Range extension of a bimorph varifocal micromirror through actuation by a Peltier element

Paterson, Alan and Bauer, Ralf and Li, Li and Lubeigt, Walter and Uttamchandani, Deepak (2015) Range extension of a bimorph varifocal micromirror through actuation by a Peltier element. IEEE Journal of Selected Topics in Quantum Electronics, 21 (4). 2701007. ISSN 1077-260X (https://doi.org/10.1109/JSTQE.2014.2381464)

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Abstract

A bimorph varifocal micromirror actuated thermoelectrically by a Peltier element is reported. The single crystal silicon micromirror is 1.2 mm in diameter with a centered 1 mm diameter gold coating for broadband reflection. The actuation principle is capable of varying the micromirror temperature above and below the ambient temperature, which contributed to a 57% improvement in the addressable curvature range in comparison to previously reported electrothermal and optothermal actuation techniques for the device. Altering the device temperature from 10 C to 100 C provided a mirror surface radius of curvature variation from 19.2 mm to 30.9 mm respectively. The experimental characterization of the micromirror was used as a basis for accurate finite element modeling of the device and its actuation. Negligible optical aberrations are observed over the operating range, enabling effectively aberration-free imaging. Demonstration in an optical imaging system illustrated sharp imaging of objects over a focal plane variation of 212 mm.

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