Characterization of the supermirror hard-x-ray telescope for the InFOC mu S balloon experiment


Okajima T., Tamura K., Ogasaka Y., Haga K., Takahashi S., Ichimaru S., ...More

APPLIED OPTICS, vol.41, no.25, pp.5417-5426, 2002 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 41 Issue: 25
  • Publication Date: 2002
  • Doi Number: 10.1364/ao.41.005417
  • Title of Journal : APPLIED OPTICS
  • Page Numbers: pp.5417-5426

Abstract

A hard-x-ray telescope is successfully produced for balloon observations by making use of depth-graded multilayers, or so-called supermirrors, with platinum-carbon (Pt/C) layer pairs. It consists of four quadrant units assembled in an optical configuration with a diameter of 40 cm and a focal length of 8 m. Each quadrant is made of 510 pieces of coaxially and confocally aligned supermirrors that significantly enhance the sensitivity in an energy range of 20-40 keV. The configuration of the telescope is similar to the x-ray telescope onboard Astro-E, but with a longer focal length. The reflectivity of supermirrors is of the order of 40% in the energy range concerned at a grazing angle of 0.2 deg. The effective area of a fully assembled telescope is 50 cm(2) at 30 keV. The angular resolution is 2.37 are min at half-power diameter 8.0 keV. The field of view is 12.6 arc min in the hard-x-ray region, depending somewhat on x-ray energies. We discuss these characteristics, taking into account the figure errors of reflectors and their optical alignment in the telescope assembly. This hard-x-ray telescope is unanimously afforded in the International Focusing Optics Collaboration for muCrab Sensitivity balloon experiment. 0 2002 Optical Society of America.