Resonantly Driven Fabry-Perot Filter for Long-Wave Infrared Spectrometry

ALTAIR Center proposes to develop an innovative Fabry-Perot filter (FPF) for Long-Wave Infrared Spectrometry with high tuning rate using an original approach. Key point of the proposed concept is developing a resonantly vibrating mechanical system thatcomprises FPF mirrors but contains no elements exciting the vibrations. The vibrations at the resonant frequency are initiated from an external low-power piezoelectric driver. Owing to the resonance, small amplitude of vibrations of the driver results inlarge amplitude of vibrations of a FPF mirror, which can easily approach the required value of 10 mm and more. As this takes place, the vibration frequency can substantially exceed the current limit of 100 Hz, reaching several kHz and tens of kHz,depending on diameter of the mirror. An original scheme of controlled mirror deformations, relevant to the operation at very high frequencies, maintains high degree of parallelism of the mirrors. Besides, fabrication of the resonant system from a thermallystable material enables excellent stability of initial operating point of the FPF.In addition to applications for spectral imaging of airborne chemicals, the proposed tunable FPF can be used as research instrumentation for spectral analyses in the mid- andlong-wave infrared ranges, for example, of analysis of radiation generated by gas and solid-state lasers, Raman lasers, and parametric amplifiers. It is anticipated that after development of the technology for fabrication of inexpensive FPF based on theproposed approach, these FPF will be quite competitive with liquid-crystal tunable FPF even in the visible and near-infrared ranges, in which there is a very large demand for such spectral devices.