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Refraction signals of a PEEK monofilament immersed in water using the real (a) and virtual (b) edge configurations, and the beam tracking (c) method. In (d), (e), and (f), a vertical profile extracted from each image is compared to the theoretical refraction angle.

Refraction signals of a PEEK monofilament immersed in water using the real (a) and virtual (b) edge configurations, and the beam tracking (c) method. In (d), (e), and (f), a vertical profile extracted from each image is compared to the theoretical refraction angle.

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We propose two different approaches to retrieve x-ray absorption, refraction, and scattering signals using a one dimensional scan and a high resolution detector. The first method can be easily implemented in existing procedures developed for edge illumination to retrieve absorption and refraction signals, giving comparable image quality while reduc...

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... Retrieval of three contrast channels -namely transmission, refraction and ultra-small angle scattering (or dark field) -was performed using the so-called beam tracking approach [5,6], which had previously only been used with much higher energy x-rays. A schematic representation of the working principle underlying the beam tracking approach and the retrieval method is shown in Figure 2. The x-ray beam is shaped into an array of beamlets by the intensity-modulation mask, generating a signal represented by the red curve in Figure 2. Introducing a sample, between mask and detector, produces a number of modifications in the shaped beamlets. ...
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... In this case, since we have developed a scanning-based system, masks and detector that are much longer in the vertical than in the horizontal direction have been used; however, the principle is perfectly applicable to a static system with square masks, and indeed several such systems have been built in the past. 18 , and to be useful in several applications, including the imaging of lungs 19,20 , breast calcifications 12,21 , damage in composite materials 22 , aluminium welds 23 . To retrieve a scatter image alongside refraction and attenuation, at least three input images are required 12 ; a third one with aligned mask apertures is typically added to the two "opposite partial illumination" ones used to retrieve attenuation and refraction (see above). ...
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... A simpler alternative consists in using a detector with a sufficiently small pixel to resolve the beamlets created by the sample mask [123], effectively an x-ray embodiment of the Hartmann wavefront sensor [124]. This approach was shown to be easily adaptable to laboratory sources [125], including with limited coherence [126]. ...
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... With an assumption of sample homogeneity, it is possible to retrieve quantitative parameters about the sample (typically thickness) with a single sample image [14,15]. In circumstances where individual beams are larger than the pixels being employed, such that they may be well resolved [16,17], it is also possible to separate the sample properties into attenuation, phase and scattering maps with a single image frame. Since small pixel sizes often mean low efficiency, especially at high x-ray energies, implementation of such techniques with larger, more efficient pixels, would avoid losing any advantages in dose reduction being employed. ...
... Other XPCi methods, such as grating interferometry (GI), analyzer-based imaging (ABI), or Shack-Hartmann imaging, are also capable of extracting attenuation, phase and scattering maps [18][19][20], though with differing conditions on system length or detector resolution, optical elements, processing methods [21][22][23][24]. Concerning Fourier methods of signal retrieval, Vittoria et al [16] showed that the use of these methods with polychromatic beams, and in the presence of pixel crosstalk, may lead to an underestimation of absorption signals and produce spurious dark field signals. While GI and ABI have broadly been applied in various settings, their use is reliant upon spatially coherent or monochromatic X-rays respectively, with a more thorough discussion of the systems' requirements made available by Diemoz et al [25]. ...
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... The middle panel (b) presents a sketch of the beam tracking approach. This method can be implemented by removing the detector mask, and adapted to synchrotron radiation [33,34] as well as to laboratory microfocal X-ray tubes [32]. In the third panel (c) the most commonly used configuration is depicted. ...
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Edge illumination X-ray phase contrast imaging techniques are capable of quantitative retrieval of differential phase, absorption and X-ray scattering. We have recently developed a series of approaches enabling high-resolution implementations, both using synchrotron radiation and laboratory-based set-ups. Three-dimensional reconstruction of absorption, phase and dark-field can be achieved with a simple rotation of the sample. All these approaches share a common trait which consists in the use of an absorber that shapes the radiation field, in order to make the phase modulations introduced by the sample detectable. This enables a well-defined and high-contrast structuring of the radiation field as well as an accurate modelling of the effects that are related to the simultaneous use of a wide range of energies. Moreover, it can also be adapted for use with detectors featuring large pixel sizes, which could be desirable when a high detection efficiency is important.
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... EI has been extensively applied using both monochromatic synchrotron radiation [1,[5][6][7][8] and polychromatic and divergent beams generated by X-ray tubes [2,[9][10][11][12][13]. In particular, the applicability to X-ray tubes in table-top laboratory setups is possible thanks to the low coherence requirements of the technique, both in terms of beam polychromaticity and focal spot size [2,10,14,15]. ...
... The detector was a PCO Edge camera, consisting of a scintillator, magnifying visible light optics and a sCMOS sensor, with an effective pixel size at the sample plane of 0.8 lm. In this experiment, the so-called ''virtual edge" EI configuration was employed [8], whereby no detector slit is physically present. Instead, thanks to the high resolution of the detector, a virtual edge is created by multiplying the acquired frame by a Heaviside function, so as to select half of the pixels along the vertical direction [8]. ...
... In this experiment, the so-called ''virtual edge" EI configuration was employed [8], whereby no detector slit is physically present. Instead, thanks to the high resolution of the detector, a virtual edge is created by multiplying the acquired frame by a Heaviside function, so as to select half of the pixels along the vertical direction [8]. A scan of the sample with a 1.6 lm step was performed. ...
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Purpose: Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has been under development at University College London in recent years, and has shown great potential for both laboratory and synchrotron applications. In this work, we propose a new acquisition and processing scheme. Contrary to existing retrieval methods for EI, which require as input two images acquired in different setup configurations, the proposed approach can retrieve an approximate map of the X-ray phase from a single image, thus significantly simplifying the acquisition procedure and reducing data collection times. Methods: The retrieval method is analytically derived, based on the assumption of a quasi-homogeneous object, i.e. an object featuring a constant ratio between refractive index and absorption coefficient. The noise properties of the input and retrieved images are also theoretically analyzed under the developed formalism. The method is applied to experimental synchrotron images of a biological object. Results: The experimental results show that the method can provide high-quality images, where the "edge" signal typical of XPCI images is transformed to an "area" contrast that enables an easier interpretation of the sample geometry. Moreover, the retrieved images confirm that the method is highly stable against noise. Conclusions: We anticipate that the developed approach will become the method of choice for a variety of applications of EI XPCI, thanks to its ability to simplify the acquisition procedure and reduce acquisitions time and dose to the sample. Future work will focus on the adaptation of the method to computed tomography and to polychromatic radiation from X-ray tubes.