Dresden 2009 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 34: Microfluidics I: Applications and Devices
CPP 34.7: Vortrag
Donnerstag, 26. März 2009, 11:15–11:30, ZEU 160
Focusing X-ray beam by dynamic compound refractive lenses in a microfluidic device — •Yasutaka Iwashita1, Christian Bahr1, Ralf Seemann1,2, and Stephan Herminghaus1 — 1MPI for Dynamics and Self-Organization, D-37073 Goettingen — 2Experimental Physics, Saarland University, D-66041 Saarbruecken
Compound refractive lenses (CRL), composed of a large number of individual lenses of small radii in a row embedded in a solid medium, have been developed as X-ray lenses [1]. To broaden the possibilities and functions of CRL’s, we designed a ‘dynamic CRL’ composed of gas bubbles in a liquid, where the bubbles are generated in situ and flowing consecutively in a microfluidic device. Here, the lamellae between the bubbles act as lenses. Due to the continuous renewal of the materials, this system leads to a high stability against high X-ray intensities. Furthermore, the variation of bubble shape controlled via flow parameters allows in situ optimization of the optical properties.
We generate dynamic CRL structures with gas - octadecane foams stabilized by surface freezing and gas - dodecylcyanobiphenyl (liquid crystal) foam stabilized by surface ordering. The advantages of these systems are high X-ray transmittance and stabilization without surfactants. As an example, the theoretically estimated lens properties of a generated dynamic foam, i.e., the focal length, gain and transmittance along the optical axis, were 97.7 µm, 1800 and 50.3 %, respectively, for X-ray energy of 8 keV.
[1] A. Snigirev, V. Kohn, I. Snigireva and B. Lengeler, Nature 384(6604), 49(1996).