Adjustable height glass spacers for bonding and aligning X-ray mirror stacks

Brandon D. Chalifoux, Ian J. Arnold

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

1 Scopus citations


Future sub-arcsecond resolution, large-effective area X-ray telescopes that use segmented grazing-incidence mirrors will require a bonding and alignment method that simultaneously: 1) achieves the accuracy needed for scientific observations, 2) possesses the strength needed to survive the ride to space, and 3) has high throughput to bond and align tens of thousands of components in a couple years. Current bonding and alignment processes are either over-constrained to achieve high strength with modest accuracy, or quasi-kinematic to achieve high accuracy but with lower strength. We propose an over-constrained mounting approach where spacers separating mirrors have set-and-forget adjustable height. This approach may provide the advantages of high strength and high accuracy simultaneously, while loosening initial assembly tolerances to improve process throughput. In our proposed process, glass spacers are fabricated with μm-accuracy using ultrashort pulsed laser-assisted chemical etching and Bessel beam optics. Their length is adjusted after assembly and bonding, using the same laser and optics. We show examples of our fabricated spacers assembled into stacks of mirrors and bonded using epoxy with spacer beads. In a separate experiment, we show that the length of spacers can be quickly and stably adjusted with μm-range and with nm-resolution as required for aligning X-ray mirrors. This bonding and alignment process may help solve a longstanding and critical challenge for future sub-arcsecond resolution large-effective area X-ray telescopes.

Original languageEnglish (US)
Title of host publicationSpace Telescopes and Instrumentation 2022
Subtitle of host publicationUltraviolet to Gamma Ray
EditorsJan-Willem A. den Herder, Shouleh Nikzad, Kazuhiro Nakazawa
ISBN (Electronic)9781510653436
StatePublished - 2022
EventSpace Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray - Montreal, United States
Duration: Jul 17 2022Jul 22 2022

Publication series

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


ConferenceSpace Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray
Country/TerritoryUnited States


  • optical alignment
  • optical assembly
  • strain
  • ultrashort pulsed laser
  • X-ray astronomical optics

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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