共查询到17条相似文献,搜索用时 125 毫秒
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数字微镜器件在视频全息中的应用 总被引:6,自引:2,他引:4
为研究数字微镜器件在视频全息中的应用,探讨了基于数字微镜器件的全息编码方法。基于数字微镜器件的微观物理结构,讨论二维离散微镜像素结构、开态微镜列的闪耀光栅特性和脉宽调制的微镜偏转工作原理。将数字微镜器件分辨力、微镜尺寸、间隔、旋转角度、参考光入射角以及衍射条件等因素结合到计算全息编码中,提出干涉面抽样方法、相位补偿技术和无偏置二元全息编码方法,使产生的计算全息图适应数字微镜器件独特的空间光调制特性和计算视频全息的要求。实验表明,该方法调整了重构物光波的衍射方向,集中了衍射光在重构像中的分布,增加了成像清晰度和光能有效利用率,提高了全息编码效率。 相似文献
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全息光刻可通过空间光调制器数字微镜器件(DMD)加载计算全息图构建数字掩膜来实现,罗曼编码是常用的编制计算全息图的方法,它采用透明矩形孔的高度和位置分别编码全息图抽样单元的幅值和相位。通常,DMD再现此类二元全息图需合并多个微镜来表示单个矩形孔,这会大大降低其像素利用率和分辨率。针对这个问题,提出一种改进的罗曼编码,该编码充分利用DMD的二进制脉宽调制特性,采用灰度值编码全息图抽样单元的幅值,将全息图的透过率由二元型转换成灰阶型,从而有效减少单个抽样单元所占用的微镜数。采用MATLAB编程对改进的罗曼编码和博奇编码计算全息图进行模拟再现分析,得到改进的罗曼编码衍射效率约是博奇编码的3倍。以DMD为核心搭建了全息再现实验,得到改进的罗曼编码衍射效率约是博奇编码的2倍。可得出采用改进的罗曼编码可以显著提高衍射效率。 相似文献
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数字微镜器件的相位调制性质 总被引:5,自引:0,他引:5
为了提高数字微镜器件(DMD)的空间光调制性能,发挥其在光信息处理中的作用,研究了的数字微镜器件相位调制性质。通过分析数字微镜器件的微观物理结构,考察了数字微镜器件的光栅特性;从计算的角度研究了其对相干光波的相位调制,并给出数学描述和实验结果。重点研究了数字微镜器件的衍射光栅特性,分析了其工作原理及微镜偏转导致的镜片空间相对位置的改变,利用闪耀光栅理论计算了偏转微镜间的相位差,得出了数字微镜器件光栅的闪耀规律,实现了闪耀状态。提出了利用不同方向的微镜列状态研究数字微镜器件相位调制性质的方法,推导和模拟了关于数字微镜器件的微结构和工作原理,在数字微镜器件光调制研究方面提供了一些结果,对数字微镜器件在信息光学中的更广泛应用有一定意义。 相似文献
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在数字全息研究中,为了充分利用CCD器件有限的卒间带宽积,常采用同轴全息记录.然而用同轴全息图再现时,再现物光波和共轭物光波是混在一起无法分开的.有效消除同轴全息图再现光波场中的共轭像是数字全息应用中的一项关键技术.基于菲涅耳衍射运算和逆运算,提出一种用同轴数字全息图重构物光波面的迭代算法.该方法利用同轴全息图再现时,再现物光波和共轭物光波衍射特性的不同来剔除共轭物光波成分,从而将再现物光波成分有效分离出,实现单幅同轴全息图的物光波面数值重构.计算机模拟实验证明了该方法简单易行. 相似文献
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提出了一种双Lloyd镜数字全息显微测量技术.其基本思想是将Lloyd镜的共光束自干涉特性与双波长光学相位解包裹方法相结合,使用两个Lloyd镜调节参考光与物光夹角以形成共光束自干涉,从而获得一张双波长复合全息图,再通过角谱法再现得到每个波长对应的包裹相位,利用两波长的相位差求得解包裹后的相位图和三维高度分布图.采用532和632 nm两波长记录全息图,通过数值再现重构被测物体的振幅和相位信息.与标定值相比,实验值的误差小于5%,证明了该方法的有效性. 相似文献
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A new method is investigated for phase-only hologram synthesis. The method combines iterative calculation of the hologram phase function with the coding of the amplitude-phase characteristics of the complex transmission function into phase characteristics. The results of computational experiments are presented. The phase masks and reconstructed object images are also presented. 相似文献
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《中国光学快报(英文版)》2016,(1)
Past research has demonstrated that a phase-only hologram can be obtained by down-sampling the intensity image of the object scene prior to the generation of the hologram. In this Letter, we extend the method to the generation of binary phase-only holograms. A hologram derived with our proposed method is referred to as a binary-sampled phase-only hologram(BSPOH). Being different from the parent scheme, we have adopted an offaxis configuration in the generation of the BSPOH to avoid the quantization noise, the zeroth-order light, and the conjugate lights. An experimental evaluation reveals that the reconstructed image of the BSPOH is of good quality, and only contains slight amount of noise. 相似文献
