Browsing by Author "Nuss, Martin C."

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    Applications of Terahertz Imaging
    (1998-08-01) Mittleman, Daniel M.; Neelamani, Ramesh; Baraniuk, Richard G.; Nuss, Martin C.; Digital Signal Processing (http://dsp.rice.edu/)
    The recent advances involving imaging with sub-picosecond terahertz pulses have opened up a wide range of possibilities in the applications of far-infrared technology. For the first time, a commercially viable terahertz imaging spectrometer seems a realizable prospect. However, several substantial engineering research challenges remain to be overcome before this goal can be achieved. One of these involves the necessity for a femtosecond laser system, required for gating the emitter and receiver antennas used in the THz-TDS system. The demonstration experiments performed to date have employed rather crude signal processing algorithms. The shortcomings of these are evident in some of the results presented here, highlighting the need for a more sophisticated treatment.
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    Gas Sensing using Terahertz Time-Domain Spectroscopy
    (1998-01-15) Mittleman, Daniel M.; Jacobsen, R.H.; Neelamani, Ramesh; Baraniuk, Richard G.; Nuss, Martin C.; Center for Multimedia Communications (http://cmc.rice.edu/); Digital Signal Processing (http://dsp.rice.edu/)
    A method for detection and identification of polar gases and gas mixtures based on the technique of terahertz time-domain spectroscopy is presented. This relatively new technology promises to be the first portable far-infared spectrometer, providing a means for real-time spectroscopic measurements over a broad bandwidth up to several THz. The measured time-domain waveforms can be efficiently parameterized using standard tools from signal processing, including procedures developed for speech recognition applications. These are generally more efficient than conventional methods based on Fourier analysis, and are easier to implement in a real-time sensing system. Preliminary results of real-time gas mixtures analysis using a linear predictive coding algorithm are presented. A number of possible avenues for improved signal processing schemes are discussed. In particular, the utility of a wavelet-based signal analysis for tasks such as denoising is demonstrated.
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    Recent advances in Imaging and Spectroscopy with T-rays
    (1998-12-01) Mittleman, Daniel M.; Neelamani, Ramesh; Gupta, Maya; Baraniuk, Richard G.; Nuss, Martin C.; Digital Signal Processing (http://dsp.rice.edu/)
    Recent work in terahertz "T-Ray" imaging is reported. With the ongoing development of commercially viable THz-TDS imaging system, opitmail signal processing strategies for the THz waveforms must be developed. Algorithms based on wavelet decomposition of the time and frequency-localized signals offer a number of advantages. Examples of denoising, deconvolution, and other waveform anaylsis tools are described.