PROCEEDINGS ARTICLE | September 24, 2013
Proc. SPIE. 8846, Terahertz Emitters, Receivers, and Applications IV
KEYWORDS: Mathematical modeling, Diffraction, Beam splitters, Holography, Millimeter wave imaging, 3D image reconstruction, Wavefronts, Phase retrieval, Terahertz radiation, Terahertz spectroscopy
In this paper, we present review and latest results obtained in the scope of terahertz holographic and other
methods for phase retrieval in terahertz imaging. Not only accurate change of amplitude, but also rigorous
phase retrieval is essential for precise calculation of optical parameters of the samples in terahertz range. Pulse
terahertz holography introduced some years ago shows itself as perfect method for overall-object phase retrieval
technique, but in the same time it allows measurement with low signal to noise that leads to less precise derivation
of sample optical parameters. And certainly just point-by-point terahertz time-domain spectroscopy provides the
most precise information of sample phase, but it is rather time consuming and has low spatial resolution as well.
The other possible way assumes, in contrary to pulse terahertz holography and spectroscopy, using narrow-band
continuous terahertz source, which tunability might also make the measurement process easier. And diffraction
patterns registered with microbolometer array or any other terahertz intensity sensor placed at several different
distances from the object and/or taken for several different terahertz frequencies are used for phase retrieval in
this case. We present both numerical predictions and experimental results for the proposed methods, estimate
the achievable spatial and other limits of the techniques and compare them to the others used in different spectral
ranges.
