The design of the next generation of hard-X-ray focusing telescopes requires highly optimized reflecting coatings, with the maximum efficiency over a broad energy band and a relatively large field of view. Multilayer coatings based on layer thicknesses with power-law distribution are often considered as a convenient solution to achieve angular and energetic broad band reflection of X-ray at grazing incidence, being also particularly suitable for numerical optimization. In this work we consider the optimization of the telescope for the New Hard X-ray Mission, an Italian project based on four optical modules with multilayer-coated Nickel-replicated Wolter optics, able to focus high-energy X-ray radiation (up to 80 keV) with good imaging resolution (20 arcsec HEW). The optimization of the telescope was studied from the point of view of shell sizes, coating materials and multilayer structures. In particular, the best structure of the coating is determined by means of numerical optimization methods introducing also the number of layers as optimization parameters. Very effective solutions are found even with a low number of bilayers (~100).

Date Published: 31 August 2009
PDF: 12 pages
Proc. SPIE 7437, Optics for EUV, X-Ray, and Gamma-Ray Astronomy IV, 743717 (31 August 2009); doi: 10.1117/12.827347

Published in SPIE Proceedings Vol. 7437:
Optics for EUV, X-Ray, and Gamma-Ray Astronomy IV
Stephen L. O'Dell; Giovanni Pareschi, Editor(s)