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一、全息存储的基本原理及其特点一般的光学体全息数据存取机理可简单描述为:待存储的数据(数字或模拟)经空间光调制器(spatial lightmodulator)SLM被调制到信号光上,形成一个二维信息页,然后与参考光在记录介质中发生干涉,利用材料的光折变效应形成体全息图,从而完成信息的记录(如图1所示);读出时使用和原来相同的参考光寻址,可以读出相应的存储在晶体中的全息图(如图2所示),然后使用光信号探测器件如面阵CCD将读出的图像输入到计算机中。根据体全息图的布拉格角度选择性或者布拉格波长选择性,改变参考光的入射角度或波长以实现多重存储。由于布拉格选择性非常高,所以体全息存储可以在一个单位体积内复用多幅图像,达到超高密度存储的目的。
First, the basic principles of holographic storage and its characteristics General optical body holographic data access mechanism can be simply described as: to be stored data (digital or analog) by spatial light modulator (spatial lightmodulator) SLM is modulated onto the signal light, Form a two-dimensional information page, and then interfere with the reference light in the recording medium to form a volume hologram using the photorefractive effect of the material to complete the recording of the information (as shown in FIG. 1); the same as Of the reference light, the corresponding hologram stored in the crystal can be read (as shown in Fig. 2) and then the image read out can be input to the computer using an optical signal detection device such as an area array CCD. Depending on Bragg angle selectivity or Bragg wavelength selectivity of the volume hologram, the angle of incidence or wavelength of the reference light is changed to achieve multiple storage. Due to the very high selectivity of Bragg, volume holographic storage can multiplex multiple images in one unit volume for the purpose of ultra-high density storage.