Parabolic Refractive X-ray Lenses Research Articles

Nanofocusing with aberration-corrected rotationallyparabolic refractive X-ray lenses.

Wavefront errors of rotationally parabolic refractive X-ray lenses made of beryllium (Be CRLs) have been recovered for various lens sets and X-ray beam configurations. Due to manufacturing via an embossing process, aberrations of individual lenses within the investigated ensemble are very similar. By deriving a mean single-lens deformation for the ensemble, aberrations of any arbitrary lens stack can be predicted from the ensemble with \bar{\sigma} = 0.034λ. Using these findings the expected focusing performance of current Be CRLs are modeled for relevant X-ray energies and bandwidths and it is shown that a correction of aberrations can be realised without prior lens characterization but simply based on the derived lens deformation. The performance of aberration-corrected Be CRLs is discussed and the applicability of aberration-correction demonstrated over wide X-ray energy ranges.

Parabolic refractive X-ray lenses made of quartz glass for high-energy X-ray focusing

We have fabricated planar parabolic refractive X-ray lenses made of quartz glass for high-energy X-ray focusing by optical lithography and dry etching techniques. We succeeded in 100-µm-deep etching, realizing highly efficient microfocusing for high-energy X-rays. We measured the size and photon flux of the X-rays focused by two lenses with a crossed geometry at BL13XU of SPring-8. High-flux (more than 2 × 109 photons/s) microbeams with 25 and 30 keV X-rays were successfully obtained.

Focusing XFEL SASE pulses by rotationally parabolic refractive x-ray lenses

Using rotationally parabolic refractive x-ray lenses made of beryllium, we focus hard x-ray free-electron laser pulses of the Linac Coherent Light Source (LCLS) down to a spot size in the 100 nm range. We demonstrated efficient nanofocusing and characterized the nanofocused wave field by ptychographic imaging [A. Schropp, et al., Sci. Rep. 3, 1633 (2013)] in the case of monochromatic LCLS pulses produced by a crystal monochromator that decreases the LCLS bandwidth down to ΔE/E = 1.4 · 10−4. The full spectrum of LCLS pulses generated by self-amplified spontaneous emission (SASE), however, fluctuates and has a typical bandwidth of a few per mille (ΔE/E ≈ 2 · 10−3). Due to the dispersion in the lens material, a polychromatic nanobeam generated by refractive x-ray lenses is affected by chromatic aberration. After reviewing the chromaticity of refractive x-ray lenses, we discuss the influence of increased bandwidth on the quality of a nanofocused SASE pulse.

Development of high aspect ratio X-ray parabolic compound refractive lens at Indus-2 using X-ray lithography

A synchrotron beamline dedicated to soft and deep X-ray lithography is operational on Indus-2 synchrotron source and is being used for high aspect ratio microfabrication. This X-ray lithography facility provides the access to X-ray mask fabrication, X-ray exposures and development of micro-nano structures. We report the development of planar parabolic refractive X-ray lenses in SU-8 for energy range 8---20 keV using this facility. The focussing properties of X-ray lenses were studied with synchrotron radiation in the X-ray energy range 8---20 keV on the moderate emittance machine Indus-2. A focal spot of 11 μm at 15.9 keV is obtained with a gain of 18.

Highly efficient 2-D nano focusing by an optical system of planar refractive lenses

A lens system of two parabolic refractive X-ray lenses giving an intensity gain over 108 for a focal spot size below 10 nm for photon energies above 10 keV is suggested.

Hard X-ray scanning microscopy with fluorescence and diffraction contrast

Based on nanofocusing parabolic refractive x-ray lenses we have developed and built a hard x-ray scanning microscope that was tested and put to use at beamline ID13 of the ESRF. It can provide a monochromatic hard x-ray nanobeam with lateral extension below 100 nm (down to 50 nm) and a flux up to 109 ph/s in the energy range from 15 to 25 keV. The microscope exploits transmission, fluorescence, and diffraction contrast to obtain local elemental and nanostructural information from the sample. Tomographic scanning yields high resolution elemental maps from the inside of an object. Coherent x-ray diffraction imaging with nanofocused illumination yields images of objects with highest spatial resolution, e. g., 5 nm in a given example.

Refractive x-ray lenses

Parabolic refractive x-ray lenses are novel optical components for the hard x-ray range from about 5 keV to about 120 keV. They are compact, robust, and easy to align and to operate. They can be used like glass lenses are used for visible light, the main difference being that the numerical aperture is much smaller than 1 (of the order of 10−4–10−3). They have been developed at Aachen University and are made of beryllium, boron, aluminium and silicon. Their main applications are in micro- and nanofocusing, in imaging by absorption and phase contrast. In combination with tomography they allow for three-dimensional imaging of opaque media with sub-micrometre resolution. Finally, they can be used in speckle spectroscopy by means of coherent x-ray scattering. References to a number of applications are given.

