Proceedings Volume 1546

Multilayer and Grazing Incidence X-Ray/EUV Optics

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Proceedings Volume 1546

Multilayer and Grazing Incidence X-Ray/EUV Optics

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Volume Details

Date Published: 1 January 1992
Contents: 11 Sessions, 54 Papers, 0 Presentations
Conference: San Diego, '91 1991
Volume Number: 1546

Table of Contents

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Table of Contents

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  • Characterization of Multilayer Optics
  • Fabrication of Multilayer Optics
  • Characterization of Multilayer Optics
  • Fabrication of Multilayer Optics
  • Grazing Incidence Optics
  • X-Ray Microscopy and Interferometry
  • X-Ray Optics Test Facilities
  • X-Ray Microscopy and Interferometry
  • X-Ray Telescopes
  • X-Ray Observations
  • Grazing Incidence Optics
  • X-Ray Observations
  • X-Ray, EUV Spectrometers, and Polarimeters
  • History of X-Ray Optics
  • Poster Session
  • X-Ray Microscopy and Interferometry
  • Additional Paper
  • Poster Session
  • X-Ray Microscopy and Interferometry
  • Poster Session
  • Characterization of Multilayer Optics
  • Poster Session
  • X-Ray Telescopes
  • Poster Session
  • Grazing Incidence Optics
  • X-Ray Telescopes
  • Fabrication of Multilayer Optics
  • Grazing Incidence Optics
Characterization of Multilayer Optics
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Magnesium-silicide-based multilayers for soft x-ray optics
Pierre Boher, Philippe Houdy, Louis Hennet, et al.
Using a diode rf-sputtering technique, different magnesium silicide based multilayer systems have been deposited in very thin films for optical applications in the soft x-ray range. A detailed structural analysis of the different multilayers has been made using in-situ kinetic ellipsometry, ex-situ grazing x-ray reflection at the copper K-(alpha) line and transmission electron microscopy. The multilayer performances have been measured by synchrotron radiation at the magnesium K-(alpha) and L-(alpha) lines and related to the structural characteristics. For short wavelength, the W/Mg2Si system shows characteristics very similar to those of the more common W/Si system. Non-negligible interdiffusion and limited interface roughness allow the layer thicknesses to be reduced to very low values. Well-defined Bragg peaks are observed even when the double period is as low as 44 angstrom. First Bragg peak reflectivity as high as 31 has been measured at 9.89 angstrom for a multilayer with a double period equal to 84 angstrom and a limited number of periods. This preliminary result is very promising for future applications in the field of x-ray fluorescence analysis. W/Mg2Si and Si3N4/Mg2Si multilayers have also been fabricated for use at higher wavelengths around the Mg L-(alpha) line (286 angstrom). In the case of the W/Mg2Si multilayers have also been fabricated for use at higher wavelengths around the Mg L-(alpha) line (286 angstrom). In the case of the W/Mg2Si system, the tungsten layers are crystallized due to their higher thickness and consequently the interface roughness is slightly higher. In spite of this, more than 20 reflectivity at the first Bragg peak has been measured at normal incidence on different W/Mg2Si samples, with a selectivity two times better than conventional Mo/Si mirrors ((lambda) /(delta) (lambda) approximately equals 20). When we replace tungsten by a thin silicon nitride layer deposited by reactive sputtering, we increase the selectivity up to (lambda) /(delta) (lambda) approximately equals 30, and the thermal stability is drastically improved ( 800 degree(s)C).
Tungsten/boron nitride multilayers for XUV optical applications
Pierre Boher, Louis Hennet, F. Pierre, et al.
W/BN multilayers are theoretically efficient x-ray mirrors at the nitrogen and boron K-(alpha) lines (31.3 angstroms and 67.6 angstroms, respectively). Their most attractive potential application is detection of light elements by x-ray fluorescence spectrometry. The performances of W/BN mirrors depend not only on the structural quality of the multilayers but also on the stoichiometry of the boron nitride layers, especially in the water window (20 - 40 angstroms). In order to get stoichiometric BN layers with low surface roughness, the deposition of thick boron nitride films has been studied in detail. In-situ kinetic ellipsometry, x-ray photoemission, grazing x-ray reflection and scanning electron microscopy show that quasi-stoichiometric BN films with low surface roughness are obtained only with a low total deposition pressure and an additional nitrogen partial pressure. This result is related to the chemical and structural properties of the BN films. W/BN multilayers with medium period value (2d approximately equals 120 angstroms) show about 80 of the maximum reflectivity at the W M4-5 line. When the period is reduced, the performances are reduced, but good quality W/BN multilayers with very low period values (2d approximately equals 50 angstroms) and a great number of periods ( 100) have been fabricated. The best structural quality is obtained when a low nitrogen partial pressure is introduced during the deposition of the BN layers. The optical indice contrast is improved and the tungsten-boron interdiffusion is reduced.
Comparison of measured and calculated values for the diffraction line profiles and integral reflection coefficients for multiple diffraction orders of multilayer structures
Philip G. Burkhalter, John V. Gilfrich, R. K. Freitag, et al.
Double-crystal and single-crystal spectrometer measurements of line profile and integral reflection coefficient versus diffraction order are presented. These results are compared with theoretical predictions. The ability of the use of an intermediate layer in the theoretical model to explain the results is emphasized.
