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Feng Zhao Yun Zhang Lingzhen Jiang Chengjiang LiWanzhen Geng Jing Hong 《Chinese Journal of Lasers》1993,2(4):369-375
The properties of simultaneously recorded multiple hologram are studied. A new model to describe the behaviors of the hologram is proposed. From this model, an analytic formulas of diffraction efficienies are given. It is shown that the efficiencies can not reach at 100% due to the coupling between diffraction orders through intermodulation gratings. And the comparisions are made for this model with the results by Kogelnik's coupled wave theory for N=1 and those by L. Solymar's model for neglecting the effect of intermodulation gratings respectively. It is shown that these results are in agreement to each other. 相似文献
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光致聚合物中单体及粘结剂对全息性能的影响 总被引:14,自引:2,他引:12
研究了单体及粘结剂等成份对全息光致聚合物薄膜光存储性能的影响。在相同引发条件下.以丙烯酰胺作为单体时,光聚物的衍射效率明显高于以丙烯酸和N羟甲基丙烯酰胺作为单体时光聚物的衍射效率。向丙烯酰胺中加入少量N-羟甲基丙烯酰胺,可以改善膜表面的光学质量.降低散射光强度,并提高膜的保存时间。在聚乙烯醇膜中单体聚合程度明显优于在聚乙烯吡咯烷酮中的程度,在大分子量的聚乙烯醇中的衍射效率及感光灵敏度高于在小分子量中的衍射效率和感光灵敏度,而且大分子量的聚乙烯醇能够制备厚膜,这是实现全息海量存储的一个重要因素。 相似文献
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We propose to implement a modal wavefront sensor (MWS) using a multiplexed phase computer-generated hologram (MPCGH). Based on general orthogonal aberration modes, the theoretical treatments of the MWS employing a MPCGH are presented with scalar diffraction approximations and Fourier analysis. Under the small aberration approximations, we give the analytical formula for characterizing the relationship between the sensor signal and the amplitude of the aberration mode. We design several MPCGHs with an effective method of modified off-axis reference beam holograms superposition, and code some common orthogonal Zernike aberration modes into the MPCGH. The numerical simulation is carried out to investigate the performance of MWS to detect particular aberration mode(s). The results exhibit the expected responses of the corresponding symmetric spot pair, and indicate that the wavefront distorted by a special Zernike aberration mode, after modulated by the MPCGH, can be transformed into beams with an intensity-normalized differential signal, which can reflect the change trend of the aberration coefficients in the test wavefront. The experimental demonstration with designed MPCGHs in conjunction with two phase-only spatial light modulators was carried out to test the performance of the MWS. 相似文献
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Holographic storage of three-dimensional image and data using photopolymer and polymer dispersed liquid crystal films 下载免费PDF全文
We present holographic storage of three-dimensional(3D) images and data in a photopolymer film without any applied electric field.Its absorption and diffraction efficiency are measured,and reflective analog hologram of real object and image of digital information are recorded in the films.The photopolymer is compared with polymer dispersed liquid crystals as holographic materials.Besides holographic diffraction efficiency of the former is little lower than that of the latter,this work demonstrates that the photopolymer is more suitable for analog hologram and big data permanent storage because of its high definition and no need of high voltage electric field.Therefore,our study proposes a potential holographic storage material to apply in large size static 3D holographic displays,including analog hologram displays,digital hologram prints,and holographic disks. 相似文献
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An adaptation of the source-encoded image subtraction system is used to form an in-plane holographic image of a colour transparency. The colour image can be retrieved by simple spatial filtering with a white-light optical processor. 相似文献
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一种获得大视角彩虹全息图的新方法:全息共轭法 总被引:2,自引:0,他引:2
提出一种利用全息相位共轭法获得大视角彩虹全息图的新方法,和全息聚光屏的概念.与一般彩虹全息法相比,全息相位共轭法所得彩虹全息图的视场不受透镜孔径的限制.简述了全息共轭法的基本原理,从理论上和实验上证明了该方法的可行性. 相似文献
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We present a new method for numerically reconstructing holography image on tilted planes within the Fresnel domain. The method is based on the Fresnel diffraction algorithm and object wave rotation transform. By suitable rotation the object wave on recording plane and once fast Fourier transformation this method can be implemented. The proposed method can render the real image of the hologram not only on parallel plane but also on the tilted. Experimental results are presented to demonstrate the method for a single axis rotation. 相似文献
