5. Conclusion and outlook

We have tried to show the advantages (healthy radiation, high penetration power, beam shaping and guidance, etc.) and limitations (resolution linked to the wavelength used) of terahertz-band hyperspectral imaging. For example, it is possible to access a vast amount of information on the physical properties of materials (index and absorption over three frequency decades), even if the objects are encapsulated or not visible by conventional optical means. Unrealistic projects just a few decades ago, technological advances now make it possible to envisage transfers to industry as a complement to existing techniques. Extremely interesting prospects are emerging, based on the use of these systems for non-destructive testing, the detection of harmful elements at a distance and without contact, and vision through opaque objects. The next step is likely to be the development of a true terahertz...