基于内插与外推的数字全息分辨率增强方法

A Resolution Enhancement Method Based on Interpolation and Extrapolation in Digital Holography

为了提高数字全息再现图像的分辨率,分析了增强图像分辨率的典型方法,提出了同时采用图像内插与外推的数字全息分辨率改进方法。对采集的全息图运用图像算法进行向内插值与向外填充,在全息面和物面之间采用角谱方法进行双向衍射迭代。通过该方法可以实现全息图的内插与外推,内插过程可以增加全息图空间采样频率而外推过程扩大了全息图数值孔径。同时,讨论了内插与外推的限制因素,并将新的改进方法与单独采用外推或内插进行了比较,模拟和实验结果证明,运用该方法可以明显改善再现图像分辨质量。

In order to improve the resolution of reconstruction image in digital holography, the traditional resolution enhancement methods are studied. Here, a resolution improvement method based on extrapolation add with interpolation is proposed. The recorded hologram is interpolated and extra-padded using image algorithm. An iterative process is applied by diffracting the wave-field between hologram plane and object plane. The interpolated and extrapolated hologram can be retrieved by this method. The interpolation process can increase the special sample frequency while the extrapolation can enlarge the numerical aperture. Simultaneously, limiting factors of interpolation and extrapolation are also discussed. We have compared the new method with interpolation or extrapolartion, respectively. The simulation and experimental results show that the resolution of reconstructed image is improved significantly by using this proposed method.