Fabrication and test of one-dimensional Bragg-Fresnel lens using Ag/Al multilayer zone plate

A 1D Bragg-Fresnel lens for monochromatizing and focusing hard x-rays has been developed using a multilayer zone plate and a crystal. In the present study, Ag and Al have been chosen as material for opaque and transparent layers, respectively. About 300 layers of Ag and Al were alternately deposited on a plane substrate according to the Fresnel's formula using a helicon plasma sputtering technique, in which Ar gas pressure was less than 1 mTorr. The total thickness of the layers is about 100 micrometers. The multilayered plane was sliced vertically and glued onto Ge(211) crystal, and thinned to about 15 micrometers. By combining the dispersive characteristics of the crystal with the focusing capability of the multilayer zone plate, a new type of Bragg-Fresnel lens has been developed. Experimental tests have been performed at BL-17A of Photon Factory. The projected image of the synchrotron light source has been recorded on nuclear plates.