Manufacture of aspherical molding dies for x-ray telescopes after ASTRO-H

Yoshiharu Namba, Anthony Beaucamp, Hironori Matsumoto, Keisuke Tamura, Yuzuru Tawara, Hideyo Kunieda, Tadayuki Takahashi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

Producing X-ray imaging space telescopes is a very expensive endeavor, due in great part to the difficulty of fabricating thin mirrors for Wolter type-I optical assemblies. To meet this challenge, replication from optical molding dies (also called mandrels) has become the preferred method, as it is reliable and economical. Several replication methods exist: in the case of the ASTRO-H mission, DC magnetron sputtering was used to deposit Pt/C multilayer coating on glass molding dies. The multilayer coating was then bonded with epoxy to aluminum shells and then separated from the die. Another mirror replication method consists of slumping thin glass sheets over a full (or a section of) revolution molding die under high temperature. This method was demonstrated in the case of the NuSTAR mission. But the challenge of fabricating truly aspheric Wolter type molding dies, which are capable of highly accurate angular resolution (below 5 arcs), remains very expensive and time consuming. In this paper, three methods for producing X-ray optic molding dies are presented. Each method uses a different substrate material and process chain, as follows: electroless nickel plated aluminum (first diamond turned then correctively polished), fused silica (first precision ground then correctively polished), and CVD silicon carbide (which can be finished entirely with a newly developed Shape Adaptive Grinding process). The process chains employed for each method are explained in details, and their relative merits discussed. A way forward for the next generation of X-ray telescopes after ASTRO-H is then drawn out.

Original languageEnglish
Title of host publicationSpace Telescopes and Instrumentation 2014
Subtitle of host publicationUltraviolet to Gamma Ray
EditorsTadayuki Takahashi, Jan-Willem A. den Herder, Mark Bautz
PublisherSPIE
ISBN (Electronic)9780819496126
DOIs
Publication statusPublished - 2014
Externally publishedYes
EventSpace Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray - Montreal, Canada
Duration: 2014 Jun 222014 Jun 26

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9144
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceSpace Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray
Country/TerritoryCanada
CityMontreal
Period14/6/2214/6/26

Keywords

  • X-ray optics
  • diamond turning
  • grinding
  • molding dies
  • polishing
  • replication
  • thin mirrors
  • ultra-precision

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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