共查询到20条相似文献,搜索用时 62 毫秒
1.
部分相干光栅衍射效应和干涉术 总被引:1,自引:1,他引:0
本文提出一种新的部分相干照明的光栅衍射干涉仪.先分析了光栅的介于Talbot和Lan效应之间的部分相干衍射效应.部分相干干涉图的特点是条纹由频率成倍的两种光栅状载波所表征.调整光源狭缝,系统在两相干性极端分别转成Talbot和Lau干涉仪.理论分析采用了模糊函数方法.最后给出了实验. 相似文献
2.
脉冲响应函数与平面周期物体构成任意光学系统的成象特性研究——理论与实验 总被引:1,自引:1,他引:0
本文首先用线性系统中脉冲响应函数的概念分析了光学系统中平面周期物体的广义Talbot效应,利用我们以前导得的Talbot和Lau成象条件,导出了广义Talbot成象条件,得到十分简洁的系统脉冲响应表示式,然后利用光学系统的线性叠加和相关原理研究了任意光学系统中Talbot效应、Lau效应和多重成象现象及其相互关系,最后讨论了任意光学系统中三者之间的关系,并进行了实验证明。所用方法简单明了。 相似文献
3.
借助模糊函数理论分析了空间周期相干光照明产生的自成像现象及Lau效应。理论分析结果表明:当照明光源满足一定条件时,会出现自成像现象及Lau效应。根据分析结果讨论了这些现象的可能应用。 相似文献
4.
Lau效应在导向(航)信标中的应用 总被引:1,自引:1,他引:0
本文讨论了莫尔技术和Lua效应在导向(航)信标中的应用。在无穷远处观察到的莫尔条纹其形状不仅指明了应修正的方向,并可定量的给出偏差距离。 相似文献
5.
6.
根据计量光栅的特点,可以利用双光栅效应测量透镜焦距.本文简述了利用双光栅Lau效应测量透镜焦距的实验原理、实验装置及测量方法,并计算了测量结果的不确定度. 相似文献
7.
基于分数Talbot效应,利用纯位相光栅设计了一种二维棋盘格状阵列照明器。利用菲涅尔衍射理论分析了平面光波照射下纯位相光栅衍射光场,得到位相调制为(0,π/2)的二阶纯位相光栅可以实现压缩比为2的棋盘格状阵列照明。利用二元光学器件制作技术,在光学玻璃基底上制作了位相光栅。在扩束激光光束照射下,在分数Talbot距离处获得了效率为83.2%的棋盘格状明暗相间光斑阵列。实验结果很好地验证了理论分析结论。研究结果对于光互连、光通信、光电混合处理领域中阵列微光束生成和应用都具有较高的理论和实用价值。 相似文献
8.
在空域-频域空间,基于魏格纳变换和魏格纳分布函数,分析讨论了一维物体的自成像及其形成过程.从成像过程中各衍射频谱分量的光程差,给出了Talbot效应和Montgomery效应的统一解释.对于周期物的Talbot效应,得到了用杨氏双缝干涉解释自成像现象的理论依据.周期物的自成像是物平面上间距为两倍周期、光程差为波长的整数平方倍的各衍射频谱分量同相相干迭加的结果.Montgomery效应是物平面上间距为抛物线关系、光程差为波长整数倍的各衍射频谱分量同相相干迭加的结果. 相似文献
9.
利用杨氏双缝干涉讨论Talbot效应 总被引:5,自引:3,他引:2
利用杨氏双缝干涉原理讨论了平行光垂直照射下光栅的Tablot及分数Tablot现象.在成像平面上所观察到的光栅衍射条纹实质上是光栅中一定缝距的许多双缝对的杨氏干涉条纹的可除相干叠加条纹,其条纹间距和明暗中心位置都未变化;但是像相对于光栅即条纹分布相对于光栅刻线可能有半个周期的偏移,这可由双缝对参数α的奇偶决定,如果α为偶数则没有偏移,如果α为奇数则有偏移. 相似文献
10.
11.
A new phase-space distribution, linear canonical ambiguity function (LCAF), is proposed based on the linear canonical transform (LCT). The properties and physical meaning of the LCAF are given. The LCT moments are introduced and the relationships between the LCAF and the LCT moments are also derived. As an application, simple expressions for the center of gravity of the LCT power spectra and the effective width of the first-order optical system diffracted beam are derived. Compared with the conventional ambiguity function, the LCAF has three additional freedoms, i.e., the parameters characterizing a LCT, which make the LCAF more attractive for the analysis of optical signals. 相似文献
12.
