A Miniaturized Lamellar Grating Based Fourier Transform Spectrometer With Electrostatic Actuation

We report a miniaturized oscillating Fourier transform spectrometer (FTS), of which the novel features are specially designed suspension springs with reduced thickness and a square honey-combed platform which supports the movable grating facets. The proposed design is electrostatically driven by parallel plate actuators at its resonant frequency of 230 Hz. It uses lamellar grating to modulate the incident radiation and the movable part of the grating is capable of bidirectional out-of-plane motion. A maximum displacement of about 100 is achieved with an 80 V peak-to-peak driving voltage superimposed on a DC bias of 110 V in ambient pressure. The optical performance of the model is tested using a tunable infrared (IR) laser source. Fringe counting technique is employed in the IR interferogram acquisition process to ensure accurate sampling of the interferogram at constant optical path difference (OPD) intervals. The reconstructed spectra yielded detected wavelengths which deviated by less than 1 nm from the actual wavelengths, indicating excellent wavelength accuracy and an impressive resolving power.