Micromechanical Gratings for Visible and Near-Infrared Spectroscopy

We present a micromechanical grating array that acts as a configurable optical filter for low-cost and compact visible and near-infrared spectrometric sensors. We show how the grating array can be used either as a fast scanning monochromator or as a diffractive filter, and that the expected signal-to-noise ratio is approximately equal for the two modes of measurement. The free spectral range of the filter can be matched to a defined spectral measurement region, so that we can optimize the relationship between spectral resolution and electromechanical complexity. We have numerically studied diffraction efficiency and errors in filter shape. Finally, we fabricated a small configurable grating array and present measurement results that demonstrate electrostatic filter modulation.