GAS-SENSING USING TERAHERTZ TIME-DOMAIN SPECTROSCOPY

A method for detection and identification of polar gases and gas mixtu res based on the technique of terahertz time-domain spectroscopy is pr esented. This relatively new technology promises to be the first porta ble far-infrared spectrometer, providing a means for real-time spectro scopic measurements over a broad bandwidth up to several THz. The meas ured time-domain waveforms can be efficiently parameterized using stan dard tools from signal processing, including procedures developed for speech recognition applications. These are generally more efficient th an conventional methods based on Fourier analysis, and are easier to i mplement in a real-time sensing system. Preliminary results of real-ti me gas mixture analysis using a linear predictive coding algorithm are presented. A number of possible avenues for improved signal processin g schemes are discussed. In particular, the utility of a wavelet-based signal analysis for tasks such as denoising is demonstrated.