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Millimeter and terahertz waves offer novel solutions for nondestructive testing such as imaging and layer thickness measurements within dielectrics. For the thickness measurement of plastics, we use the frequency modulation continuous wave technique within fully electronic terahertz systems. The available modulation bandwidth inherently restricts the resolution to several millimeters. Our correlation...
Terahertz time-domain spectroscopy relies on the knowledge of the time delay between two ultrashort laser pulses. This time delay is most commonly introduced by mechanically driven delay lines, where often a linear movement or in the case of oscillation based devices a sinusoidal movement is assumed or measured only imprecisely. We present a highly accurate method to measure the real time delay by...
Terahertz (THz) spectroscopy is a powerful technique for identification of dangerous materials like drugs and explosives, especially when hidden under optically opaque concealments. Multiple-reflections within such sample systems lead to additional spectral features which could be misinterpreted as artificial material absorption bands. We show that combinations of different chemometric tools help...
Combining different chemometric tools we demonstrate the reliable identification of substances out of real-world terahertz-spectra. Systematic evaluation of the spectra allows for the distinction between spectral properties arising from samples geometry versus true material absorption.
We present a novel technique to generate a continuous, broadband terahertz spectrum with non AR-coated laser diodes. The combination of two spectrally controlled diode lasers and the use of their combined output in a terahertz cross-correlation spectroscopy setup results in signals principally comparable to that of femtosecond pumped TDS systems.
We present a novel miniature module for terahertz attenuated total reflection spectroscopy. It is made of high resistivity silicon by applying free form optics fabrication and features two parabolic surfaces which act as the sensitive interfaces. Fiber coupling of highly integrated emitter and detector chips provides a high degree of flexibility.
Terahertz time-domain magneto-optics using pulsed magnetic fields is demonstrated with two different approaches. The first uses a fiber coupled high-speed delay line in combination with a long duration pulsed magnet. The second uses a table-top short duration pulsed magnet scanned repetitively and a step-scan readout of the THz electric field.
Terahertz time-domain spectroscopic imaging (THz-TDS imaging) producesimages with hundreds of channels. Automatic as well as manual imageanalysis is therefore difficult. We propose to use a feature set thatreduces the number of channels down to and still preserves all importantinformation. Both spectral and time-domain features areincluded in this set, and thereby information aboutdifferent content...
We present time-resolved cyclotron resonance spectra of holes in p-germanium measured during a single magnetic field pulse by using a rapid-scanning, fiber-coupled THz time-domain spectroscopy system.
We present a pulsed terahertz imaging system with a line focus intended to speed up measurements. A balanced 1-D detection scheme working with two industrial line cameras is used. The instrumental characteristics are determined.
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