Fabrication of Multilayer Optics
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Description and performance of mirrors and multilayers for the extreme ultraviolet imaging telescope of the SOHO mission
Jean-Pierre Chauvineau, Jean-Yves Clotaire, Gilles Colas, et al.
The description fabrication and test of the primary and secondary mirrors of a Ritchey-Chretien telescope designed to provide the SOHO mission with a global view of the solar corona are discussed in details. Design fabrication and test of multilayers deposited on quadrants of the mirrors in order to select four narrow band-passes in the extreme ultra-violet range are presented and actual performances are reported.
Characterization of Multilayer Optics
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Evaluation of reflectors for soft x-ray optics
Kazuyuki Etoh, Noriyoshi Hoshi, Toshihiro Yonemitu, et al.
It is necessary to characterize surface roughness in order to clarify the relation between reflectivity and roughness. A comparison between characterized roughness of direct measurement of surface and calculated roughness from measured reflectivity is made. Surface roughness was improved using the dual ion beam sputtering method as a parameter of assisting ion energy. As a result, those two roughnesses showed good agreement and the surface roughness becomes minimum at assisting ion energy of 50 eV.
Method for characterizing multilayer coatings on curved substrates
George Gutman, Kevin Parker, James Scholhamer, et al.
The x-ray characterization of multilayer coatings at very low angles on curved substrates is limited by the radius of curvature and surface dimensions. Plane and cylindrical multilayers were manufactured in the same process and characterized as deposited. After flattening the cylindrical surface and curving the plane surface, the same were recharacterized. These measurements and the techniques used to characterize cylindrical surfaces are discussed with the goal of developing techniques for future application to the characterization of spherical, elliptical, or paraboloidal surfaces.
Reflectivity measurements of Ni/V, Ni/Ti, and W/C multilayer mirrors in the 2-6nm wavelength region using synchrotron radiation
Hiroshi Nagata, Yukinobu Ishino, Shoji Seki, et al.
Recent progress in the fields of physical vapor deposition (PVD), coupled with increased interest in the soft x-ray region of the electromagnetic spectrum, has driven the development of layered synthetic microstructures (LSMs) to the point that useful nongrazing incidence optics based on this technology are used in a variety of applications (e.g., solar astronomy, soft x-ray microscopy, and plasma spectroscopy). Our goal, as a production facility for thin film devices, was to demonstrate the capability for surement at 0.154 nm (CuK(alpha) ).
Fabrication of Multilayer Optics
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Fabrication of large layered synthetic microstructures of uniform reflectivity performance
Peter J. Biltoft, Steven Falabella, Edward H. Noble
Recent progress in the fields of physical vapor deposition (PVD), coupled with increased interest in the soft x-ray region of the electromagnetic spectrum, has driven the development of layered synthetic microstructures (LSMs) to the point that useful nongrazing incidence optics based on this technology are used in a variety of applications (e.g., solar astronomy, soft x-ray microscopy, and plasma spectroscopy). Our goal, as a production facility for thin film devices, was to demonstrate the capability for mass production of LSMs having uniform reflectivity performance (2d +/- 1 angstrom, Rp +/- 5) across the surface of a 10 cm diameter planar surface. We achieved this goal through the use of a large vacuum deposition chamber which accommodates a 66 cm diameter rotating substrate platen and two fixed position 15 cm diameter magnetron sputter deposition sources. Deposition flux masks positioned below the substrates in the vacuum process chamber provided the fine control of deposition flux necessary to achieve our uniformity goals. These masks were designed using a computer code that modeled the deposition system geometry and used empirical deposition rate data. Results obtained from soft x-ray mapping of the surface of LSMs fabricated with and without these deposition masks indicates a reduction in layer period (d-spacing) variation of +/- 13 angstroms to +/- 1 angstrom over a 10 cm diameter, and a significant improvement in reflectivity uniformity through the use of deposition masks. We are in the process of expanding our modeling and fabrication work to allow for deposition of multilayer optical coatings onto figured substrates.
New method of manufacturing elastically bent crystals and multilayer mirrors
George Gutman, James L. Wood
We present a new high-precision and cost-efficient method of manufacturing aspheric crystals and pseudo-crystals. The concept including calculations, limits of precision, and manufacturing details is discussed. The advantages of this method are illustrated by the application and use of a Johansson bent quartz crystal in an x-ray sequential spectrometer. The resolving power of the spectrometer is compared with the Siemens SRS 300 and the Fisons/ARL 8420 by a comparative measurement of uranium ore. The comparison involves the detection of 0.006 Rb (K(alpha) ) present as background. Options for future investigations and applications of this method are discussed.
Fabrication and analysis of Mo-Si multilayers
Lawrence Shing, Richard C. Catura
Molybdenum-Silicon (Mo-Si) multilayers have been fabricated in our laboratory for reflecting various soft x-ray wavelengths. Several normal incidence mirrors have been produced for a solar sounding rocket flight. Using properly shaped masks on 3 in. diameter dc magnetrons, we can produce multilayers of a similar size having a uniformity of better than +/- 3 over their entire surface area. Peak reflectance of the multilayers are as high as 42 at 171 angstroms. Efforts are underway to deposit several layers of different period on top of the multilayers in order to attenuate the reflection of 304 angstroms, a very bright line of He II in the solar spectrum. In the interim, we have made a Mo-Si mirror that reflects at 304 angstroms. In addition to obtaining information on the solar corona at this wavelength, this will greatly reduce the effects of the He II line when its image is appropriately subtracted from others. These results and a discussion of the current status of our multilayer research is presented.
