Nuclear Instruments and Methods in Physics Research A 470 (2001) 131–134 Silicon planar refractive lenses with the optimized design V. Aristov a , M. Grigoriev a , S. Kuznetsov a , L. Shabelnikov a, *, V. Yunkin a , C. Rau b , A. Snigirev b , I. Snigireva b , T. Weitkamp b , M. Hoffmann c , E. Voges c a Institute of Microelectronics Technology RAS, 142432 Chernogolovka, Russia b European Synchrotron Radiation Facility (ESRF), B.P. 220, Grenoble, France c University of Dortmund, D-44227 Dortmund, Germany Abstract Silicon planar parabolic refractive lenses including lenses with minimized absorption are created by the microfabrication technique. Focusing properties of the lenses were studied with synchrotron radiation in the X-ray energy range of 8–25keV at the ESRF. The intensity transmission of a lens with minimized absorption is two times greater than that of simple parabolic lenses at 8 keV and in the X-ray energy range over 15keV it exceeds 90%. Spectral and heatload properties of lenses with minimized absorption are discussed in detail. r 2001 Elsevier Science B.V. All rights reserved. PACS: 41.50.+h; 07.85.@m Keywords: Xrays; Refraction; Lenses; Parabolic; Transmission; Gain; Heatload; Microfabrication; Focusing 1. Introduction Silicon is widely used in X-ray focusing optics and its microfabrication technologies possess the potential to create refractive lenses with radii of curvature of a few micrometers [1,2]. As a refracting material, Si satisfies the compound refractive lens demands [3–8]. The planar technology has a great advantage in the design and manufacture of kinoform lenses [2,8,9] with the combination of refractive and diffractive properties. This refractive profile can be realized by removing the passive parts of the simple parabolic lens material, where the phase variation is a multiple of 2p. Thus a wide range of possible arrangements of parabolic segments becomes possible where the phase relationship among them is not disrupted. In addition, the microfabrication technique allows to multiply the lenses up to a desired number not only to shorten the focal length by an order just as for the compound refractive lens (CRL) [3–7] but mainly in an effort to minimize technological inaccuracies and heatload. Here we present an experimental investigation of silicon planar parabolic lenses with synchrotron radiation as well as a detailed analysis of spectral and heatload properties. *Corresponding author. Tel.: +7-095-524-4081; fax: +7- 095-962-8047. E-mail address: lgs@ipmt-hpm.ac.ru (L. Shabelnikov). 0168-9002/01/$-see front matter r 2001 Elsevier Science B.V. All rights reserved. PII:S0168-9002(01)01024-5