*** ABSTRACT 96-61638 Gabl This Small Business Innovation Research Phase I program will develop a compact, reliable, terahertz (THz) time-domain spectrometer. This instrument will be used to provide comprehensive far-infrared absorption measurement. THz time-domain spectroscopy is conceptually a very general technique. However, until now, the complexity of the required femtosecond source has severely limited the diffusion of this spectroscopic technique. This Phase I program addresses this main issue. During our Phase I we will demonstrate a prototype THz spectrometer operating with one of our compact femtosecond source. In our Phase II we will developed a field-portable Terahertz time-domain spectrometer. The proposed THz time-domain spectrometer will use a compact femtosecond laser to gate a coherent receiver. This approach offers superb signal to noise ratios (108:1 in power). The coverage of this spectrometer will extend continuously over a wide spectral range, from 0.1 to greater than 6 THz, permitting the simultaneous detection of many species. This THz source generates a well-collimated, low-divergence beam for which the receiver has a corresponding small acceptance angle. Thus, the proposed technique combined with mathematical techniques commonly used in tomography should provide 3-D data. Our program goals will be reached in collaboration with the inventor of THz time-domain spectroscopy, Professor D. Grischkowsky (Oklahoma State University). THz time-domain spectroscopy has applications in non-contact measurement of water vapor, non-contact measurement of doping levels in semi-conductor wafers, non-contact monitoring of flame emission and flame temperature, and detection of concealed explosives. ***
