【作者】 李莎；

【导师】 刘旭；

【作者基本信息】 浙江大学 ， 光学工程， 2006， 硕士

【摘要】 为了实现动态的全息显示,本文研究了基于TFT-LCD(Thin-film-transistor Liquid Crystal Display)再现的计算全息。采用TFT-LCD作为空间光调制器实时地显示计算全息图,从而在接收面上得到动态的再现像。但由于TFT-LCD的像素结构对再现像的情况会产生很大的影响,包括TFT-LCD的分辨率、开口率以及“黑栅效应”;而已有的研究都是从LCD器件入手,既增加了光学系统的复杂性,又难于实现。另一方面,计算全息图的归一化方法不同也会影响再现像的像质,目前几乎没有这方面的研究。因此,本文主要对以上两方面进行了分析和研究。 本文研究内容,主要包括计算全息图的制作、模拟基于TFT-LCD的计算全息的再现过程、TFT-LCD的像素结构对全息再现像的影响、消除TFT-LCD黑栅效应、计算全息图的归一化方法。 计算全息图的制作,包括抽样、计算、编码。重点介绍了计算全息的再现方法,比较了同轴再现和离轴再现的优缺点以及数字再现的几种算法。本文采用博奇全息图研究光学再现,采用同轴全息图研究数字再现。 本文主要采用计算机模拟的方法来进行研究,包括对TFT-LCD黑栅结构的模拟以及全息再现的过程模拟,提出用“像素分割”的方法模拟TFT-LCD的黑栅,并给出了模拟结果。利用计算机模拟的方法,研究TFT-LCD的分辨率和开口率对再现像的影响,分析出再现像与TFT-LCD像素结构的关系曲线,便于今后选择适当结构的TFT-LCD;提出“差分补偿法”消除TFT-LCD的“黑栅效应”,使一定接收面内得到理想的单个再现像,便于后续光路或电路的处理,并通过计算机模拟和光学实验相结合的方法,进行了论证。 此外,计算全息图的归一化方法不同,也会对再现像的像质产生很大的影响。本文讨论了归一化方法对全息图的保真度和衍射效率的影响,总结出既能保证归一化后的全息图不失真又能得到较高衍射效率的归一化方法,以得到较好像质的再现像。更多还原

【Abstract】 To achieve dynamic holography display, this paper studies the reconstruction of CGH (Computer-Generated H ologram) based on TFT-LCD (Thin-film-transistor Liquid Crystal Display). The CGH is displayed in TFT-LCD which is a SLM (Spatial Light Modulator), and the dynamic reconstructed image can be received. Due to the pixel structure of TFT-LCD, the reconstructed image can be deeply effect by the effect of BM (Black Matrix). Pre-studies always started with LCD devices, making the optical system complicated and difficult to carry out. Otherwise, the normalization method of CGH also effects the reconstruction, but almost no pre-studies are done. So, this paper does.Our studies include calculating CGH, simulating the reconstruction of CGH based on TFT-LCD, the effects of TFT-LCD pixel structure to the reconstructed image, eliminating the effect of BM and researching normalization methods of CGH.To calculate CGH, sampling, calculating and encoding must be done. The in-line and off-line optical reconstructions of CGH are introduced, also some algorithms of digital reconstruction. We use Burch-CGH to optical reconstruction and in-line-CGH to digital reconstruction.Computer is used to simulate TFT-LCD pixel structure and the reconstruction of CGH. The BM of TFT-LCD is simulated by ’Splitting Pixel Method’ and the result is given. By simulation, the curvilinear relationship between TFT-LCD pixel structure and the reconstructed image is achieved, which is useful to choose out suitable TFT-LCD. ’Differential Compensation Method’ is supposed to eliminating the effect of BM, receiving the ideal single reconstructed image and easily being processed, which has been demonstrated by computer simulation and optical experiments.This paper also discusses the influence of normalization to the fidelity and diffraction efficiency of CGH, generalizes the best normalization method to meet undistorted and high diffraction efficiency CGH, which makes good quality reconstructed image.更多还原