动感像素全息母版图案的设计制作研究

本文介绍了一种新颖的数码像素全息高速拍摄装置来实现全息母版的制作。提出和介绍了运用Photoshop软件一些特殊的图像处理功能设计制作动感像素全息图的方法,并结合多种防伪技术,使产生的图案具有不可仿制的图形畸变特点,并列举了设计实例。     

Full Complex Amplitude Digital Holograms： Design, Fabrication and Optical Characterization

Diffractive optical elements have a large number of industrial applications, such as beam shaping and optical filtering. Traditionally, these elements modulate the phase of the incoming light or its amplitude, but not both. To overcome this limitation, full complex-amplitude modulation diffractive optical elements were developed. Well-established integrated circuit fabrication steps were employed to fabricate the devices with high precision. Using this approach, the new element‘s optical performances are improved also for near field operations. With this device it is possible to obtain 100% efficient spatial filtering and low noise reconstructed images.     

有自聚焦功能的付里叶计算全息

在制作付里叶计算全息过程中，加入适当的二次位相因子，使此种全息图在相干光照明下就可预定的位置上只再现一个像，省略了过去丙现此种计算全息图必要的付里叶透镜，并且使两个互为共轭像分离，从而拓宽了此种计算全息的应用领域，实验结果与理论分析相符。     

用脉冲全息法分析冲床的动态特性

介绍了双脉冲激光全息照相对机床结构动态特性的现场测量技术,并应用它成功地分析研究了冲床整机的动刚度和振型。     

Hash算法在数据库安全中的应用

介绍了Hash算法在数据库加密系统中的应用,包括在用户身份验证中的应用,在数据库完整性认证中的应用,以及在密文检索中的应用。     

Numerical investigation of zoomable holographic projection without a zoom lens

Holographic projection is for laser displays and has the merits of being aberration free, producing high‐contrast images, having the ability of color reconstruction with one spatial light modulator, and so on. In this paper, we propose a zoomable holographic projection without using a zoom lens and verify the proposed method by using numerical simulation. Although such a system can be readily realized to use the features of holography, which is capable of recording a large image exceeding the hologram size, the required calculation is very time consuming. For acceleration, we used shifted Fresnel diffraction for setting different sampling rates on a hologram and projected image. The proposed method can project any zoom‐in and zoom‐out image between zeroth‐order and first‐order lights, and the processing time and required memory for the zoom are constant.     

Research on malicious traffic identification technology in encrypted traffic

The encrypted transmission of network traffic is one of the development trends of the Internet.The identification of malicious traffic in encrypted traffic is an important way to maintain the security of cyberspace.One of the prior tasks of identifying malicious traffic is to classify encrypted traffic into the encrypted/unencrypted,different kinds of the application programs and encryption algorithms in order to improve the efficiency of identification.Then they are transformed into the image,matrix,n-gram or other forms which will be sent into the machine learning training model,so as to realize the binary classification and multi classification of benign malicious traffic.However,the machine learning based way relies seriously on the number and quality of samples,and can not effectively deal with the data after traffic shaping or confusion.Fortunately,cryptography based malicious traffic identification can search malicious keywords over encrypted traffic to avoid such problems,which must integrate searchable encryption technology,deep packet inspection and a provable security model to protect both data and rules.Finally,some unsolved problems of malicious traffic identification technology in encrypted traffic are presented.     

Fast computation of computer-generated hologram using Xeon Phi coprocessor

We report fast computation of computer-generated holograms (CGHs) using Xeon Phi coprocessors, which have massively x86-based processors on one chip, recently released by Intel. CGHs can generate arbitrary light wavefronts, and therefore, are promising technology for many applications: for example, three-dimensional displays, diffractive optical elements, and the generation of arbitrary beams. CGHs incur enormous computational cost. In this paper, we describe the implementations of several CGH generating algorithms on the Xeon Phi, and the comparisons in terms of the performance and the ease of programming between the Xeon Phi, a CPU and graphics processing unit (GPU).     

New multicolor and rewritable holographic polymer film for three‐dimensional holographic display

We have developed a new multicolor holographic polymer film. Our holographic polymer film contains 3‐[(2,4,6‐trichloro)azo]‐9H‐carbazole‐9‐ethanol (A‐1) and poly(methyl methacrylate). The holographic polymer film can be recorded with a holographic image without applying an external electric field. The diffraction efficiency was 57% at A‐1 with a 20 wt% of dope ratio. The writable holographic image writing for the holographic polymer film step used the silver halide photographic emulsion master plate 532‐nm laser beam under the nonelectric field. After the copy hologram is formed, our holographic polymer film can be displayed in red and green holographic images. Even though our holographic polymer film is rewritten over 200 times, the diffraction efficiency does not fall. As the holographic polymer film is manufactured using roll‐to‐roll techniques, although still in a laboratory scale in this study, it has a strong possibility of being manufactured in larger sizes with lower cost.     

一种可验证的公钥可搜索加密方案

公钥可搜索加密能实现基于密文的信息检索,适用于云计算环境。但现有公钥可搜索加密方案普遍依赖于双线性对,并且无法对服务器返回的搜索结果进行验证,效率和安全性较低。为此,基于El Gamal加密算法提出一种可验证的公钥可搜索加密方案。该方案使用El Gamal加密算法替代双线性对运算,与传统算法相比具有较低的计算复杂度,并且易于实现。在密文关键词及加密文件生成算法中,采用El Gamal签名算法对关键词的哈希值进行数字签名。当收到服务器返回的搜索结果后,用户可以通过计算得到发送者的公钥,并对相应的签名值进行验证,从而有效防止服务器返回错误结果。