Advanced applications to security of IR smart microbolometers

Advanced IR emitters and sensors are under development for high detection probability, low false alarm rate and identification capability of toxic gases. One of the most reliable technique to identify the gas species is Spectroscopy, especially in the infrared spectral range, where most of existing toxic compounds exhibit their stronger roto-vibrational absorption bands. Following the results obtained from simulations and analysis of expected absorption spectra, a compact non dispersive infrared multi-spectral system has been designed and developed for security applications. It utilizes a few square millimeters thermal source, a novel design multipass cell, and a smart architecture microbolometric sensor array coupled to a linear variable spectral filter to perform toxic gases detection and identification. This is done by means of differential absorption spectroscopic measurements in the spectral range of the LWIR (Long Wavelength Infrared) spectral region. Preliminary tests for sensitivity and selectivity are undergoing using mixtures of ammonia and ethylene. Detection capability down to tens of ppm has been demonstrated. Possible improvements owing to open path sensor or hollow-fiber based sensor implementation are also presented for future systems evolution.