菲涅耳双棱镜干涉实验中距离参数的研究

讨论了菲涅耳双棱镜实验中距离参数对两虚光源距离和干涉区域的影响,得到干涉条纹间距与距离参数的关系式,并给出实验中距离参数的推荐值.理论分析与实验数据符合较好.     

信息光学视角下菲涅耳双棱镜干涉的研究

菲涅耳双棱镜干涉在相衬成像和全息显微术中有重要应用。为了促进其应用,本文从信息光学角度研究双棱镜干涉,首先利用光场与脉冲响应函数之间的关系,理论导出了菲涅耳双棱镜干涉条纹强度公式,分析并讨论了狭缝缝宽及狭缝到双棱镜距离对菲涅耳双棱镜干涉条纹的影响,狭缝宽度大于0. 1 mm时,干涉条纹分辨率变差。接着给出了改变狭缝宽度(变化量为0. 08 mm)和改变狭缝到双棱镜的距离(从8 cm变化到12 cm)的实验结果,理论分析和实验结果一致。该结果有助于促进菲涅耳双棱镜干涉在相衬成像等领域的应用。     

菲涅耳双棱镜干涉实验中虚光源位置的讨论

讨论了菲涅耳双棱镜实验中虚光源的位置,计算了两虚光源间的距离,并进行了实验测量,理论分析与实验相一致.     

双光束干涉法测量双棱镜的楔角

在双光束干涉实验中测量出干涉条纹间距,在波长已知的条件下计算出虚光源的间距。利用光的折射定律可推导出虚光源间距和双棱镜的楔角的关系,从而计算出双棱镜的楔角。     

费涅耳双棱镜干涉实验中的虚光源

通过推导得出了费涅耳双棱镜干涉实验中的虚光源位置及其间距,提出了改进实验的一种方案。     

干涉方法测菲涅尔双棱镜棱角及玻璃折射率

干涉方法测菲涅尔双棱镜棱角及玻璃折射率麻福厚，张建秋（乌鲁木齐八一农学院基础部乌鲁木齐８３００５２）杨氏双缝，菲涅尔双棱镜等以分割波阵面获得干涉．牛顿环，劈形膜等以分割振幅获得干涉．教学中分波阵面的干涉与分振幅的干涉均以各自独立的实验进行，互不关联．...     

关于"双棱镜必须均匀照亮"的深入探讨

讨论了菲涅耳双棱镜实验中，双棱镜“必须均匀照亮”的意义，并强调指出，只要双棱镜的中心(棱脊的附近)被“均匀照亮”即可，从而对教材中的“均匀照亮”的含义作了明确的界定．     

菲涅尔双棱镜干涉实验中双棱镜两种放置方法的讨论

在菲涅尔双棱镜干涉实验中,双棱镜有两种不同的放置方法,分析了这两种放置方法中两虚光源的距离、干涉区域范围、干涉条纹间距、干涉条纹数目应相同,因而得到双棱镜的两种放置方法是等价的结论。     

在分光计上做双棱镜干涉实验

提出在分光计上做双棱镜干涉实验的实验方法,并论述了该方法的实验原理,给出了测量光波波长的公式.该方法克服了在光具座上进行实验时的调节难度大、不易测量和测量误差大等问题.     

Unidirectional transmission realized by two nonparallel gratings made of isotropic media

We realize a unidirectional transmission by cascading two nonparallel gratings (NPGs) made of isotropic, lossless, and linear media. For a pair of orthogonal linear polarizations, one of the gratings is designed as a polarizer, which is a reflector for one polarization and a transmitter for the other; another grating is designed as a polarization converter, which converts most of one polarized incident wave into another polarized transmitted wave. It is demonstrated by numerical calculation that more than 85% of the incident light energy can be transmitted with less than 1% transmission in the opposite direction for linearly polarized light at normal incidence, and the relative bandwidth of the unidirectional transmission is nearly 9%. The maximum transmission contrast ratio between the two directions is 62 dB. Unlike one-way diffraction grating, the transmitted light of the NPGs is collinear with the incident light, but their polarizations are orthogonal.     

Interference with beams sheared in orthogonal axes

Modifications to a cyclic interferometer have been made in order to obtain interference with lateral displacement, or linear compression, of the wavefronts in orthogonal axes. The interference patterns recorded with these shears are compared to the interference patterns obtained with conventional lateral and linear compressive shears.     

