Kinoform lenses avoid the absorption losses from a comparable refractive lens by removing all material causing redundant 2π phase shifts. Such optics allow high resolution imaging with a theoretical 94% focusing efficiency. While fabrication of kinoform lenses for two-dimensional focusing is difficult, standard lithographic processes can be utilized to fabricate optics in silicon which produce a line focus. By putting two single-dimension kinoform lenses in a crossed-pair arrangement, a two-dimensional spot is achieved. First attempts at imaging with a crossed pair of kinoform lenses are presented.
To image weakly absorbing materials (e.g. biological specimens, thin films, etc.) with hard x-ray photons, phase-contrast methods have to be applied to enhance the image contrast. Micro-fabricated Fresnel prisms in silicon have been manufactured to enable wavefront division of the incoming x-ray beam for phase-contrast applications. To maximize the efficiency and aperture of these optics, multiples of 2π phase-shifting regions in a conventional prism structure have been deleted, leading to structures that are arrays of micro-prisms. We show preliminary results of x-ray beam deflection using a variety of micro-prism arrays at the NSLS X13B undulator beamline at 11.3 keV.
One application of Kinoform Fresnel Lenses is to generate small focal spots of hard X-ray photons with high gain for micro-diffraction experiments. A Kinoform lens can be obtained from a refractive lens by deleting material such that at the design photon energy, the deleted regions correspond to with modulo 2π phase-shifts in the phase front. At photon energies different from the design photon energy, the phase jumps are no longer 2π, and the diffractive properties of the kinoform become more significant. We present measurements and calculations of spot size versus photon energy.