Terahertz imaging using an interferometric array

Abstract

Most methods of imaging in the terahertz (THz) spectral region utilize either pulsed-laser sources or require the THz generation and detection sources to be phase coherent. The application of interferometric imaging to the THz range is described. Interferometric imaging offers considerable advantages in this regard due to its ability to image with only a handful of detector elements, image many sources of THz radiation at once, image incoherent as well as coherent sources, and provide spectral information as well as spatial imaging information. The THz interferometric imaging method is potentially useful for remote detection of explosives.

<title>THz standoff detection and imaging of explosives and weapons (Invited Paper)</title>

“…1,39 Recent experimental measurements of THz image reconstruction using interferemetric imaging methods compare well with theoretical predictions. 37 When is it preferable to use an interferometric imaging approach rather than a focal plane approach? What are the tradeoffs?…”

“…Interferometric Imaging 1,37,38,39,40 has been suggested as a novel imaging modality for stand-off detection of explosives, weapons, and other threats. The interferometric THz imaging array design does not require a particular coherent or incoherent source of THz.…”

Terahertz imaging using an interferometric array

“…6. From theoretical considerations, 18,19 the angular resolution of a planar array can be approximated as min / b θ λ = . At a distance Z o away, the lateral spatial resolution is…”

“…1,18,19 In this paper, a CW THz generation and detection method is used to demonstrate the reconstruction of a THz image using the interferometric technique.…”

Correlative Interferometric Imaging of Extended Objects for Near Field Arrays

“…The Fourier transform relationship that exists between source intensity and far field autocorrelation is then used to reconstruct the source distribution. The use of correlative interferometry is also being advocated for terahertz imaging [2]. This is motivated by the fact that focal plane array imaging technology is not well developed in the 1 -10 THz region where investigations are being carried out for applications such as the detection of concealed explosives [3].…”