A varifocal convex micromirror driven by a bending moment

Ryohei Hokari, Kazuhiro Hane

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


A varifocal micromirror is designed and fabricated usng silicon micromachining technology. A spherical convex surface of mirror is generated by applying a bending moment to the circumference of micromirror. This method is different from the conventional technique in which a distributed force is exerted on the central area of mirror. On the basis of the theory of materials strength, the deformation of a plate is purely spherical if only a bending moment is applied to the circumference. Spherical surface is well approximated to be a parabola if deflection is small. In order to generate only a bending moment, a force is applied to the plate in the region outside the fulcrum, by which the plate is supported freely in rotation. The proposed mirror was fabricated from a silicon on insulator wafer and a glass plate, which were connected by anodic bonding. The deviation in surface profile of mirror from a parabola was measured with an optical interferometer to be less than 4.7 nm rms in the mirror region inside the 400- μm-diameter fulcrum at the voltage lower than 215 V. The focal length of the fabricated mirror was varied from approximate infinity to 24 mm.

Original languageEnglish
Article number4982731
Pages (from-to)1310-1316
Number of pages7
JournalIEEE Journal on Selected Topics in Quantum Electronics
Issue number5
Publication statusPublished - 2009 Sept


  • Adaptive optics
  • Microelectromechanical devices
  • Mirrors

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering


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