以球面波为参考光的体全息图衍射特性研究

Diffraction Properties of Volume Hologramwith Spherical Reference Waves

研究以球面波为参考光时体全息图的相对衍射效率问题，从理论计算中发现，当以球面波为参考光时，体全息图的串扰（ｃｒｏｓｓ－ｔａｌｋ）性能比用平面波时要略好一些，文章对此进行了分析解释并给出了实验验证。根据分析及实际读出的存储图像，发现球面参考光相对于平面参考光也不引起像质退化。这些特性表明了体全息存储器对于参考光平行度调节的要求并不十分严格。此外，文章还给出了以球面波为参考光时体全息图相对衍射效率的近似解析计算公式。

We investigate the relative diffraction efficiency of a volume hologram where a spherical wave is used as the reference beam. Through theoretical analysis we find that the crosstalk performance of a volume hologram with a spherical reference wave is somewhat better than that with a planar reference wave. This phenomenon is explained and demonstrated. After comparing the readout images by a spherical reference wave with those by a planar reference wave, we also verify that a spherical reference wave is of little effects on the readout image quality. These features imply not so rigorous requirements on the parallelism of the reference beam in a volume holographic memory. In addition, a phenomenal analytical expression to approximately calculate the relative diffraction efficiency of a volume hologram with a spherical reference beam is presented.