High-Resolution 3D Imaging Microscopy Using Hard X-Rays

AbstractThe key strength of hard x-ray full-field microscopy is the large penetration depth of hard x-rays into matter, which allows one to image the interior of opaque objects. Combined with tomographic techniques, the three-dimensional inner structure of an object can be reconstructed without the need for difficult and destructive sample preparation. Projection microscopy and microtomography are now routinely available at synchrotron radiation sources. The resolution of these techniques is limited by that of the detector to 1 µm or slightly less. X-ray images and tomograms at higher spatial resolution can be obtained by x-ray optical magnification, for example, by using parabolic refractive x-ray lenses as a magnifying optic. Combining magnifying x-ray imaging with tomography allows one to reconstruct the three-dimensional structure of an object, such as a microprocessor chip, with resolution well below 1 µm. In x-ray scanning microscopy, the sample is scanned through a small-diameter beam. The great advantage of scanning microscopy is that x-ray analytical techniques such as fluorescence analysis, diffraction, and absorption spectroscopy can be used as contrast mechanisms in the microscope. In combination with tomography, fluorescence analysis makes it possible to reconstruct the distribution of different chemical elements inside an object (fluorescence microtomography), while combining absorption spectroscopy with tomography yields the distribution of different oxidation states of atomic species.

Nano-tomography based on hard X-ray microscopy with refractive lenses

~Received 19 March 2002; accepted for publication 25 June 2002!Based on parabolic refractive x-ray lenses we have built a hard x-ray microscope that allows one toimage the interior of opaque samples with submicrometer resolution. We have combined magnifiedimaging with tomography to obtain the three-dimensional structure of the sample at a resolutionwell below 1 mm. Using an aluminum lens to record a magnified tomogram of a test sample~microprocessor!, a resolution of slightly above 400 nm was found for the three-dimensionalreconstruction. Lenses made of beryllium are expected to improve this resolution to well below 100nm. The resulting challenges concerning instrumentation and numerical methods arediscussed. © 2002 American Institute of Physics. @DOI: 10.1063/1.1501451#One major advantage of hard x-ray microscopy overother microscopy techniques, such as visible light or electronmicroscopy, is the large penetration depth of hard x-rays thatallows one to investigate the interior of opaque sampleswithout the need to lay open the region of interest. By com-bining x-ray microscopy with tomographic techniques, thethree-dimensional structure inside a specimen can be recon-structed with minimal sample preparation. In particular, thethree-dimensional region of interest can be left untouched,widely avoiding the introduction of artifacts by samplepreparation. Over the last few years, hard x-ray microimag-ing and tomography have been developed to sophistication,

Beryllium parabolic refractive X-ray lenses for full field imaging and scanning microscopy with hard X-rays

Beryllium parabolic refractive X-ray lenses for full field imaging and scanning microscopy with hard X-rays

Nanofocusing parabolic refractive x-ray lenses

Parabolic refractive x-ray lenses with short focal distance can generate intensive hard x-ray microbeams with lateral extensions in the 100 nm range even at a short distance from a synchrotron radiation source. We have fabricated planar parabolic lenses made of silicon that have a focal distance in the range of a few millimeters at hard x-ray energies. In a crossed geometry, two lenses were used to generate a microbeam with a lateral size of 380 nm by 210 nm at 25 keV in a distance of 42 m from the synchrotron radiation source. Using diamond as the lens material, microbeams with a lateral size down to 20 nm and below are conceivable in the energy range from 10 to 100 keV.

Nanotomography based on hard x-ray microscopy with refractive lenses

Based on parabolic refractive x-ray lenses we have built a hard x-ray microscope that allows one to image the interior of opaque samples with submicrometer resolution. We have combined magnified imaging with tomography to obtain the three-dimensional structure of the sample at a resolution well below 1 μm. Using an aluminum lens to record a magnified tomogram of a test sample (microprocessor), a resolution of slightly above 400 nm was found for the three-dimensional reconstruction. Lenses made of beryllium are expected to improve this resolution to well below 100 nm. The resulting challenges concerning instrumentation and numerical methods are discussed.

Parabolic refractive X-ray lenses for microscopy and microanalysis

Parabolic refractive X-ray lenses for microscopy and microanalysis

Parabolic refractive X-ray lenses.

Parabolic refractive X-ray lenses are optical components, especially suitable for third-generation synchrotron radiation sources. This article describes the status of the development of our lenses and illustrates the possibilities for micrometre and submicrometre focusing and for X-ray imaging in absorption and phase contrast. The parabolic lens profile ensures distortion-free imaging of high quality. First characteristics of Be lenses are given. A microscope based on Be lenses is expected to have a lateral resolution below 80 nm.

Parabolic refractive X-ray lenses: a breakthrough in X-ray optics

Refractive X-ray lenses, considered for a long time as unfeasible, have been realized with a rotational parabolic profile at our institute: The main features of the new lenses are: they focus in two directions and are free of spherical aberration. By varying the number of individual lenses in the stack the focal length can be chosen in a typical range from 0.5 to 2 m for photon energies between about 6 and 60 keV . The aperture of the lens is about 1 mm matching the angular divergence of undulator beams at 3d generation synchrotron radiation sources. They cope without problems with the heat load from the white beam of an undulator. Finally, they are easy to align and to operate. Refractive X-ray lenses can be used with hard X-rays in the same way as glass lenses can be used for visible light, if it is take into account that the numerical aperture is small (of the order 10 −4). Being high-quality optical elements, the refractive X-ray lenses can be used for generating a focal spot in the μm range with a gain of a factor 1000 and more, or for imaging purposes as in a hard X-ray microscope. Recent examples from microanalysis, microtomography, fluorescence tomography, X-ray microscopy will be shown to demonstrate the state of the art. Possible new developments will be discussed.