Magnetically actuated micromirror and measurement system for motion characteristics using specular reflection

Micromachined magnetically actuated torsional micromirrors have been fabricated. The micromirrors based on silicon were actuated by moving magnet system using hard magnetic (Co-Pt) or soft magnetic (Fe-Ni) thin films. And a system to measure motion characteristics of the micromirrors was assembled with an optical table, optical mounts, and optics. The system is based on a specular reflection of He-Ne laser from the micromirrors. We measured static and resonance characteristics of the micromirrors with Co-Pt film or Fe-Ni film. Then we measured Q factors of the micromirrors; with Co-Pt film in vacuum. Using our system for measurements, we obtained motion characteristics of micromirrors at large angular deflections. Measured resonance characteristics of all micromirrors are in good agreement with the equation of forced vibration with viscous damping. Micromirrors with Co-Pt films have better reproducibility of torsional motions than ones with Fe-Ni films in both dc magnetic field and ac magnetic field. And micromirrors with Fe-Ni films have torsional motion with subpeak at resonance characteristics. The Co-Pt film is more useful as a magnetic film for the micromirror than the Fe-Ni film at static and resonance characteristics.