Picart Pascal, Montresor Silvio, Sakharuk Oleksandr, Muravsky Leonid
Opt Lett. 2017 Jan 15;42(2):275-278. doi: 10.1364/OL.42.000275.
This Letter presents an alternative approach for image refocusing in digital Fresnel holography. In the literature, a large majority of reported focus detection criteria is based on amplitude contrast or phase contrast. We propose a focus detection criterion based on the speckle phase coherence factor. This factor reaches its maximum value at the best focus distance. At any reconstruction distance, estimation of the coherence factor is based on robust noise estimation from anisotropic diffusion. We propose a theoretical relation to estimate the coherence factor from the measured standard deviation. Experimental results for the case of three-color holographic imaging and interferometry are provided. Experimental results show the suitability of the proposed approach for image plane refocusing.
本信函提出了一种用于数字菲涅耳全息术中图像重新聚焦的替代方法。在文献中，绝大多数报道的聚焦检测标准是基于幅度对比度或相位对比度。我们提出了一种基于散斑相位相干因子的聚焦检测标准。该因子在最佳聚焦距离处达到其最大值。在任何重建距离处，相干因子的估计基于来自各向异性扩散的稳健噪声估计。我们提出了一种从测量的标准偏差估计相干因子的理论关系。提供了三色全息成像和干涉测量情况下的实验结果。实验结果表明了所提出的方法对像平面重新聚焦的适用性。
