提出了用归一化灰度线性度误差来评价体全息再现图像的灰度保真度,并在此基础上实验研究了光折变晶体中全息存储的灰度保真度与记录物参光强比的关系,结果与理论预期符合得很好；研究了全息存储过程灰度线性度误差随记录时间演变,表明只要选择适当的记录物参光强比,即使记录时间较短(衍射效率较低)也能获得较高的灰度保真度。

In this paper, a new quantity, normalized nonlinear error (NNE) is proposed for the first time to our knowledge for the estimation of the gray scale fidelity of images retrieved from volume holograms stored in photorefractive Fe∶LiNbO3 crystals. Based on this, the dependence of gray scale fidelity on recording object-reference beam ratios is experimentally investigated, and the results agree well with theoretical predictions. The dynamic evolution of the normalized nonlinear error during hologram recording is also studied. The results show that a satisfactory gray scale fidelity can be obtained as long as the recording beam ratio is carefully chosen, even if the recording time is short, hence the diffraction efficiency is quite low.