Wollaston式多光束分束棱镜的设计研究

基于方解石晶体的光学特性和传统Wollaston棱镜的结构特点,设计了一种新型Wollaston式多光束分束棱镜。棱镜的两块晶体的光轴不再是垂直的,而是呈现一定的角度。通过结合玻璃棱镜,可以实现三束或四束光束平行光束的出射。以晶体光轴夹角为45°角为例,对该棱镜进行了讨论研究。研究得出:当一束自然单色光入射时,当入射光束的光斑大小大于两平行光束之间的距离时,可以实现两束相互垂直的偏振光和一束自然光出射,当光斑大小小于棱镜中两平行光束之间的距离时,能够产生四束分开程度可调并且平行出射的偏振光。该棱镜能为不同的应用环境提供可调节的偏振出射光束,从而节约成本。     

Interference of two Bose-Einstein condensates

The visibility of the density interference pattern of two Bose-Einstein condensates, which are produced in traps and overlap after the trapping potential is switched off, is investigated. Coherent wave packets are used to describe the order parameter in a second-quantization formalism. This results in a decrease of the visibility of the interference fringes with increasing time delay between the formation of the condensates and the observation of interference. In the two limiting cases of ideal and very dense gases the correlation time increases, τ→∞, and the result is identical to that obtained using an approach based on the Gross-Pitaevskii equation. Under the conditions of the experiment performed by M. R. Andrews, C. G. Townsend, H. J. Miesner et al., Science 275, 6367 (1997), the computed correlation time τ≈0.2 s is much longer than the confinement time of the condensate, and it is possible to observe the predicted decrease of visibility of the interference fringes of the density of the atoms. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 7, 491–496 (10 April 1999)     

基于介质环形柱结构的二维光子晶体中Dirac点的实现

利用偶然简并方法在二维正方格子介质环形柱结构光子晶体中成功实现了Dirac点, 并利用平面波展开法对实现Dirac点的过程进行了研究. 研究结果表明, 对于二维正方格子介质环形柱结构光子晶体, 在一定的外径R_O范围内(0.37a<R_O<0.5a), 当Dirac点存在时(n>1.4), 介质环内径R_I与外径R_O满足一个不随介质环折射率n变化的恒定关系式. 同时, Dirac点对应的光子约化频率f随折射率n及外径R_O的增大而减小. 利用所得的关系式对特定介质环折射率n条件下能实现Dirac点的环形光子晶体进行了预判设计.     

Interference patterns of two non-diffracting beams

The interference field of two non-diffracting beams is derived analytically. We arrange the experiments with an axicon illuminated by two monochromatic oblique beams. Based on the diffraction properties of an axicon in the case of oblique illumination, the intensity distribution of interference pattern was calculated, and it was demonstrated to be the superposition of zero-order Bessel functions. The locus of interference fringes is also analyzed to be hyperbola according to the zero formula of zero-order Bessel function. The experimental results are verified the numerical simulation.     

强流电子二极管中阴极等离子体的膨胀

研究了强流四脉冲条件下电子真空二极管中阴极等离子体产生、膨胀和由于阴极等离子体膨胀导致二极管短路现象，通过所建立模型和大量实验数据给出了阴极等离子体膨 胀速率为0.5—4cm/μs，且脉冲过程中不均匀.分析了阴极等离子体膨胀对真空二极管电压、阻抗的影响和对多脉冲强流电子束参数的影响，并给出初步解决方案. 关键词： 多脉冲二极管 阴极等离子 膨胀速率     

Interference of two photons of different color

We consider the interference of two photons with different colors in the context of a Hong-Ou-Mandel experiment, in which single photons enter each of the input ports of a beam splitter, and exit together in the same, albeit undetermined, output port. Such interference is possible if one uses an active (energy-non-conserving) beam splitter. We find scenarios in which one “red” and one “blue” photon enter the beam splitter, and either two red or two blue photons exit, but never one of each color. We show how the precise form of the active beam-splitter transformation determines in what way the spectral degrees of freedom of the input photons should be related to each other for perfect destructive interference of the different-color components in the output. We discuss two examples of active beam splitters: one is a gedanken experiment involving a moving mirror and the other is a more realistic example involving four-wave mixing in an optical fiber.