Probe reconstruction for holographic X-ray imaging
نویسندگان
چکیده
In X-ray holographic near-field imaging the resolution and image quality depend sensitively on the beam. Artifacts are often encountered due to the strong focusing required to reach high resolution. Here, two schemes for reconstructing the complex-valued and extended wavefront of X-ray nano-probes, primarily in the planes relevant for imaging (i.e. focus, sample and detection plane), are presented and compared. Firstly, near-field ptychography is used, based on scanning a test pattern laterally as well as longitudinally along the optical axis. Secondly, any test pattern is dispensed of and the wavefront reconstructed only from data recorded for different longitudinal translations of the detector. For this purpose, an optimized multi-plane projection algorithm is presented, which can cope with the numerically very challenging setting of a divergent wavefront emanating from a hard X-ray nanoprobe. The results of both schemes are in very good agreement. The probe retrieval can be used as a tool for optics alignment, in particular at X-ray nanoprobe beamlines. Combining probe retrieval and object reconstruction is also shown to improve the image quality of holographic near-field imaging.
منابع مشابه
Holographic and diffractive x-ray imaging using waveguides as quasi-point sources
We report on lensless nanoscale imaging using x-ray waveguides as ultra-small sources for quasi-point-like illumination. We first give a brief account of the basic optical setup, an overview of the progress in waveguide fabrication and characterization, as well as the basics of image formation. We then compare one-step holographic and iterative ptychographic reconstruction, both for simulated a...
متن کاملSingle-shot femtosecond x-ray holography using extended references.
In the context of x-ray lensless imaging, we present a recent approach for Fourier transform holography based on the use of extended references. Major advances shown here rely on a high signal efficiency and on the direct image reconstruction of the object performed by a simple linear derivative. Moreover, the extended holographic reference is easy to manufacture and can be applied to a variety...
متن کاملInvestigation of dosimetric characteristic of NIPAM polymer gel using x-ray CT
Introduction: Polymer gel dosimeters contain chemical materials sensitive to the radiation which are polymerized by the radiation as a function of absorbed dose. So information of spatial dose distribution can be extracted by imaging from irradiated gel. Among imaging techniques, computed tomography (CT) poses as an attractive method because of practical advantages such as acce...
متن کاملHolographic x-ray image reconstruction through the application of differential and integral operators.
We introduce a noniterative image-reconstruction technique for coherent diffractive imaging. Through the application of differential and integral operators, an extended reference can be used to recover the complex-valued transmissivity of an object, in closed form, from a measurement of its far-field (Fraunhofer) diffraction intensity. We demonstrate the feasibility of this approach, using a re...
متن کاملApproximation and Optimization in Image Restoration and Reconstruction
Positron emission tomography (PET) is a biomedical imaging technique that allows for the visualization and the measurement of biological processes. PET is based on the injection to the patient of a molecular probe for the process of interest. The probe is labeled with radio-isotopes that decay by emitting a positron. The emitted positron annihilates almost immediately with an electron, resultin...
متن کامل