Grazing Incidence Optics
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Calibration of the verification engineering test article-I for AXAF using the VETA-I x-ray detection system
Advanced X-ray Astrophysics Facility (AXAF) X-ray optics testing is conducted by VETA-I, which consists of six nested Wolter type I grazing-incidence mirrors; VETA''s X-ray Detection System (VXDS) in turn measures the imaging properties of VETA-I, yielding FWHM and encircled energy of the X-ray image obtained, as well as its effective area. VXDS contains a high resolution microchannel plate imaging X-ray detector and a pinhole scanning system in front of proportional-counter detectors. VETA-I''s X-ray optics departs from the AXAF flight configuration in that it uses a temporary holding fixture; its mirror elements are not cut to final length, and are not coated with the metal film used to maximize high-energy reflection.
Feasibility study of the use of synchrotron radiation in the calibration of AXAF: initial reflectivity results
Dale E. Graessle, Roger J. V. Brissenden, J. C. Cobuzzi, et al.
The 1-percent calibration accuracy goal of the Advanced X-ray Astrophysics Facility is being approached by way of an experiment at the National Synchrotron Light Source that will demonstrate the accuracy achievable in reflectance measurements conducted on coated flat mirrors in the 50 eV-12 keV energy range. The coatings will be of commercially produced Au, Ni, and Ir, deposited either by sputtering or by e-beam deposition. Optical constants will be estimated via the reflectance vs. angle-of-incidence method.
Grazing-incidence x-ray reflectivity: studies for the AXAF Observatory
Patrick O. Slane, Daniel A. Schwartz, Leon P. Van Speybroeck, et al.
The energy bandwidth and total throughput of a grazing incidence optics system is a strong function of the X-ray reflectivity of the surface coating. In support of the Advanced X-ray Astrophysics Facility (AXAF), studies are underway to evaluate and characterize the reflectivity of potential AXAF coatings. Here we report on results obtained for Au, Ir, and Ni coatings produced by electron-beam evaporation, evaporation with ion-assist, and sputtering. Effects of coating thickness and deposition angle have been evaluated at 6.4 and 8.1 keV; the highest reflectivities are those of the thinner, about 200 A vs about 700 A, coatings. While considerable variations exist, the best Ir samples have higher reflectivity than any of the Au coatings. Data results have been compared with models for theoretical reflectivity, particularly with regard to the effective density of the coatings. Independent measurements of the coating densities have been carried out for comparison with the reflectivity results.
X-ray focusing using microchannel plates
George W. Fraser, John Ernest Lees, James F. Pearson, et al.
In this paper, we consider the use of lead glass microchannel plates (MCPs) as focusing elements for soft x rays. In particular, we discuss the possible realization of the wide field-of- view `Lobster Eye'' astronomical optics originally proposed by Angel using MCPs with confocal channels of square cross-section. Preliminary laboratory measurements are presented of the point-to-point focusing of both white light and soft x rays by a planar square-pore MCP with 85 (mu) channels. The practical realization of a Lobster Eye x-ray monitor for a possible small satellite mission is considered.
X-ray scattering measurements from thin-foil x-ray mirrors
Finn Erland Christensen, B. P. Byrnak, Allan Hornstrup, et al.
Thin foil X-ray mirrors are to be used as the reflecting elements in the telescopes of the X-ray satellites Spectrum-X-Gamma (SRG) and ASTRO-D. High resolution X-ray scattering measurements from the Au coated and dip-lacquered Al foils are presented. These were obtained from SRG mirrors positioned in a test quadrant of the telescope structure and from ASTRO-D foils held in a simple fixture. The X-ray data is compared with laser data and other surface structure data such as STM, atomic force microscopy (AFM), TEM, and electron micrography. The data obtained at Cu K-alpha(1), (8.05 keV) from all the mirrors produced on Al foils shows a scatter which limits the obtainable half-power width to above 1.5 arcmin. Mirrors based on electroformed Ni foils, however, show local regions with a factor of 4 better performance, and they are being developed for future applications.
Fabrication and characterization of replicated and lacquer-coated grazing incidence optics for x-ray astronomy
Melville P. Ulmer, Rudy H. Haidle, Robert I. Altkorn, et al.
In this paper we discuss the fabrication and testing of electroformed replica Wolter I optics made from gold-coated lacquered mandrels. We also discuss testing of gold- and palladium- coated lacquered test flats. X ray and (5 keV for Wolter I mirror and 8 - 40 keV for test flats) and optical (Wyko NCP-1000 profiler measurements were used to evaluate the mirrors.
X-Ray Microscopy and Interferometry
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Prospect of space-based interferometry at EUV and soft x-ray wavelengths
We review the current capabilities of high-resolution, spectroscopic, space-borne instrumentation available for both solar and stellar observations in the EUV and soft X-ray wavelength regimes, and describe the basic design of a compact, all-reflection interferometer based on the spatial heterodyne technique; this is capable of producing a resolving power (lambda/Delta-lambda) of about 20,000 in the 100-200 A region using presently available multilayer optical components. Such an instrument can be readily constructed with existing technology. Due to its small size and lack of moving parts, it is ideally suited to spaceborne applications. Based on best estimates of the efficiency of this instrument at soft X-ray wavelengths, we review the possible use of this high-resolution interferometer in obtaining high-resolution full-disk spectroscopy of the sun. We also discuss its possible use for observations of diffuse sources such as the EUV interstellar background radiation.
