用于彩虹彩色全息记录的彩色负片的光学分色

用天津全息Ⅰ、Ⅲ型干版，红、绿、蓝三色滤光片，在普通放大机上成功制作了彩色鱼片的黑白放大分色干版。作为掩模，该分色版完全满足了记录激光彩虹彩色全息图的需要。     

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.     

一种水性胶复合透明全息新材料

激光全息图像用于防伪,因其是目视直观识别,在商品市场上广为大众所推崇。随着经济市场发展的需要,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,使透明全息的图像质量更高,防伪效果更好。另一方面:全息图像载体材料也不断更新,由初期的窄幅不透明镀铝标识发展到大规模宽幅生产的半透明透视全息膜、镀高折射率无机介质的全息膜、涂纳米胶的透明全息膜,规模日益扩大,这种材料可制成带有     

凹非球面检测的双计算全息图设计及制作

基于全息补偿检验非球面的原理,提出并设计了一种二元纯相位型双计算全息图.该全息图由主全息和对准全息两部分组成,用于检测非球面的主全息位于基底的中心,而对准全息位于其边缘,用来精确定位主全息,从而消除离焦、偏心及倾斜所引入的误差.两部分全息同心是实现对主全息准确定位的前提,为此,提出了"一次曝光,两次刻蚀"的制作方法,即一次性将两部分图形在同一块掩膜版上制作出,曝光一次后,基底经两次刻蚀制作出具有两种不同相位深度的双计算全息图.最后给出了一个检测?40、F2抛物面镜的双计算全息设计实例,并将其检测结果与自准直检测结果比较,二者吻合良好,验证了该设计方法的正确性及制作工艺的可行性.     

数字全息信息记录最大化及简化相移技术

本丈从信息论的角度研究了数字全息信息量与记录光路的关系,证明了同轴傅里叶变换全息是实现全息信息量最大记录的光路.同时提出了一种新的简化相移数字全息显微技术,本技术采用四分之一波片作为相移器,结合计算机模拟原参考光,只需进行一次相移,拍摄两次全息图和一次物光强度分布图就可以有效的消除数字全息再现像中的零级像和共轭像.将新的相移技术与同轴无透镜傅里叶变换全息相结合,简化了相移步骤,实现了数字全息再现实像最高像素输出,从而提高了数字全息再现像分辨力.     

彩色全息的进展

本文介绍真彩色全息技术的进展，包括早期的彩色全息术，白光处理彩色全息术，透射彩色彩虹全息术，彩色傅里叶变换全息术，反射彩色全息术。阐述全息图的构成与再现过程，给出了这些技术的实验例证。     

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。     

用全息三波面干涉法产生透镜阵列

采用三次曝光在全息图上依次记录下三个两两波法线夹角相等的平面波。然后用原参考光照射处理后的全息图，同时再出现三个平面波，得到三光束干涉的六角形蜂窝状阵列式空间光强分布。     

医学层析图像的计算全息三维可视化

提出了一种医学层析图像的计算全息三维可视化技术。首先研究了层析图像序列的三维信息融合,将层析图像序列的二维信息融合成三维信息,用计算全息图的方法进行三维信息记录。然后结合空间光调制器的结构特性,对全息系统的空间频率、参物光夹角、取样间隔以及全息再现像的再现区域和视角等进行了讨论和分析,并设置了相关参数,使计算全息系统与电子显示系统相匹配。最后用液晶空间光调制器作为全息图显示载体,用计算机控制全息图的实时输出,用雾屏承载三维空间再现像,建立三维图像光电再现与实时显示系统,实现层析图像序列的三维可视化,给出了理论分析与实验结果。     

物理学防伪技术综述

1.激光全息 利用激光彩色全息图制版技术和模压复制技术制成的激光彩虹模压全息图文,可以在产品上制成可见的或不可见的图文或信息。由于全息图中的色块组合是随机编码,即使用同一设备也难复制出完全相同的母版,故彩虹全息图可用作防伪标志,也可将其直接转印到纸品     

Novelty filter that uses a bacteriorhodopsin film

We propose a new novelty optical filter that uses a bacteriorhodopsin film. This filter is based on the time-dependent nonlinear diffraction efficiency of real-time holograms recorded in the film. As soon as the signal beam carrying a pattern is diffracted by the polarization hologram recorded in the bacteriorhodopsin film, it begins to erase the hologram and suppresses the diffraction of the beam at the position of the stationary part of the pattern. This filter enhances only leading edges of moving patterns. In this system undesired scattered light, which is orthogonally polarized to the diffracted beam, is discriminated by a polarizer.     

Color holography using the angular selectivity of volume recording media

A display hologram of an object can be recorded and reconstructed in three primary colors if the angular selectivity of volume recording media is exploited. Three holograms are recorded in the same medium, each at a different primary color. These three holograms are reconstructed by simultaneous illumination of the hologram with the original reference beams. By proper choice of the angles that the reference beams make to the hologram, it is possible to suppress strongly cross talk between the different reconstructions (e.g., the red object reconstruction in green light). The technique exhibits high resolution, high diffraction efficiency, and vivid colors. Through the addition of three holographically recorded volume gratings it is possible to reconstruct the hologram with a beam of white light. The saturation and brightness of each primary color in the reconstruction can be adjusted by selection of an appropriate thickness for the corresponding grating.     

