Terahertz reflection hyperspectral 3D imaging using beam scanning

Terahertz (THz) radiation has the capability to combine spectroscopy and imaging in a single system. The resulting hyperspectral images can reveal concealed objects and identify materials by means of characteristic spectral features. For security applications, THz is attractive for its non-contact and non-destructive measurement capabilities. For such applications, objects may be too absorbing for transmission measurements, or only one side of an object may be accessible, necessitating a reflection measurement configuration. This work details the development and demonstration of a compact fiber-coupled hyperspectral imaging reflection system suited to field use for security and industrial applications. The system uses beam steering to measure objects of up to 150 mm diameter with a depth range of up to 255 mm, allowing for 3-dimensional mapping of objects, while simultaneously acquiring spectral data. Spectral information between 0.2-1.8 THz is extracted from a hyperspectral image and used to identify lactose, tartaric acid, and 4-aminobenzoic acid in high and low humidity environments.