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Corso A.J.,National Research Council Italy | Corso A.J.,University of Padua | Zuppella P.,National Research Council Italy | Windt D.L.,Reflective X-ray Optics, LLC | And 3 more authors.
Optics Express | Year: 2012

In this work we present the design of a Pd/B4C multilayer structure optimized for high reflectance at 6.67 nm. The structure has been deposited and also characterized along one year in order to investigate itstemporal stability. This coating has been developed for the beam transport system of FERMI@Elettra Free Electron Laser: the use of an additional aperiodic capping layer on top of the structure combines the high reflectance with filter properties useful in rejecting the fundamental harmonic when the goal is to select the third FEL harmonic. ©2012 Optical Society of America.


Kjornrattanawanich B.,Brookhaven National Laboratory | Windt D.L.,Reflective X-ray Optics, LLC | Seely J.F.,U.S. Navy
Applied Optics | Year: 2010

The optical constants β and δ of the complex refractive index n = 1 - δ + iβ of Sm, Ho, and Er were obtained in the 1.5-850 eV energy range using a transmittance method. Thin films of Sm, Ho, and Er were deposited by magnetron sputtering, and transmittance was measured using synchrotron radiation under a high vacuum condition. All films were directly coated on Si photodiodes, which were used as coating substrates, as well as photon detectors. Si was used as capping layer while a thin W layer was used as barrier against interface diffusion between Si and the highly reactive rare earth elements. The constants β were extracted from transmittance results, and the constants S were calculated based on measured β values using the Kramers-Kronig formalism. Small deficiencies determined from the present data using the partial sum rules were partly attributed to the sputtered film densities that could be slightly lower than the bulk values. © 2010 Optical Society of America.


Windt D.L.,Reflective X-ray Optics, LLC | Conley R.,Argonne National Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

This paper describes a new variation of the differential deposition/differential erosion technique for mid-frequency surface-height error correction. In our approach, the technique is extended to two dimensions in order to correct surfaceheight errors in thin-shell cylindrical mirror segments with high throughput. We describe the new infrastructure currently being developed to realize this technique, including an LTP system for surface metrology of mid-frequency surfaceheight errors, a new UHV linear stage for precise substrate motion during deposition or erosion, and most crucially, the development of electronically-actuated aperture arrays that are mounted in front of a rectangular magnetron cathode, or a rectangular ion source, in order to modulate the deposition/erosion rate of material in two dimensions, in real-time. © 2015 SPIE.


Windt D.L.,Reflective X-ray Optics, LLC
Review of Scientific Instruments | Year: 2015

A laboratory-based X-ray reflectometer has been developed to measure the performance of hard X-ray multilayer coatings at their operational X-ray energies and incidence angles. The instrument uses a sealed-tube X-ray source with a tungsten anode that can operate up to 160 kV to provide usable radiation in the 15-150 keV energy band. Two sets of adjustable tungsten carbide slit assemblies, spaced 4.1 m apart, are used to produce a low-divergence white beam, typically set to 40 μm × 800 μm in size at the sample. Multilayer coatings under test are held flat using a vacuum chuck and are mounted at the center of a high-resolution goniometer used for precise angular positioning of the sample and detector; additionally, motorized linear stages provide both vertical and horizontal adjustments of the sample position relative to the incident beam. A CdTe energy-sensitive detector, located behind a third adjustable slit, is used in conjunction with pulse-shaping electronics and a multi-channel analyzer to capture both the incident and reflected spectra; the absolute reflectance of the coating under test is computed as the ratio of the two spectra. The instrument's design, construction, and operation are described in detail, and example results are presented obtained with both periodic, narrow-band and depth-graded, wide-band hard X-ray multilayer coatings. © 2015 AIP Publishing LLC.


Windt D.L.,Reflective X-ray Optics, LLC | Gullikson E.M.,Lawrence Berkeley National Laboratory
Applied Optics | Year: 2015

A new extreme ultraviolet (EUV) multilayer coating has been developed comprising Pd and Y layers with thin B4C barrier layers at each interface, for normal incidence applications near 10 nm wavelength. Periodic, nonperiodic, and dual-stack coatings have been investigated and compared with similar structures comprising either Mo/Y or Pd/B4C bilayers. We find that Pd/B4C/Y multilayers provide higher reflectance than either Mo/Y or Pd/B4C, with much lower film stress than Pd/B4C. We have also investigated the performance of periodic multilayers comprising repetitions of Pd/Y, Ru/Y, or Ru/B4C/Y, as well as Pd/B4C multilayers deposited using reactive sputtering with an Ar:N2 gas mixture in order to reduce stress: these material combinations were all found to provide poor EUV performance. The temporal stability of a periodic Pd/B4C/Y multilayer stored in air was investigated over a period of 16 months, and a slight reduction in peak reflectance was observed. Periodic Pd/B4C/Y multilayers were also found to be thermally stable up to 100K°C; at higher temperatures (200K°C and 300K°C) we observe a slight reduction in peak reflectance and a slight increase in multilayer period. High-resolution transmission electron microscopy and selected area diffraction of an as-deposited Pd/B4C/Y film indicates a fully amorphous structure, with interfaces that are both smoother and more abrupt than those observed in a comparable Pd/B4C multilayer in which the Pd layers are polycrystalline. The new Pd/B4C/Y multilayers are suitable for normal-incidence imaging and spectroscopy applications, including solar physics, plasma physics, high-brightness EUV light sources, and others. © 2015 Optical Society of America.


