* Corresponding address. Lawrence Berkeley National La- boratory, Materials Science Division, MS 2-100, 1-Cyclotron road, Berkeley, CA 94720, USA. Tel.: #1-510-486-4581; fax:#1-510-486-5530. E-mail address: smarchesini@lbl.gov (S. Marchesini). Nuclear Instruments and Methods in Physics Research A 457 (2001) 601}606 Instrumental development of X-ray atomic holography at ESRF S. Marchesini*, O. Ulrich, G. Faigel, M. Tegze, M. Belakhovsky, A.S. Simionovici  Service de Physique des Mate & riaux et Microstructures, De & partement de Recherche Fondamentale sur la Matie & re Condense & e, CEA Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France Research Institute for Solid State Physics and Optics, BOB 49, H-1525 Budapest, Hungary European Synchrotron Radiation Facility, BP220, F-38043 Grenoble Cedex, France Received 17 April 2000; received in revised form 24 June 2000; accepted 27 June 2000 Abstract We have developed an X-ray Fluorescence Holography (XFH) setup at the European Synchrotron Radiation Facility (ESRF). The main di$culty inherent to XFH is that the holographic signal is in the low 10 range compared to the background isotropic #uorescent radiation. This requires a very pure #uorescent signal and the highest possible count rate. Therefore, we designed a focusing analyser system with large solid angle acceptance. The photons of the focused beam were counted by an avalanche photodiode in single-photon counting mode up to a few MHz. At even higher intensity, we switched to a Si diode working in the photocurrent mode. Due to the relatively weak requirements on the bandwidth of the exciting incident radiation, we could directly use the undulator beam, discriminating lower harmonics by an absorber and higher ones by re#ecting the beam on a Si mirror. By developing a fast, continuous `spirala scanning technique, a full hologram could be recorded in 30 sec.  2001 Elsevier Science B.V. All rights reserved. PACS: 07.85.Qe; 42.40.-i Keywords: Holography; X-ray; Focusing optics; Undulator radiation 1. Introduction X-ray Fluorescence Holography (XFH) is a de- veloping technique for structural studies. It was "rst experimentally demonstrated in 1996 [1]. Based on the same concept as photoelectron holo- graphy [2], but with X-ray #uorescent photons, the technique consists of measuring the interference between the #uorescent radiation directly emitted by the excited atoms and the same radiation scat- tered by neighbour atoms. In practice, one has to measure the #uorescent intensity as a function of the direction of emission on as large solid angle as it is possible. This method, where the #uorescent atoms inside the sample act as sources and the intensity is measured in the far "eld, is called 0168-9002/01/$ - see front matter  2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 9 0 0 2 ( 0 0 ) 0 0 7 9 1 - 9