3. Terahertz imaging

3.1 Why image with THz

As in conventional optics, THz imaging systems can be broken down into two families: passive imaging, which consists in forming a THz image of an object or scene by exploiting its thermal radiation, and active imaging, in which the scene is illuminated with a continuous or pulsed terahertz source.

As mentioned above, THz waves combine the advantages of optical waves and radio-frequency electromagnetic waves. With the former, they share directivity, i.e. the ability to make devices that are larger than the wavelength, so that they can be oriented or focused towards a given point - in short, manipulated. With the latter, we have the techniques of transmission and detection through the use of antennas, but above all the waves can penetrate...