Microspot x-ray focusing using a short focal-length compound refractive lenses

Abstract

We have fabricated and tested short focal-length compound refractive lenses (CRLs) composed of microbubbles embedded in epoxy encased in glass capillaries. The interface between the bubbles formed 90 to 350 spherical biconcave microlenses reducing the overall focal length inversely by the number of lenses or bubbles. When compared with CRLs manufactured using other methods, the microbubble lenses have shorter focal lengths with higher transmissions and larger gains for moderate energy x rays (e.g., 7 -20 keV). We used beamline 2-3 at the Stanford Synchrotron Radiation Laboratory and beamline 5BM-D-DND at the Advanced Photon Source to measure focal lengths between 100-250 mm with lens apertures varying between 97 and 321 m. Transmission profiles were measured giving, for example, a peak transmission of 46% for a 240 mm focal length CRL at 20 keV. The focal-spot sizes were also measured yielding, for example, a vertical spot size of 1.2 m resulting from an approximate 20-fold demagnification of the APS 23 m source size. The measured gains in intensity over that of unfocused beam were between 9 and 26.

Projection-type x-ray microscope based on a spherical compound refractive x-ray lens

“…Experiments on measuring lens focal length of compound epoxy lenses at Stanford Synchrotron Radiation Laboratory and Advanced Photon Source shown validity of formula 4 for calculation lens focal length [13,14]. Compound X-ray lenses consisting of spherical microlenses may be characterized by absorption aperture radius R a that in a good approximation can be calculated as:…”

Design and Application of X-Ray Lens in the Form of Glass Capillary Filled by a Set of Concave Epoxy Microlenses

“…Photon Source by Adelphi Technology, Inc. shown validity of formula 6 for calculation lens focal length (Dudchik et al, 2004).…”

“…Measured and calculated parameters of microcapillary refractive X-ray lens for SSRL BL 2-3 source Used was the beamline 2-3 on the Stanford Synchrotron Radiation Laboratory's (SSRL's) synchrotron (Dudchik et al, 2004). This beamline possesses a double-crystal monochromator that was capable of giving x-rays from 2400 to 30000 eV with a 5 x 10 -4 resolution.…”

“…Compound X-ray lens consisting of spherical microlenses may be characterized by absorption aperture radius R a that in a good approximation can be calculated as (Snigirev et al, 1996;Dudchik et al, 2004;Piestrup et al, 2005):…”

“…For example the lens in the form of 200 microns in diameter capillary and filled by 103 microlenses has 13-cm focal length for 8 keV X-rays. It was shown experimentally by Adelphi Technology, Inc. using beamline 2-3 at the Stanford Synchrotron Radiation Laboratory (SSRL) (Dudchik et al, 2004). Such short-focal-length lenses are suitable for imaging not only with synchrotron X-rays, but with X-rays from laboratory sources of radiation (Piestrup et al, 2005).…”