X-Ray Optics Test Facilities
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Construction of a micro-zone-plate for a scanning x-ray microscope at Hefei
Yong Feifei Zhao, Xingshu Xie, Xinya Lei, et al.
At the Hefei Synchrotron Radiation Laboratory (HESYRL), beamline 6A is dedicated to soft x-ray imaging studies. We are constructing a prototype scanning soft x-ray microscope. An effort in the fabrication of microzone plate has been started. We have designed and fabricated the first Fresnel zone plate as a microzone plate in China. Our microzone plates are fabricated by UV exposure. The finest width of the outmost zone is about 0.5 micrometers . In this paper, we describe the design and fabrication of our microzone plate and report first results.
X-Ray Microscopy and Interferometry
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Design and analysis of soft x-ray imaging microscopes
David L. Shealy, Cheng Wang, Wu Jiang, et al.
The spherical Schwarzschild microscope for soft X-ray applications in microscopy and projection lithography consists of two concentric spherical mirrors configured such that the third-order spherical aberration and coma are zero. Since multilayers are used on the mirror substrates for X-ray applications, it is desirable to have only two reflecting surfaces in a microscope. To reduce microscope aberrations and increase the field of view, generalized mirror surface profiles are here considered. Based on incoherent and sine wave modulation transfer function calculations, the object plane resolution of a microscope has been analyzed as a function of the object height and numerical aperture (NA) of the primary for several spherical Schwarzschild, conic, and aspherical Head reflecting two-mirror microscope configurations. The Head microscope with a NA of 0.4 achieves diffraction limited performance for objects with a diameter of 40 microns. Thus, it seems possible to record images with a feature size less than 100 A with a 40x microscope when using 40 A radiation.
X-Ray Telescopes
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Graded d-spacing multilayer telescope for high-energy x-ray astronomy
Finn Erland Christensen, Allan Hornstrup, Niels J. Westergaard, et al.
A high energy telescope design is presented which combines grazing incidence geometry with Bragg reflection in a graded d-spacing multilayer coating to obtain significant sensitivity up to --6O keV. The concept utilizes total reflection and first order Bragg reflection in a graded d-spacing multilayer structure in a way that higher energies are reflected from the deepest layers in the stack. The specific design presented in this paper is based on Ni/C and Mo/C structures with dspacings ranging from 25A to 100 A. X-ray reflectivity data obtained with Cu Kc1 (8. 05 keV) are presented from the first graded d-spacing structures of this kind.
Imaging characteristics of the development model of the JET-X x-ray telescope
Oberto Citterio, Paolo Conconi, Francesco Mazzoleni, et al.
The Joint European X-ray Telescope, ''JET-X'', which is to be the core instrument of the Russian Spectrum-X astrophysics mission in 1994, will study the 3-10 keV-band emission from X-ray sources. The instrument is configured as two identical coaligned X-ray imaging telescopes; focal plane imaging is furnished by a cooled CCD detector which yields both good spectral resolution and high spatial resolution. The mirror shells have Wolter I geometry, and are manufactured by means of an electroforming replication process.
Solar observations with the multispectral solar telescope array
Richard B. Hoover, Arthur B. C. Walker II, Joakim F. Lindblom, et al.
The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding rocket-borne solar observatory which was succesfully launched on May 13, 1991, from the White Sands Missile Range, NM. Ultrahigh resolution, full-disk solar X-ray, EUV, and FUV images were obtained with the MSSTA Herschelian, Cassegrain, and Ritchey-Chretien telescopes. We describe the payload and provide some preliminary scientific results from the flight.
Photographic films for the multispectral solar telescope array
Richard B. Hoover, Arthur B. C. Walker II, Craig Edward DeForest, et al.
The rocketborne Multi-Spectral Solar Telescope Array (MSSTA) uses an array of Ritchey-Chretien, Cassegrain, and Herschelian telescopes to produce ultrahigh-resolution full-disk images of the sun within the soft X-ray, EUV, and FUV ranges. Such imaging of the solar disk and corona out to several solar radii placed great demands on the MSSTA''s data storage capabilities; in addition, its photographic films required very low outgassing rates. Results are presented from calibration tests conducted on the MSSTA''s emulsions, based on measurements at NIST''s synchrotron facility.
X-Ray Observations
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Soft x-ray telescope for Solar-A: design evolution and lessons learned
Marilyn E. Bruner
The Japanese Solar-A satellite mission''s Soft X-ray Telescope uses grazing-incidence optics, a CCD detector, and a pair of filter wheels for wavelength selection. A coaxially-mounted visible-light lens furnished sunspot and magnetic plage images, together with aspect information which aids in aligning the soft X-ray images with those from the satellite''s Hard X-ray Telescope. Instrument electronics are microprocessor-based, and imbedded in a tightly integrated distributed system. Control software is divided between the instrument microprocessor and the spacecraft control computer.
