直接二元搜索法合成二元位相计算全息图

提出了用递归直接二元搜索算法（ＤＢＳ）设计二元位相计算全息图的新方法，分析了ＤＢＳ型位相计算全息图的设计原理，计算机模拟定量地分析恢复象的质量和衍射效率，分析结果表明该位相计算全息图恢复象质量较好、衍射效率高，在光电技术、光学信息处理等领域中有重要的应用前景     

CT图像的计算机制全息三维重建

提出用计算机制全息术实现CT图像的三维重建。首先研究了CT图像的三维信息融合,用计算机模拟CT图像的物光波,用菲涅耳计算全息图的方法,把CT图像的二维信息融合成三维信息,获得菲涅耳全息图。然后将计算机制全息与光学全息相结合,记录彩虹全息图。最后用扩展的白光再现,获得逼真无畸变的真正的三维立体图像,充分发挥了计算机制全息与光学全息的优势。在全息图的计算中利用了快速傅里叶算法,大大缩短计算时间。根据不同的观察需要制作了两种不同效果的全息图,并给出了理论分析和实验结果。     

用计算机模拟再现傅里叶计算全息的研究

介绍一种用计算机模拟再现傅里叶计算全息图的方法,它不但比传统的光学再现更方便和快捷,不可以通过调节各种参数来模拟和研究影响再现质量的实验条件。给出了由于全息片表面不平、曝光过度或不足、分辨力高低等条件下不同再现像的模拟结果,证明该方法是研究计算全息图再现的有效方法。     

提高防伪全息技术的功效性

如今，全息图是一种非常流行的安防技术，在全球广为接受，并越来越多地用于防伪应用、产品认证和证件鉴定。安防全息图一般按照其所使用的原始技术来归类，可分为2D/3D、点矩和e-波控制。有很多特殊的科学原因以及显性和隐性的特征使得这些聚合复制光学变量技术（OVDs）具有安防价值。但是，随着科技的快速发展，伪造者也不断采用新的方法来制作“仿造”全息图，给全世界的执法部门、原始制造商和消费者带来巨大威协。本文根据最近一些科学技术的发展，旨在调查研究这些领域，并设计提供一套提高全息图功效的方法，使之成为一种先进的防伪工具。     

用计算机全息方法改变激光束横模的研究

以圆对称高斯光束变换为十字光束为例，提出一种全息光学元件的设计理论和方法，推导出计算机制全息图的衍射方程，同时给出设计结果的计算机模拟验证方法，动用ＨＯＥ可以解决光束能量转换效率及能量重新分配问题。     

二维彩色全息图的色彩效果研究

讨论了用单色激光器记录三个彩虹全息图来合成二维真彩色全息图时,彩色全息图的彩色特性、狭缝位置和色彩亮度等问题.     

Gyrator变换计算全息图及其新型编码方法

基于gyrator变换数值算法和计算全息理论提出了gyrator变换计算全息图,采用罗曼编码方法制作出了在不同变换角度下的gyrator变换计算全息图并实现了相应的数字再现,其再现规律与相关文献报道的gyrator变换全息图的再现规律一致,表明制作gyrator变换计算全息图是可行的。在此基础上提出了一种新的计算全息编码方法即梯形等效面积编码方法,该方法能有效提高在单个抽样单元中进行相位编码时的相位量化级数。应用该编码方法完成了傅里叶变换计算全息图的产生和数字再现的仿真实验,实验表明采用新型编码方法的离轴物体的计算全息图能实现零级衍射成像。采用新型编码方法也实现了gyrator变换计算全息图的产生和数字再现的仿真实验。上述实验结果表明本文提出的新型编码方法是可行的和有效的。     

计算全息的设计制作与应用

计算全息是建立在计算机科学与光学结合的全息图制作的一种新技术。要比一般光学全息具有更独特的优点。介绍计算全息的设计制作,对开拓其应用范围有重要的参考价值。     

香烟包装上的全息图应用及全息制版新技术

自从极品云烟率先在其包装上烫印三维立体全息图以来，模压全息图作为防伪和促销的手段，已逐渐广泛应用于各类高档香烟的软硬包装中。巧妙地利用全息图，以其普通印刷所不可代替的图象显示方式来提高传统印刷技术的表现能力，已成为当今高档印刷包装的发展趋势。     

水性胶复合透明全息防伪材料分析

激光全息图像防伪产品，因其可目视直观识别，在市场上广为推崇，随着相关技术的发展，全息制品的开发也日新月异，一方面，激光全息制版技术不断革新，如计算机全息图、双光束雕刻全息图、真彩色全息图、合成全息图、密码全息图等都可以应用于透明全息技术，     

递归二元搜索型计算全息图的研究

在分析递归二元搜索算法合成计算全息图原理的基础上，计算机编程设计了递归二元搜索型计算全息图，并在实验上研究了计算全息图的恢复象。实验结果表明，递归二元搜索算法可合成任意波前分布的傅里叶变换计算全息图，并具有恢复象质量好，衍射效率高的特点。     

On the real-time reconstruction of digital holograms displayed on photosensitive liquid crystal systems

Dynamic optical reconstruction of digital binary holograms projected on optically addressed liquid crystal spatial light modulators with the use of a computer driven multimedia projector is described. A high spatial resolution, sensitivity and full reversibility of the manufactured spatial light modulators are achieved by the use of a photoconducting PVK:TNF polymer layer serving as a transducer of incoming light intensity pattern into modulation of refractive index inside the adjacent LC layer. Linearly polarized laser light reconstructs the phase holograms at the video rate. The advantages and drawbacks of the presented system are discussed.     

