AVS 47th International Symposium
    MEMS Wednesday Sessions
       Session MM-WeM

Paper MM-WeM5
A Micromachined Scanning Fabry-Perot Interferometer

Wednesday, October 4, 2000, 9:40 am, Room 309

Session: Microfabricated Sensors
Presenter: F.C. LI, Northeastern University
Authors: F.C. LI, Northeastern University
N.E. McGruer, Northeastern University
P.M. Zavracky, Northeastern University
K.L. Denis, Northeastern University
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This work describes a novel process to fabricate a micromachined scanning Fabry-Perot interferometer (FPI) employing electrostatic actuators. The Northeastern University MEtal Micromachining (NUMEM) is used to build the electrostatic actuators, which consist of four free standing gold cantilever beams. Two highly reflective mirrors are fabricated separately. @footnote 1@ The final assembly step bonds the upper mirror to the beams and completes the device. The two plane parallel mirrors are initially separated by a gap of approximately 600nm. By applying appropriate control voltages between the beams and electrodes on the substrate, the device can be tuned to wavelengths in the visible spectrum from 450 to 750 nm. Four sense capacitors are placed underneath the upper mirror to detect the spacing between the two mirrors. The spacing information is supplied to a closed-loop control circuit which scans the upper mirror vertically and maintains parallelism. Devices fabricated with aluminum mirrors (reflectivity approximately of 85%) showed resolving powers of 26, 24 and 18.2 at the wavelengths of 525nm, 615nm and 660nm, respectively. Proposed applications of the micromachined FPI include in situ measurements of plasma composition, colorimetric, and chemical analysis. @FootnoteText@ @footnote 1@ P.M. Zavracky, K.L. Denis, H.K. Xie, T. Wester and P. Kelly, "A Micromachined Scanning Fabry-Perot Interferometer", Proceedings of SPIE-The International Society for Optical Engineering, v 3514 p 179-187, Sep 21-22, 1998.