Grazing Incidence Optics
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In-flight performance of the broadband x-ray telescope
Robert Petre, Peter J. Serlemitsos, F. E. Marshall, et al.
The Broad-Band X-Ray Telescope (BBXRT) was designed to carry out moderate resolution spectrophotometry of cosmic X-ray sources in the 0.3-12 keV band from the Space Shuttle. It consists of a pair of coaligned conical foil telescopes, with cryogenically cooled Si(Li) spectrometers as focal instruments. It was flown as part of the Astro-1 mission in December, 1990. The in-flight performance of the instrument was essentially as predicted on the basis of ground calibration and modelling. We discuss the performance of the system, with emphasis on the conical mirror systems, and present some preliminary scientific results which illustrate the power of broad band, high sensitivity X-ray spectrophotometry.
X-Ray Observations
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Ultrahigh-resolution XUV spectroheliograph III: a modified configuration for a free-flying platform
Arthur B. C. Walker II, Joakim F. Lindblom, J. Gethyn Timothy, et al.
The Ultra-High Resolution XUV Spectroheliograph (UHRXS) is a comprehensive solar observatory capable of studying solar phenomena at soft X-ray, XUV, EUV, and VUV wavelengths with normal incidence imaging multilayer telescopes capable of very high angular resolution (about 0.1 arcsec), and spectrographs able to achieve high spectral resolution. This instrument has been selected by NASA for flight as an attached payload on the Space Station Freedom. Recent developments have made it clear that accommodations for attached payloads on Freedom will not become available during the initial operations of Freedom and may never be available. We have studied the changes that must be made to place the UHRXS instrument on a Free Flying Plafform such as the Delta Launched Explorer Bus. We report on the configuration, performance, and accommodation on a free flying platform of the revised UHRXS concept.
Solar/stellar coronal explorer and the solar/stellar coronal observatory
Arthur B. C. Walker II, Joakim F. Lindblom, J. Gethyn Timothy, et al.
The Solar/Stellar Coronal Explorer (SSCE) carries six identical Ritchey-Chretien Telescopes of 127 mm aperture each; their images will be recorded by multianode microchannel-array detectors. The mirrors of five of the telescopes are coated with multilayer reflecting structures that select narrow XUV wavelength bands corresponding to strong emission lines emitted by solar or stellar coronal plasmas. Also noted here is a larger explorer mission concept, that of the Solar/Stellar Coronal Observatory, which will undertake more extensive spectroscopic observations.
X-Ray, EUV Spectrometers, and Polarimeters
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Hydrogen Lyman alpha coronagraph/polarimeter
Silvano Fineschi, Richard B. Hoover, Arthur B. C. Walker II
The present treatment of vector magnetic field measurement in coronas by means of the Hanle effect of the Lyman-alpha line uses data from all-reflecting imaging coronagraph/polarimeters. The polarization sensitivity, bandpass, and spatial resolution of these instruments are defined through a modeling of the Hanle-effect signature in Lyman-alpha emission from coronal magnetic loops; the line-of-sight integration through an inhomogeneous coronal medium is taken into account. The use of the Hanle effect to measure solar corona vector magnetic fields is verified.
Optical configurations of H I Lyman alpha coronagraph/polarimeters
Richard B. Hoover, Silvano Fineschi, Arthur B. C. Walker II, et al.
The Multi-Spectral Solar Telescope Array (MSSTA) has obtained numerous high-resolution soft X-ray/EUV/FUV solar images with multilayer telescopes; these show dramatic prominences, spicules, and threadlike limb structures. There is excellent correlation between faint Lyman-alpha coronal structures seen in the digitized MSSTA images and prominences seen in H-alpha images gathered by ground-based observatories. The MSSTA has established the feasibility of an all-reflecting, imaging Ly-alpha coronagraph/polarimeter.
Multispectral solar telescope array II: soft-x-ray/EUV reflectivity of the multilayer mirrors
Troy W. Barbee Jr., John W. Weed, Richard B. Hoover, et al.
We have developed seven compact soft X-ray/EUV (XUV) multilayer coated and two compact FUV interference film coated Cassegrain and Ritchey-Chretien telescopes for a rocket borne observatory, the Multi-Spectral Solar Telescope Array. We report here on extensive measurements of the efficiency and spectral bandpass of the XUV telescopes carried out at the Stanford Synchrotron Radiation Laboratory.
Design and test of a high-resolution EUV spectroheliometer
Thomas E. Berger, J. Gethyn Timothy, Arthur B. C. Walker II, et al.
The HiRES High-Resolution EUV Spectroheliometer is a sounding rocket instrument yielding very high spatial, spectral, and temporal resolution images of the solar outer atmosphere, on the basis of a 45-cm Gregorian telescope feeding a normal-incidence stigmatic EUV spectrometer with imaging multianode microchannel-array detector system, as well as an IR spectrometer with imaging CCD detector system. Attention is given to the expected performance of this system, including the effects of vibrational misalignments due to the sounding rocket flight environment.
