A first focusing test of the undulator radiation at SPring-8 has been done using two types of x-ray refractive lenses in thin glass capillaries. One (lens No. 1) contained bubbles in a glue whereas the other (lens No. 2) contained bubbles in glycerol. The capillaries had inner diameters of 0.2 and 0.8 mm, respectively. Using x rays of 17–18 keV, the undulator source image was investigated at the focal plane. The spherical aberrations and the field distortions were carefully examined by taking the images of a gold mesh. Lens No. 1 had an advantage of high transmissivity in the hard x-ray region (18% at 18 keV) and high tolerance to severe radiation damage, e.g., ∼5×1012 photons/s/0.03 mm2 of the 18 keV x rays for an exposure time of 1 h. On the other hand, lens No. 2 had an advantage of a large aperture, 0.8 mm, and a small field distortion, e.g., less than 10% inside a diameter of 300 μm.

No abstract

We present x-ray images of grid meshes and biological material obtained using an unfiltered x-ray tube and a compound refractive lens composed of microbubbles embedded in epoxy inside a glass capillary. Images obtained using this apparatus are compared with those using a synchrotron source and the same lens. We find that the field of view is larger than that obtained using the synchrotron source, whereas the contrast and resolution are reduced. Geometrical distortion around the edges of the field of view is also reduced. The experiments demonstrate the usefulness of the apparatus in a modest laboratory setting.

A new method for producing a compound refractive X-ray lens is described. The lens is designed as glass capillary "lled by a set of concave individual lenses. The method is appropriate for the preparation of 10}1000 spherical lenses in a glass capillary with a diameter of 0.1}1 mm. Lens aberrations are considered and simple formulas for spot size are derived. Ray-tracing simulations on the focusing experiments using 18 keV X-rays are reported.

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.