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Volumetric spectral analysis of materials using terahertz-tomography techniques

: Brahm, A.; Kunz, M.; Riehemann, S.; Notni, G.; Tünnermann, A.


Applied Physics. B 100 (2010), No.1, pp.151-158
ISSN: 0340-3793
ISSN: 0721-7269
ISSN: 0946-2171
ISSN: 1432-0649
Journal Article
Fraunhofer IOF ()

We present for the first time a system and new algorithms for spectral THz-tomography. The electric field of single cycle ultra short THz-pulses can be measured time resolved in amplitude and phase. By focusing ultra short THz-pulses to a sample and analyzing the transmitted or reflected beams the inner structure of the sample can be investigated with a resolution up to 0.4 mm by evaluating the time resolved data. Thus a spectrum of every scanned THz-pulse can be calculated with the usage of the fast Fourier transform. In contrast to classical computed tomography (CT) with X-rays a higher amount of information can be obtained. Based on the characteristic absorption spectra of varying materials it is now possible to identify different substances inside a sample by terahertz-tomography with probabilities that are higher than 80%.