Speckle-Based X-Ray Phase-Contrast and Dark-Field Imaging with a Laboratory Source

Abstract

We report on the observation and application of near-field speckles with a laboratory x-ray source. The detection of speckles is possible thanks to the enhanced brilliance properties of the used liquid-metal-jet source, and opens the way to a range of new applications in laboratory-based coherent x-ray imaging. Here, we use the speckle pattern for multimodal imaging of demonstrator objects. Moreover, we introduce algorithms for phase and dark-field imaging using speckle tracking, and we show that they yield superior results with respect to existing methods.

Simulations of multi-contrast x-ray imaging using near-field speckles

“…The algorithm used to analyse the distortions of the speckle pattern caused by the sample and to convert them into image signals is described elsewhere [9]. The refraction angle, transmission and visibility-contrast (dark-field) images obtained with this algorithm are shown in Fig.…”

“…The setup, data acquisition and analysis procedures are relatively simple, it provides multicontrast signals in different directions, and it works well not only at synchrotron facilities, but also at polychromatic laboratory sources [9,10]. Speckle-based imaging relies on the sample-induced distortions of a near-field speckle pattern produced by a static random phase modulator (e.g.…”

“…The working principles of the method and the procedures to retrieve the image signals are described in detail in Refs. [4,5,9].…”

X-ray pulse wavefront metrology using speckle tracking

“…The subset size is usually chosen in the range 13 Â 13 pixels to 27 Â 27 pixels which are sizes offering a good compromise between precision, resolution and speed of calculation. Instead of the zero-normalized cross-correlation criterion of equation (5), another equivalent criterion sometimes employed for subset tracking is the zero-normalized sum of squared difference (Pan et al, 2009;Yoshizawa, 2009;Zanette et al, 2014).…”

2D-Omnidirectional Hard-X-Ray Scattering Sensitivity in a Single Shot

“…Least mean square fitting can be utilized to estimate the shift ðρ 0 ; θ 0 Þ and in turn ðx 0 ; y 0 Þ. The phase shift can also be extracted by other methods based on the cross correlation of the two fringes like spatial mapping [22][23].…”