One-dimensional Grazing Incidence Zone Plate For Focusing Soft X-rays.

We have designed and manufactured a grazing incidence FZP having a non-symmetrical one-dimensional zone structure in order to minimize an outermost zone width. The focal spot size obtained by the FZP is determined by the outermost zone width, and which depends on the manufacturing technique. The projected zone width can be decreased as sine function of the incidence angle. Overall dimension of the zone plate is calculated on the basis that the optical pass difference must be the multiple of a half the wavelength. Two dimensional focusing can be conducted by using a pair of them for vertical and horizontal focusing, correspondingly. Another advantage of the device is that the same focal length can be obtained in case of changing the wavelength. In the case of conventional FZP, experiments using variable wavelength, such as micro-EXAFS, are very difficult because the focal length shifts inversely proportional to the wavelength. The focal length shift can be corrected by changing the incidence angle in the case of the grazing incidence FZP. Electron beam lithography and reactive ion etching technique are used to manufacture FZP. Vanadium is chosen as FZP material since it has high etching rate with CF4 gas. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]