Windt D.L.,Reflective X-ray Optics, LLC
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

This paper describes recent progress in the development of new EUV multilayer coatings for solar physics. In particular, we present results obtained with Pd/B4C/Y, Al/Zr, and Al-Mg/SiC multilayers, designed for normal incidence operation in the 9-50 nm wavelength range. We describe the development of both periodic multilayer films designed for narrowband imaging, and non-periodic multilayers designed to have a broad-spectral response for spectroscopy. The higher EUV reflectance provided by these new coatings, relative to older-generation coatings such as Si/Mo, Mo/Y, and others, will facilitate the development of future solar physics instruments for both imaging and spectroscopy having higher spatial and spectral resolution, while supporting the exposure times and cadences necessary to capture the evolution of flares, jets, CMEs and other dynamic processes in the solar atmosphere. © 2015 SPIE.


Windt D.L.,Reflective X-ray Optics, LLC
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

This paper is focused on recent progress in the development of broad-band multilayer coatings designed for hard X-ray energies, for use in future astronomical telescopes. We describe a new laboratory-based hard X-ray reflectometer for atwavelength characterization of multilayer films, we present the results of an experimental comparison of the hard X-ray performance of several W-based periodic multilayer coatings, and we describe the optimization and experimental performance of new non-periodic Co-based multilayer coatings (both depth-graded and aperiodic), designed for continuous response through the W and Pt K-edges near 70 and 80 keV, respectively. We discuss future research directions in light of these new results. © 2015 SPIE.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 125.00K | Year: 2013

We propose to develop and commercialize a new class of aperiodic multilayer coating that is designed to provide high normal-incidence reflectance over a wide spectral band-pass in the extreme ultraviolet (EUV) region, specifically from 9 to 14 nm. A broad-band reflective coating working at these wavelengths will enable, for the first time, the construction of high-resolution imaging spectrometers for solar physics utilizing diffraction gratings operating near normal incidence in this range, akin to previous instruments utilizing normal-incidence optics working at longer EUV wavelengths (i.e., lambda>17 nm) such as the Hinode/EIS satellite instrument and the EUNIS sounding rocket instrument. The development of high-resolution, normal-incidence grating spectrometers operating in the 9?14 nm range will in turn allow for detailed investigations of important solar emission lines, such as those from Fe XVIII?XXIII, that can provide unique diagnostics of high temperature plasma associated with solar flares and active regions. The successful development of efficient, broad-band EUV multilayers for the 9?14 nm region as we propose will thus enable future flights of the EUNIS rocket to target this band, and will also enable the development of high resolution spectrometers that can meet the science requirements of future NASA satellite missions, such as RAM, Solar-C and others that are currently being contemplated.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 125.00K | Year: 2012

We propose to develop and commercialize a new class of multilayer interference coating that is designed to provide high reflection efficiency in two disparate wavelength bands in the extreme ultraviolet (EUV), a so-called 'dual-band' EUV multilayer. A high-performance dual-band multilayer coating will allow for solar imaging or spectroscopy instruments that operate in two different EUV channels using a single instrument aperture. The realization of dual-band multilayer coatings having high reflectance at the target wavelengths, low reflectance of unwanted wavelengths, low film stress, and good thermal and temporal stability, will enable the construction of future solar instruments that have much higher collection efficiency, lower mass and volume, and lower costs than is currently possible using existing multilayer coating technology.The goal of our proposed Phase I program is to experimentally investigate the performance of a new type of dual-band coating design comprising two periodic multilayers separated by a low-absorption spacer layer. This approach results in the ability to independently tune the spectral response of both EUV wavebands, and to suppress unwanted wavelengths. We will explore both B4C/Si-Si-B4C/Mo-Si and SiC/Al-Al-Zr/Al designs. We also will investigate the use of novel capping layer structures comprising Ir, Ru or other metals, for enhanced reflectance and better coating resilience in harsh environments.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 600.00K | Year: 2010

We propose to develop and commercialize a new type of low-stress iridium (Ir) X-ray mirror coating technology that can be used for the construction of high-resolution X-ray telescopes comprising thin-shell mirror substrates, such as the Flight Mirror Array (FMA) currently being developed for the IXO mission. The urgent need for low-stress Ir coating technology is driven by the current limitations on telescope angular resolution resulting from substrate distortions caused by conventional reflective Ir coatings that typically have very high stress. In particular, we have measured film stresses in excess of 4 GPa in the case of Ir films deposited by conventional magnetron sputtering. It is thought that the distortions in the thin glass mirror shells (such as those proposed for the IXO FMA) resulting from such extremely large coating stresses presently make the largest contribution to the telescope imaging error budget, of order 10 arcsec or more. Consequently, it will be difficult, if not impossible, to meet the imaging requirements of IXO, or other high-resolution X-ray missions in the future that use thin-shell mirror technology, unless high-quality Ir coatings having significantly lower stresses can be developed. The development of such coatings is precisely the aim of our proposal. Specifically, building on our successful Phase I effort, we propose to complete the development of low-stress Ir/Cr bilayers, and also investigate the use of Ir/Ti bilayers. We also propose to investigate the properties single-layer Ir films, as well as Ir/Cr and Ir/Ti bilayers, prepared by reactive sputtering with nitrogen. Finally, we plan to transfer the low-stress Ir coating technology to our large, production-class sputtering system so that we can coat GSFC-supplied thin-shell mirror substrates and conclusively demonstrate reduced stress-driven substrate distortions.

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