Ultraprecision machining characteristics of poly-crystalline germanium

Jiwang Yan, Yasunori Takahashi, Jun'ichi Tamaki, Akihiko Kubo, Tsunemoto Kuriyagawa, Yutaka Sato

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


Germanium is an excellent infrared optical material. On most occasions, single-crystalline germanium is used as optical lens substrate because its homogeneous structure is beneficial for fabricating uniform optical surfaces. In this work, we attempt to use poly crystals as lens substrates instead of single crystals, which may lead to a significant reduction in production cost. We conducted ultraprecision cutting experiments on poly-crystalline germanium to examine the microscopic machinability. The crystal orientations of specific crystal grains were characterized, and the machining characteristics of these crystal grains including surface textures, cutting forces, and grain boundary steps were investigated under various machining conditions. It was possible to produce uniformly ductile-cut surfaces cross all crystal grains by using an extremely small undeformed chip thickness (∼80nm) under negative tool rake angles (∼ -45°). This work indicates the possibility of fabricating high-quality infrared optical components from poly-crystalline germanium.

Original languageEnglish
Pages (from-to)63-69
Number of pages7
JournalJSME International Journal, Series C: Mechanical Systems, Machine Elements and Manufacturing
Issue number1
Publication statusPublished - 2006 Sept 15
Externally publishedYes


  • Diamond turning
  • Ductile regime machining
  • Germanium
  • Optical surface
  • Poly crystal
  • Ultraprecision machining

ASJC Scopus subject areas

  • Mechanical Engineering
  • Industrial and Manufacturing Engineering


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