Diffraction-enhanced beam-focusing for X-rays in curved multi-plate crystal cavity

Abstract

Unusual x-ray focusing effect is reported for parabolic curved multi-plate x-ray crystal cavities of silicon consisting of compound refractive lenses (CRL). The transmitted beam of the (12 4 0) back reflection near 14.4388 keV from these monolithic silicon crystal devices exhibits extraordinary focusing enhancement, such that the focal length is reduced by as much as 18% for 2-beam and 56% for 24-beam diffraction from the curved crystal cavity. This effect is attributed to the presence of the involved Bragg diffractions, in which the wavevector of the transmitted beam is bent further when traversing several curved crystal surfaces.

Focusing X-Rays with Curved Multiplate Crystal Cavity

“…Moreover, there are more dispersion sheets (96 in total) involved in the 24-beam diffraction [18]. That implies that there are more chances for the transmitted beam to focus on to point O [10].…”

“…Very recently, two-and multi-plate X-ray cavities of silicon have been realized using X-ray back reflection and X-ray interference fringes due to cavity resonance been observed [7,8]. In addition, attempts to combine this Fabry-Perot type crystal cavity with CRL lenses of circular [9] and parabolic shapes [10] for X-ray focusing have been pursued. In this paper, an overview is given of this development of utilizing crystal cavities for focusing X-rays.…”