MICROMACHINED OPTICAL TUNABLE FILTER FOR LONG-TERM STABILITY GAS SENSORS

A new component is presented: a tunable optical filter that can provid e autocalibration of optical gas sensors and thus improve their long t erm stability. The device comprises three micromachined silicon wafers separated by two air gaps. It is shown that it can be applied as an e lectrically tunable Fabry-Perot filter, and used for the detection of gases that have spectral absorption bands in the infrared domain of wa velengths between 2 and 8 mu m. Calculations are performed to explain the mechanical and optical properties of the device under different ap plied voltages.