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Proceedings Paper

Multilayer reflectors for the "water window"
Author(s): Shi Xu; Brian L. Evans
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Paper Abstract

Near normal incidence imaging optics for use at wavelengths A in the 'water window' (2.4X4.4nm) utilise the in-phase reflections from a multilayer stack deposited on a figured substrate. The reflectivity of such a multilayer depends upon the number N of contributing interfaces and the amplitude reflectivity r at each interface where r M + ituz is determined by the difference in the real and imaginary parts of the refractive indices of the media defining the interface. Thus r may be predominantly determined by (Class I) or & (Class II) or a combination of both (Class III). The spectral variation of r (2 .3X4 .8nm) has been computed for interfaces formed by a-C and fifty four different elements which are thereby classified as I, II or III. The normal incidence reflectivity R versus A of representative multilayers from each class has been calculated as a function of N and layer thickness ratio 'y and criteria established for the most suitable choice of layer materials for the 'water window' region. In practice the particulate nature of the thin metal film components of the multilayer results in the experimental values of R being much less than the theoretical values.

Paper Details

Date Published: 1 February 1991
PDF: 12 pages
Proc. SPIE 1343, X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography, (1 February 1991);
Show Author Affiliations
Shi Xu, Univ. of Reading (United Kingdom)
Brian L. Evans, Univ. of Reading (United Kingdom)

Published in SPIE Proceedings Vol. 1343:
X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography

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