Objective double-crystal spectrometer
Arthur B. C. Walker II, Thomas D. Willis, Richard B. Hoover
The solar corona, supernova remnants, the hot diffuse interstellar gas in the Galaxy, galactic halos, and the hot intracluster gas in rich clusters of galaxies, are examples of extended astrophysical plasmas which emit line-rich spectra in the X-ray spectral range from 1.5 to 25 A. These phenomena represent a significant fraction of the baryonic matter in the universe. The study of the composition, structure and dynamics of these astrophysical plasmas requires observations with both high spectral and spatial resolution simultaneously. The Objective Double Crystal Spectrometer, coupled with a grazing incidence X-ray telescope, represents a stigmatic instrument which is highly efficient for the study of such sources. We describe the configuration and performance (spatial resolution, spectral resolution and efficiency) of the Objective Double Crystal spectrometer.
History of X-Ray Optics
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Historical description of selected experiments in the early development of x-ray optics
Albert V. Baez
The pioneering experiments in x-ray optics that took place in the 1940s and 1950s at Stanford University, the University of Redlands, and the Smithsonian Astrophysical Observatory are described. The original work of Paul Kirkpatrick and his students had as its objective the design and construction of grazing incidence x-ray microscopes, but Gabor''s work in microscopy by reconstructed wavefronts led to the exploration of x-ray holography as an alternative approach to x-ray optics. This led to the focusing of x rays by diffraction using an x-ray Fresnel zone plate. By 1958 it was clear that x-ray telescopes could be designed utilizing both grazing incidence reflectors and zone plates. Nested pairs of mirrors in the Kirkpatrick- Baez configuration were tested as a prototype high-throughput x-ray telescope in 1960.
Soft x-ray optics 1971-1981: a personal history
This paper is a recollection of my involvement in the development of multilayer x-ray optics, from the first day in 1971 to 1981. The period covers the time from the discovery to the first conferences where multilayer structures were recognized as important elements for x-ray imaging, especially for astronomy.
Poster Session
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Soft x-ray ion chamber
Bo Chen, Ling Ma, Futian Li, et al.
The technique of soft x-ray ion chamber includes the measurement of the ion current as a function of rare gas pressure in the ion chamber. The true photoionization current, and hence absolute photon flux, is obtained by extrapolating ion current to zero gas pressure. This paper describes measurement of the absolute photon flux at He II 25.6 nm and CK(alpha) 4.47 nm.
X-Ray Microscopy and Interferometry
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Development of the water-window imaging x-ray microscope
The Water Window Imaging X-Ray Microscope is a doubly reflecting, multilayer optical system configured to operate within the biologically important narrow spectral range known as the `water window.'' Within this x-ray waveband, which lies between the K absorption edges of oxygen (23.3 angstroms) and carbon (43.62 angstroms), water is relatively highly transmissive and carbon is highly absorptive. Consequently, this high resolution microscope can obtain high contrast images of carbon-based structures within living cells in aqueous physiological environments. This new multilayer x-ray microscope should afford ultrasensitive detection and analysis advantages not available with conventional microscopes. The Stanford/MSFC/LLNL Rocket X-Ray Spectroheliograph flight of 1987 achieved the first solar images with a doubly reflecting multilayer telescope and conclusively established the power of multilayer optics. During the MSFC X-Ray Microscope program, we theoretically established that high resolution multilayer x-ray imaging microscopes could be achieved with spherical optics in the Schwarzschild configuration and with aspherical optics. Advanced flow polishing techniques were used to fabricate ultrasmooth concave and convex spherical mirror substrates of zerodur and hemlite-grade sapphire. Atomic force microscopy and Zygo profilometer tests revealed these mirror substrates to have surface smoothness ranging from 0.5 angstrom rms (sapphire) to 2.0 angstroms rms (zerodur). In this paper, we discuss the fabrication and testing of the optical and mechanical components of the x-ray microscope.
Additional Paper
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Selective photodevices for the VUV
William R. Hunter, John F. Seely
Usually one wants a vuv detector to cover a very broad range of wavelengths (broad band) to avoid the inconvenience of changing detectors. Under certain conditions however narrow band detectors are most useful. Reflecting interference cathodes have been designed for the near infrared[l]. We propose to use limited versions of interference cathodes in the vuv the limitations being imposed by the generally large extinction coefficients of materials in that wavelength range. Thus far calculations have been made for the spectral region between 700 and 2000 A and for detectors used in normal incidence.
Poster Session
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Development of hard x-ray optics
Marshall K. Joy, Martin C. Weisskopf
Studies of cosmic X-ray sources have suffered from lack of focussing optics in the hard X-ray spectral region (E above 10 keV); in the absence of imaging optics, celestial X-rays are masked by the cosmic ray background, which severely degrades the detector sensitivity. There are several possible ways to develop grazing incidence imaging optics for this spectral region; we describe here one approach which utilizes numerous large diameter silicon wafers to form a flat-plate imaging telescope. A prototype imager of this type has been constructed, and we present measurements of surface quality, coalignment accuracy, and imaging ability.
Boron carbide as atomic oxygen protection for the Lexan-carbon filter on the ROSAT wide-field camera
Barry J. Kent, Bruce Miles Swinyard, Hans-Joerg Maier, et al.
