We introduce the concept of a miniaturized compound refractive X-ray zoom lens consisting of SU-8 lenses fabricated by deep X-ray lithography. The focal length can be varied by changing the number of lens elements placed in the beam. We use suitable actuators to move single lens elements reversibly out of the beam. The X-ray zoom lens can accept different X-ray energies while keeping a fixed working distance, or vary the focal distance for a fixed energy. The latter is useful in tuning the magnification factor in full field microscopy.

Early science commissioning results of the sub-micron resolution X-ray spectroscopy beamline (SRX) in the field of materials science and engineering Abstract. In synchrotron facilities, imaging techniques are on high demand from the scientific community. Those related to X-ray microscopy are among the most prominent ones. Such techniques include scanning transmission x-ray microscopy (STXM), full-field transmission x-ray microscopy (TXM), and coherent diffraction imaging (CDI) which have a wide spectrum of applications ranging from clinical and biomedical sciences to nanotechnology and cultural heritage. Their advancement is achieved through specialisation and focused studies, often requiring dedicated beamline end-stations. On the other hand, scientific applications benefit from the combination of techniques in a complementary manner. Beamlines suitably designed to offer multiple techniques, instead of a single one, can host efficiently such combinatorial studies. In this paper, we present the diverse Soft X-ray microscopy techniques in use at the TwinMic beamline at Elettra Sincrotrone Trieste, namely, STXM combined with XRF spectroscopy, full-field TXM and Ptychography. We demonstrate the capabilities by examining two specific biological samples: U87MG cells exposed to CoFe 2 O 4 nanoparticles and a stem section of a Solanum lycopersicum (tomato) plant. These specimens are representatives of a large sample class used in a wide range of scientific studies. The results show the potential that can be achieved in terms of imaging by accessing X-ray microscopy techniques during a single beamtime access in TwinMic.

Point focus x-ray mosaic lenses are limited in aperture by the aspect ratio that can be reached in the micro fabrication process. In lithography based micro fabrication processes, which are used to fabricate the lens pillar structures, the achievable aspect ratio is restricted by structure collapse due to capillary forces which occur during drying after development. Capillary forces can be avoided by freeze drying, hence avoiding the direct phase change from liquid to gas. Substituting conventional drying by freeze drying using cyclohexane at a temperature of  −10 °C, we could increase the achievable aspect ratio for the triangular pillar structures with edge length of 10 to 45 µm of the x-ray mosaic lenses by up to a factor of 2.2 with no further changes in process, material or structural geometry. A maximum aspect ratio of 30 was achieved for pillars with 10 µm edge length. The process can readily be employed to other structures or lithography techniques.

We present results on the characterization of an X-ray zoom lens [1] via full field microscopy and enlarged cone beam projection. The X-ray zoom lens is fabricated from Compound Refractive X-ray Lenses (CRLs) made out of SU-8 negative photoresist by deep X-ray lithography [2]. The commonly known CRLs with variable focal length like the transfocator [3] or the F-switch [4] are mainly used for beam conditioning with focal length in the meter range and focal spot size in the tens-to hundredmicrometer range. Our X-ray zoom lens is capable of changing the focal length from centimeter up to meter range very fast. It shows a focal spot size in the sub-micrometer range with at the same time large field of view (FoV) and therefore can be used as an objective lens. It can be installed easily in different experimental setups due to its compactness of about one liter.The proof of concept and characterization regarding focal lengths and focal spot sizes of such an X-ray zoom lens at ID01, ESRF, and P05, PETRA III, was reported recently [1]. For the first time this lens was built up in a full field microscope setup at the IMAGE beamline at the KIT synchrotron. The setup contains a Siemens-star X500-200-30 as test structure, the X-ray zoom lens as objective and a PCO4000 detector. At a photon energy of E Ph = 17.5 keV the X-ray zoom lens showed a focal length of f = 324 mm and a magnification factor of M = 6. Our aim was to image a sample fast with different energies without touching the microscope setup. Therefore, we adapted the number of the lens elements in the beam to keep the focal distance constant. Thus, the magnification factor M in the microscope setup was constant without repositioning any optical element. In Figure 1 two different X-ray lens configurations are compared; one with N = 36 lens elements in the beam at E Ph = 17.5 keV and the other with N = 28 lens elements in the beam at E Ph = 15.43 keV. With a large FoV of 185 µm x 200 µm it was possible to resolve the complete Siemens-star (Figure 1 (a), (b)) with smallest feature size of 0.5 µm (Figure 1 (c),(d)) and show an equivalent quality in resolution, sharpness and magnification. This characteristic of our X-ray zoom lens opens the possibility of fast spectroscopy measurements in a wide X-ray regime.Additionally, we demonstrated for the first time the possibility to investigate a sample with different magnification M and FoV without touching the experiment. We used our X-ray zoom lens with eccentrics as actuators in an enlarged cone beam projection setup at B16, beamline at DIAMOND. This lens showed a focal spot size of σ = 0.6 µm (FWHM) measured with a 200 µm thick gold wire in a knife edge scan. The imaged sample was a grating with 2.3 µm period and with 11 µm Nickel on a 525 µm Sisubstrate (fabricated at KIT/IMT). It was positioned s d = 534 mm behind the X-ray zoom lens, followed by a PCO4000 detector 646 mm behind the sample. The photon energy stays constant at E Ph = 19 keV as well as the complete enlarged cone beam projection setup. Only the number o...

A new technique is presented to overcome beam size limitation in full field imaging at high brilliance synchrotron sources using specially designed refractive X-ray optics. These optics defocus the incoming beam in vertical direction and reshape the intensity distribution from a Gaussian to a more desirable top-hat-shaped profile at the same time. With these optics X-ray full-field imaging of extended objects becomes possible without having to stack several scans or applying a cone beam geometry in order to image the entire specimen. For in situ experiments in general and for diffraction limited sources in particular this gain in field of view and the optimization of the intensity distribution is going to be very beneficial.