A MEMS-based tunable infrared filter for spectroscopy

We report here on the development of a tunable high-pass infrared transmission filter for application to chemical detection and IR spectral analysis. The tunability of the filter allows one to vary the long-wavelength cutoff over the useful wavelength range of the detector material. The tunable filter uses an electromagnetic actuator to mechanically drive the filter structure, which consists of an array of vertical parallel metal plates connected at the side edges by springs or flexures. When driven by the actuator, the flexures allow the plate spacing and the transmission properties of the filter to be changed while keeping the filter plates parallel and equally spaced.