利用单个元件实现相干光Walsh变换

利用扫描曝光法制备的单个元件实现了二维相干光Walsh变换。其特点是能量利用率高、光路简单。文中给出了原理及实验结果。 关键词：     

基于光学沃尔什变换特征提取的图像匹配

采用光电结合的方法实现了沃尔什 （Walsh）分量变换,提出出反映图像主要特征的分量,用于大容量图像库的内容匹配查找,基于以非相干光相关器为核心的光电混合图像处理系统,实现了基于光学沃尔什变换特征提取的图像匹配算法。     

Walsh 变换光学实现的一种方案

本文分析了Walsh变换的光学实现问题,并给出了为实现二维空间8×8复数Walsh变换所需的全息透镜系统的光学设计。 关键词：     

快速Walsh变换与多视角视频编码

本文针对多视角视频编码提出了一种新的编码方法。在此方法中,结合四维Walsh操作算子,以达到压缩目的。利用4维n阶矩阵Walsh变换,对先前彩色视频流的编码加以扩展,将其应用到八个视角的视频编码中,包括视频序列分块,Walsh正变换及反变换,反分块。这种方法能够利用视频序列之间的相关性并且减少视频序列之间的冗余。本文以VC++6.0为工具,编程实现了基于快速Walsh变换的多视角视频编码,研究了不同压缩比条件下的压缩性能。通过对实验数据的分析,本文提出的方法既保证了视频质量又具有很好的快速压缩性能。实验结果表明:本文方法具有可行性及有效性,且易于在编码端快速实现,为多视角视频的进一步研究奠定了基础。     

抛物面镜系统的光学图像处理

讨论了抛物面镜的变换特性;提出用一个凹抛物面反射镜组成光学图像处理系统,进行了相干光,部分相干光和白光的若干光学图像处理实验,证明了系统的可行性,并对系统的实用意义作了若干讨论.     

关于n平面线性相干光处理系统的讨论(Ⅰ)

讨论n平面线性相干光处理系统(简称n平面线性系统)的一般性质。在两个特例情况下,借助于傅里叶变换的相似性定理和空间频率的标度变换,可以证明:n平面线性系统的(n—1)个间距参数{z_i}_n-1不是实质性参数。利用所得结果,演示了相干光成象和空域中的频率的标度变换,说明理论结果是有效的。 关键词：     

光学变换中的离散取样方法

本文研究了光学变换中的离散取样问题。基于幺正变换的考虑,求得了光学变换中离散取样方法所依据的条件。导出了包含取样单元透光孔作用的光传播矩阵。最后,以自然序Walsh变换为例,具体计算了变换所需全息透镜的振幅与相位分布及相应的误差。 关键词：     

小波包变换对CO-OFDM系统高峰均比的抑制性能研究

针对相干光正交频分复用系统中出现的高峰值平均功率比问题,提出用小波包变换取代传统快速傅里叶变换的相干光正交频分复用系统.仿真实验证明了具有良好正交性的小波包变换对高峰值平均功率比起到一定程度上的抑制作用,且误码率性能优于传统的快速傅里叶变换.随着小波尺度函数及小波函数对称性的提升,其避免信号处理过程中的相移的能力提高,系统性能有所改善.与传统的快速傅里叶变换系统相比,基于小波包变换的系统中,小波基函数haar小波的互补累计分布函数为0.01时,门限值降低约2dB,且在误码率为10-3的情况下,性能优化1.5dB.在此基础上,将小波提升算法应用到相干光正交频分复用系统中,得到的抑制峰均比及误码率性能与应用Mallat算法时一致,但算法的结构复杂度降低.     