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M.M. El-Nicklawy A.F. Hassan M.E. El-Zaiki T.A. El-Dessouki S.E.-S.Abd El-Ghany 《Optics & Laser Technology》1996,28(7):491-496
The visibility of the speckle pattern resulting from the scattered radiation of transmitted beams through a diffusing surface has been studied for a Gabor hologram and speckle photography. The cases of strictly- and quasi-monochromatic light are also considered. Mathematical expressions for the dependence of the visibility on the distance from the centre of the undiffracted illuminating beam, its spectral half-width Δf and the amplitude ratio m between the reference beam and the integrated scattered beams are obtained. A graphical method is found for determining m and Δf from the visibility as a function of the distance from the centre of the undiffracted illuminating beam. 相似文献
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Sun-Hee Kim 《Optik》2011,122(20):1814-1820
In a Virtual Reality based Computer-Aided Design (VR-CAD) system, the designer creates three-dimensional shapes using human-computer interaction (HCI) technique such as voice commands, hand motions, and finger motions. In this system, 3-D displays can provide the visual feedback to the designer a realistic graphical perception about the part she/he is designing. Especially, holographic method is particularly regarded as one of the most attractive approaches for creating the most authentic illusion of observing volumetric objects. Therefore, holographic 3-D display is the most suitable method for the VR-CAD system. Therefore, in this paper, we propose the fast generation method of 3-D hologram pattern using spatio-temporal redundant data of 3-D scene in VR-CAD system. Some experiments are carried out and its results are comparatively discussed with those of the conventional methods in terms of computational speed and required memory space. 相似文献
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A multi-image encryption scheme based on interference of computer generated holograms (CGH) is proposed. The encrypted information can be divided into several parts and recorded by corresponding CGHs that distribute randomly. With interference of all CGHs, the original information can be reconstructed. So the multi-image encryption is achieved, and every hologram can be regarded as the key to the corresponding image. Multi-user authentication and storage of information is implemented by applying unique CGH to interfere the common CGH. Furthermore, the CGHs can be cascaded to implement classification of images. When images of different level are assigned to corresponding user, hierarchical encryption is completed successfully. Numerical simulation verifies the feasibility of the method, and demonstrates the security of the algorithm and the decryption characteristics. Flexibility and variability of scheme can be higher than the existing methods. There are a lot of scheme's details still to consider and fulfill in the future. 相似文献
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为了提高数字全息相位重建精度,研究了基于Hilbert变换重建相位的理论和方法,并通过像面数字全息实验对该方法的有效性进行了验证,同时与数字全息常规重建方法得到的结果进行了比较.结果表明:Hilbert变换本身具有消除直流项的作用,对利用频域滤波滤除零级谱后的全息图进行Hilbert变换,能够彻底消除零级衍射项的干扰,从而提高相位重建精度.与常规重建结果相比,基于Hilbert变换的相位重建结果的标准偏差降低了14.0%.本文结果对提高数字全息相位重建精度具有重要的指导意义. 相似文献
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It is experimentally demonstrated that the image resolution from an in-line Fraunhofer hologram degrades appreciably when the centre of the diffraction pattern from a 5-bar resolution target is located asymmetrically in the hologram aperture. This effect is confirmed and analysed using calculated and experimentally measured images from holograms of a one-dimensional wire. Increasing asymmetry results in an increasing error in the measured linewidth, and a reduction of image resolution. A simple model based on average fringe contrast is used to predict this decrease in resolution with transverse object position. 相似文献
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本文研究了全息存储实验中以波长532 nm的半导体激光器作为记录和读出光源,碱性品红作为光敏剂的丙烯酰胺基光致聚合物薄膜的光致光衍射现 象.它可以考虑为透过全息干涉条纹的原始入射光和反射光,与来自光聚物中未曝光的不均匀表面和内部的散射光四波混频的结果.根据简并四波混频理论中的位相匹配条件对双光束全息写入时产生的衍射光锥,以及单光束辐照复现时产生的衍射光锥现象分别做出了理论解释;并且利用全息散射理论结合三角学知识对入射光的入射角与衍射光锥的锥角的依赖关系进行了深入讨论.
关键词:
全息
光致聚合物
衍射光锥
碱性品红 相似文献
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可实现存储光栅快速增强的新型全息存储结构 总被引:4,自引:0,他引:4
提出一种新型全息数据存储结构,该结构包含两块存储的内容完全相同的光折变晶体,无需相位共轭器,仅利用两束时域快速调制的平面参光波便可实现对存储全息图的迅速增强。文章讨论了调制速率,读出光强比,晶体非线性耦合强度及初始光栅强度对增强速度及可获得的饱和衍射效率的影响。 相似文献