Broadening the field of view with a fan-shaped source grating

The grating fabrication team recently presented a new solution for the beam alignment of high aspect ratio gratings in imaging systems with an X-ray tube. The field of view of an X-ray Talbot-Lau interferometry setup has been increased by 1.5 times thanks to a source grating with a fan-shaped microstructure. We invented a novel tilted etching method by modulating the electric field during the plasma etching process (see figure below). A model is built with finite elements method and experiments validate the simulation results, showing that a desired tilt profile can be achieved with a proper parameters tuning. The tilted plasma etching method can be applied for many other optics that need a continuous slant gradient.

Schematic diagram of the novel tilted etching method. Local electric field in presence of an electric field modulator (d the inter-slabs distance, h the slab thickness and l the slab width), and a sketched profile of grating lines with tilted etching θ as a function of position x. The equipotential lines are plotted as curved lines in grey scale.
Original Publications

High aspect ratio tilted gratings through local electric field modulation in plasma etching, Z. Shi, K. Jefimovs, A. La Magna, M. Stampanoni, L. Romano, Applied Surface Science, 152938 (2022)

Laboratory X-ray interferometry imaging with a fan-shaped source grating, Z. Shi, K. Jefimovs, L. Romano, J. Vila-Comamala, M. Stampanoni, Optics Letters 46, 3693-3696 (2021)

Zhitian Shi
PhD Student, Paul Scherrer Institut, +41 56 310 2474,
Dr. Lucia Romano
Institute for Biomedical Engineering, University and ETH Zürich, 8092, Zürich, Switzerland
Senior Scientist, Paul Scherrer Institut, +41 56 310 5688,