光纤光栅传输矩阵研究 总被引:5,自引:0,他引:5
利用模耦合理论给出并分析了一般坐标系下相移布喇格光纤光栅中的传输矩阵及其特性,所给出的传输矩阵具有分段不变性,而且不能被分解为一个矩阵和一个相移矩阵的乘积.利用该传输矩阵可以研究均匀、相移、啁啾、超结构等光纤光栅及光栅的级联等.计算了相移光栅的反射谱和相移量的关系,以及两个光栅级联时的反射谱.结果表明,同样相移量时的反射谱和已有文献不同,两个光栅级联时,也不同于已有文献,各自的谐振波长与光栅的级联没有关系. 相似文献
13.
M. Gatti R. Gaudron C. Mirat L. Zimmer T. Schuller 《Proceedings of the Combustion Institute》2019,37(4):5197-5204
The frequency response of three lean methane/air flames submitted to flowrate perturbations is analyzed for flames featuring the same equivalence ratio and thermal power, but a different stabilization mechanism. The first flame is stabilized by a central bluff body without swirl, the second one by the same bluff body with the addition of swirl and the last one only by swirl without central insert. In the two last cases, the swirl level is roughly the same. These three flames feature different shapes and heat release distributions, but their Flame Transfer Function (FTF) feature about the same phase lag at low frequencies. The gain of the FTF also shows the same behavior for the flame stabilized by the central insert without swirl and the one fully aerodynamically stabilized by swirl. Shedding of vortical structures from the injector nozzle that grow and rollup the flame tip controls the FTF of these flames. The flame stabilized by the swirler-plus-bluff-body system features a peculiar response with a large drop of the FTF gain around a frequency at which large swirl number oscillations are observed. Velocity measurements in cold flow conditions reveal a strong reduction of the size of the vortical structures shed from the injector lip at this forcing condition. The flame stabilized aerodynamically only by swirl and the one stabilized by the bluff body without swirl do not exhibit any FTF gain drop at low frequencies. In the former case, large swirl number oscillations are still identified, but large vortical structures shed from the nozzle also persist at the same forcing frequency in the cold flow response. These different flame responses are found to be intimately related to the dynamics of the internal recirculation region, which response strongly differs depending upon the injector used to stabilize the flame. 相似文献
14.
15.
由于锤击激励跟响应的时间对应关系以及系统的非线性因素在传递函数计算中很难考虑,导致传递函数的估计误差很大。本文在选择合适的传递函数计算公式基础上,充分考虑激励信号与响应信号时间对应关系,建立了多次激励平均的脉冲锤击传递函数计算方法,并结合锤击激励信号、响应信号各自的自谱及它们的相干函数,确定出传递函数线性有效可用频段,使得脉冲锤击传递函数的估计更加系统和完善。另外仿真实验验证了此传递函数估计方法具有较高的估计精度。此方法的建立对于舰艇振动噪声传递的定量分析具有重要意义。 相似文献
16.
R. J. Baxter 《Journal of statistical physics》2008,132(6):959-982
We consider the Ising model on a cylindrical lattice of L columns, with fixed-spin boundary conditions on the top and bottom rows. The spontaneous magnetization can be written in
terms of partition functions on this lattice. We show how we can use the Clifford algebra of Kaufman to write these partition
functions in terms of L by L determinants, and then further reduce them to m by m determinants, where m is approximately L/2. In this form the results can be compared with those of the Ising case of the superintegrable chiral Potts model. They
point to a way of calculating the spontaneous magnetization of that more general model algebraically. 相似文献
17.
R. J. Baxter 《Journal of statistical physics》2008,132(6):983-1000
We adapt our previous results for the “partition function” of the superintegrable chiral Potts model with open boundaries
to obtain the corresponding matrix elements of e−α
H
, where H is the associated Hamiltonian. The spontaneous magnetization ℳ
r
can be expressed in terms of particular matrix elements of e−α
H
S
1
r
e−β
H
, where S
1 is a diagonal matrix. We present a conjecture for these matrix elements as an m by m determinant, where m is proportional to the width of the lattice. The author has previously derived the spontaneous magnetization of the chiral
Potts model by analytic means, but hopes that this work will facilitate a more algebraic derivation, similar to that of Yang
for the Ising model. 相似文献
18.
We consider two-dimensional Ising models bounded by general parabolic curves and study their transfer matrices and associated quantum spin chains. We derive their eigenvalue spectra numerically and analytically, both at the critical point and in its vicinity. From this we find how the geometrical form of the system is reflected in the spectrum and how it influences the critical behaviour near the tip. 相似文献
19.