Ultra-lightweight X-ray telescope fabricated with multiple MEMS technologies for GEO-X mission

Masaki Numazawa, Yuichiro Ezoe, Kumi Ishikawa, Daiki Ishi, Aoto Fukushima, Sae Sakuda, Tomoki Uchino, Ayata Inagaki, Hiromi Morishita, Yoko Ueda, Takatoshi Murakawa, Luna Sekiguchi, Yukine Tsuji, Ikuyuki Mitsuishi, Hiroshi Nakajima, Yoshiaki Kanamori, Kohei Morishita, Kazuhisa Mitsuda

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

3 Citations (Scopus)


We have been developing an ultra-lightweight Wolter type-I X-ray telescope fabricated with MEMS technologies for GEO-X (GEOspace X-ray imager) which is an 18U CubeSat (∼20 kg) to perform soft X-ray imaging spectroscopy of the entire Earth’s magnetosphere from Earth orbit near the Moon. The telescope is our original micropore optics which possesses lightness (∼15 g), a short focal length (∼250 mm), and a wide field of view (∼5 × ∼5). The MEMS X-ray telescope is made of 4-inch Si (111) wafers. The Si wafer is firstly processed by deep reactive ion etching such that they have numerous curvilinear micropores (20-µm width) whose sidewalls are utilized as X-ray reflective mirrors. High-temperature hydrogen annealing and chemical mechanical polishing processes are then applied to make those sidewalls smooth and flat enough to reflect X-rays. After that, the wafer is plastic-deformed into a spherical shape and Pt-coated by plasma atomic layer deposition (ALD) process to focus X-rays with high reflectivity. Finally, we assemble two optics bent with different curvatures (1000- and 333-mm radius) into the Wolter type-I telescope. Optimizing the annealing and polishing processes, we found that the optic achieves an angular resolution of ∼5.4 arcmins in HPW. This is comparable with the requirement for GEO-X (∼5 arcmins in HPD at single reflection). Our optic was also successfully Pt-coated by a plasma-enhanced ALD process to enhance X-ray reflectivity. Moreover, we fabricated an STM telescope and confirmed its environmental tolerances by conducting an acoustic test with the H-IIA rocket qualification test level and a radiation tolerance test with a 100 MeV proton beam for 30 krad equivalent to a 3-year duration in the GEO-X orbit.

Original languageEnglish
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
Publication statusPublished - 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

All Science Journal Classification (ASJC) codes

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


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