The ROSAT Wide Field Camera, launched in June 1990, uses large area (50 cm2) thin film (typically 0.5 micrometers thick), band pass filters to select different extreme ultra violet wavelength bands. One of the filters consists of a substrate of the plastic polycarbonate, Lexan$DAG, interleaved with carbon and is thus susceptible to erosion by atomic oxygen in the ROSAT low earth orbit at 580 km altitude. The filter was protected against this erosion mechanism by using a thin overcoating of boron carbide. We describe the boron carbide coating process, the technique used to minimize the heat load on the fragile plastic foil, and the need for an additional adhesion layer of carbon. The chemical composition of the boron carbide as evaporated material on glass slides has been measured using several surface science techniques as well as by analysis of the soft x-ray and EUV transmission of sample foils and completed flight filters. Additionally, using ion and atomic oxygen sources, the effectiveness of the coating has been evaluated by laboratory measurements on sample foils.
Plasma imaging in the XUV wavelength range (175 A) using curved layered-synthetic-microstructure coated surfaces
Sean P. Regan, L. K. Huang, Michael Finkenthal, et al.
A recently constructed calibration facility utilizing a Manson soft x-ray line source in the wavelength range of 8 - 114 angstroms and a Penning ionization discharge (PID) in the 100 - 350 angstroms range, has been used to map the reflectivity across a curved layered synthetic microstructure (LSM) coated surface. This calibrated mirror was also used to image the Al III emission ((lambda) equals 170 - 175 angstroms) from the PID.
Thin-film interference optics for imaging in the O II 834 A airglow and rejection of 1216 A radiation
John F. Seely, William R. Hunter
Normal incidence thin-film interference mirrors and filters, using MgF2 as the spacer material, were designed to image the O II 834 angstroms airglow and to reject the intense H I radiation at 1216 angstroms. Peak mirror reflectance of 60 can be obtained with a passband 200 angstroms wide centered on 834 angstroms. An interference filter is designed to transmit 834 angstroms and to attenuate 1216 angstroms radiation. The throughput at 1216 angstroms is smaller than the throughput at 834 angstroms by a factor of 500.
Cosmic x-ray spectroscopy with multilayer optics
Arthur B. C. Walker II, Dennis S. Martinez-Galarce, Elizabeth S. Paris, et al.
Multilayer optics operated at normal incidence offer a powerful new technology for the study of the solar spectrum in the XUV. The spectra of most cosmic X-ray sources are strongly extinguished at wavelengths above 40 A due to absorption and scattering by interstellar grains. We describe a number of configurations which allow multilayer optics to be used at nonnormal angles of incidence in conjunction with grazing incidence optics to analyze the spectra of cosmic X-ray sources in the wavelength interval between 1.5 and 40 A. These optical configurations utilize both multilayer mirrors and gratings, and permit the efficient observation of extended sources using stigmatic spectrographs. The response of the instruments described to typical cosmic X-ray sources is also discussed.
Narrow-band solar images in the soft x-ray regime with multilayer optics
Arthur B. C. Walker II, Charles C. Kankelborg, Richard B. Hoover, et al.
High quality multilayers with 2d spacings as short as about 44 A have been used successfully for astronomical observations. Observation of both the sun and cosmic X-ray sources (for which radiation longward of the carbon edge at about 44 A is strongly attenuated by interstellar matter) are possible at wavelengths shorter than 40 A with current multilayer technology, if mirrors are used at nonnormal angles of incidence. We discuss several configurations which are suitable for high resolution solar imaging observations in the wavelength interval between 0.5 and 50 A. We also describe the design and anticipated performance of a multilayer optical system we are currently developing for a rocketborne solar observatory.
High-resolution telescope cluster I: overview and technical status
Arthur B. C. Walker II, Richard B. Hoover, William T. Roberts, et al.
A major component of the Advanced Solar Observatory is the High Resolution Telescope Cluster (HRTC) for investigations of the solar atmosphere at soft X-ray, XUV, EUV, and VUV wavelengths, via high resolution spectroheliograms in lines and continuum emitted over the full, (4500 to 100,000,000 K) range of temperatures of the outer solar atmosphere; angular resolution may be as high as 0.03 arcsec. An analysis is conducted of a model HRTC instrument complement encompassing a 60-90 cm aperture VUV telescope, a 40-50 cm aperture EUV telescope, three 40-50 cm aperture XUV telescopes, and a 40-cm aperture soft X-ray telescope, as well as flare spectrometers and polarimeters and four coronagraph/spectrographs.
X-Ray Microscopy and Interferometry
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Metrology of x-ray optics utilizing shearing interferometric techniques
This paper will discuss the optical testing of extreme grazing incidence mirror systems and normal incidence high-precision mirror systems during fabrication processing of the optical substrates. The optical metrology is closely coupled with an advanced material removal process which will be discussed in terms of the optical metrology. Interferometric data will be presented of the optical surfaces. Surface roughness data will be shown and discussed.
Poster Session
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Diffraction of multilayer-coated plane gratings in terms of the reciprocal space
Yan Wu, William K. Warburton
We present a model for multilayer coated plane gratings that uses a reciprocal space description similar to the standard treatment of crystal diffraction. This model enables us to separate the contributions from the multilayer coating and the underlying substrate. We demonstrate its use on laminar and blazed gratings, and show that it can be easily applied to more complicated grating substrates as well. Because the separation between the two terms is complete, we suggest replacing the multilayer term with a dynamic diffraction calculation when additional model accuracy is required.
Characterization of Multilayer Optics
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Characterization of SnO2 GIAR films
Meiman Kentjana, Hitoshi Homma, Ercan E. Alp, et al.