Photopolymer system and its application to a color hologram

We present a new type of photopolymer system for recording reflection holograms. The photopolymer system with radical and cationic photopolymerization controlled by the wavelength of light gives us enhanced diffraction efficiencies and a balanced recording sensitivity (20-60 mJ/cm(2)) in the blue to red region of the spectrum. In color hologram recordings, diffraction efficiencies of ? 60% are obtained when a photopolymer film is used that is composed of different spectrally sensitive photopolymer layers.     

Low-bit-rate computer-generated color Fresnel holography with compression ratio of over 1600 times using vector quantization [Invited

We propose a method for compressing a digital color Fresnel hologram based on vector quantization (VQ). The complex color hologram is first separated into three complex holograms, each representing one of the primary colors. Subsequently, each hologram is converted into what we call a real Fresnel hologram and compressed with VQ based on a universal codebook. Experimental evaluation reveals that our scheme is capable of attaining a compression ratio of over 1600 times and still preserving acceptable visual quality on the reconstructed images. Moreover, the decoding process is free from computation and highly resistant to noise contamination on the compressed data.     

Modified Fresnel computer-generated hologram directly recorded by multiple-viewpoint projections

An efficient method for obtaining modified Fresnel holograms of real existing three-dimensional (3-D) scenes illuminated by incoherent white light is presented. To calculate the hologram, the method uses multiple-viewpoint projections of the 3-D scene. However, contrary to other similar methods, this one is able to calculate the Fresnel hologram of the 3-D scene directly rather than calculating a Fourier hologram first. This significantly decreases the amount of calculations needed to obtain the hologram and also reduces the reconstruction errors. The proposed method is first mathematically introduced and then demonstrated by both simulations and experiments.     

Frequency and phase swept holograms in spectral hole-burning materials

A new hologram type in spectral hole-burning systems is presented. During exposure, the frequency of narrow-band laser light is swept over a spectral range that corresponds to a few homogeneous linewidths of the spectrally selective recording material. Simultaneously the phase of the hologram is adjusted as a function of frequency-the phase sweep function. Because of the phase-reconstructing properties of holography, this recording technique programs the sample as a spectral amplitude and phase filter. We call this hologram type frequency and phase swept (FPS) holograms. Their properties and applications are summarized, and a straightforward theory is presented that describes all the diffraction phenomena observed to date. Thin FPS holograms show strongly asymmetric diffraction into conjugated diffraction orders, which is an unusual behavior for thin transmission holograms. Investigations demonstrate the advantages of FPS holograms with respect to conventional cw recording techniques in freq ncymultiplexed data storage. By choosing appropriate phase sweep functions, various features of holographic data storage can be optimized. Examples for cross-talk reduction, highest diffraction efficiency, and maximal readout stability are demonstrated. The properties of these FPS hologram types are deduced from theoretical considerations and confirmed by experiments.     

Suppression of undesired diffraction orders of binary phase holograms

A method to remove undesired diffraction orders of computer-generated binary phase holograms is demonstrated. Normally, the reconstruction of binary Fourier holograms, made from just two phase levels, results in an undesired inverted image from the minus first diffraction order, which is superposed with the desired one. This can be avoided by reconstructing the hologram with a diffuse light field with a pseudorandom, but known, phase distribution, which is taken into account for the hologram computation. As a consequence, only the desired image is reconstructed, whereas all residual light is dispersed, propagating as a diffuse background wave. The method may be advantageous to employ ferroelectric spatial light modulators as holographic display devices, which can display only binary phase holograms, but which have the advantage of fast switching rates.     

Dynamic holographic interconnects that use ferroelectric liquid-crystal spatial light modulators

Dynamic interconnect holograms are designed by the use of a simulated annealing algorithm and written to a 128 × 128 pixel ferroelectric spatial light modulator that is used in a binary-phase mode. Dynamic holograms are used to implement a 2 × 2 crossbar with single-mode fiber inputs and outputs, which function with as high as 27 dB of isolation between output ports. The principle is extended to two-dimensional interconnection holograms, and arbitrary fan-out to as high as 64 points is demonstrated with good performance.

Images of interconnection holograms are transferred from the spatial light modulator to an optically addressed spatial light modulator that is used in a binary-phase mode. The addition of a fixed array generator computer-generated hologram permits replication of the hologram image, thus creating a larger hologram with a high space-bandwidth product on the optically addressed spatial light modulator.

Results of a preliminary experiment are presented.

     

Complex Fresnel hologram display using a single SLM

We propose a novel optical method to display a complex Fresnel hologram using a single spatial light modulator (SLM). The method consists of a standard coherent image processing system with a sinusoidal grating at the Fourier plane. Two or three position-shifted amplitude holograms displayed at the input plane of the processing system can be coupled via the grating and will be precisely overlapped at the system's output plane. As a result, we can synthesize a complex hologram that is free of the twin image and the zero-order light using a single SLM. Because the twin image is not removed via filtering, the full bandwidth of the SLM can be utilized for displaying on-axis holograms. In addition, the degree of freedom of the synthesized complex hologram display can be extended by involving more than three amplitude holograms.     

Moiré pattern encoded extended fractional Fourier transform security hologram

This paper describes a simple method for making extended fractional Fourier transform (EFRT) based Moiré pattern encoded security holograms. These security holograms contain multifold concealed and encoded anticounterfeit security features that can only be read through a key hologram and periodic patterns in the final reading process. The encoded features in these holograms are concealed and unknown to the counterfeiter. These features are encoded separately for each individual recording in angularly multiplexed extended fractional Fourier transform hologram (EFRTH). The principle of recording and reconstruction of the proposed security hologram along with experimental results are presented.