Open AccessFast focus estimation using frequency analysis in digital holography
Author(s) -
Sangeun Oh,
ChiYoung Hwang,
Il-Kwon Jeong,
Sung-Keun Lee,
JaeHyeung Park
Publication year - 2014
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.22.028926
Subject(s) - focus (optics) , optics , holography , spatial frequency , digital holography , fourier transform , computer science , fast fourier transform , physics , algorithm , quantum mechanics
A novel fast frequency-based method to estimate the focus distance of digital hologram for a single object is proposed. The focus distance is computed by analyzing the distribution of intersections of smoothed-rays. The smoothed-rays are determined by the directions of energy flow which are computed from local spatial frequency spectrum based on the windowed Fourier transform. So our method uses only the intrinsic frequency information of the optical field on the hologram and therefore does not require any sequential numerical reconstructions and focus detection techniques of conventional photography, both of which are the essential parts in previous methods. To show the effectiveness of our method, numerical results and analysis are presented as well.