Double-sided zone plates
To obtain Fresnel zone plates with very high resolution and good diffraction efficiency requires the fabrication of nanostructures with extreme aspect ratios. Within a collaboration funded by the Nanoscopium beam line of Synchrotron SOLEIL, we have developed schemes for the stacking of two zone plates, in order to increase the effective structure height of Fresnel zone plates beyond todays nanofabrication limits. By patterning both sides of the same support membrane (see Figure 1&2), we can provide a pair of stacked zone plates as a monolithic device.
Using this approach were able to produce double-sided zone plates with 30 nm outermost zone width and 1200 nm effective zone height, corresponding to an aspect ratio of 40 . The devices showed an enhanced diffraction efficiency of 10% at 9 keV photon energy (see Figure 3). The shape of the focal spot was reconstructed from a ptychographic data set , revealing a spot size matching the expected value of 30 nm FWHM.
- I. Mohacsi, I. Vartiainen, M. Guizar-Sicairos, P. Karvinen, C. Kewish, A. Somogyi, V.A. Guzenko, E. Müller, E. Färm, M. Ritala, and C. David, Double-sided diffractive X-ray optics for hard X-ray microscopy Optics Express 23 (2015) p. 776
- J. Vila-Comamala, A. Diaz, M. Guizar-Sicairos, A. Mantion, C. M. Kewish, A. Menzel, O. Bunk and C. David , Characterization of high-resolution diffractive x-ray optics by ptychographic coherent diffractive imaging, Optics Express 19 (2011) p. 21333