Precise control of micromirror curvature is critical in many optical microsystems. Micromirrors with current-controlled curvature are demonstrated. The working principle is that resistive heating changes the temperature of the micromirrors and thermal expansion induces a controlled curvature whose magnitude is determined by coating design. For example, for wide focal-length tuning, the radius of curvature of a gold-coated mirror was tuned from 2.5 to 8.2 mm over a current-induced temperature range from 22° to 72 °C. For fine focal-length tuning, the radius of curvature of a dielectric-coated (SiO<sub>2</sub> /Y<sub>2</sub>O<sub>3</sub>λ/4pairs) mirror was tuned from -0.68 to -0.64mm over a current-induced temperature range from 22 to 84 °C. These results should be readily extendable to mirror flattening or real-time adaptive shape control.
© 2003 Optical Society of America
Wei Liu and Joseph J. Talghader, "Current-controlled curvature of coated micromirrors," Opt. Lett. 28, 932-934 (2003)