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A super-resolution imaging method using dynamic grating based on liquid-crystal spatial light modulator (SLM) is developed to improve the resolution of a digital holographic system. The one-dimensional amplitude cosine grating is loaded on the SLM, which is placed between the object and hologram plane in order to collect more high-frequency components towards CCD plane. The point spread function of the system is given to confirm the separation condition of reconstructed images for multiple diffraction orders. The simulation and experiments are carried out for a standard resolution test target as a sample, which confirms that the imaging resolution is improved from 55.7 μm to 31.3 μm compared with traditional lensless Fourier transform digital holography. The unique advantage of the proposed method is that the period of the grating can be programmably adjusted according to the separation condition. 相似文献
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在传统的纯相位全息显示系统中, 一般基于快速傅里叶变换(FFT)算法来计算相位全息图, 在FFT的计算中需要遵循Nyquist采样定理, 因此, 重建图像的尺寸往往受限于空间光调制器的固定采样率. 这个限制可以通过卷积算法或者两步菲涅耳衍射算法来解决, 但是需要使用多个FFT的计算, 导致计算量增大. 鉴于此, 提出了一种基于透镜的纯相位全息图计算方法. 在全息图的计算中, 通过透镜的成像原理建立一个采样率可变的虚拟全息面, 通过调节相应的距离参数使得在全息图的计算中可以任意调节原始图像的采样率, 摆脱了传统方法中液晶空间光调制器带宽积对重建图像尺寸的限制, 并且这种算法只需使用一次FFT就能达到变采样率的衍射计算, 大幅提高了全息图的计算速度. 数值模拟及光学实验结果证明了此方法可以在全息显示光学系统中清晰地重建不同尺寸的图像. 同时该系统可以有效地消除由空间光调制器的像素化结构带来的零级衍射. 相似文献
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We propose a method for the digital reconstruction of an object whose diffraction pattern has been recorded on a hologram. The fractional Fourier transform is used for the object reconstruction. To determine the position of the object, the fractional order is scanned. The fractional cosine and fractional Hartley transforms are also employed for object reconstruction. These two transforms are real valued and allow the reconstruction to be done with lower computing complexity. Simulations and experimental results are presented. 相似文献
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Qinwei Xu Yongdong Wang Shi Yong Siew Jiao Lin Yilei Zhang 《Applied physics. B, Lasers and optics》2014,117(1):141-144
We report a new approach for generating an Airy beam by using a digital micromirror device (DMD) and a holographic technique where the DMD loads the desired hologram. Unique characteristics of an Airy beam, such as the non-diffraction and self-acceleration properties, were demonstrated to prove the successful construction of this type of waveform. Experimental results showed good agreement with theoretical calculations. This approach can also be used to generate other special beams. 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