In an attempt to develop a monochromator of synchrotron radiation ((Delta) E approximately 10-6 eV) using grazing incidence antireflection (GIAR) principle, we made SnO2 GIAR films on Pd (buffer layer) / (alpha) -Al2O3 (substrate). Films are fabricated by magnetron sputtering technique and characterized film thickness and interface roughness by x-ray diffraction technique using the conventional and synchrotron radiation sources. We demonstrated the electronic scattering suppression of approximately 10-2 and that the present system is feasible to achieve the required goals for monochromatization of synchrotron radiation source for the energy range of 23.87 keV.
Poster Session
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Slit aperture for the monitoring x-ray experiment
James C. Lochner, William C. Priedhorsky
We have investigated a slit aperture as an alternative to the square pinhole aperture for the MOXE detectors, which are to be put on the Soviet satellite Spectrum X-Gamma. A slit offers advantages for better discrimination of sources in crowded regions, eliminates the need for support structures for the aperture window, and does not compromise the signal-to-noise ratio (S/N) of a point source. We find that in a single 24 hr pointing of the satellite, MOXE can determine the position of a 10 mCrab source to better than 0.5 degrees with the slit. The structure of a titanium grate which supports the detector''s beryllium window constrains the slit to be 0.5 cm x 2.56 cm, oriented at an angle of 26.6 degrees to either side of the center lines of the detector. We illustrate an arrangement of the slits on each of the six detectors which optimizes source localization for a number of pointings.
X-Ray Telescopes
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JET-X instrument for the USSR Spectrum-RG mission: its design and performance
Alan A. Wells, G. C. Stewart, Martin J. L. Turner, et al.
The Joint European X-ray Telescope, JET-X, is one of the core instruments in the scientific payload of the USSR''s Spectrum Roentgen-Gamma (RG) high energy astrophysics mission. JET-X consists of two identical co-aligned X-ray imaging telescopes, each with a spatial resolution of 20 arc second. Focal plane imaging is achieved with cooled X-ray sensitive CCD detectors, which provide high spectral resolution and good background rejection efficiency, in addition to the necessary imaging capability. An optical monitor telescope, also co-aligned with the two X-ray telescopes, permits simultaneous observation and identification of optical counterparts of X-ray target sources. The system design of JET-X is reviewed, and performance data obtained from measurements on the instrument prototype are presented.
Poster Session
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Measurement of molybdenum mirror reflectivities
Richard L. Blake, Jeffrey C. Davis, Ping P. Gong, et al.
The reflectivity versus angle for a variety of molybdenum mirrors has been measured for both hard and soft x rays in an attempt to deduce any variation in performance between single crystal, polycrystalline, and evaporated mirrors. A fitting technique has been used to arrive at the roughness of the mirrors. An approach to utilize such measurements to characterize mirrors and derive low energy optical constants for many elements is outlined.
Grazing Incidence Optics
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Lobster-eye x-ray optics using microchannel plates
Philip E. Kaaret, Phillip Geissbuehler
We describe a novel system for focusing X-rays based on the eye of a lobster and a method for fabricating such optics using microchannel plates which have pores with square cross sections. Lobster eye optics will enable us to construct X-ray telescopes capable of simultaneously viewing a large fraction of the sky, making possible a new class of X-ray astronomy survey and monitoring missions. We have tested the X-ray optical properties of one of the first available square pore MCP''s. We find that the angular resolution of the MCP lense is 5 arcminutes (FWHM). The resolution is limited by misalignment of the pore surfaces.
X-Ray Telescopes
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Normal incidence soft x-ray lambda=63.5 A telescope of 1991
Eberhard Adolf Spiller, Janusz S. Wilczynski, Leon Golub, et al.
63.5 A telescope of 1991Spiller, Eberhard; Wilczynski, Janusz S.; Golub, Leon; Nystrom, George U.
Fabrication of Multilayer Optics
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Rocket flight of a multilayer-coated high-density EUV toroidal grating
A multilayer coated high density toroidal grating was flown on a sounding rocket experiment in the Solar EUV Rocket Telescope and Spectrograph (SERTS) instrument. To our knowledge this is the first space flight of a multilayer coated grating. Pre-flight performance evaluation showed that the application of a 10-layer Ir/Si multilayer coating to the 3600 l/mm blazed toroidal replica grating produced a factor of 9 enhancement in peak efficiency near the design wavelength around 30 nm in first order over the standard gold coating, with a measured EUV efficiency that peaked at 3.3 percent. In addition, the grating''s spectral resolution of better than 5000 was maintained. The region of enhanced grating efficiency due to the multilayer coating is clearly evident in the flight data. Within the bandpass of the multilayer coating, the recorded film densities were roughly equivalent to those obtained with a factor of six longer exposure on the previous flight of the SERTS instrument.
Grazing Incidence Optics
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Modeling of capillary optics as a focusing hard x-ray concentrator
The development of glass microcapillary arrays by Kumakhov and co-workers in the Soviet Union suggests that it is possible to construct novel devices for concentrating and focussing X-ray beams. Hypothetical focussing concentrators made up of capillary arrays have been configured to operate over a broad range of X-ray energy and its characteristics have been studied with a Monte Carlo ray tracing code. These modeling results indicate that the concentrators would have significant effective area up to 100 keV while their dimensions are similar to conventional grazing incidence telescopes that operate in the soft X-ray band.