Mosaic-like micropillar array for hard x-ray focusing—one-dimensional version

Abstract

An array of microstructures resembling a Fresnel version of the classical parabolic x-ray refractive lens shape shows a significant improvement towards focal spot size and intensity. The proposed polymer microstructures with the acting refractive surface have a pillar-like form with a triangular cross-section. Their arrangement and the parameters of the triangles change along the lenses in accordance with the x-ray propagation law, yielding a focusing effect in the hard x-ray range. The great number of micropillars arranged in one row conduct the x-ray beam like a waveguide, with its transparency increasing with decreasing pillar size. A multi-row lens can collect x-rays into a focus down to several nanometres. The specific regular arrangement of the pillars resembles a mosaic ornament, which led to the chosen name. Fabricating the lenses by means of deep x-ray lithography is essential for avoiding various potential manufacturing difficulties. The one-dimensional focusing lenses overcome the diffraction limit defined for the classical parabolic lenses due to their large aperture that results from the waveguide-like rows formed by the pillar arrangement.