Terahertz imaging

Keywords terahertz imaging subwavelength imaging millimeter-wave radar atmospheric effects terahertz sources terahertz detectors. 

Figure 17. A Terahertz image collected by a scanned cooled bolometer [33].

Case Study 10 Terahertz Imaging for Electromagnetic Materials Research... 

Time-resolved terahertz imaging is capable of providing information about the dynamics of chemical reactions in materials science, chemistry, and biology. 

Terahertz imaging offers the possibility of understanding complex reactions in which the chemical state of the sample under study changes with time. An extension of this ability is the control of chemical reactions in a highly specific manner this will require the manipulation and channeling of the energy in a system such that the possible outcomes (degrees of freedom) are narrowed to those that one desires. 

A wide variety of imaging system architectures have been designed or proposed for millimeter-wave and terahertz imaging systems. These include passive FPAs, passive mechanically-scanned systems, active mechanically-scanned focused lens systems (both through transmission and reflection), active holographic scanned imaging, and SAR imaging. 

E. Jacobs, R. G. Driggers, K. Krapels, F. C. De Lucia, and D. Petkie, Terahertz imaging performance model for concealed weapon identification, Proceedings of SPIE - The International Society for Optical Engineering, vol. 5619, pp. 98, 2004. 

Terahertz imaging approaches have typically used either short-pulsed laser or continuous wave (CW) THz generation and detection. The short-pulsed method usually involves the generation and detection of sub-picosecond THz pulses using either photoconductive antenna structures or optical rectification in a non-linear crystal. Pulsed sources seem to be more favorable (in particular for close proximity applications) because they can be used for acquiring depth information. Spectral information is retrieved by a Fourier transform of the time-domain data to the frequency domain. 

Experimental terahertz imaging 5.1. Terahertz photo-mixing system... 

Terahertz images by themselves are generally not sufficient to identify hidden explosives because of the complicating effects of barrier materials, noise, and potential image... 

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