Abstract-Two novel experimental schemes for terahertz tomography

Till Mohr,  Wolfgang Elsäßer,

http://ieeexplore.ieee.org/document/8024769/

In this contribution, we present two novel and compact terahertz tomography spectroscopy concepts. First, we exploit continuous-wave (CW) terahertz radiation generation and phase-sensitive detection in the same single photoconductive antenna (PCA), a homodyne self-mixing detection approach and apply it within a 2D terahertz tomography imaging application where we reconstruct the two-dimensional image of a hollow-core Teflon cylinder filled with α-lactose as a proof-of-concept demonstration. Second, we realize a single-pixel tomography scheme where 2D tomographic spatial information is achieved by spatially-resolved photodoping of a high-resistivity silicon wafer plate giving rise to fast transverse single-pixel information (via a digital micro mirror device (DMD)) with the subsequent rotation of the object for tomography. Both concepts offer a significantly reduced complexity and consequently lower cost of the terahertz spectroscopy set-up and their THz performance will be discussed and compared.

Abstract-Two-dimensional tomographic terahertz imaging by homodyne self-mixing

Till Mohr, Stefan Breuer, G. Giuliani, and Wolfgang Elsäßer
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-23-21-27221

We realize a compact two-dimensional tomographic terahertz imaging experiment involving only one photoconductive antenna (PCA) simultaneously serving as a transmitter and receiver of the terahertz radiation. A hollow-core Teflon cylinder filled with α-Lactose monohydrate powder is studied at two terahertz frequencies, far away and at a specific absorption line of the powder. This sample is placed between the antenna and a chopper wheel, which serves as back reflector of the terahertz radiation into the PCA. Amplitude and phase information of the continuous-wave (CW) terahertz radiation are extracted from the measured homodyne self-mixing (HSM) signal after interaction with the cylinder. The influence of refraction is studied by modeling the set-up utilizing ZEMAX and is discussed by means of the measured 1D projections. The tomographic reconstruction by using the Simultaneous Algebraic Reconstruction Technique (SART) allows to identify both object geometry and α-Lactose filling.

© 2015 Optical Society of America

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