Abstract: A method of controlling a short-etalon Fabry-Perot interferometer used in an NDIR measurement apparatus includes generating a measurement signal using a radiant source. The measurement signal is provided to a sample point containing a gas mixture to be measured. The measurement signal is bandpass-filtered with an electrically tuneable Fabry-Perot interferometer using at least two wavelengths of the interferometer passband. The measurement signal is passed via an optical filter component prior to detection, and the filtered measurement signal is detected by a detector. During the measurement cycle, the passband frequency of the interferometer is controlled to coincide at least partially with the cutoff wavelength range of the optical filter component.

Abstract: A single-channel gas concentration measurement method and apparatus. According to the method, a radiant source is employed to generate a measuring signal, the measuring signal is subsequently directed to a measurement object containing a gas mixture to be measured, the measuring signal is subsequently bandpass filtered using at least two passband wavelengths, and the filtered measuring signals are detected by a detector. According to the invention, the bandpass filtering step is implemented by a single electrostatically tunable, short-resonator Fabry-Perot interferometer.

Abstract: The invention relates to a silicon micromechanically fabricated infrared detector having an infrared radiation absorbing layer (7, 44) deposited on an insulating substrate and a detector (11, 24, 25) for detecting the amount of radiation absorbed in the metallic absorbing layer. According to the invention, on the path of the radiation, prior to the absorbing layer (7, 44) is located an electrically controllable Fabry-Perot interferometer (1, 2, 5) manufactured by silicon micromechanical techniques and having the absorbing layer (7, 44) integrally coupled with one of the mirrors (1, 2) thereof).