Fabrication of a fractal pattern device for focus characterizations of X-ray imaging systems by Si deep reactive ion etching and bottom-up Au electroplating

Precisely aligned optical components are crucial prerequisites for X-ray tomography at high resolution. We propose a device with a fractal pattern for precise automatic focusing. The device is etched in a Si substrate by deep reactive ion etching and then filled by a self-terminating bottom-up Au electroplating process. The fractal nature of the device produces an X-ray transmission image with globally homogeneous macroscopic visibility and high local contrast for pixel sizes in the range of 0.165 mu m to 11 mu m, while the high absorption contrast provided between Au and Si enables its use for X-ray energies ranging from 12 keV to 40 keV. (C) 2022 Optica Publishing Group