A Full-Field KB-FZP Microscope for Hard X-Ray Imaging with Sub-100 nm Resolution C. Rau *1,2,3 , V. Crecea 1 , K.M. Peterson 1 , P.R. Jemian 1 , C.-P. Richter 4 , U. Neuhäusler 5 , G. Schneider 6 , X. Yu 1 , P. V. Braun 1 , I. K. Robinson 1 . 1 Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA, 2 Purdue University, 480 Stadium Mall Dr.,West Lafayette, IN 47907-2050, USA, 3 NIST, Gaithersburg, MD, 20899, USA, 4 Northwestern University, 200 E. Superior St., Chicago, IL, 60611, USA 5 Universität Bielefeld, Fakultät für Physik Postfach 10 01 31, 33501 Bielefeld, Germany, 6 BESSY GmbH, Albert-Einstein-Str.15, 12489 Berlin, Germany A full-field hard X-ray microscope has been built at the UNICAT/APS beamline 34ID-C. A Kirkpatrick-Baez mirror is used for the condenser and a micro-Fresnel Zone Plate (FZP) as the objective lens. The zone plates available give access to 50-85 nm spatial resolution operating the microscope between 6-12keV photon energy. The first tomography experiments have been per- formed with this device. KEYWORDS: hard x-rays, tomography, full-field microscopy, Fresnel Zone Plate, Kirkpatrick-Baez mirror * Address: Advanced Photon Source, ANL, Argonne, IL, 60439, USA 1. Introduction Hard X-rays are advantageous for imaging and tomogra- phy, due to their high penetration depth and the ease of sample handling. Customized sample environments can be realized while preserving the integrity and functionality of the object. With respect to Full-field X-ray microscopy, the depth of focus of the objective lens becomes more important with increasing photon energy. The advantage for tomogra- phy applications is, that large volumes can be visualized sharply. For many scientific applications with hard X-rays, micro-tomography has become a well established technique. In particular, instruments built at third generation synchro- trons make use of the high coherence, the high intensity of the radiation and the possibility of tuning the incident en- ergy. In-line phase contrast imaging renders not only to fea- tures with low absorption contrast visible, but also features smaller than the detector resolution. Often scientific prob- lems require higher spatial resolution as features of interest are spread over several length scales. Since high-resolution optics like Fresnel Zone Plates (FZPs) 1,2) are also suitable for the hard X-ray regime, it has become possible to build a hard X-ray microscope that significantly overcomes the mi- crometer limit given by the spatial resolution of the detec- tion system. Sub-100 nm resolution was demonstrated 3) with a setup including a Kirkpatrick-Baez multilayer-mirror (KB) 4) as a condenser followed by a micro-FZP as an objec- tive lens 5) . The microscope at UNICAT/APS is working in the energy range of 6-12 keV with the capacity to provide 50 nm resolution. We performed first tomography scans and plan in addition to apply phase contrast imaging, such as the Zernike method. For applications in material science the absorption contrast is likely be sufficient to render features visible, whereas the phase contrast techniques have to be considered for biomedical studies. 2. Experimental The experiment was performed at the Advanced Photon Source (APS), a synchrotron radiation source of the third generation. The station 34ID-C is dedicated to coherent dif- fraction and imaging, operated by the University of Illinois at Urbana-Champaign (UIUC) within the UNICAT consor- tium. Fig. 1: Scheme of beamline and microscope. The X-rays are generated with an undulator in a high- section of the electron storage ring. The source size is 600 μm by 40 μm (horizontal x vertical) and the beam di- vergence is 40 μrad by 12 μrad (horizontal x vertical). At 34 ID the beam is shared between two different hutches 6) . When the settings of the undulator are controlled by the 34 ID-E station this operation mode called "parasitic mode". The beam splitting is realized by inserting a platinum-coated silicon single-crystal mirror into the beam, deviating the main cone of the x-ray beam to the C hutch. The liquid ni- trogen-cooled mirror rejects higher undulator harmonics above 15 keV at an incidence angle of 5 mrad. The fixed- exit double crystal monochromator is water cooled and yields an energy bandwidth of E/E=10 -4 using Si (111) crystals over an energy range of 6-30 keV. Optionally it can be removed for experiments with pink beam. The beam size is ~1 mm 2 at a distance of 55 m from the source and the flux is about 10 13 Photons/second. The theoretical value for the vertical coherence length is about 50 μm and about 10 μm for the horizontal coherence length. The imaging and tomo- 55 m 55.1 m 2.3 cm Undu- lator Mirror Mono- chromator Condenser Sample Objective Detector 20 cm 10 cm 50-100 cm Proc. 8th Int. Conf. X-ray Microscopy IPAP Conf. Series 7 pp.7-8 7