X-ray focusing by planar parabolic refractive lenses made of silicon

First refractive planar parabolic lenses are realized in Si. They comprise a set of parabolic profiles (planar parabolic lenses) or parabolic segments (planar parabolic lenses with minimized absorption) with symmetry axis lyi ng in Si wafer surface plane. The relief depth achieved by dry etching proc esses is 100 mu m. Experimental testing of lenses has been carried out on a n RU-200 rotating anode generator with Cu K alpha radiation (8.05 keV). The focal length, estimated and confirmed by experiment, is F = 18 cm for plan ar parabolic lenses. The lenses with minimized absorption have shorter foca l length F = 16.8 cm, showing a 5 mu m recorded source image. The calculate d transmission for these lenses reaches T = 37%, approaching values of tran smission for compound refractive lenses made of low Z materials. (C) 2000 E lsevier Science B.V. All rights reserved.