A detailed study of the science, engineering and applications of terahertz technology, based on room-temperature solid-state devices, which are seen as the key technology for wider applications in this frequency range. The relative merits of electronic and optical devices are discussed and new device principles identified. Issues of terahertz circuit design, implementation and measurement are complemented by chapters on current and future applications in communications, sensing and remote surveillance. Audience: The unique coverage of all aspects of terahertz technology will appeal to both new and established workers in the field, as well as providing a survey for the interested reader.

Terahertz frequency sensing has a unique part to play in the detection and identification of materials and objects. This frequency range, corresponding to a wavelength of around 0.1 mm, can be used to identify materials from their molecular spectra and to produce images of concealed objects. Terahertz spectra of drugs of abuse and explosives presented by a number of the contributing authors show that the presence of these materials can be detected in envelopes, packages and through clothing.

The technology of terahertz detection has largely been developed around expensive and bulky femtosecond laser systems but, as described in this book, advances in semiconductor superlattice technology are leading to compact electronic sources such as the quantum cascade laser, two-terminal Gunn type oscillators and even a THz frequency amplifier. These advances towards electronic (as opposed to optical) THz systems mean that the technology will become portable and much less costly.

Terahertz remote sensing is also discussed with the possibility of detection over distances of up to 30m using existing technology or even through the use THz waves generated locally in the vicinity of a target using only air as the transducer."

Terahertz technology has moved on from being a useful but expensive circuit technique, applied largely in astronomy and space science, to become a subject in its own right, with important applications - terahertz imaging in particular. Indeed, the driving force in terahertz technology is currently imaging and spectroscopy. We now have the means to obtain images and chemical information in this frequency band. The images reproduced in this volume are striking and, not surprisingly, the clinical and analytical uses are the subject of intense activity. There is still, however, no complete range of active THz electronic components, but an encouraging conclusion of the book is that THz electronics will become necessary in communications systems in the foreseeable future. Terahertz technology has come of age, and the future lies open to new, exciting science and vital applications.

Terahertz technology has moved on from being a useful but expensive circuit technique, applied largely in astronomy and space science, to become a subject in its own right, with important applications - terahertz imaging in particular. Indeed, the driving force in terahertz technology is currently imaging and spectroscopy. We now have the means to obtain images and chemical information in this frequency band. The images reproduced in this volume are striking and, not surprisingly, the clinical and analytical uses are the subject of intense activity. There is still, however, no complete range of active THz electronic components, but an encouraging conclusion of the book is that THz electronics will become necessary in communications systems in the foreseeable future. Terahertz technology has come of age, and the future lies open to new, exciting science and vital applications.

L'etude morphologique des tissus pathologiques en microscopie d' elements: optique comporte schematiquement deux types 1) les cellules, 2) les Fibres conjonctives intercellulaires. Ces Fibres, qui constituent Ie "squelette mou," servent de support aux elements cellwlaires, contribuent a maintenir l'architecture des tissu, et interviennent dans la circulation des liquides intercellu laires. La quantite, la structure et la repartition de ces Fibres sont etroitement liees a l'activite physiologique des populations cellulaires et a leur pathologie.L'etude de leurs modiFications est tres utile dans Ie diagnostic d'une lesion, mais la complexite et la variete des images de ces reseaux Fibrillaires rend leur description et leur classiFication tres diFFiciles. L'application des methodes morphometriques peut etre un moyen utile pour obtenir des parametres objectiFs susceptibles de preciser ces structures. C'est uniquement l'etude des Fibres conjonctives que nous envisa gerons pour Ie moment. L'emploi, en pratique courante, des methodes morphometriques comme aide au diagnostic anatomo-pathologique, ne peut se concevoir que si les techniques utilisees sont relativement simples et surtout rapides. Dans ce but, nous avons entrepris, depuis I973, avec les moyens du Laboratoire, la realisation d'un appareil automatique specialement con u pour essayer de repondre aux exigences particulieres de ce type d' e'tudes."

Want an overview of where the technology of terahertz detection has been going? Here it is. The technology has largely been developed around expensive and bulky femtosecond laser systems but, as described in this book, advances in semiconductor superlattice technology are leading to compact "electronic" sources such as the quantum cascade laser, two-terminal "Gunn" type oscillators and even a THz frequency amplifier. These advances towards electronic (as opposed to optical) THz systems mean that the technology will become portable and much less costly.

A detailed study of the science, engineering and applications of terahertz technology, based on room-temperature solid-state devices, which are seen as the key technology for wider applications in this frequency range. The relative merits of electronic and optical devices are discussed and new device principles identified. Issues of terahertz circuit design, implementation and measurement are complemented by chapters on current and future applications in communications, sensing and remote surveillance. Audience: The unique coverage of all aspects of terahertz technology will appeal to both new and established workers in the field, as well as providing a survey for the interested reader.