known phase shift of π/2, a small unknown phase shift is employed instead in the proposed method, which eliminates the need for phase shifting devices. Further investigation shows that small phase shifts are preferable over large phase shifts in this method. Shearographic experiments conducted have demonstrated the effectiveness of the proposed technique. 相似文献
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利用色散关系研究了弱电流不守恒情况下的π-→π0+e+ν衰变过程。在对π—π散射相移作了一些假定后,证明了π、π中间态的贡献很小。在N、N中间态项中出现的N、N湮灭矩阵元用Chew-Ball理论及湮灭实验估计,同时出现的核子弱作用形状因子又用色散关系计算,证明了N、N中间态对它的贡献很小,计算了π、π中间态对它的贡献。根据现有N、N湮灭实验估计,π-→π0+e+ν过程的衰变几率<6×10-4秒-1。 相似文献
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We show that, by adding a π-phase shift to one-half of a linearly polarized beam, the roles of the transversal and longitudinal field components of the focused beam are interchanged, resulting in better focusing of the longitudinal component in the direction perpendicular to the phase jump line. For this component the scheme produces a spot with FWHM >15% smaller than a spot generated with either linearly or radially polarized light for any NA. The scheme has a similar advantage when applied to circularly polarized light, and it holds for both a plane wave and a realistic case of a Gaussian incident beam. This technique may find applications when using recording media responsive to the longitudinal field only, particularly in read/write for optical storage where the resolution in one transverse dimension is most important. 相似文献
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we vector dependence of the light scattering spectra of DKDP is investigated for the scattering angles π/4, π/2 and 3π/4. Brillouin shift concerned with an elastic stiffness C66 is obtained from the angular dependence of the quasi-longitudinal and quasi-transverse mode frequencies in the ab plane observed in the VV scattering. The results indicate that the phase velocity associated with C66 decreases slightly near Ttr in the case of π/4 scattering, but does not in π/2 and 3π/4 scatterings. 相似文献