The influence of structural parameters of CCD on the reconstruction image of digital holograms

The influence of structural parameters of CCD including the size of the pixel, sampling interval and sensitive area on the reconstruction image of digital holograms is discussed. We find that such associating structural parameters interacting with the system related to the optical arrangement for recording the digital holograms, have influences on the brightness, the size and the resolution of the reconstruction image. Considering these influences, we suggest an optimal optical setup for recording high quality digital holograms.     

Analytical design for computer-generated Fourier holograms of shaded multi-polygonal three-dimensional objects

We report here on design and computer simulation of computer-generated holograms for three dimensional (3D) imaging and display. Angular spectrum of general polygon patches was calculated in closed analytical form that includes angular dependence of the intensity and linear gradient of phase at each polygon. Special attention was paid to reduction of the dynamic range in the amplitude transmittance of the hologram by proper random choices of slopes and initial phases of each polygon. Numerical computer simulation results proved that our polygon-patched design demonstrates halftones of object shades and shows expected sharp focusing of different parts of the reconstructed 3D images in their different cross-sections.     

Digital recording and reconstruction of holograms in hologram interferometry and shearography

The fundamentals of digital recording and mathematical reconstruction of Fresnel holograms are described. The object is recorded in two different states, and the holograms are stored electronically with a charge-coupled-device detector. In the process of reconstruction the digitally sampled holograms are applied to the different coherent optical methods as hologram interferometry and shearography. If the holograms are superimposed and reconstructed jointly, a holographic interferogram results. If a shearing is introduced in the reconstruction process, a shearogram results. This means that the evaluation technique, e.g., hologram interferometry or shearography, can be influenced by numerical methods.     

Wavelength Mismatch Correcting Elements for Volume Holograms Written on a Laser Pattern Generator

Abstract

Holographic optical lenses based on volume gratings commonly suffer from severe aberrations due to wavelength mismatch between recording (blue-sensitive material) and application (often employing diode lasers). Here, methods are described for the precompensation of the aberrations at the recording. Both, aberrations in the phase of the reconstructed wave from the desired wave (‘wave aberration’), as well as aberrations in intensity resulting from deviations from the Bragg condition during reconstruction (‘Bragg aberration’) need to be compensated for. The design method for generating the computer generated holograms is described which are used as precompensating elements in the recording step of the interferometrically produced holographic optical elements. The computer generated holograms are written on a laser pattern generator. Test results of our laser pattern generator are shown to demonstrate its capability for this process. The measurement of the aberrations at the design wavelength in the near infrared is a very important step because it allows to eliminate in a second recording process misadjustment errors which will occur during the first recording step. By modification of at least one of the computer generated holograms the convergence of the procedure can be achieved.     

Optimally tuned spatial light modulators for digital holography

Digital holography and comparative digital holography are applications that require computer-addressable modulators for the optical reconstruction of digital holograms. The quality of the reconstructed holograms depends on the modulator's properties. Therefore a characterization of the modulators is required. We show the result of a modulator characterization and the modulator's influence on the quality of the reconstructed hologram. We then compare qualitatively and quantitatively the optical reconstruction of phase and amplitude holograms by considering their level of detail and their diffraction efficiency.     

Underwater digital holography for studies of marine plankton

Conventional and digital holographies are proving to be increasingly important for studies of marine zooplankton and other underwater biological applications. This paper reports on the use of a subsea digital holographic camera (eHoloCam) for the analysis and identification of marine organisms and other subsea particles. Unlike recording on a photographic film, a digital hologram (e-hologram) is recorded on an electronic sensor and reconstructed numerically in a computer by simulating the propagation of the optical field in space. By comparison with other imaging techniques, an e-hologram has several advantages such as three-dimensional spatial reconstruction, non-intrusive and non-destructive interrogation of the recording sampling volume and the ability to record holographic videos. The basis of much work in optics lies in Maxwell's electromagnetic theory and holography is no exception: we report here on two of the numerical reconstruction algorithms we have used to reconstruct holograms obtained using eHoloCam and how their starting point lies in Maxwell's equations. Derivation of the angular spectrum algorithm for plane waves is provided as an exact method for the in-line numerical reconstruction of digital holograms. The Fresnel numerical reconstruction algorithm is derived from the angular spectrum method. In-line holograms are numerically processed before and after reconstruction to remove periodic noise from captured images and to increase image contrast. The ability of the Fresnel integration reconstruction algorithm to extend the reconstructed volume beyond the recording sensor dimensions is also shown with a 50% extension of the reconstruction area. Finally, we present some images obtained from recent deployments of eHoloCam in the North Sea and Faeroes Channel.     

Applying gray-scaled detour phase hologram on liquid crystal on silicon spatial light modulator (LCoS-SLM)

In order to solve the representation problem of computer-generated holograms, multiple algorithms have been devised. One of which is the well-known detour phase method. This method has recently been modified to be optimized to display the generated hologram on twisted nematic spatial light modulators. In this paper, we apply the modified gray-scaled detour phase holograms on another type of spatial light modulators, which is of utmost importance in the field, namely the reflective liquid crystal on silicon spatial light modulator.