利用单个全息透镜实现光学变换的理论

在离散取样情形下,证明了利用单个全息透镜所组成的光学系统能够实现任意给定的线性变换;给出了为实现给定变换而设计全息透镜振幅和相位分布的方法;并以三种不同序的八维Walsh变换为例,得到了实现这些变换的全息透镜的振幅和相位分布。 关键词：     

基于小波变换的长距离光正交频分复用系统中四波混频引起的相位噪声分析

四波混频（FWM）效应是相干光正交频分复用（CO-OFDM）系统中最主要的非线性作用。分析基于小波变换的相干光正交频分（WT-OOFDM）系统原理,研究小波变换对FWM效应和光放大器自发辐射（ASE）引起的相位噪声的改善效果。数值结果表明,在采用常规G. 652光纤,100 Gbit/s的WT-OOFDM传输1500 km时,非线性相位噪声降低20%,总相位噪声降低15%。     

高序光学变换

从低序光学变换到高序光学变换在实验上存在着困难。本文分析研究了这些困难问题,并提出用5平面光学系统能够较为理想地解决这些问题。并以一维32序的Walsh变换为例,在实验上建立了3平面和5平面两个相干光学系统,对此进行具体的实验研究。实验结果与理论预期一致。 关键词：     

Wavefront reconstruction algorithm for wavefront sensing based on binary aberration modes

We propose a new algorithm for wavefront sensing based on binary intensity modulation. The algorithm is based on the fact that a wavefront can be expended with a series of orthogonal and binary functions, the Walsh series. We use a spatial light modulator(SLM) to produce different binary-intensity-modulation patterns which are the simple linear transformation of the Walsh series. The optical fields under different binary-intensity-modulation patterns are detected with a photodiode.The relationships between the incident wavefront modulated with the patterns and their optical fields are built to determinate the coefficients of the Walsh series. More detailed and strict relationship equations are established with the algorithm by adding new modulation patterns according to the properties of the Walsh functions. An exact value can be acquired by solving the equations. Finally, with the help of phase unwrapping and smoothing, the wavefront can be reconstructed. The advantage of the algorithm is providing an analytical solution for the coefficients of the Walsh series to reconstruct the wavefront. The simulation experiments are presented and the effectiveness of the algorithm is demonstrated.     

Catalytic Coherence Transformation and Distillation for Special Mixed States

The coherence transformation and distillation for a class of special mixed coherent states of rank-2 under incoherent operations (IO) is discussed. Similar to the entanglement transformation for mixed entangled states, the catalytic coherence transformation for this class of special mixed coherent states is analyzed. On the one hand, it is found that some of the mixed coherent states can be converted into other mixed coherent states under IO. But for those mixed coherent states which fail in the coherence conversion under IO, the catalytic coherence manipulation can solve this problem. In this case, a mixed coherent state cannot be converted into another under IO, while the coherence transformation can be realized with the help of coherence-assisted incoherent operations, that is, catalytic coherence transformation. On the other hand, these special mixed coherent states can be distilled into the maximally pure coherent states or mixed states of arbitrary dimensions by strictly incoherent operations with certain probabilities. Finally, the coherence transformation of this type of mixed states can be generalized to the case of higher rank in a similar way, which is discussed at the end of this paper.     

Utility transforms of optical fields employing deformable mirror

Diffraction optical devices of modest degrees of freedom (DOF), such as deformable mirrors, have not been exploited as general-purpose transformers of optical fields. Described in this Letter is a method that guides deformable mirrors to optimal surfaces allowed by the DOF for various desirable outcomes. The method is based on a modal optimization procedure with the help of Walsh functions in controlling the variables of the mirrors, i.e. the actuators. It is shown that a deformable mirror of modest DOF can provide field transformations for arbitrary beam-splitting, formation of ring-shaped beams, and coherent beam combining.     

Darboux transformation of coherent states for a Lobachevski plane

A Darboux transformation of coherent states is considered for a singular oscillator. A coordinate representation and a holomorphic representation are obtained for the Darboux transformation operator and the coherent states. The Hermitian metric and the Kaler potential of the transformed system are calculated. It is established that a Darboux transformation corresponds to curvature of the phase space of the classical system. Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 29–36, September, 1997.