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Proceedings Paper

Reflectance calibrations of AXAF mirror samples at absorption edges using synchrotron radiation
Author(s): Dale E. Graessle; T. H. Burbine; J. C. Cobuzzi; Edwin M. Kellogg; Daniel A. Schwartz; Richard L. Blake; Ping P. Gong
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Paper Abstract

We are developing a system to calibrate reflectances of witness coupons to the AXAF flight mirrors at the National Synchrotron Light Source over the 0.05-12 keV energy range. These witness coupons will be coated in the same process as the AXAF mirror elements. One of the key issues is the accurate determination of mirror efficiencies across the absorption edges of the mirror coating elements. We present a series of reflectance measurements with 2 eV resolution of a nickel-coated flat mirror in the region of the Ni L-II (870 eV) and L-III (853 eV) absorption edges. Scans of reflectance versus grazing angle at fixed energies in this region show distinct interference fringes at grazing angles larger than the critical angle which are extinguished as the photon energy is increased beyond the low point of the L-III edge, indicating total absorption of the evanescent wave within the Ni film. At 51 arc minutes grazing angle, measured reflectance decreases smoothly by 35 percent and then recovers in an 8 eV band at the L-III edge. We have also measured reflectances in the M absorption edge region for gold, platinum, and iridium coated mirrors. We derive optical parameters n and k specific to the film for comparison to the existing data tables.

Paper Details

Date Published: 21 January 1993
PDF: 16 pages
Proc. SPIE 1742, Multilayer and Grazing Incidence X-Ray/EUV Optics for Astronomy and Projection Lithography, (21 January 1993); doi: 10.1117/12.140554
Show Author Affiliations
Dale E. Graessle, Smithsonian Astrophysical Observatory (United States)
T. H. Burbine, Smithsonian Astrophysical Observatory (United States)
J. C. Cobuzzi, Smithsonian Astrophysical Observatory (United States)
Edwin M. Kellogg, Smithsonian Astrophysical Observatory (United States)
Daniel A. Schwartz, Smithsonian Astrophysical Observatory (United States)
Richard L. Blake, Los Alamos National Lab. (United States)
Ping P. Gong, EG&G Energy Measurements (United States)

Published in SPIE Proceedings Vol. 1742:
Multilayer and Grazing Incidence X-Ray/EUV Optics for Astronomy and Projection Lithography
Richard B. Hoover; Arthur B. C. Walker, Editor(s)

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