The development of high brilliance X-ray sources coupled with advances in manufacturing technologies has led to significant improvements in submicrometre probes for spectroscopy, diffraction and imaging applications. The generation of a small beam spot size is commonly based on three principles(1) total reflection las used in optical elements involving mirrors or capillaries), refraction (such as in refractive lenses(2)) and diffraction. The latter effect is employed in Bragg-Fresnel or Soret lenses, commonly known as Fresnel zone plate lenses. These lenses currently give the best spatial resolution, but are traditionally limited to rather soft X-rays-at high energies, their use is still limited by their efficiency. Here we report the fabrication of high-efficiency, high-contrast gold and nickel multistep (quaternary) Fresnel zone plates using electron beam lithography. We achieve a maximum efficiency of 55% for the nickel plate at 7 keV. In addition to their high efficiency, the lenses offer the advantages of low background signal and effective reduction of unwanted diffraction orders. We anticipate that these lenses should have a significant impact on techniques such as microscopy(3), micro-fluorescence(4) and micro-diffraction(5), which require medium resolution (500-100 nm) and high flux at fixed energies
Focusing of 8 keV x rays to a spot size of 150 and 90 nm full width at half maximum have been demonstrated at the first-and third-order foci, respectively, of a phase zone plate ͑PZP͒. The PZP has a numerical aperture of 1.5 mrad and focusing efficiency of 13% for 8 keV x rays. A flux density gain of 121 000 was obtained at the first-order focus. In this article, the fabrication of the PZP and its experimental characterization are presented and some special applications are discussed.
Articles you may be interested inLowdistortion electronbeam lithography for fabrication of highresolution germanium and tantalum zone plates J. Vac. Sci. Technol. B 13, 2762 (1995); 10.1116/1.588261Highperformance multilevel blazed xray microscopy Fresnel zone plates: Fabricated using xray lithography Soft Xray nano lithography of semitransparent masks for the generation of highresolution high contrast zone plates AIP Conf.
X-ray photoelectron spectroscopy has become a true microscopic technique at third generation soft X-ray synchrotron sources, finding applications in many domains of academic and applied research. This paper describes the present status of scanning photoemission microscopy, where by using photon optics the photon beam can be focused to micron or submicron dimensions and imaging or spectroscopy can be performed. It discusses different photon focusing optical elements and describes the major components of the constructed scanning microscopes. The applications of imaging and spectroscopy with high lateral resolution in surface science are illustrated, and some recent results obtained in different laboratories are briefly reviewed. Surf. Rev. Lett. 1999.06:265-286. Downloaded from www.worldscientific.com by NANYANG TECHNOLOGICAL UNIVERSITY on 08/21/15. For personal use only.
A linear and a circular zone plate with a blazed zone profile (ZPBP) have been fabricated and characterized using synchrotron x rays. The ZPBPs have significantly improved performances in terms of focusing efficiency and the background near the focus compared to those of a zone plate with a square profile, of which the transmission function can be characterized by a binary square wave. In many respects and practical cases, an x-ray ZPBP may be used in a way analogous to an optical lens in the visible light region. In this article, the experimental characterization of the ZPBPs is presented and some special applications are discussed.
A hard x-ray imaging microscope based on a phase zone plate has been developed and tested. The zone plate, with a 5 cm focal length and a 0.2 pm smallest linewidth, was used to image 8 keV x rays from the samples. The imaging microscope can be used to obtain nearly diffraction-limited resolution over the entire imaging field, and its resolution is almost independent of source size and source motions. We have tested such an imaging microscope, and a resolution of about 0.4 pm was obtained. The images were obtained with an exposure time of less than 1 min, for a magnification factor of 30 in the x rays. The x rays were then converted into visible light, and another 7 times magnification were obtained by using a lens system coupled to a charge coupled device camera. The results from the imaging microscope, and possible applications, will be discussed. 0 1995 American Institute of Physics.-1NTRODUCTlON
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