Open AccessA phase demodulation method with high spatial resolution for two-dimensional single-shot X-ray Talbot interferometry
Author(s) -
Kentaro Nagai,
Genta Sato,
Takashi Date,
Soichiro Handa,
K. Yamaguchi,
Takeshi Kondoh,
Takashi Nakamura
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.22.004316
Subject(s) - optics , fourier transform , demodulation , spatial frequency , interferometry , noise (video) , signal (programming language) , optical transfer function , signal to noise ratio (imaging) , image resolution , fast fourier transform , computer science , physics , algorithm , artificial intelligence , telecommunications , image (mathematics) , channel (broadcasting) , quantum mechanics , programming language
A new phase demodulation approach is proposed that uses windowed Fourier transforms to achieve high spatial resolution in fringe pattern analysis with a high signal-to-noise ratio for single-shot X-ray grating-based interferometry. Conventionally, Fourier transforms have been used to demodulate single-fringe patterns, but this requires a fringe pattern with a long period to obtain an acceptable signal-to-noise ratio among the demodulated parameters. However, by controlling the signal-to-noise ratio, the spatial resolution of demodulated parameters is degraded below that obtained from the phase-stepping method, which requires several images to obtain these parameters. In this paper, we introduce the use of a windowed Fourier transform with a process for analyzing the objective spectrum in isolation from other spectra on the Fourier space to overcome the limitations of the Fourier transform method. It is proved that with suitable assumptions the objective spectrum is isolated theoretically, and the spatial resolution is improved by practically accepting the limitations from the assumptions. We demonstrate the validity of the proposed method by comparing the modulation transfer function of a synthetic phantom with the conventional FT method. The proposed method is also valid on practical data obtained by an experimental setup, by which it is demonstrated that a high spatial resolution with high signal-to-noise ratio can be achieved by our proposed method.