Diffractive X-ray optics, like Fresnel zone plate lenses, are widely employed X-ray optics for collimation and focusing. While they are extremely versatile and easy to use optical elements, they generally suffer from limited efficiency due to limitations in fabrication possibilities. Near-field stacking is an established concept for overcoming fabrication limitations, yet its existing implementations suffer from issues regarding complexity and stability. In this work, an alternative stacking concept is explored, by patterning both the front and back sides of a single membrane. Such double-sided zone plates are shown to exchange conventional zone plate stacks in increasing the efficiency or resolution of conventional zone plate optics. In conventional stacking, they achieve 9.9% focusing efficiency at 9 keV with 30 nm smallest half-pitch and diffraction limited optical performance. Following the blazed stacking scheme, they are shown to provide up to 54.7% diffraction efficiency at 6.2 keV. Finally, using the novel concept of interlaced stacking, they demonstrate the feasibility of large aperture X-ray optics for sub-10 nm X-ray nanofocusing.
We have developed a prototype instrument with a novel interferometrically controlled differential scanning stage system. The system consists of 9 DC-motor-driven stages, 4 picomotor-driven stages, and 2 PZT-driven stages. A custom-built laser Doppler displacement meter system provides two-dimensional (2D) differential displacement measurement with subnanometer resolution between the zone-plate x-ray optics and the sample holder. The entire scanning system was designed with high stiffness, high repeatability, low drift, flexible scanning schemes, and possibility of fast feedback for differential motion. Designs of the scanning stage system, as well as preliminary mechanical test results, are presented in this paper.