While modern x-ray microscopes at synchrotron radiation sources and free-electron lasers require x-ray optics of highest quality, these optics often show aberrations due to limitations in fabrication technology. Based on ptychography, we determine these aberrations and fabricate tailor made refractive phase plates to compensate for them. Starting from the aberrated optics, diffraction-limited beams can be generated by introducing the phase plate behind these optics. In addition, the wavefront can be modified to generate custom beams for special needs, such as donut-shaped beams with orbital angular momentum or for structured-illumination microscopy. The nanofocused beam can be engineered in shape and phase by introducing specially designed phase plates. We introduce a general scheme for wavefront engineering and illustrate it with a numerical example.
The X-ray scanning microscope PtyNAMi at beamline P06 of PETRA III at DESY in Hamburg, Germany, is designed for high-spatial-resolution 3D imaging with high sensitivity. Besides optimizing the coherent ux density on the sample and the precision mechanics of the scanner, special care has been taken to reduce background signals on the detector. The optical path behind the sample is evacuated up until the sensor of a four-megapixel detector that is placed into the vacuum. In this way, parasitic scattering from air and windows close to the detector is avoided. The instrument has been commissioned and is in user operation. The main commissioning results of the low-background detector system are presented. A signal-to-noise model for small object details is derived that includes incoherent background scattering.
To date, compound refractive X-ray lenses made out of Beryllium (Be CRLs) have been seldom applied for full-field microscopy with high spatial resolution, which was probably due to residual aberrations of these optics. However, in combination with the recent development of made-to-measure phase plates, the typical spherical aberration of beryllium compound refractive lenses (Be CRLs) can now be completely removed. In this way, distortion-free images of a sample are obtained, which is especially important for tomographic applications. First full-field imaging experiments with aberration-corrected Be CRLs were carried out at beamline P06 at the synchrotron radiation X-ray source PETRA III (DESY Hamburg, Germany). In order to maximize the magnification of the X-ray microscope for full-field microscopy, the full length of the beamline combining the micro- and nanohutch was utilized, enabling a large sample-to-detector distance. In this contribution, we present first imaging results, demonstrating the potential of Be CRLs for direct high-resolution X-ray tomography.
In recent years, ptychography has revolutionized x-ray microscopy in that it is able to overcome the diffraction limit of x-ray optics, pushing the spatial resolution limit down to a few nanometers. However, due to the weak interaction of x rays with matter, the detection of small features inside a sample requires a high coherent fluence on the sample, a high degree of mechanical stability, and a low background signal from the x-ray microscope. The x-ray scanning microscope PtyNAMi at PETRA III is designed for high-spatial-resolution 3D imaging with high sensitivity. The design concept is presented with a special focus on real-time metrology of the sample position during tomographic scanning microscopy.
Frank Seiboth, Andreas Schropp, Maria Scholz, Felix Wittwer, Christian Rödel, Martin Wünsche, Tobias Ullsperger, Stefan Nolte, Jussi Rahomäki, Karolis Parfeniukas, Stylianos Giakoumidis, Ulrich Vogt, Ulrich Wagner, Christoph Rau, Ulrike Boesenberg, Jan Garrevoet, Gerald Falkenberg, Eric Galtier, Hae Ja Lee, Bob Nagler, Christian Schroer
We developed a corrective phase plate that enables the correction of residual aberration in reflective, diffractive, and refractive X-ray optics. The principle is demonstrated on a stack of beryllium compound refractive lenses with a numerical aperture of 0.49 10-3 at three synchrotron radiation and x-ray free-electron laser facilities, where we corrected spherical aberration of the optical system. The phase plate improved the Strehl ratio of the optics from 0.29(7) to 0.87(5), creating a diffraction-limited, large aperture, nanofocusing optics that is radiation resistant and very compact.
Due to the weak interaction of X-rays with matter and their small wavelength on the atomic scale, stringent requirements are put on X-ray optics manufacturing and metrology. As a result, these optics often suffer from aberrations. Until now, X-ray optics were mainly characterized by their focal spot size and efficiency. How- ever, both measures provide only insufficient information about optics quality. Here, we present a quantitative analysis of residual aberrations in current beryllium compound refractive lenses using ptychography followed by a determination of the wavefront error and subsequent Zernike polynomial decomposition. Known from visible light optics, we show that these measures can provide an adequate tool to determine and compare the quality of various X-ray optics.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.