Wednesday, May 2, 2018

Abstract-Broadband in-line terahertz 2D imaging: comparative study with time-of-flight, cross-correlation, and Fourier transform data processing

Aleksandr Ushakov, Pavel Chizhov, Vladimir Bukin, Andrei Savel’ev, and Sergei Garnov

A pulsed broadband (from 0.1 to 1.5 THz), in-line, terahertz (THz) time domain electro-optical sampling is applied for the visualization of phase objects by using a large-aperture electro-optical crystal (ZnTe, 
). The waveforms of the THz pulses are generated in a lithium niobate () crystal pumped by femtosecond pulses with a tilted amplitude front, and measured by a 2D THz imaging system. This system images the object under study in the THz range via a polytetrafluoroethylene (PTFE) lens in the  geometry onto a ZnTe crystal and then images the crystal surface on a CMOS camera using electro-optical sampling. Reconstruction of the image in such a scheme is implemented by processing the received 3D spatial-temporal distributions of the THz field in three different ways: (i) by detecting the displacement of the maximum peak position of the THz pulse due to a phase delay in the object under study; (ii) by using a cross-correlation function analysis; and (iii) by a Fourier transformation of a THz waveform and subsequent extraction of the phase difference at each THz frequency. Images of transparent PTFE objects were obtained. Main features of the resulting imaging system are discussed.

© 2018 Optical Society of America

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