Focusing hard x rays beyond the critical angle of total reflection by adiabatically focusing lenses

• Published in: Applied physics letters Vol. 110; no. 10
• Main Authors: Patommel, Jens, Klare, Susanne, Hoppe, Robert, Ritter, Stephan, Samberg, Dirk, Wittwer, Felix, Jahn, Andreas, Richter, Karola, Wenzel, Christian, Bartha, Johann W., Scholz, Maria, Seiboth, Frank, Boesenberg, Ulrike, Falkenberg, Gerald, Schroer, Christian G.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 06-03-2017; American Institute of Physics (AIP)
• Subjects: Adiabatic flow; Angle of reflection; Applied physics; Critical angle; Microscopes; NUCLEAR PHYSICS AND RADIATION PHYSICS; Numerical aperture; Refractive lenses; X ray optics; X-rays
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4977882

In response to the conjecture that the numerical aperture of x-ray optics is fundamentally limited by the critical angle of total reflection [Bergemann et al., Phys. Rev. Lett. 91, 204801 (2003)], the concept of adiabatically focusing refractive lenses was proposed to overcome this limit [Schroer and Lengeler, Phys. Rev. Lett. 94, 054802 (2005)]. We present an experimental realization of these optics made of silicon and demonstrate that they indeed focus 20 keV x rays to a 18.4 nm focus with a numerical aperture of 1.73(9) × 10−3 that clearly exceeds the critical angle of total reflection of 1.55 mrad.